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We have obtained an exceptionally high S/N, high resolution spectrum of the gravitationally lensed quasar Q1422+231 in order to investigate the metal enrichment of the IGM. A column density distribution function (CDDF) is determined for CIV, which is well fit by a power law with index 1.44 +/- 0.05. Once a correction for incompleteness is applied, we find that the CDDF is consistent with a power law down to log N(CIV) = 11.75, a factor of 10 more sensitive than previously determined. In order to determine whether the CIV enrichment extends to even lower column density HI clouds, we find that an analysis of individual pixel optical depths is more robust than the stacking technique. The results obtained from this optical depth method are compared with analyses of simulated spectra enriched with varying CIV enrichment recipes. From these simulations, we conclude that more CIV than is currently directly detected in Q1422+231 is required to reproduce the optical depths determined from the data, consistent with the conclusions drawn from consideration of the power law distribution. (Abridged)
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我们获得了引力透镜类星体Q1422+231的极高信噪比、高分辨率光谱，以研究星系际介质（IGM）的金属丰度。我们确定了CIV的柱密度分布函数（CDDF），其可由指数为1.44 ± 0.05的幂律函数很好地拟合。在对不完备性进行校正后，我们发现CDDF在log N(CIV) = 11.75处仍符合幂律分布，比此前确定的灵敏度高十倍。为了确定CIV丰度是否延伸至更低柱密度的HI云中，我们发现对单个像素光学深度的分析比叠加技术更为稳健。我们将该光学深度方法所得结果与采用不同CIV丰度模型的模拟光谱分析结果进行了比较。根据这些模拟，我们得出结论：要重现从数据中确定的光学深度，所需CIV含量超过了目前在Q1422+231中直接探测到的量，这与基于幂律分布分析所得结论一致。（节选）
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Measurement-based quantum computation is a framework of quantum computation, where entanglement is used as a resource and local measurements on qubits are used to drive the computation. It originates from the one-way quantum computer of Raussendorf and Briegel, who introduced the so-called cluster state as the underlying entangled resource state and showed that any quantum circuit could be executed by performing only local measurement on individual qubits. The randomness in the measurement outcomes can be dealt with by adapting future measurement axes so that computation is deterministic. Subsequent works have expanded the discussions of the measurement-based quantum computation to various subjects, including the quantification of entanglement for such a measurement-based scheme, the search for other resource states beyond cluster states and computational phases of matter. In addition, the measurement-based framework also provides useful connections to the emergence of time ordering, computational complexity and classical spin models, blind quantum computation, etc. and has given an alternative, resource-efficient approach to implement the original linear-optic quantum computation of Knill, Laflamme and Milburn. Cluster states and a few other resource states have been created experimentally in various physical systems and the measurement-based approach offers a potential alternative to the standard circuit approach to realize a practical quantum computer.
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পরিমাপ-ভিত্তিক কোয়ান্টাম কম্পিউটেশন কোয়ান্টাম কম্পিউটেশনের একটি কাঠামো, যেখানে জটিলতা (entanglement) একটি সম্পদ হিসাবে ব্যবহৃত হয় এবং কিউবিটগুলির স্থানীয় পরিমাপগুলি কম্পিউটেশন চালানোর জন্য ব্যবহৃত হয়। এটি রাউসেনডরফ ও ব্রিগেলের এক-পথ কোয়ান্টাম কম্পিউটার থেকে উৎপন্ন হয়েছে, যারা জটিল সম্পদ অবস্থার ভিত্তি হিসাবে একটি একত্রীকরণ অবস্থা (cluster state) নামে পরিচিত অবস্থা চালু করেন এবং দেখান যে কোনো কোয়ান্টাম সার্কিট কেবলমাত্র আলাদা আলাদা কিউবিটগুলির স্থানীয় পরিমাপ করে কার্যকর করা যেতে পারে। পরিমাপের ফলাফলের এলোমেলো স্বভাবকে ভবিষ্যতের পরিমাপ অক্ষগুলি সামঞ্জস্য করে নিয়ন্ত্রণ করা যায়, যাতে কম্পিউটেশন নির্ধারিত হয়। পরবর্তী কাজগুলি এই পরিমাপ-ভিত্তিক কম্পিউটেশন সংক্রান্ত আলোচনাকে বিভিন্ন বিষয়ে প্রসারিত করেছে, যার মধ্যে রয়েছে এমন পরিমাপ-ভিত্তিক পদ্ধতির জন্য জটিলতার পরিমাপ, একত্রীকরণ অবস্থার বাইরে অন্যান্য সম্পদ অবস্থার অনুসন্ধান এবং পদার্থের গাণিতিক অবস্থা। এছাড়াও, পরিমাপ-ভিত্তিক কাঠামোটি সময় ক্রমবিন্যাসের উদ্ভব, গাণিতিক জটিলতা এবং ক্লাসিকাল স্পিন মডেল, ব্লাইন্ড কোয়ান্টাম কম্পিউটেশন ইত্যাদির সঙ্গে কার্যকর সংযোগ প্রদান করেছে এবং নিল, লাফলাম্মে ও মিলবার্নের মূল লাইনার-অপটিক কোয়ান্টাম কম্পিউটেশন বাস্তবায়নের জন্য একটি বিকল্প, সম্পদ-দক্ষ পদ্ধতি দিয়েছে। বিভিন্ন পদার্থগত ব্যবস্থাতে পরীক্ষামূলকভাবে একত্রীকরণ অবস্থা এবং কয়েকটি অন্যান্য সম্পদ অবস্থা তৈরি করা হয়েছে এবং পরিমাপ-ভিত্তিক পদ্ধতি একটি বাস্তব কোয়ান্টাম কম্পিউটার বাস্তবায়নের জন্য মানক সার্কিট পদ্ধতির একটি সম্ভাব্য বিকল্প প্রদান করে।
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Relativistic shocks are one of the most plausible sites of the emission of strongly variable, polarized multi-wavelength emission from relativistic jet sources such as blazars, via diffusive shock acceleration (DSA) of relativistic particles. This paper summarizes recent results on a self-consistent coupling of diffusive shock acceleration and radiation transfer in blazar jets. We demonstrate that the observed spectral energy distributions (SEDs) of blazars strongly constrain the nature of hydromagnetic turbulence responsible for pitch-angle scattering by requiring a strongly energy-dependent pitch-angle mean free path. The prominent soft X-ray excess ("Big Blue Bump") in the SED of the BL Lac object AO 0235+164 can be modelled as the signature of bulk Compton scattering of external radiation fields by the thermal electron population, which places additional constraints on the level of hydromagnetic turbulence. It has further been demonstrated that internal shocks propagating in a jet pervaded by a helical magnetic field naturally produce polarization-angle swings by 180$^o$, in tandem with multi-wavelength flaring activity, without requiring any helical motion paths or other asymmetric jet structures. The specific application of this model to 3C279 presents the first consistent, simultaneous modeling of snap-shot SEDs, multi-wavelength light curves and time-dependent polarization signatures of a blazar during a polarization-angle (PA) rotation. This model has recently been generalized to a lepto-hadronic model, in which the high-energy emission is dominated by proton synchrotron radiation. It is shown that in this case, the high-energy (X-ray and $\gamma$-ray) polarization signatures are expected to be significantly more stable (not showing PA rotations) than the low-energy (electron-synchrotron) signatures.
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နှိမ့်ချခံရသော ရိုက်ခတ်မှုများသည် ဘလေဇာများကဲ့သို့သော နှိမ့်ချခံရသည့် ဂျက်အရင်းအမြစ်များမှ ပြင်းထန်စွာ ပြောင်းလဲသည့်၊ သံလိုက်ဝန်းရံမှုရှိသော အလင်းရောင်မျိုးစုံ ထုတ်လွှတ်မှုကို နှိမ့်ချခံရသော အမှုန်များ၏ ပျံ့နှံ့သော ရိုက်ခတ်မှု တိုးမြှင့်မှု (DSA) ကနေတစ်ဆင့် ထုတ်လွှတ်သည့် နေရာများအနက် တစ်ခုအဖြစ် အလားအလာရှိသည်။ ဤစာတမ်းသည် ဘလေဇာဂျက်များတွင် ပျံ့နှံ့သော ရိုက်ခတ်မှု တိုးမြှင့်မှုနှင့် ရောင်ခြည် လွှဲပြောင်းမှုကို ကိုယ်ပိုင် ကိုက်ညီစွာ ချိတ်ဆက်ခြင်းဆိုင်ရာ မကြာသေးမီက ရရှိထားသည့် ရလဒ်များကို စုစည်းဖော်ပြထားသည်။ ဘလေဇာများ၏ စွဲမက်ဖွယ် စွမ်းအင်ဖြန့်ကျက်မှု (SEDs) များသည် ထောင်လိုက် ရွေ့လျားမှု ပျမ်းမျှ အကွာအဝေးကို စွမ်းအင်အဆင့်အလိုက် အလွန်အမင်း မှီခိုနေရသည်ဟု လိုအပ်ချက် ပြုလုပ်ခြင်းဖြင့် ထောင်လိုက် ပြောင်းလဲမှုကို ဖြစ်စေသည့် ဟိုက်ဒရိုမက်ဂျက်နစ် ပြင်ပ လှိုင်းများ၏ သဘောသဘာဝကို အလွန်ကန့်သတ်ထားကြောင်း ကျွန်ုပ်တို့ ပြသထားသည်။ BL Lac အရာဝတ္ထု AO 0235+164 ၏ SED တွင် ထင်ရှားသော နူးညံ့သည့် X-ray အပိုထွက်ရှိမှု ("Big Blue Bump") ကို ပြင်ပ ရောင်ခြည် ကွင်းများကို သာမိုနျူထရွန် အီလက်ထရွန် လူဦးရေများမှ အုပ်စုလိုက် Compton ပြန်လည်တိုက်ခတ်မှု၏ လက္ခဏာအဖြစ် မော်ဒယ်လုပ်နိုင်ပြီး ဟိုက်ဒရိုမက်ဂျက်နစ် ပြင်ပလှိုင်းများ၏ အဆင့်ကို ထပ်မံကန့်သတ်မှုများ ပေးစေသည်။ ထို့အပြင် ဟယ်လစ်ကယ် သံလိုက်ကွင်းဖြင့် ဖြည့်နှီးနေသော ဂျက်အတွင်း ပျံ့နှံ့နေသည့် အတွင်းပိုင်း ရိုက်ခတ်မှုများသည် ဟယ်လစ်ကယ် ရွေ့လျားမှု လမ်းကြောင်းများ သို့မဟုတ် အခြားသော မမှန်မကန် ဂျက် ဖွဲ့စည်းပုံများကို မလိုအပ်ဘဲ မျိုးစုံသော အလင်းရောင်များနှင့် တစ်ပြိုင်နက် လုပ်ဆောင်နေစဉ် 180$^o$ ဖြင့် သံလိုက်ဝန်းရံမှု ထောင့် ရွေ့လျားမှုများကို သဘာဝအတိုင်း ထုတ်လုပ်နိုင်ကြောင်း ထပ်မံပြသထားသည်။ ဤမော်ဒယ်ကို 3C279 တွင် သတ်မှတ် အသုံးချခြင်းသည် သံလိုက်ဝန်းရံမှု ထောင့် (PA) လှည့်ခြင်းအတွင်း ဘလေဇာတစ်ခု၏ အချိန်ကုန်လွန်မှုနှင့်အတူ ဖြစ်ပေါ်သော SED များ၊ မျိုးစုံသော အလင်းရောင် မျဉ်းကြောင်းများနှင့် အချိန်ပေါ် မူတည်သော သံလိုက်ဝန်းရံမှု လက္ခဏာများကို တစ်ပြိုင်နက် ကိုက်ညီစွာ မော်ဒယ်လုပ်နိုင်ခဲ့သည့် ပထမဆုံး ဥပမာဖြစ်သည်။ ဤမော်ဒယ်ကို မကြာသေးမီက လက်ပ်တို-ဟာဒရောနစ် မော်ဒယ်အဖြစ် ယေဘုယျပြုခဲ့ပြီး အထူးသဖြင့် အမြင့်စွာသော စွမ်းအင် ထုတ်လွှတ်မှုသည် ပရိုတွန် စီးန်ခရိုထရွန် ရောင်ခြည်ဖြင့် အဓိက ထိန်းချုပ်ထားသည်။ ဤကိစ္စတွင် အမြင့်စွာသော စွမ်းအင် (X-ray နှင့် $\gamma$-ray) သံလိုက်ဝန်းရံမှု လက္ခဏာများသည် နိမ့်ကျသော စွမ်းအင် (အီလက်ထရွန်-စီးန်ခရိုထရွန်) လက္ခဏာများနှင့် နှိုင်းယှဉ်ပါက သိသိသာသာ ပိုမိုတည်ငြိမ်မှုရှိမည် (PA လှည့်ခြင်း မပြသခြင်း) ဖြစ်ရန် မျှော်လင့်ရကြောင်း ပြသထားသည်။
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We present a comprehensive spectroscopic imaging survey of the distribution and kinematics of atomic hydrogen (HI) in 16 nearby spiral galaxies hosting low luminosity AGN, observed with high spectral and spatial resolution (resolution: ~20 arcsec, 5 km/s) using the NRAO Very Large Array (VLA). The sample contains a range of nuclear types, ranging from Seyfert to star-forming nuclei and was originally selected for the NUclei of GAlaxies project (NUGA) - a spectrally and spatially resolved interferometric survey of gas dynamics in nearby galaxies designed to identify the fueling mechanisms of AGN and the relation to host galaxy evolution. Here we investigate the relationship between the HI properties of these galaxies, their environment, their stellar distribution and their AGN type. The large-scale HI morphology of each galaxy is classified as ringed, spiral, or centrally concentrated; comparison of the resulting morphological classification with AGN type reveals that ring structures are significantly more common in LINER than in Seyfert host galaxies, suggesting a time evolution of the AGN activity together with the redistribution of the neutral gas. Dynamically disturbed HI disks are also more prevalent in LINER host galaxies than in Seyfert host galaxies. While several galaxies are surrounded by companions (some with associated HI emission), there is no correlation between the presence of companions and the AGN type (Seyfert/LINER).
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Біз НАРҚ-ның Үлкен Массивын (VLA) қолданып (бұрыштық шешімділік: ~20 арксек, жылдамдық шешімділігі: 5 км/с), жарықтылығы төмен АЯЯ-ның 16 жақын орналасқан спиральді галактикаларындағы атомдық сутегінің (HI) таралуы мен кинематикасын кеңінен қамтитын спектрлік бейне алу зерттеуін ұсынамыз. Таңдама Сейферт ядросынан бастап жұлдыздық түзілу ядросына дейінгі әртүрлі ядролық типтерді қамтиды және бастапқыда галактикалар ядроларының жобасы (NUGA) үшін таңдалған — бұл жақын орналасқан галактикалардағы газ динамикасының спектрлік және кеңістіктік шешімділігі бар интерферометриялық зерттеу, АЯЯ-ның қоректену механизмдерін және олардың негізгі галактикамен эволюциялық байланысын анықтау мақсатында жасалған. Бұл жерде біз осы галактикалардың HI қасиеттері, олардың қоршаған ортасы, жұлдыздардың таралуы және АЯЯ типі арасындағы байланысты зерттейміз. Әрбір галактиканың үлкен масштабты HI морфологиясы сақиналы, спиральді немесе центрде шоғырланған деп жіктеледі; нәтижесінде алынған морфологиялық жіктеуді АЯЯ типімен салыстыру LINER галактикаларында Сейферт галактикаларына қарағанда сақиналы құрылымдардың айтарлықтай жиі кездесетінін көрсетеді, бұл бейтарап газдың қайта таралуымен бірге АЯЯ белсенділігінің уақыт бойынша эволюциясына әкеледі. Динамикалық бұзылған HI дискілері де LINER галактикаларында Сейферт галактикаларына қарағанда жиірек кездеседі. Бірнеше галактикалар серіктермен қоршалған (кейбіреулеріне HI шығарылуы байланысты), бірақ серіктердің болуы мен АЯЯ типі (Сейферт/LINER) арасында байланыс жоқ.
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kk
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Scientific research is a continuous process, and the speed of future progress can be estimated by the pace of finding explanations for previous research questions. In this observers based view of stellar pulsation and asteroseismology, we start with the earliest observations of variable stars and the techniques used to observe them. The earliest variable stars were large amplitude, radial pulsators but were followed by other classes of pulsating stars. As the field matured, we outline some cornerstones of research into pulsating star research with an emphasis on changes in observational techniques. Improvements from photographs, to photometry, CCDs, and space telescopes allowed researchers to separate out pulsating stars from other stars with light variations, recognize radial and nonradial pulsation courtesy of increased measurement precision, and then use nonradial pulsations to look inside the stars, which cannot be done any other way. We follow several highlighted problems to show that even with excellent space data, there still may not be quick theoretical explanations. As the result of technical changes, the structure of international organizations devoted to pulsating stars has changed, and an increasing number of conferences specialized to space missions or themes are held. Although there are still many unsolved problems, such as mode identification in non-asymptotic pulsating stars, the large amount of data with unprecedented precision provided by space missions (MOST, CoRoT, Kepler) and upcoming missions allow us to use asteroseismology to its full potential. However, the enormous flow of data will require new techniques to extract the science before the next missions. The future of asteroseismology will be successful if we learn from the past and improve with improved techniques, space missions, and a properly educated new generation.
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과학 연구는 지속적인 과정이며, 향후 진전 속도는 이전 연구 질문들에 대한 설명을 찾는 속도로 추정할 수 있다. 항성 맥동과 항성진동학에 대한 관측자 중심의 관점에서 우리는 변광성에 대한 최초의 관측과 이를 관측하기 위해 사용된 기술들로부터 시작한다. 최초의 변광성들은 진폭이 큰 방사형 맥동 별들이었으나, 이후 다른 종류의 맥동성들이 계속 발견되었다. 이 분야가 성숙함에 따라 우리는 관측 기술의 변화에 초점을 맞추어 맥동성 연구의 몇 가지 주요 이정표들을 개관한다. 사진 촬영에서 광도 측정, CCD, 그리고 우주 망원경으로의 발전을 통해 연구자들은 광도 변화를 보이는 다른 별들로부터 맥동성을 가진 별들을 구분할 수 있게 되었고, 측정 정밀도의 향상 덕분에 방사형 및 비방사형 맥동을 인식할 수 있게 되었으며, 이후 비방사형 맥동을 이용해 별 내부를 들여다볼 수 있게 되었는데, 이는 다른 방법으로는 불가능한 일이다. 우리는 몇 가지 주목할 만한 문제들을 따라가며, 훌륭한 우주 관측 데이터가 있더라도 이에 대한 이론적 설명이 즉각적으로 나오지 않을 수 있음을 보여준다. 기술적 변화의 결과로 맥동성 연구에 헌신하는 국제 기구들의 구조가 변화하였으며, 우주 임무나 특정 주제에 특화된 회의들이 점점 더 많이 개최되고 있다. 비점근적 맥동성에서의 진동 모드 식별과 같은 해결되지 않은 문제가 여전히 많지만, 우주 임무(MOST, CoRoT, Kepler)와 향후 예정된 임무들에 의해 제공되는 전례 없는 정밀도의 방대한 데이터 덕분에 항성진동학을 그 잠재력의 극한까지 활용할 수 있게 되었다. 그러나 엄청난 양의 데이터 흐름은 다음 임무 이전에 과학적 성과를 추출하기 위한 새로운 기술을 요구할 것이다. 우리는 과거로부터 배우고, 개선된 기술과 우주 임무, 그리고 적절히 교육받은 새로운 세대와 함께 발전한다면, 항성진동학의 미래는 성공할 것이다.
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ko
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We propose to develop a high-energy heavy-ion experimental database and make it accessible to the scientific community through an on-line interace. This database will be searchable and cross-indexed with relevant publications, including published detector descriptions. Since this database will be a community resource, it requires the high-energy nuclear physics community's financial and manpower support. This database should eventually contain all published data from the Bevalac, AGS and SPS to RHIC and LHC energies, proton-proton to nucleus-nucleus collisions as well as other relevant systems and all measured observables. Such a database would have tremendous scientific payoff as it makes systematic studies easier and allows simpler benchmarking of theoretical models to a broad range of old and new experiments. Furthermore, there is a growing need for compilations of high-energy nuclear data for applications including stockpile stewardship, technology development for intertial confinement fusion and target and source development for upcoming facilities such as the Next Linear Collider. To enhance the utility of this database, we propose periodically performing evaluations of the data and summarizing the results in topical reviews.
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نقترح تطوير قاعدة بيانات تجريبية للإيونات الثقيلة ذات الطاقة العالية وجعلها متاحة للمجتمع العلمي من خلال واجهة إلكترونية. ستكون هذه القاعدة قابلة للبحث ومرتبطة بشكل متقاطع بالمنشورات ذات الصلة، بما في ذلك وصفات الكاشفة المنشورة. وبما أن هذه القاعدة تمثل مورداً مجتمعياً، فإنها تتطلب دعماً مالياً وبدنياً من مجتمع فيزياء النوى عالية الطاقة. ينبغي أن تحتوي هذه القاعدة في نهاية المطاف على جميع البيانات المنشورة من بيفالاك وAGS وSPS وحتى طاقات RHIC وLHC، ومن التصادمات البروتون-بروتون إلى التصادمات نواة-نواة، فضلاً عن الأنظمة الأخرى ذات الصلة وجميع الكميات القابلة للقياس التي تم قياسها. سيكون لهذا النوع من قواعد البيانات عائد علمي هائل، إذ يسهل الدراسات المنظمة ويجعل المقارنة مع النماذج النظرية عبر نطاق واسع من التجارب القديمة والحديثة أكثر سهولة. علاوة على ذلك، هناك حاجة متزايدة لتجميعات بيانات النوى عالية الطاقة في تطبيقات تشمل الإشراف على المخزون النووي، وتطوير التكنولوجيا للاندماج المحفور بالقصور الذاتي، وتطوير الأهداف والمصادر للمرافق المستقبلية مثل المُسرّع الخطي القادم. ولتعزيز فائدة هذه القاعدة، نقترح إجراء تقييمات دورية للبيانات وتلخيص النتائج في مراجعات متخصصة.
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ar
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We combine the catalogs of compact high-velocity HI clouds extracted from the LDS and HIPASS surveys and analyze the all-sky properties of the ensemble. Five principal observables are defined for the CHVC population: (1) the spatial deployment of the objects on the sky, (2) the kinematic distribution, (3) the number distribution of observed HI column densities, (4) the number distribution of angular sizes, and (5) the number distribution of HI linewidth. Two classes of models are considered to reproduce the observed properties. The agreement of models with the data is judged by extracting these same observables from simulations, in a manner consistent with the sensitivities of the observations and explicitly taking account of Galactic obscuration. We show that models in which the CHVCs are the HI counterparts of dark-matter halos evolving in the Local Group potential provide a good match to the observables. The best-fitting populations have a maximum HI mass of 10^7 M_Sun a power-law slope of the HI mass distribution in the range -1.7 to -1.8, and a Gaussian dispersion for their spatial distributions of between 150 and 200 kpc centered on both the Milky Way and M31. Given its greater mean distance, only a small fraction of the M31 sub-population is predicted to have been detected in present surveys. An empirical model for an extended Galactic halo distribution for the CHVCs is also considered. While reproducing some aspects of the population, this class of models does not account for some key systematic features of the population.
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我们将从LDS和HIPASS巡天中提取的致密高速中性氢云（CHVC）星表进行合并，并分析该整体样本的全天特性。我们为CHVC总体定义了五个主要可观测量：（1）天体在天空中的空间分布，（2）运动学分布，（3）观测到的中性氢柱密度的数目分布，（4）角尺寸的数目分布，以及（5）中性氢谱线宽度的数目分布。我们考虑了两类模型以重现观测特性。通过以与观测灵敏度一致的方式从模拟中提取相同的可观测量，并明确考虑银河系遮挡效应，来评估模型与数据的符合程度。我们发现，若将CHVC视为在本星系群引力势中演化的暗物质晕的中性氢对应体，则此类模型能很好地匹配所有可观测量。最符合的总体具有约10^7倍太阳质量的最大中性氢质量，中性氢质量分布的幂律指数在-1.7至-1.8之间，其空间分布呈高斯型，相对于银河系和M31中心的弥散尺度介于150至200千秒差距之间。由于M31子总体的平均距离更远，预计目前巡天仅探测到其中一小部分。我们也考虑了一种经验性的CHVC银河系晕延展分布模型。尽管该类模型能够重现部分总体特征，但无法解释该总体中一些关键的系统性特征。
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zh
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A recent publication provides the network graph for a neocortical microcircuit comprising 8 million connections between 31,000 neurons (H. Markram, et al., Reconstruction and simulation of neocortical microcircuitry, Cell, 163 (2015) no. 2, 456-492). Since traditional graph-theoretical methods may not be sufficient to understand the immense complexity of such a biological network, we explored whether methods from algebraic topology could provide a new perspective on its structural and functional organization. Structural topological analysis revealed that directed graphs representing connectivity among neurons in the microcircuit deviated significantly from different varieties of randomized graph. In particular, the directed graphs contained in the order of $10^7$ simplices {\DH} groups of neurons with all-to-all directed connectivity. Some of these simplices contained up to 8 neurons, making them the most extreme neuronal clustering motif ever reported. Functional topological analysis of simulated neuronal activity in the microcircuit revealed novel spatio-temporal metrics that provide an effective classification of functional responses to qualitatively different stimuli. This study represents the first algebraic topological analysis of structural connectomics and connectomics-based spatio-temporal activity in a biologically realistic neural microcircuit. The methods used in the study show promise for more general applications in network science.
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Una publicación reciente proporciona el grafo de red para un microcircuito neocortical que comprende 8 millones de conexiones entre 31.000 neuronas (H. Markram et al., Reconstrucción y simulación de la microcircuitría neocortical, Cell, 163 (2015) n.º 2, 456-492). Dado que los métodos tradicionales de teoría de grafos podrían no ser suficientes para comprender la inmensa complejidad de una red biológica como esta, exploramos si los métodos de la topología algebraica podrían ofrecer una nueva perspectiva sobre su organización estructural y funcional. El análisis topológico estructural reveló que los grafos dirigidos que representan la conectividad entre neuronas en el microcircuito se desviaban significativamente de diversas variedades de grafos aleatorizados. En particular, los grafos dirigidos contenían del orden de $10^7$ símplices {\DH} grupos de neuronas con conectividad dirigida total a total. Algunos de estos símplices contenían hasta 8 neuronas, lo que los convierte en el motivo de agrupamiento neuronal más extremo jamás reportado. El análisis topológico funcional de la actividad neuronal simulada en el microcircuito reveló nuevas métricas espacio-temporales que proporcionan una clasificación efectiva de las respuestas funcionales a estímulos cualitativamente diferentes. Este estudio representa el primer análisis topológico algebraico de la conectómica estructural y de la actividad espacio-temporal basada en conectómica en un microcircuito neuronal biológicamente realista. Los métodos utilizados en el estudio muestran potencial para aplicaciones más generales en la ciencia de redes.
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es
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We present an analysis of the optical spectroscopy of 58 stars in the Galactic plane at $l=27$\arcdeg, where a prominent excess in the flux distribution and star counts have been observed in several spectral regions, in particular in the Two Micron Galactic Survey (TMGS) catalog. The sources were selected from the TMGS, to have a $K$ magnitude brighter than +5 mag and be within 2 degrees of the Galactic plane. More than 60% of the spectra correspond to stars of luminosity class I, and a significant proportion of the remainder are very late giants which would also be fast evolving. This very high concentration of young sources points to the existence of a major star formation region in the Galactic plane, located just inside the assumed origin of the Scutum spiral arm. Such regions can form due to the concentrations of shocked gas where a galactic bar meets a spiral arm, as is observed at the ends of the bars of face-on external galaxies. Thus, the presence of a massive star formation region is very strong supporting evidence for the presence of a bar in our Galaxy.
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আমরা আকাশগঙ্গার তলের $l=27$\arcdeg অবস্থানে 58টি তারার আলোক বর্ণালীবিদ্যার একটি বিশ্লেষণ উপস্থাপন করছি, যেখানে বিভিন্ন আলোক বর্ণালী অঞ্চলে, বিশেষ করে টু মাইক্রন গ্যালাকটিক সার্ভে (TMGS) ক্যাটালগে, ফ্লাক্স বন্টন এবং তারা গণনায় একটি সুস্পষ্ট অতিরিক্ততা লক্ষ্য করা গেছে। TMGS থেকে উৎসগুলি নির্বাচন করা হয়েছিল যাদের $K$ মাত্রা +5 mag-এর চেয়ে উজ্জ্বল এবং গ্যালাকটিক তল থেকে 2 ডিগ্রির মধ্যে অবস্থিত। বর্ণালীগুলির 60% এর বেশি আলোকমাত্রা শ্রেণী I-এর তারার সাথে মিলে যায় এবং বাকি অংশের একটি উল্লেখযোগ্য অংশ খুবই পরবর্তী দৈত্য তারা যারা দ্রুত বিবর্তিত হচ্ছে বলে মনে হয়। এই অত্যন্ত উচ্চ ঘনত্বে যুব উৎসগুলি আকাশগঙ্গার তলে একটি প্রধান তারা গঠন অঞ্চলের অস্তিত্বের ইঙ্গিত দেয়, যা ধরে নেওয়া স্কুটাম ঘূর্ণন বাহুর উৎপত্তির ঠিক ভিতরে অবস্থিত। এমন অঞ্চলগুলি গঠিত হতে পারে সেখানে যেখানে আকাশগঙ্গার দণ্ড একটি ঘূর্ণন বাহুর সাথে মিলিত হয় এবং আঘাতপ্রাপ্ত গ্যাসের ঘনত্ব ঘটে, যেমনটা মুখোমুখি বাহ্যিক আকাশগঙ্গাগুলির দণ্ডের প্রান্তগুলিতে পর্যবেক্ষণ করা যায়। সুতরাং, একটি বৃহৎ তারা গঠন অঞ্চলের উপস্থিতি আমাদের আকাশগঙ্গাতে একটি দণ্ডের উপস্থিতির জন্য খুবই শক্তিশালী সমর্থনমূলক প্রমাণ হিসাবে কাজ করে।
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bn
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Scientific research is a continuous process, and the speed of future progress can be estimated by the pace of finding explanations for previous research questions. In this observers based view of stellar pulsation and asteroseismology, we start with the earliest observations of variable stars and the techniques used to observe them. The earliest variable stars were large amplitude, radial pulsators but were followed by other classes of pulsating stars. As the field matured, we outline some cornerstones of research into pulsating star research with an emphasis on changes in observational techniques. Improvements from photographs, to photometry, CCDs, and space telescopes allowed researchers to separate out pulsating stars from other stars with light variations, recognize radial and nonradial pulsation courtesy of increased measurement precision, and then use nonradial pulsations to look inside the stars, which cannot be done any other way. We follow several highlighted problems to show that even with excellent space data, there still may not be quick theoretical explanations. As the result of technical changes, the structure of international organizations devoted to pulsating stars has changed, and an increasing number of conferences specialized to space missions or themes are held. Although there are still many unsolved problems, such as mode identification in non-asymptotic pulsating stars, the large amount of data with unprecedented precision provided by space missions (MOST, CoRoT, Kepler) and upcoming missions allow us to use asteroseismology to its full potential. However, the enormous flow of data will require new techniques to extract the science before the next missions. The future of asteroseismology will be successful if we learn from the past and improve with improved techniques, space missions, and a properly educated new generation.
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Penelitian ilmiah merupakan proses yang berkelanjutan, dan kecepatan kemajuan di masa depan dapat diperkirakan dari laju penemuan penjelasan atas pertanyaan penelitian sebelumnya. Dalam pandangan berbasis pengamat terhadap getaran bintang dan asteroseismologi ini, kami memulai dengan pengamatan paling awal terhadap bintang variabel serta teknik-teknik yang digunakan untuk mengamatinya. Bintang variabel pertama yang diamati adalah bintang berdenyut radial dengan amplitudo besar, namun kemudian diikuti oleh kelas-kelas lain bintang berdenyut. Seiring berkembangnya bidang ini, kami menguraikan beberapa tonggak penting dalam penelitian bintang berdenyut dengan penekanan pada perubahan teknik pengamatan. Perkembangan dari teknik fotografi, fotometri, CCD, hingga teleskop luar angkasa memungkinkan para peneliti memisahkan bintang berdenyut dari bintang lain yang mengalami variasi cahaya, mengenali denyut radial dan nonradial berkat peningkatan ketepatan pengukuran, dan kemudian menggunakan denyut nonradial untuk mengamati bagian dalam bintang, yang tidak dapat dilakukan dengan cara lain. Kami mengikuti beberapa permasalahan utama untuk menunjukkan bahwa meskipun data luar angkasa sangat baik, penjelasan teoretis yang cepat belum tentu muncul. Sebagai akibat dari perubahan teknis tersebut, struktur organisasi internasional yang berfokus pada bintang berdenyut juga berubah, dan semakin banyak konferensi khusus yang diselenggarakan, baik yang berfokus pada misi luar angkasa maupun tema tertentu. Meskipun masih banyak masalah yang belum terpecahkan, seperti identifikasi mode pada bintang berdenyut non-asimtotik, jumlah besar data dengan ketepatan yang belum pernah terjadi sebelumnya dari misi luar angkasa (MOST, CoRoT, Kepler) dan misi-misi mendatang memungkinkan kita memanfaatkan asteroseismologi secara maksimal. Namun, aliran data yang sangat besar ini akan memerlukan teknik-teknik baru untuk mengekstraksi ilmu pengetahuan sebelum misi-misi berikutnya. Masa depan asteroseismologi akan sukses jika kita belajar dari masa lalu, terus memperbaiki diri melalui teknik-teknik yang lebih baik, misi luar angkasa, serta generasi baru yang terdidik dengan baik.
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A critical discussion of the present status of the CERN experiments on charm dynamics and hadron collective flow is given. We emphasize the importance of the flow excitation function from 1 to 50 A$\cdot$GeV: here the hydrodynamic model has predicted the collapse of the $v_1$-flow and of the $v_2$-flow at $\sim 10$ A$\cdot$GeV; at 40 A$\cdot$GeV it has been recently observed by the NA49 collaboration. Since hadronic rescattering models predict much larger flow than observed at this energy we interpret this observation as potential evidence for a first order phase transition at high baryon density $\rho_B$. A detailed discussion of the collective flow as a barometer for the equation of state (EoS) of hot dense matter at RHIC follows. Additionally, detailed transport studies show that the away-side jet suppression can only partially ($<$ 50%) be due to hadronic rescattering. We, finally, propose upgrades and second generation experiments at RHIC which inspect the first order phase transition in the fragmentation region, i.e. at $\mu_B \approx 400$ MeV ($y \approx 4-5$), where the collapse of the proton flow should be seen in analogy to the 40 A$\cdot$GeV data. The study of Jet-Wake-riding potentials and Bow shocks -- caused by jets in the QGP formed at RHIC -- can give further information on the equation of state (EoS) and transport coefficients of the Quark Gluon Plasma (QGP).
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Uma discussão crítica sobre o estado atual dos experimentos do CERN sobre a dinâmica do charme e o fluxo coletivo de hádrons é apresentada. Enfatizamos a importância da função de excitação do fluxo entre 1 e 50 A$\cdot$GeV: aqui, o modelo hidrodinâmico previu o colapso do fluxo $v_1$ e do fluxo $v_2$ em $\sim 10$ A$\cdot$GeV; em 40 A$\cdot$GeV, essa observação foi recentemente feita pela colaboração NA49. Como modelos de rescatamento hadrônico prevêem um fluxo muito maior do que o observado nessa energia, interpretamos essa observação como evidência potencial de uma transição de fase de primeira ordem em alta densidade barionica $\rho_B$. Segue-se uma discussão detalhada do fluxo coletivo como um barômetro para a equação de estado (EoS) da matéria quente e densa no RHIC. Além disso, estudos detalhados de transporte mostram que a supressão do jato do lado oposto pode ser apenas parcialmente ($<$ 50%) devida ao rescatamento hadrônico. Finalmente, propomos melhorias e experimentos de segunda geração no RHIC que investiguem a transição de fase de primeira ordem na região de fragmentação, ou seja, em $\mu_B \approx 400$ MeV ($y \approx 4-5$), onde o colapso do fluxo de prótons deverá ser observado, em analogia aos dados em 40 A$\cdot$GeV. O estudo dos potenciais de "Jet-Wake-riding" e de choques de proa — causados por jatos no PGC formado no RHIC — pode fornecer informações adicionais sobre a equação de estado (EoS) e os coeficientes de transporte do Plasma de Quarks e Glúons (PGC).
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The recently-discovered stellar system in Canis Major is analysed using He-burning Red Clump stars as tracers. Canis Major turns out to be the strongest and most spatially confined overdensity of the whole Galactic Disc, both in terms of number density and of statistical significance. When projected onto the Galactic Plane, it appears as an elongated and compact overdensity extending from l ~ 200 to l ~ 280 with a roundish core toward l ~ 240. We find that the main body of the system has an integrated absolute magnitude M_V=-14.4 +/- 0.8, a central surface brightness \mu_{V,0} = 24.0 +/- 0.6 mag/arcsec^2 and a line-of-sight profile peaked at D_{sun}=7.2 +/- 1.0 kpc with Half Width at Half Maximum ~ 2.0 kpc, in excellent agreement with the results obtained with widely different tracers (M giants and Main Sequence stars) in previous analyses. The mean distance to the main body of Canis Major is observed to increase with increasing Galactic longitude, from D_{sun} ~ 6.3 kpc at l ~ 225, to D_{sun} ~ 9.3 kpc at l ~ 265, in good agreement with the predictions of our more recent N-body simulation that models CMa as a dwarf galaxy being accreted in a planar orbit onto the disc of the Milky Way. We confirm that the Canis Major system has all the characteristics of the relic of a dwarf galaxy seen on top of a large-scale overdensity that we detect all over the third and fourth Galactic quadrants (180<l<360, with a strong maximum around l=290 and b> -5) that is identified as the stellar component of the southern Galactic Warp... (Abridged)....
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ລະບົບດາວທີ່ຖືກຄົ້ນພົບໃໝ່ໃນກຸ່ມດາວ Canis Major ໄດ້ຖືກວິເຄາະໂດຍໃຊ້ດາວ Red Clump ທີ່ເຜົາໄໝ້ຮັງສີ He ເປັນຕົວຕິດຕາມ. Canis Major ພົບວ່າເປັນບັນດາພື້ນທີ່ທີ່ມີຄວາມໜາແໜ້ນເກີນໄປ (overdensity) ທີ່ເຂັ້ມແຂງທີ່ສຸດ ແລະ ມີຂອບເຂດໃນອະວະກາດທີ່ຊັດເຈນທີ່ສຸດໃນທຸກພື້ນທີ່ຈານຂອງກາແລັກຊີ ທັງໃນດ້ານຄວາມໜາແໜ້ນຂອງຈຳນວນ ແລະ ຄວາມໝາຍທາງສະຖິຕິ. ເມື່ອຖືກໂຄ້ນລົງໃສ່ແບບພິມຂອງກາແລັກຊີ ມັນປາກົດຕົວເປັນພື້ນທີ່ມີຄວາມໜາແໜ້ນເກີນໄປທີ່ຍືດຍາວ ແລະ ມີຂອບເຂດກະທັດຮັດ ເຊິ່ງກະຈາຍຕົວຈາກ l ~ 200 ເຖິງ l ~ 280 ໂດຍມີສ່ວນກາງທີ່ມົນກົມກ່ຽວກັບ l ~ 240. ພວກເຮົາພົບວ່າຕົວຫຼັກຂອງລະບົບນີ້ມີຂະໜາດແສງສະຫວ່າງສຳພັດ M_V=-14.4 +/- 0.8, ມີຄວາມສະຫວ່າງຜິວໜ້າກາງ \mu_{V,0} = 24.0 +/- 0.6 mag/arcsec^2 ແລະ ແຜ່ນໂປຣໄຟລ໌ຕາມທິດສະດີດ່ຽວ (line-of-sight) ທີ່ສູງສຸດຢູ່ທີ່ D_{sun}=7.2 +/- 1.0 kpc ໂດຍມີຄວາມກວ້າງກາງທີ່ຄຳນວນຈາກຄ່າສູງສຸດ (Half Width at Half Maximum) ປະມານ 2.0 kpc, ທີ່ກົງກັນດີກັບຜົນໄດ້ຮັບຈາກການໃຊ້ຕົວຕິດຕາມທີ່ແຕກຕ່າງກັນຢ່າງກວ້າງຂວາງ (ດາວ M giants ແລະ ດາວ Main Sequence) ໃນການວິເຄາະກ່ອນໜ້ານີ້. ພວກເຮົາສັງເກດເຫັນວ່າໄລຍະທາງສະເລ່ຍໄປຫາຕົວຫຼັກຂອງ Canis Major ເພີ່ມຂຶ້ນຕາມຄວາມຍາວຂອງກາແລັກຊີທີ່ເພີ່ມຂຶ້ນ, ຈາກ D_{sun} ~ 6.3 kpc ທີ່ l ~ 225 ເຖິງ D_{sun} ~ 9.3 kpc ທີ່ l ~ 265, ຊຶ່ງກົງກັບຄາດໝາຍຈາກການສຳຫຼວດ N-body ລ້າສຸດຂອງພວກເຮົາ ທີ່ຈຳລອງການດູດຊຶມຂອງ CMa ເຂົ້າມາໃນວົງໂຄຈອນແບບດິດ (planar orbit) ໃສ່ຈານຂອງກາແລັກຊີ Milky Way. ພວກເຮົາຢືນຢັນວ່າລະບົບ Canis Major ມີຄຸນລັກສະນະທັງໝົດຂອງເງົາເຫຼືອຈາກດາວຄູ່ນ້ອຍ (dwarf galaxy) ທີ່ຖືກມອງເຫັນຢູ່ເທິງພື້ນທີ່ໜາແໜ້ນຂະໜາດໃຫຍ່ ທີ່ພວກເຮົາພົບເຫັນຢູ່ທົ່ວຈຸດທີ່ສາມ ແລະ ສີ່ຂອງກາແລັກຊີ (180<l<360, ມີຈຸດສູງສຸດຢ່າງເດັ່ນຢູ່ l=290 ແລະ b> -5) ທີ່ຖືກຈຳແນກວ່າເປັນສ່ວນປະກອບຂອງດາວທີ່ເກີດຈາກການເບື່ອງຂອງກາແລັກຊີດ້ານໃຕ້... (ຫຍໍ້)...
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lo
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Source code (Context) and its parsed abstract syntax tree (AST; Structure) are two complementary representations of the same computer program. Traditionally, designers of machine learning models have relied predominantly either on Structure or Context. We propose a new model, which jointly learns on Context and Structure of source code. In contrast to previous approaches, our model uses only language-agnostic features, i.e., source code and features that can be computed directly from the AST. Besides obtaining state-of-the-art on monolingual code summarization on all five programming languages considered in this work, we propose the first multilingual code summarization model. We show that jointly training on non-parallel data from multiple programming languages improves results on all individual languages, where the strongest gains are on low-resource languages. Remarkably, multilingual training only from Context does not lead to the same improvements, highlighting the benefits of combining Structure and Context for representation learning on code.
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លេខកូដប្រភព (បរិបទ) និងដើមឈើវាក្យសម្បទាដែលបានវិភាគ (AST; រចនាសម្ព័ន្ធ) គឺជាការតំណាងពីរប្រភេទបំពេញបន្ថែមគ្នាសម្រាប់កម្មវិធីកុំព្យូទ័រតែមួយ។ ប្រពៃណីមក អ្នករចនាម៉ូដែលរៀនសូត្រពីម៉ាស៊ីន បានពឹងផ្អែកជាចម្បងលើរចនាសម្ព័ន្ធ ឬបរិបទ។ យើងស្នើម៉ូដែលថ្មីមួយ ដែលរៀនរួមគ្នាលើបរិបទ និងរចនាសម្ព័ន្ធនៃលេខកូដប្រភព។ ផ្ទុយពីវិធីសាស្ត្រមុនៗ ម៉ូដែលរបស់យើងប្រើតែលក្ខណៈទូទៅសម្រាប់ភាសា ឧទាហរណ៍ លេខកូដប្រភព និងលក្ខណៈដែលអាចគណនាបានដោយផ្ទាល់ពី AST។ ក្រៅពីទទួលបានលទ្ធផលដ៏ល្អបំផុតនៅលើការសង្ខេបកូដតែមួយភាសាលើភាសាសរសេរកម្មវិធីទាំងប្រាំដែលពិចារណាក្នុងការងារនេះ យើងស្នើម៉ូដែលសង្ខេបកូដពហុភាសាដំបូងគេ។ យើងបង្ហាញថា ការបណ្តុះបណ្តាលរួមគ្នាលើទិន្នន័យមិនស្មើគ្នាពីភាសាសរសេរកម្មវិធីច្រើន បានធ្វើឱ្យលទ្ធផលប្រសើរឡើងលើភាសានីមួយៗ ដែលការកើនឡើងខ្លាំងបំផុតគឺនៅលើភាសាដែលមានធនធានទាប។ គួរកត់សម្គាល់ថា ការបណ្តុះបណ្តាលពហុភាសាតាមរយៈបរិបទតែមួយគត់ មិននាំទៅរកការកែលម្អដូចគ្នានោះទេ ដែលបញ្ជាក់ពីអត្ថប្រយោជន៍នៃការបញ្ចូលរចនាសម្ព័ន្ធ និងបរិបទសម្រាប់ការរៀនតំណាងលើកូដ។
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A recent publication provides the network graph for a neocortical microcircuit comprising 8 million connections between 31,000 neurons (H. Markram, et al., Reconstruction and simulation of neocortical microcircuitry, Cell, 163 (2015) no. 2, 456-492). Since traditional graph-theoretical methods may not be sufficient to understand the immense complexity of such a biological network, we explored whether methods from algebraic topology could provide a new perspective on its structural and functional organization. Structural topological analysis revealed that directed graphs representing connectivity among neurons in the microcircuit deviated significantly from different varieties of randomized graph. In particular, the directed graphs contained in the order of $10^7$ simplices {\DH} groups of neurons with all-to-all directed connectivity. Some of these simplices contained up to 8 neurons, making them the most extreme neuronal clustering motif ever reported. Functional topological analysis of simulated neuronal activity in the microcircuit revealed novel spatio-temporal metrics that provide an effective classification of functional responses to qualitatively different stimuli. This study represents the first algebraic topological analysis of structural connectomics and connectomics-based spatio-temporal activity in a biologically realistic neural microcircuit. The methods used in the study show promise for more general applications in network science.
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Una pubblicazione recente fornisce il grafo di rete per un microcircuito neocorticale composto da 8 milioni di connessioni tra 31.000 neuroni (H. Markram et al., Reconstruction and simulation of neocortical microcircuitry, Cell, 163 (2015) n. 2, 456-492). Poiché i metodi tradizionali della teoria dei grafi potrebbero non essere sufficienti a comprendere l'enorme complessità di una rete biologica di questo tipo, abbiamo esplorato se metodi della topologia algebrica potessero offrire una nuova prospettiva sulla sua organizzazione strutturale e funzionale. L'analisi topologica strutturale ha rivelato che i grafi diretti rappresentanti la connettività tra neuroni nel microcircuito si discostano significativamente da diverse varietà di grafi randomizzati. In particolare, i grafi diretti contenevano nell'ordine di $10^7$ simplessi {\DH} gruppi di neuroni con connettività diretta totalizzata. Alcuni di questi simplessi contenevano fino a 8 neuroni, risultando così il motivo di aggregazione neuronale più estremo mai riportato. L'analisi topologica funzionale dell'attività neuronale simulata nel microcircuito ha rivelato nuove metriche spazio-temporali che forniscono una classificazione efficace delle risposte funzionali a stimoli qualitativamente diversi. Questo studio rappresenta la prima analisi topologica algebrica della connettomica strutturale e dell'attività spazio-temporale basata sulla connettomica in un microcircuito neurale biologicamente realistico. I metodi utilizzati nello studio mostrano potenzialità per applicazioni più generali nella scienza delle reti.
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The cosmic microwave background (CMB) temperature anisotropies exhibit a large-scale dipolar power asymmetry. To determine whether this is due to a real, physical modulation or is simply a large statistical fluctuation requires the measurement of new modes. Here we forecast how well CMB polarization data from \Planck\ and future experiments will be able to confirm or constrain physical models for modulation. Fitting several such models to the \Planck\ temperature data allows us to provide predictions for polarization asymmetry. While for some models and parameters \Planck\ polarization will decrease error bars on the modulation amplitude by only a small percentage, we show, importantly, that cosmic-variance-limited (and in some cases even \Planck) polarization data can decrease the errors by considerably better than the expectation of $\sqrt 2$ based on simple $\ell$-space arguments. We project that if the primordial fluctuations are truly modulated (with parameters as indicated by \Planck\ temperature data) then \Planck\ will be able to make a 2$\sigma$ detection of the modulation model with 20--75\% probability, increasing to 45--99\% when cosmic-variance-limited polarization is considered. We stress that these results are quite model dependent. Cosmic variance in temperature is important: combining statistically isotropic polarization with temperature data will spuriously increase the significance of the temperature signal with 30\% probability for \Planck.
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Le anisotropie di temperatura della radiazione cosmica di fondo (CMB) mostrano un'asimmetria dipolare su larga scala nella potenza. Per determinare se ciò sia dovuto a una modulazione fisica reale o semplicemente a una grande fluttuazione statistica, è necessario misurare nuove modalità. In questo lavoro prevediamo con quale precisione i dati sulla polarizzazione della CMB del satellite \Planck\ e di futuri esperimenti potranno confermare o vincolare modelli fisici di modulazione. Adattando diversi di questi modelli ai dati di temperatura di \Planck, siamo in grado di fornire previsioni per l'asimmetria di polarizzazione. Mentre per alcuni modelli e parametri i dati di polarizzazione di \Planck\ ridurranno le barre di errore sull'ampiezza della modulazione solo di una piccola percentuale, mostriamo, in modo importante, che dati sulla polarizzazione limitati dalla varianza cosmica (e in alcuni casi persino quelli di \Planck) possono ridurre gli errori notevolmente meglio del fattore atteso di $\sqrt 2$ basato su semplici argomentazioni nello spazio-$\ell$. Prevediamo che, se le fluttuazioni primordiali sono effettivamente modulate (con parametri indicati dai dati di temperatura di \Planck), \Planck\ sarà in grado di effettuare una rivelazione a 2$\sigma$ del modello di modulazione con una probabilità compresa tra il 20% e il 75%, che aumenta al 45–99% quando si considerano dati di polarizzazione limitati dalla varianza cosmica. Sottolineiamo che questi risultati dipendono fortemente dal modello. La varianza cosmica nella temperatura è importante: combinare dati di polarizzazione statisticamente isotropi con i dati di temperatura aumenterebbe in modo spurio la significatività del segnale di temperatura con una probabilità del 30% per \Planck.
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it
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We report multifrequency Very Long Baseline Array observations of twelve active galactic nuclei seen toward the Galactic anticenter. All of the sources are at |b| < 10 degrees and seven have |b| < 0.5 degrees. Our VLBA observations can detect an enhancement in the angular broadening of these sources due to an extended H II disk, if the orientation of the H II disk in the outer Galaxy is similar to that of the H I disk. Such an extended H II disk is suggested by the C IV absorption in a quasar's spectrum, the appearance of H I disks of nearby spiral galaxies, and models of Ly-alpha cloud absorbers and the Galactic fountain. We detect eleven of the twelve sources at one or more frequencies; nine of the sources are compact and suitable for an angular broadening analysis. A preliminary analysis of the observed angular diameters suggests that the H II disk does not display considerable warping or flaring and does not extend to large Galactocentric distances (R >~ 100 kpc). A companion paper (Lazio & Cordes 1997) combines these observations with those in the literature and presents a more comprehensive analysis.
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은하 반대쪽 중심 방향으로 관측된 12개의 활동은하핵에 대한 다중주파수 초장기선 배열(Very Long Baseline Array, VLBA) 관측 결과를 보고한다. 모든 천체는 |b| < 10도에 위치하며, 7개는 |b| < 0.5도에 있다. 외부 은하에서 H II 성운 원반의 방향이 H I 성운 원반의 방향과 유사하다면, 우리의 VLBA 관측은 이러한 천체들의 각도 확장이 확장된 H II 원반으로 인해 증가하는 현상을 감지할 수 있다. 이러한 확장된 H II 원반의 존재는 준성계(quasar) 스펙트럼에서 나타나는 C IV 흡수, 인근 나선은하들의 H I 원반 형태, 리만-알파 구름 흡수체 모델 및 은하 분수(갤럭틱 파운틴) 모델에 의해 제시된다. 12개의 천체 중 11개를 하나 이상의 주파수에서 감지하였으며, 이 중 9개는 콤팩트하여 각도 확장 분석에 적합하다. 관측된 각지름에 대한 예비 분석 결과에 따르면, H II 원반은 상당한 비틀림이나 퍼짐(warping or flaring)을 나타내지 않으며, 큰 은하중심 거리(R >~ 100 kpc)까지 확장되지 않는다. 동반 논문(Lazio & Cordes 1997)은 본 관측 결과를 문헌상의 다른 관측과 통합하여 보다 포괄적인 분석을 제시한다.
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ko
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Fast Radio Bursts (FRBs) are bright enigmatic radio pulses of roughly millisecond duration that come from extragalactic distances. As part of the MeerTRAP project, we use the MeerKAT telescope array in South Africa to search for and localise those bursts to high precision in real-time. We aim to pinpoint FRBs to their host galaxies and, thereby, to understand how they are created. However, the transient nature of FRBs presents various challenges, e.g. in system design, raw compute power and real-time communication, where the real-time requirements are reasonably strict (a few tens of seconds). Rapid data processing is essential for us to be able to retain high-resolution data of the bursts, to localise them, and to minimise the delay for follow-up observations. We give a short overview of the data analysis pipeline, describe the challenges faced, and elaborate on our initial design and implementation of a real-time triggering infrastructure for FRBs at the MeerKAT telescope.
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Rajadas Rápidas de Rádio (FRBs) são pulsos de rádio brilhantes e enigmáticos com duração de aproximadamente um milissegundo que vêm de distâncias extragalácticas. Como parte do projeto MeerTRAP, utilizamos a matriz de telescópios MeerKAT na África do Sul para buscar e localizar essas rajadas com alta precisão em tempo real. Nosso objetivo é identificar com exatidão as galáxias hospedeiras das FRBs e, assim, compreender como elas são geradas. No entanto, a natureza transitória das FRBs apresenta diversos desafios, por exemplo, no projeto do sistema, no poder bruto de computação e na comunicação em tempo real, em que os requisitos de tempo real são razoavelmente rigorosos (algumas dezenas de segundos). O processamento rápido de dados é essencial para que possamos manter dados de alta resolução das rajadas, localizá-las e minimizar o atraso para observações de acompanhamento. Apresentamos uma breve visão geral do pipeline de análise de dados, descrevemos os desafios enfrentados e detalhamos nosso projeto inicial e implementação de uma infraestrutura de detecção em tempo real para FRBs no telescópio MeerKAT.
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pt
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We derive mass functions (MF) for halo red dwarfs (the faintest hydrogen burning stars) and then extrapolate to place limits on the total mass of halo brown dwarfs (stars not quite massive enough to burn hydrogen). The mass functions are obtained from the luminosity function of a sample of 114 local halo stars in the USNO parallax survey (Dahn \etal 1995). We use stellar models of Alexander \etal (1996) and make varying assumptions about metallicity and about possible unresolved binaries in the sample. We find that the MF for halo red dwarfs cannot rise more quickly than $1/m^2$ as one approaches the hydrogen burning limit. Using recent results from star formation theory, we extrapolate the MF into the brown-dwarf regime. We see that likely extrapolations imply that the total mass of brown dwarfs in the halo is less than $\sim 3\%$ of the local mass density of the halo ($\sim 0.3\%$ for the more realistic models we consider). Our limits apply to brown dwarfs in the halo that come from the same stellar population as the red dwarfs.
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우리는 헤일로 붉은 왜성(가장 희미한 수소 연소 별)에 대한 질량 함수(MF)를 도출한 후, 이를 외삽하여 헤일로 갈색 왜성(수소 연소에 충분한 질량이 부족한 별)의 총 질량에 대한 한계를 설정한다. 질량 함수는 USNO 시차 조사(Dahn \etal 1995)에서 얻은 국부 헤일로 별 114개로 구성된 표본의 광도 함수로부터 구하였다. 우리는 Alexander \etal(1996)의 항성 모델을 사용하며, 표본의 금속량 및 미해결 이중성계의 존재 가능성에 대해 다양한 가정을 두었다. 그 결과, 수소 연소 한계에 접근할수록 헤일로 붉은 왜성의 질량 함수는 $1/m^2$보다 더 급격히 증가할 수 없음을 발견하였다. 항성 형성 이론의 최근 결과를 이용하여, 질량 함수를 갈색 왜성 영역까지 외삽하였다. 외삽 결과, 헤일로 내 갈색 왜성의 총 질량은 헤일로의 국부 질량 밀도의 약 3% 미만임을 알 수 있었으며(고려한 모델 중 더 현실적인 모델의 경우 약 0.3%)이다. 본 연구의 한계는 붉은 왜성과 동일한 항성 집단에서 기원한 헤일로 내 갈색 왜성에 적용된다.
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A critical discussion of the present status of the CERN experiments on charm dynamics and hadron collective flow is given. We emphasize the importance of the flow excitation function from 1 to 50 A$\cdot$GeV: here the hydrodynamic model has predicted the collapse of the $v_1$-flow and of the $v_2$-flow at $\sim 10$ A$\cdot$GeV; at 40 A$\cdot$GeV it has been recently observed by the NA49 collaboration. Since hadronic rescattering models predict much larger flow than observed at this energy we interpret this observation as potential evidence for a first order phase transition at high baryon density $\rho_B$. A detailed discussion of the collective flow as a barometer for the equation of state (EoS) of hot dense matter at RHIC follows. Additionally, detailed transport studies show that the away-side jet suppression can only partially ($<$ 50%) be due to hadronic rescattering. We, finally, propose upgrades and second generation experiments at RHIC which inspect the first order phase transition in the fragmentation region, i.e. at $\mu_B \approx 400$ MeV ($y \approx 4-5$), where the collapse of the proton flow should be seen in analogy to the 40 A$\cdot$GeV data. The study of Jet-Wake-riding potentials and Bow shocks -- caused by jets in the QGP formed at RHIC -- can give further information on the equation of state (EoS) and transport coefficients of the Quark Gluon Plasma (QGP).
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Một thảo luận nghiêm ngặt về tình trạng hiện tại của các thí nghiệm tại CERN về động lực học hạt lạ (charm) và dòng chảy tập thể của hadron được trình bày. Chúng tôi nhấn mạnh tầm quan trọng của hàm kích thích dòng chảy trong khoảng từ 1 đến 50 A$\cdot$GeV: tại đây, mô hình thủy động lực học đã dự đoán sự sụp đổ của dòng $v_1$ và dòng $v_2$ ở khoảng 10 A$\cdot$GeV; hiện tượng này gần đây đã được hợp tác NA49 quan sát thấy ở 40 A$\cdot$GeV. Vì các mô hình tái tán xạ hadron dự đoán dòng chảy lớn hơn nhiều so với quan sát được ở năng lượng này, chúng tôi diễn giải quan sát này như một bằng chứng tiềm tàng cho sự chuyển pha bậc nhất tại mật độ barion cao $\rho_B$. Tiếp theo là một thảo luận chi tiết về dòng chảy tập thể như một thang đo phương trình trạng thái (EoS) của vật chất nóng, đậm đặc tại RHIC. Ngoài ra, các nghiên cứu vận chuyển chi tiết cho thấy rằng sự ức chế tia phun phía xa (away-side jet suppression) chỉ có thể một phần ($<$ 50%) là do tái tán xạ hadron. Cuối cùng, chúng tôi đề xuất các nâng cấp và các thí nghiệm thế hệ thứ hai tại RHIC nhằm khảo sát chuyển pha bậc nhất trong vùng phân mảnh, tức là tại $\mu_B \approx 400$ MeV ($y \approx 4-5$), nơi mà sự sụp đổ của dòng proton cần phải được quan sát thấy tương tự như dữ liệu ở 40 A$\cdot$GeV. Việc nghiên cứu các thế năng Jet-Wake-riding và các sóng xung kích mũi tên (Bow shocks) — gây ra bởi các tia phun trong QGP hình thành tại RHIC — có thể cung cấp thêm thông tin về phương trình trạng thái (EoS) và các hệ số vận chuyển của Plasma Quark-Gluon (QGP).
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vi
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Large amounts of labeled training data are one of the main contributors to the great success that deep models have achieved in the past. Label acquisition for tasks other than benchmarks can pose a challenge due to requirements of both funding and expertise. By selecting unlabeled examples that are promising in terms of model improvement and only asking for respective labels, active learning can increase the efficiency of the labeling process in terms of time and cost. In this work, we describe combinations of an incremental learning scheme and methods of active learning. These allow for continuous exploration of newly observed unlabeled data. We describe selection criteria based on model uncertainty as well as expected model output change (EMOC). An object detection task is evaluated in a continuous exploration context on the PASCAL VOC dataset. We also validate a weakly supervised system based on active and incremental learning in a real-world biodiversity application where images from camera traps are analyzed. Labeling only 32 images by accepting or rejecting proposals generated by our method yields an increase in accuracy from 25.4% to 42.6%.
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大量のラベル付き訓練データは、深層モデルが過去に大きな成功を収めた主な要因の一つである。ベンチマーク以外のタスクにおいては、資金と専門知識の両方を必要とするため、ラベルの取得は困難となる場合がある。ラベル付けされていない事例のうち、モデルの改善という観点から有望なもののみを選択し、そのラベルだけを取得することで、アクティブラーニングはラベル付けプロセスの時間的・コスト的な効率を高めることができる。本研究では、増分学習方式とアクティブラーニング手法を組み合わせた方法について述べる。これにより、新たに観測されたラベルなしデータを継続的に探索することが可能になる。モデルの不確実性および予想されるモデル出力の変化（EMOC）に基づく選択基準について説明する。PASCAL VOCデータセットを用いて、物体検出タスクを継続的探索の文脈で評価した。また、カメラトラップで取得した画像を解析する実世界の生物多様性アプリケーションにおいて、アクティブラーニングと増分学習に基づく弱教師ありシステムの有効性を検証した。本手法が生成する候補を承認または拒否することで、わずか32枚の画像にラベルを付けるだけで、精度が25.4%から42.6%まで向上した。
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Nowadays, the use of agile software development methods like Scrum is common in industry and academia. Considering the current attacking landscape, it is clear that developing secure software should be a main concern in all software development projects. In traditional software projects, security issues require detailed planning in an initial planning phase, typically resulting in a detailed security analysis (e.g., threat and risk analysis), a security architecture, and instructions for security implementation (e.g., specification of key sizes and cryptographic algorithms to use). Agile software development methods like Scrum are known for reducing the initial planning phases (e.g., sprint 0 in Scrum) and for focusing more on producing running code. Scrum is also known for allowing fast adaption of the emerging software to changes of customer wishes. For security, this means that it is likely that there are no detailed security architecture or security implementation instructions from the start of the project. It also means that a lot of design decisions will be made during the runtime of the project. Hence, to address security in Scrum, it is necessary to consider security issues throughout the whole software development process. Secure Scrum is a variation of the Scrum framework with special focus on the development of secure software throughout the whole software development process. It puts emphasis on implementation of security related issues without the need of changing the underlying Scrum process or influencing team dynamics. Secure Scrum allows even non- security experts to spot security issues, to implement security features, and to verify implementations. A field test of Secure Scrum shows that the security level of software developed using Secure Scrum is higher then the security level of software developed using standard Scrum.
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Hoy en día, el uso de métodos ágiles de desarrollo de software como Scrum es común en la industria y en el ámbito académico. Considerando el panorama actual de ataques, es evidente que desarrollar software seguro debería ser una preocupación principal en todos los proyectos de desarrollo de software. En proyectos de software tradicionales, los problemas de seguridad requieren una planificación detallada en una fase inicial de planificación, lo que generalmente resulta en un análisis de seguridad detallado (por ejemplo, análisis de amenazas y riesgos), una arquitectura de seguridad e instrucciones para la implementación de seguridad (por ejemplo, especificación de tamaños de claves y algoritmos criptográficos a utilizar). Se sabe que los métodos ágiles de desarrollo de software como Scrum reducen las fases iniciales de planificación (por ejemplo, el sprint 0 en Scrum) y se centran más en producir código funcional. Scrum también es conocido por permitir una rápida adaptación del software emergente a los cambios en los deseos del cliente. En cuanto a la seguridad, esto significa que es probable que no exista desde el inicio del proyecto una arquitectura de seguridad detallada ni instrucciones específicas para la implementación de seguridad. También significa que muchas decisiones de diseño se tomarán durante la ejecución del proyecto. Por lo tanto, para abordar la seguridad en Scrum, es necesario considerar los aspectos de seguridad durante todo el proceso de desarrollo de software. Secure Scrum es una variante del marco Scrum con especial énfasis en el desarrollo de software seguro a lo largo de todo el proceso de desarrollo. Pone énfasis en la implementación de cuestiones relacionadas con la seguridad sin necesidad de modificar el proceso Scrum subyacente ni influir en la dinámica del equipo. Secure Scrum permite incluso a personas no expertas en seguridad detectar problemas de seguridad, implementar funciones de seguridad y verificar implementaciones. Una prueba de campo de Secure Scrum muestra que el nivel de seguridad del software desarrollado utilizando Secure Scrum es mayor que el nivel de seguridad del software desarrollado utilizando Scrum estándar.
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es
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With the aim of better understanding the class of 4D theories generated by compactifications of 6D superconformal field theories (SCFTs), we study the structure of N = 1 supersymmetric punctures for class S_Gamma theories, namely the 6D SCFTs obtained from M5-branes probing an ADE singularity. For M5-branes probing a C^2 / Z_k singularity, the punctures are governed by a dynamical system in which evolution in time corresponds to motion to a neighboring node in an affine A-type quiver. Classification of punctures reduces to determining consistent initial conditions which produce periodic orbits. The study of this system is particularly tractable in the case of a single M5-brane. Even in this "simple" case, the solutions exhibit a remarkable level of complexity: Only specific rational values for the initial momenta lead to periodic orbits, and small perturbations in these values lead to vastly different late time behavior. Another difference from half BPS punctures of class S theories includes the appearance of a continuous complex "zero mode" modulus in some puncture solutions. The construction of punctures with higher order poles involves a related set of recursion relations. The resulting structures also generalize to systems with multiple M5-branes as well as probes of D- and E-type orbifold singularities.
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6次元超共形場理論（SCFT）のコンパクト化によって生成される4次元理論のクラスをより深く理解することを目的として、我々はクラスS_Gamma理論、すなわちM5ブレーンがADE特異点をプローブすることによって得られる6次元SCFTに対して、N = 1超対称性を持つパンクチャの構造を研究する。M5ブレーンがC^2 / Z_k特異点をプローブする場合、パンクチャは時間発展がアフィンA型キラーモデルの隣接ノードへの移動に対応する力学系によって支配される。パンクチャの分類は、周期軌道を生じる一貫した初期条件を決定することに帰着する。この系の研究は、単一のM5ブレーンの場合に特に扱いやすい。この「単純な」場合でさえ、解は顕著な複雑さを示す。初期運動量が特定の有理数値の場合にのみ周期軌道が生じ、わずかな摂動が遅い時間での挙動に大きく異なる影響を与える。クラスS理論の1/2BPSパンクチャとは異なり、いくつかのパンクチャ解には連続な複素「ゼロモード」モジュールが現れる点も異なる。高次の極を持つパンクチャの構成は、関連する再帰関係の集合を含む。得られる構造は、複数のM5ブレーン系やD型、E型のオービフォルド特異点をプローブする系へも一般化される。
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ja
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The Gemini Deep Deep Survey, GDDS, produced several significant results relating to the evolution of galaxies. All of these results are consistent with the "downsizing" concept of galaxy formation and evolution, i.e., that the active periods of star formation moved progressively from very massive galaxies at high redshift to much lower mass galaxies at the present epoch. Spectra of massive red galaxies at z ~ 1.7 demonstrates that they contain old stellar populations and hence must have formed their stars in the first ~3 Gyr of cosmic history; indicators of star formation activity show that the star formation rate in the most massive galaxies was much higher at z = 2 than today, that the activity in intermediate mass galaxies peaked near z ~ 1.5, while, since z ~ 1 the activity is primarily confined to lower mass galaxies. The GDDS also uncovered a relatively high percentage of post-starburst galaxies at z ~ 1, a result that is anticipated given all the activity seen at higher redshifts. Measurements of the strengths of metal lines of a subsample of the GDDS and CFRS galaxies at z ~ 0.7 reveal that, at a given mass, they had lower metallicities than at present. The evolution in the mass-metallicity relation is consistent with a model in which star formation lasts longest in less massive galaxies, again an expected result in the downsizing scenario.
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Gemini Derin Derin Taraması (GDDS), galaksilerin evrimiyle ilgili birkaç önemli sonuç ortaya koymuştur. Bu sonuçların tümü galaksi oluşumu ve evriminin "küçülme" (downsizing) kavramıyla uyumludur; yani yıldız oluşumunun aktif dönemleri, yüksek kırmızıya kaymanın olduğu zamanlarda çok kütleli galaksilerde başlayıp, zaman içinde bugünkü dönemde çok daha düşük kütleli galaksilere doğru kaymıştır. Z ~ 1.7 civarındaki büyük kütleli kırmızı galaksilerin tayfları, bu galaksilerin eski yıldız popülasyonlarını içerdiğini ve dolayısıyla yıldızlarını kozmik tarihin ilk yaklaşık 3 milyar yılında oluştuğunu göstermektedir; yıldız oluşumu etkinliğini gösteren belirteçler, en büyük kütleli galaksilerdeki yıldız oluşum hızının z = 2'de günümüzden çok daha yüksek olduğunu, orta kütleli galaksilerdeki etkinliğin z ~ 1.5 civarında zirveye ulaştığını ve z ~ 1'den bu yana etkinliğin çoğunlukla daha düşük kütleli galaksilere sınırlı kaldığını ortaya koymaktadır. GDDS ayrıca z ~ 1 civarında görece yüksek bir oranda yıldız oluşumundan sonra kalan galaksiler (post-starburst galaxies) ortaya çıkarmıştır ve bu, daha yüksek kırmızıya kaymalarda gözlenen tüm bu etkinlikler dikkate alındığında beklenen bir sonuçtur. GDDS ve CFRS galaksilerinin bir alt örneğindeki metal çizgilerinin z ~ 0.7'deki ölçümleri, belirli bir kütlede, bu galaksilerin şu ankinden daha düşük metalikitelere sahip olduğunu göstermektedir. Kütle-metalikite ilişkisindeki bu evrim, yıldız oluşumunun daha düşük kütleli galaksilerde daha uzun sürdüğü bir modelle uyumlu olup, bu da yine küçülme senaryosunda beklenen bir sonuçtur.
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tr
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The advantages of adaptivity and feedback are of immense interest in signal processing and communication with many positive and negative results. Although it is established that adaptivity does not offer substantial reductions in minimax mean square error for a fixed number of measurements, existing results have shown several advantages of adaptivity in complexity of reconstruction, accuracy of support detection, and gain in signal-to-noise ratio, under constraints on sensing energy. Sensing energy has often been measured in terms of the Frobenius Norm of the sensing matrix. This paper uses a different metric that we call the $l_0$ cost of a sensing matrix-- to quantify the complexity of sensing. Thus sparse sensing matrices have a lower cost. We derive information-theoretic lower bounds on the $l_0$ cost that hold for any non-adaptive sensing strategy. We establish that any non-adaptive sensing strategy must incur an $l_0$ cost of $\Theta\left( N \log_2(N)\right) $ to reconstruct an $N$-dimensional, one--sparse signal when the number of measurements are limited to $\Theta\left(\log_2 (N)\right)$. In comparison, bisection-type adaptive strategies only require an $l_0$ cost of at most $\mathcal{O}(N)$ for an equal number of measurements. The problem has an interesting interpretation as a sphere packing problem in a multidimensional space, such that all the sphere centres have minimum non-zero co-ordinates. We also discuss the variation in $l_0$ cost as the number of measurements increase from $\Theta\left(\log_2 (N)\right)$ to $\Theta\left(N\right)$.
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Keunggulan adaptivitas dan umpan balik sangat menarik dalam pemrosesan sinyal dan komunikasi, dengan berbagai hasil positif dan negatif. Meskipun telah ditunjukkan bahwa adaptivitas tidak memberikan pengurangan substansial terhadap kesalahan kuadrat rata-rata minimaks untuk jumlah pengukuran yang tetap, hasil-hasil yang ada telah menunjukkan beberapa keuntungan adaptivitas dalam hal kompleksitas rekonstruksi, akurasi deteksi dukungan, dan peningkatan rasio sinyal terhadap derau, di bawah kendala energi penginderaan. Energi penginderaan sering kali diukur dalam bentuk Norma Frobenius dari matriks penginderaan. Makalah ini menggunakan metrik berbeda yang kami sebut biaya $l_0$ dari matriks penginderaan—untuk mengukur kompleksitas penginderaan. Dengan demikian, matriks penginderaan renggang memiliki biaya yang lebih rendah. Kami menurunkan batas bawah teoretis informasi pada biaya $l_0$ yang berlaku untuk setiap strategi penginderaan non-adaptif. Kami menunjukkan bahwa setiap strategi penginderaan non-adaptif harus menanggung biaya $l_0$ sebesar $\Theta\left( N \log_2(N)\right) $ untuk merekonstruksi sinyal satu-renggang berdimensi-$N$ ketika jumlah pengukuran dibatasi hingga $\Theta\left(\log_2 (N)\right)$. Sebagai perbandingan, strategi adaptif tipe pembagian dua hanya memerlukan biaya $l_0$ paling banyak $\mathcal{O}(N)$ untuk jumlah pengukuran yang sama. Masalah ini memiliki interpretasi menarik sebagai masalah pengepakan bola dalam ruang berdimensi banyak, sedemikian sehingga semua pusat bola memiliki koordinat non-nol minimum. Kami juga membahas variasi biaya $l_0$ saat jumlah pengukuran meningkat dari $\Theta\left(\log_2 (N)\right)$ hingga $\Theta\left(N\right)$.
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id
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In this paper, we investigate a distributed optimal control problem for a convective viscous Cahn-Hilliard system with dynamic boundary conditions. Such systems govern phase separation processes between two phases taking place in an incompressible fluid in a container and, at the same time, on the container boundary. The cost functional is of standard tracking type, while the control is exerted by the velocity of the fluid in the bulk. In this way, the coupling between the state (given by the associated order parameter and chemical potential) and control variables in the governing system of nonlinear partial differential equations is bilinear, which presents an additional difficulty for the analysis. The nonlinearities in the bulk and surface free energies are of logarithmic type, which entails that the thermodynamic forces driving the phase separation process may become singular. We show existence for the optimal control problem under investigation, prove the Fr\'echet differentiability of the associated control-to-state mapping in suitable Banach spaces and derive the first-order necessary optimality conditions in terms of a variational inequality and the associated adjoint system. Due to the strong nonlinear couplings between state variables and control, the corresponding proofs require a considerable analytical effort.
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اس تحقیقی مقالے میں، ہم دینامی سرحدی شرائط کے ساتھ ایک کنویکٹو وِسکس کاہن ہلیارڈ نظام کے لیے تقسیم شدہ مثالی کنٹرول کے مسئلے کا جائزہ لیتے ہیں۔ اس قسم کے نظام ایک بے ترتیب سیال میں ایک برتن کے اندر دو مراحل کے درمیان مرحلہ علیحدگی کے عمل کو حکمرانی کرتے ہیں، اور اسی وقت برتن کی سرحد پر بھی۔ قیمتی فنکشنل معیاری ٹریکنگ قسم کا ہے، جبکہ کنٹرول بیچ میں سیال کی رفتار کے ذریعے عمل میں لایا جاتا ہے۔ اس طریقے سے، حکمرانی کرنے والے غیر خطی جزوی مساوات کے نظام میں حالت (متعلقہ آرڈر پیرامیٹر اور کیمیائی ممکنہ کی صورت میں) اور کنٹرول متغیرات کے درمیان ربط دو خطی ہوتا ہے، جو تجزیہ کے لیے ایک اضافی دشواری پیش کرتا ہے۔ بیچ اور سطحی آزاد توانائیوں میں غیر خطیت لاگرتھم قسم کی ہے، جس کا مطلب ہے کہ مرحلہ علیحدگی کے عمل کو حرکت دینے والی تھرمو ڈائنامک قوتیں منفرد ہو سکتی ہیں۔ ہم تحقیق زیرِ التوا مثالی کنٹرول مسئلے کے وجود کو ظاہر کرتے ہیں، مناسب بینچ جگہوں میں متعلقہ کنٹرول سے حالت تک نگاشن کی فریشے مختلف قابلیت کو ثابت کرتے ہیں، اور ایک متغیر نامساوات اور متعلقہ معاون نظام کے لحاظ سے پہلے درجے کی ضروری مثالیت کی شرائط کا اندازہ لگاتے ہیں۔ حالت متغیرات اور کنٹرول کے درمیان شدید غیر خطی ربط کی وجہ سے، ان متعلقہ ثبوتوں کو مناسب تجزیاتی کوشش کی ضرورت ہوتی ہے۔
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ur
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A recent publication provides the network graph for a neocortical microcircuit comprising 8 million connections between 31,000 neurons (H. Markram, et al., Reconstruction and simulation of neocortical microcircuitry, Cell, 163 (2015) no. 2, 456-492). Since traditional graph-theoretical methods may not be sufficient to understand the immense complexity of such a biological network, we explored whether methods from algebraic topology could provide a new perspective on its structural and functional organization. Structural topological analysis revealed that directed graphs representing connectivity among neurons in the microcircuit deviated significantly from different varieties of randomized graph. In particular, the directed graphs contained in the order of $10^7$ simplices {\DH} groups of neurons with all-to-all directed connectivity. Some of these simplices contained up to 8 neurons, making them the most extreme neuronal clustering motif ever reported. Functional topological analysis of simulated neuronal activity in the microcircuit revealed novel spatio-temporal metrics that provide an effective classification of functional responses to qualitatively different stimuli. This study represents the first algebraic topological analysis of structural connectomics and connectomics-based spatio-temporal activity in a biologically realistic neural microcircuit. The methods used in the study show promise for more general applications in network science.
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最近の出版物により、3万1000個のニューロン間の800万の接続からなる新皮質マイクロサーキットのネットワークグラフが提供された（H. マークランら、「新皮質マイクロサーキットの再構成とシミュレーション」、Cell、163巻（2015年）、2号、456–492頁）。このような生物ネットワークの極めて複雑な構造を理解するには、従来のグラフ理論的手法では不十分である可能性があるため、代数的トポロジーの手法がその構造的・機能的組織について新たな視点を提供できるかどうかを検討した。構造的トポロジー解析により、マイクロサーキット内のニューロン間の接続関係を表す有向グラフは、さまざまな種類のランダム化グラフと有意に逸脱していることが明らかになった。特に、これらの有向グラフには、完全に双方向接続されたニューロンのグループである単体（シンプレックス）が約10の7乗個存在した。これらの単体の中には最大8個のニューロンを含むものもあり、これまでに報告された中で最も極端なニューロンクラスタリングモチーフとなっている。マイクロサーキットにおけるシミュレートされたニューロン活動に対する機能的トポロジー解析により、質的に異なる刺激に対する機能的応答を効果的に分類できる新たな時空間的指標が明らかになった。本研究は、生物学的に現実的な神経マイクロサーキットにおける構造的コネクトミクスおよびコネクトミクスに基づく時空間活動に対して、初めて代数的トポロジー的解析を適用した事例である。本研究で用いられた手法は、ネットワーク科学全般へのより広範な応用可能性を示している。
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ja
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In this work we present the main atmospheric parameters, carbon, nitrogen and oxygen abundances, and 12C/13C ratios determined in a sample of 28 Galactic clump stars. Abundances of carbon were studied using the C2 band at 5086.2 {\AA}. The wavelength interval 7980-8130 {\AA} with strong CN features was analysed in order to determine nitrogen abundances and 12C/13C isotope ratios. The oxygen abundances were determined from the [O I] line at 6300 {\AA}. The mean abundances of C, N and O abundances in the investigated clump stars support our previous estimations that, compared to the Sun and dwarf stars of the Galactic disc, carbon is depleted by about 0.2 dex, nitrogen is enhanced by 0.2 dex and oxygen is close to abundances in dwarfs. The 12C/13C and C/N ratios for galactic red clump stars analysed were compared to the evolutionary models of extra-mixing. The steeper drop of 12C/13C ratio in the model of thermohaline mixing by Charbonnel & Lagarde better reflects the observational data at low stellar masses than the more shallow model of cool bottom processing by Boothroyd & Sackmann. For stars of about 2 Msun masses a modelling of rotationally induced mixing should be considered with rotation of about 250 km s-1 at the time when a star was at the hydrogen-core-burning stage.
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Dalam karya ini kami menyajikan parameter atmosfer utama, kelimpahan karbon, nitrogen, dan oksigen, serta rasio 12C/13C yang ditentukan dalam sampel 28 bintang raksasa klaster galaksi. Kelimpahan karbon dipelajari menggunakan pita C2 pada 5086,2 {\AA}. Interval panjang gelombang 7980-8130 {\AA} yang memiliki ciri-ciri CN yang kuat dianalisis untuk menentukan kelimpahan nitrogen dan rasio isotop 12C/13C. Kelimpahan oksigen ditentukan dari garis [O I] pada 6300 {\AA}. Rata-rata kelimpahan C, N, dan O pada bintang klaster yang diteliti mendukung estimasi sebelumnya bahwa, dibandingkan dengan Matahari dan bintang kerdil pada piringan Galaksi, karbon berkurang sekitar 0,2 dex, nitrogen meningkat sekitar 0,2 dex, dan oksigen hampir setara dengan kelimpahan pada bintang kerdil. Rasio 12C/13C dan C/N untuk bintang raksasa merah klaster galaksi yang dianalisis dibandingkan dengan model evolusi pencampuran tambahan. Penurunan yang lebih curam dari rasio 12C/13C dalam model pencampuran termohalin oleh Charbonnel & Lagarde lebih mencerminkan data pengamatan pada massa bintang rendah dibandingkan model pencampuran cool bottom processing oleh Boothroyd & Sackmann yang lebih landai. Untuk bintang dengan massa sekitar 2 massa matahari, perlu dipertimbangkan pemodelan pencampuran yang dipicu rotasi dengan kecepatan rotasi sekitar 250 km s-1 pada saat bintang berada pada tahap pembakaran inti hidrogen.
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id
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The current early stage in the investigation of the stability of the Kerr metric is characterized by the study of appropriate model problems. Particularly interesting is the problem of the stability of the solutions of the Klein-Gordon equation, describing the propagation of a scalar field in the background of a rotating (Kerr-) black hole. Results suggest that the stability of the field depends crucially on its mass $\mu$. Among others, the paper provides an improved bound for $\mu$ above which the solutions of the reduced, by separation in the azimuth angle in Boyer-Lindquist coordinates, Klein-Gordon equation are stable. Finally, it gives new formulations of the reduced equation, in particular, in form of a time-dependent wave equation that is governed by a family of unitarily equivalent positive self-adjoint operators. The latter formulation might turn out useful for further investigation. On the other hand, it is proved that from the abstract properties of this family alone it cannot be concluded that the corresponding solutions are stable.
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কার মেট্রিকের স্থিতিশীলতা নির্ণয়ের তদন্তের বর্তমান প্রাথমিক পর্যায়টি উপযুক্ত মডেল সমস্যাগুলির অধ্যয়নের মাধ্যমে চিহ্নিত করা হয়েছে। বিশেষভাবে আকর্ষণীয় হল ক্লাইন-গর্ডন সমীকরণের সমাধানগুলির স্থিতিশীলতার সমস্যা, যা একটি ঘূর্ণায়মান (কার-) ব্ল্যাক হোলের পটভূমিতে একটি স্কেলার ক্ষেত্রের প্রসারণ বর্ণনা করে। ফলাফলগুলি নির্দেশ করে যে ক্ষেত্রটির স্থিতিশীলতা তার ভর $\mu$-এর উপর নির্ভর করে। এর মধ্যে অন্যান্য বিষয়ের পাশাপাশি, এই গবেষণাপত্রটি $\mu$-এর জন্য একটি উন্নত সীমা দেয় যার উপরে বয়ার-লিন্ডকুইস্ট স্থানাঙ্কে দিগন্ত কোণে পৃথকীকরণের মাধ্যমে হ্রাসকৃত ক্লাইন-গর্ডন সমীকরণের সমাধানগুলি স্থিতিশীল হয়। অবশেষে, হ্রাসকৃত সমীকরণের নতুন সূত্র দেওয়া হয়, বিশেষত, একটি সময়-নির্ভর তরঙ্গ সমীকরণের আকারে যা ইউনিটারি সমতুল্য ধনাত্মক স্ব-সংযুক্ত অপারেটরের একটি পরিবার দ্বারা নিয়ন্ত্রিত হয়। পরবর্তী তদন্তের জন্য এই শেষোক্ত সূত্রটি উপযোগী হতে পারে। অন্যদিকে, এটি প্রমাণিত হয়েছে যে এই পরিবারের শুধুমাত্র বিমূর্ত বৈশিষ্ট্যগুলি থেকে এর অনুরূপ সমাধানগুলি স্থিতিশীল তা সিদ্ধান্ত নেওয়া যাবে না।
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bn
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A critical discussion of the present status of the CERN experiments on charm dynamics and hadron collective flow is given. We emphasize the importance of the flow excitation function from 1 to 50 A$\cdot$GeV: here the hydrodynamic model has predicted the collapse of the $v_1$-flow and of the $v_2$-flow at $\sim 10$ A$\cdot$GeV; at 40 A$\cdot$GeV it has been recently observed by the NA49 collaboration. Since hadronic rescattering models predict much larger flow than observed at this energy we interpret this observation as potential evidence for a first order phase transition at high baryon density $\rho_B$. A detailed discussion of the collective flow as a barometer for the equation of state (EoS) of hot dense matter at RHIC follows. Additionally, detailed transport studies show that the away-side jet suppression can only partially ($<$ 50%) be due to hadronic rescattering. We, finally, propose upgrades and second generation experiments at RHIC which inspect the first order phase transition in the fragmentation region, i.e. at $\mu_B \approx 400$ MeV ($y \approx 4-5$), where the collapse of the proton flow should be seen in analogy to the 40 A$\cdot$GeV data. The study of Jet-Wake-riding potentials and Bow shocks -- caused by jets in the QGP formed at RHIC -- can give further information on the equation of state (EoS) and transport coefficients of the Quark Gluon Plasma (QGP).
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CERN의 캐릭터 동역학 및 하드론 집단 흐름 실험 현황에 대한 비판적 논의를 제시한다. 우리는 1~50 A·GeV 범위에서의 흐름 여기 함수의 중요성을 강조한다. 이 범위에서 수역학적 모델은 약 10 A·GeV에서 $v_1$-흐름과 $v_2$-흐름의 붕괴를 예측하였으며, 실제로 NA49 협력단에 의해 40 A·GeV에서 최근 관측되었다. 하드론 재산란 모델은 이 에너지 영역에서 관측된 것보다 훨씬 큰 흐름을 예측하기 때문에, 우리는 이 관측 결과를 고바리온 밀도 $\rho_B$에서 1차 상전이의 잠재적 증거로 해석한다. 이어서 RHIC에서 생성되는 고온 밀도 물질의 상태방정식(EoS)을 측정하는 지표로서 집단 흐름에 대해 상세히 논의한다. 또한 정교한 전이 모델 연구에 따르면 제트의 반대편 억제 현상은 하드론 재산란에 의해 부분적으로만($<$ 50%) 설명될 수 있다. 마지막으로, 우리는 파편화 영역, 즉 $\mu_B \approx 400$ MeV ($y \approx 4-5$)에서 1차 상전이를 조사할 수 있는 RHIC의 업그레이드 및 차세대 실험을 제안한다. 여기서는 40 A·GeV 데이터와 유사하게 양성자 흐름의 붕괴가 관측되어야 한다. 또한 RHIC에서 생성된 쿼크-글루온 플라즈마(QGP) 내에서 제트가 유도하는 제트-웨이크-라이딩 포텐셜과 볼록 충격파(Bow shocks)를 연구함으로써 QGP의 상태방정식(EoS) 및 전이 계수들에 대한 추가 정보를 얻을 수 있다.
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ko
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The GEM project is designed for the next generation 2 beta decay experiments with 76-Ge. One ton of ''naked'' HP Ge detectors (natural at the first GEM-I phase and enriched in 76-Ge to 86% at the second GEM-II stage) are operating in super-high purity liquid nitrogen contained in the Cu vacuum cryostat (sphere with diameter 5 m). The latest is placed in the water shield. Monte Carlo simulation evidently shows that sensitivity of the experiment (in terms of the T1/2 limit for neutrinoless 2 beta decay) is 10^27 yr with natural HP Ge crystals and 10^28 yr with enriched ones. These bounds corresponds to the restrictions on the neutrino mass less than 0.05 eV and 0.015 eV with natural and enriched detectors, respectively. Besides, the GEM-I set up could advance the current best limits on the existence of neutralinos - as dark matter candidates - by three order of magnitudes, and at the same time would be able to identify unambiguously the dark matter signal by detection of its seasonal modulation.
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GEM жобасы 76-Ge изотопы үшін келесі ұрпақ 2 бета ыдырау тәжірибелеріне арналған. Бір тонналық «ашық» HP Ge детекторлары (бірінші GEM-I кезеңінде табиғи және екінші GEM-II кезеңінде 76-Ge-ге 86%-ға дейін байытылған) мыс вакуумдық криостатта (диаметрі 5 м болатын сфера) орналасқан супер таза сұйық азотта жұмыс істейді. Соңғысы сулы қорғаныс қабықшасының ішінде орналасқан. Монте-Карло симуляциясы тәжірибенің (нейтриносыз 2 бета ыдырау үшін T1/2 шегі бойынша) сезімталдығы табиғи HP Ge кристалдары үшін 10^27 жыл, ал байытылған кристалдар үшін 10^28 жыл болатынын көрсетеді. Бұл шектер сәйкесінше табиғи және байытылған детекторлар үшін нейтрино массасының 0,05 эВ және 0,015 эВ-тан төмен болуына сәйкес келеді. Сонымен қатар, GEM-I орнатымы нейтралдылардың — қара заттың мүмкін кандидаттарының — бар болуы бойынша қазіргі ең жақсы шектерді үш реттік шамаға жақсартуға мүмкіндік береді және бір уақытта жыл мезгілдеріне байланысты өзгеруін байқау арқылы қара заттың сигналын анық айырып тани алады.
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kk
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In echocardiography (echo), an electrocardiogram (ECG) is conventionally used to temporally align different cardiac views for assessing critical measurements. However, in emergencies or point-of-care situations, acquiring an ECG is often not an option, hence motivating the need for alternative temporal synchronization methods. Here, we propose Echo-SyncNet, a self-supervised learning framework to synchronize various cross-sectional 2D echo series without any external input. The proposed framework takes advantage of both intra-view and inter-view self supervisions. The former relies on spatiotemporal patterns found between the frames of a single echo cine and the latter on the interdependencies between multiple cines. The combined supervisions are used to learn a feature-rich embedding space where multiple echo cines can be temporally synchronized. We evaluate the framework with multiple experiments: 1) Using data from 998 patients, Echo-SyncNet shows promising results for synchronizing Apical 2 chamber and Apical 4 chamber cardiac views; 2) Using data from 3070 patients, our experiments reveal that the learned representations of Echo-SyncNet outperform a supervised deep learning method that is optimized for automatic detection of fine-grained cardiac phase; 3) We show the usefulness of the learned representations in a one-shot learning scenario of cardiac keyframe detection. Without any fine-tuning, keyframes in 1188 validation patient studies are identified by synchronizing them with only one labeled reference study. We do not make any prior assumption about what specific cardiac views are used for training and show that Echo-SyncNet can accurately generalize to views not present in its training set. Project repository: github.com/fatemehtd/Echo-SyncNet.
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Эхокардиографияда (эхо) әдетте әртүрлі жүрек көріністерін өлшемдерді бағалау үшін уақыт бойынша біріктіру үшін электрокардиограмма (ЭКГ) қолданылады. Алайда, авариялық жағдайларда немесе медициналық көмектің нүктесіндегі жағдайларда ЭКГ алу мүмкін болмай қалады, сондықтан альтернативті уақыттық синхрондау әдістерінің қажеттілігі туындайды. Бұл жерде біз сыртқы ешқандай кіріс мәліметсіз әртүрлі көлденең 2D эхо серияларын синхрондау үшін өзін-өзі басқарылатын оқыту негізінде құрылған Echo-SyncNet ұсынамыз. Ұсынылған негіз бір эхо киноның кадрлары арасындағы кеңістікті-уақыттық үлгілерге негізделген ішкі көрініс бойынша және бірнеше кинолар арасындағы өзара тәуелділікке негізделген көріністер арасындағы өзін-өзі басқару тәсілдерін пайдаланады. Біріктірілген басқару әдістері көптеген эхо киноларын уақыт бойынша синхрондауға болатын ерекшеліктерге бай ендіру кеңістігін оқып үйрену үшін қолданылады. Біз бұл негізді бірнеше тәжірибелер арқылы бағалаймыз: 1) 998 науқастың деректерін қолдана отырып, Echo-SyncNet апикалық 2 камералы және апикалық 4 камералы жүрек көріністерін синхрондау бойынша перспективалы нәтижелер көрсетті; 2) 3070 науқастың деректерін қолдана отырып, жүргізілген тәжірибелерімізде Echo-SyncNet оқып үйренген бейнелері детальды жүрек фазасын автоматты түрде анықтауға оптимизацияланған қадамды терең оқыту әдісінен асып түсетіні анықталды; 3) Жүрек кілттік кадрын анықтау бойынша бір үлгілі оқыту жағдайында оқып үйренілген бейнелердің пайдалылығын көрсетеміз. Ешқандай қосымша баптаусыз, тек бір белгіленген салыстыру зерттеуімен синхрондау арқылы 1188 тексеру науқастарының зерттеулерінде кілттік кадрлар анықталды. Біз оқытуда қандай нақты жүрек көріністерінің қолданылатыны туралы алдын ала шарт қоймаймыз және Echo-SyncNet оның оқыту жинағында болмаған көріністерге дәлме-дәл жалпылай алатынын көрсетеміз. Жобаның сақтау орны: github.com/fatemehtd/Echo-SyncNet.
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kk
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We present ALMA and ACA [CI]$^{3}P_{1}-^{3}P_{0}$ ([CI](1-0)) observations of NGC6240, which we combine with ALMA CO(2-1) and IRAM PdBI CO(1-0) data to study the physical properties of the massive molecular (H$_2$) outflow. We discover that the receding and approaching sides of the H$_2$ outflow, aligned east-west, exceed 10 kpc in their total extent. High resolution ($0.24"$) [CI](1-0) line images surprisingly reveal that the outflow emission peaks between the two AGNs, rather than on either of the two, and that it dominates the velocity field in this nuclear region. We combine the [CI](1-0) and CO(1-0) data to constrain the CO-to-H$_2$ conversion factor ($\alpha_{\rm CO}$) in the outflow, which is on average $2.1\pm1.2~\rm M_{\odot} (K~km~s^{-1}~pc^2)^{-1}$. We estimate that $60\pm20$ % of the total H$_2$ gas reservoir of NGC6240 is entrained in the outflow, for a resulting mass-loss rate of $\dot{M}_{\rm out}=2500\pm1200~M_{\odot}~yr^{-1}$ $\equiv 50\pm30$ SFR. This energetics rules out a solely star formation-driven wind, but the puzzling morphology challenges a classic radiative-mode AGN feedback scenario. For the quiescent gas we compute $\langle\alpha_{\rm CO}\rangle = 3.2\pm1.8~\rm M_{\odot} (K~km~s^{-1}~pc^2)^{-1}$, which is at least twice the value commonly employed for (U)LIRGs. We observe a tentative trend of increasing $r_{21}\equiv L^{\prime}_{\rm CO(2-1)}/L^{\prime}_{\rm CO(1-0)}$ ratios with velocity dispersion and measure $r_{21}>1$ in the outflow, whereas $r_{21}\simeq1$ in the quiescent gas. We propose that molecular outflows are the location of the warmer, strongly unbound phase that partially reduces the opacity of the CO lines in (U)LIRGs, hence driving down their global $\alpha_{\rm CO}$ and increasing their $r_{21}$ values.
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Nous présentons des observations d'ALMA et de l'ACA de la raie [CI]$^{3}P_{1}-^{3}P_{0}$ ([CI](1-0)) de NGC6240, que nous combinons avec des données ALMA de la raie CO(2-1) et des données IRAM PdBI de la raie CO(1-0) afin d'étudier les propriétés physiques de l'important flux de sortie moléculaire (H$_2$). Nous découvrons que les composantes s'éloignant et s'approchant du flux de sortie d'H$_2$, alignées est-ouest, dépassent 10 kpc en extension totale. Des images haute résolution ($0.24"$) de la raie [CI](1-0) révèlent de manière surprenante que l'émission du flux de sortie est maximale entre les deux noyaux actifs, plutôt que sur l'un ou l'autre, et qu'elle domine le champ de vitesses dans cette région nucléaire. Nous combinons les données [CI](1-0) et CO(1-0) afin de contraindre le facteur de conversion CO-H$_2$ ($\alpha_{\rm CO}$) dans le flux de sortie, dont la valeur moyenne est $2.1\pm1.2~\rm M_{\odot} (K~km~s^{-1}~pc^2)^{-1}$. Nous estimons que $60\pm20$ % du réservoir total de gaz H$_2$ de NGC6240 est entraîné dans le flux de sortie, ce qui correspond à un taux de perte de masse de $\dot{M}_{\rm out}=2500\pm1200~M_{\odot}~yr^{-1}$ $\equiv 50\pm30$ SFR. Cette énergie écarte un vent uniquement entraîné par la formation d'étoiles, mais la morphologie énigmatique contredit également un scénario classique de rétroaction d'AGN en mode radiatif. Pour le gaz tranquille, nous calculons $\langle\alpha_{\rm CO}\rangle = 3.2\pm1.8~\rm M_{\odot} (K~km~s^{-1}~pc^2)^{-1}$, valeur au moins deux fois supérieure à celle généralement utilisée pour les (U)LIRG. Nous observons une tendance préliminaire à l'augmentation des rapports $r_{21}\equiv L^{\prime}_{\rm CO(2-1)}/L^{\prime}_{\rm CO(1-0)}$ avec la dispersion de vitesse, et mesurons $r_{21}>1$ dans le flux de sortie, tandis que $r_{21}\simeq1$ dans le gaz tranquille. Nous proposons que les flux de sortie moléculaires soient le lieu d'une phase plus chaude et fortement non liée, qui réduit partiellement l'opacité des raies CO dans les (U)LIRG, abaissant ainsi leur $\alpha_{\rm CO}$ global et augmentant leurs valeurs de $r_{21}$.
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fr
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We develop a robust coarse-grained model for single and double stranded DNA by representing each nucleotide by three interaction sites (TIS) located at the centers of mass of sugar, phosphate, and base. The resulting TIS model includes base-stacking, hydrogen bond, and electrostatic interactions as well as bond-stretching and bond angle potentials that account for the polymeric nature of DNA. The choices of force constants for stretching and the bending potentials were guided by a Boltzmann inversion procedure using a large representative set of DNA structures extracted from the Protein Data Bank. Some of the parameters in the stacking interactions were calculated using a learning procedure, which ensured that the experimentally measured melting temperatures of dimers are faithfully reproduced. Without any further adjustments, the calculations based on the TIS model reproduces the experimentally measured salt and sequence dependence of the size of single stranded DNA (ssDNA), as well as the persistence lengths of poly(dA) and poly(dT) chains. Interestingly, upon application of mechanical force the extension of poly(dA) exhibits a plateau, which we trace to the formation of stacked helical domains. In contrast, the force-extension curve (FEC) of poly(dT) is entropic in origin, and could be described by a standard polymer model. We also show that the persistence length of double stranded DNA is consistent with the prediction based on the worm-like chain. The persistence length, which decreases with increasing salt concentration, is in accord with the Odijk-Skolnick-Fixman theory intended for stiff polyelectrolyte chains near the rod limit. The range of applications, which did not require adjusting any parameter after the initial construction based solely on PDB structures and melting profiles of dimers, attests to the transferability and robustness of the TIS model for ssDNA and dsDNA.
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Мы разработали надежную модель крупнозернистого описания одноцепочечной и двуцепочечной ДНК, представляя каждый нуклеотид тремя точками взаимодействия (TIS), расположенными в центрах масс сахара, фосфата и основания. Полученная модель TIS включает взаимодействия, обусловленные стэкингом оснований, водородными связями и электростатикой, а также потенциалы растяжения связей и угловых потенциалов, учитывающие полимерную природу ДНК. Выбор силовых констант для потенциалов растяжения и изгиба был осуществлен с помощью процедуры инверсии Больцмана, использующей большой репрезентативный набор структур ДНК, извлеченных из Protein Data Bank. Некоторые параметры в потенциалах стэкинга были рассчитаны с применением процедуры обучения, что обеспечило точное воспроизведение экспериментально измеренных температур плавления димеров. Без каких-либо дополнительных корректировок расчеты на основе модели TIS воспроизводят экспериментально измеренные зависимости размера одноцепочечной ДНК (ssDNA) от концентрации соли и последовательности, а также длины персистентности цепей poly(dA) и poly(dT). Интересно, что при приложении механической силы удлинение poly(dA) демонстрирует плато, которое мы связываем с формированием упорядоченных спиральных доменов. В отличие от этого, кривая «сила-удлинение» (FEC) poly(dT) имеет энтропийную природу и может быть описана стандартной полимерной моделью. Мы также показываем, что длина персистентности двуцепочечной ДНК согласуется с предсказанием, основанным на модели червеобразной цепи. Длина персистентности, уменьшающаяся с ростом концентрации соли, согласуется с теорией Одайка—Сколника—Фиксмана, предназначенной для жестких полиэлектролитных цепей вблизи предела жесткого стержня. Широкий диапазон применимости, не потребовавший настройки каких-либо параметров после первоначальной конструкции, основанной исключительно на структурах из PDB и профилях плавления димеров, свидетельствует о переносимости и надежности модели TIS для ssDNA и dsDNA.
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ru
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Fast Radio Bursts (FRBs) are bright enigmatic radio pulses of roughly millisecond duration that come from extragalactic distances. As part of the MeerTRAP project, we use the MeerKAT telescope array in South Africa to search for and localise those bursts to high precision in real-time. We aim to pinpoint FRBs to their host galaxies and, thereby, to understand how they are created. However, the transient nature of FRBs presents various challenges, e.g. in system design, raw compute power and real-time communication, where the real-time requirements are reasonably strict (a few tens of seconds). Rapid data processing is essential for us to be able to retain high-resolution data of the bursts, to localise them, and to minimise the delay for follow-up observations. We give a short overview of the data analysis pipeline, describe the challenges faced, and elaborate on our initial design and implementation of a real-time triggering infrastructure for FRBs at the MeerKAT telescope.
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Schnelle Radioblitze (FRBs) sind helle, rätselhafte Radiopulse mit einer Dauer von etwa einer Millisekunde, die aus extragalaktischen Entfernungen stammen. Im Rahmen des MeerTRAP-Projekts nutzen wir das Teleskop-Array MeerKAT in Südafrika, um diese Pulse in Echtzeit zu suchen und mit hoher Präzision zu lokalisieren. Unser Ziel ist es, FRBs bis zu ihren Wirtsgalaxien genau zuzuordnen und dadurch zu verstehen, wie sie entstehen. Die transiente Natur der FRBs bringt jedoch verschiedene Herausforderungen mit sich, beispielsweise bei der Systemgestaltung, der benötigten Rechenleistung und der Echtzeitkommunikation, wobei die Anforderungen an die Echtzeitverarbeitung recht streng sind (einige zehn Sekunden). Eine schnelle Datenverarbeitung ist für uns entscheidend, um hochauflösende Daten der Pulse speichern zu können, sie zu lokalisieren und die Verzögerung für Nachbeobachtungen möglichst gering zu halten. Wir geben einen kurzen Überblick über die Datenanalyse-Pipeline, beschreiben die auftretenden Herausforderungen und erläutern unsere anfängliche Konzeption und Implementierung einer Echtzeit-Auslöseinfrastruktur für FRBs am MeerKAT-Teleskop.
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de
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As the fast growth and large integration of distributed generation, renewable energy resource, energy storage system and load response, the modern power system operation becomes much more complicated with increasing uncertainties and frequent changes. Increased operation risks are introduced to the existing commercial Energy Management System (EMS), due to its limited computational capability. In this paper, a high-performance EMS analysis framework based on the evolving graph is developed. A power grid is first modeled as an evolving graph and then the power system dynamic analysis applications, like network topology processing (NTP), state estimation (SE), power flow (PF), and contingency analysis (CA), are efficiently implemented on the system evolving graph to build a high-performance EMS analysis framework. Its computation performance is field tested using a 2749-bus power system in Sichuan, China. The results illustrate that the proposed EMS remarkably speeds up the computation performance and reaches the goal of real-time power system analysis.
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تقسیم شدہ تولید، قابل تجدید توانائی کے وسائل، توانائی ذخیرہ کرنے کے نظام اور لوڈ ری ایکشن کی تیز رفتار ترقی اور بڑے پیمانے پر ادراج کے ساتھ جدید بجلی کے نظام کا آپریشن غیر یقینی صورتحال اور بار بار تبدیلیوں کی بنا پر کافی حد تک پیچیدہ ہو چکا ہے۔ موجودہ تجارتی توانائی انتظامی نظام (EMS) کی محدود معلوماتی صلاحیت کی وجہ سے موجودہ آپریشن کے خطرات میں اضافہ ہوا ہے۔ اس مقالے میں، متطور گراف پر مبنی ایک اعلی کارکردگی والے EMS تجزیہ کا ڈھانچہ تیار کیا گیا ہے۔ بجلی کے جال کو پہلے ایک متطور گراف کے طور پر ماڈل کیا جاتا ہے، پھر بجلی کے نظام کے متحرک تجزیہ کے اطلاقات جیسے نیٹ ورک ٹاپولوجی پروسیسنگ (NTP)، حالت کا تخمینہ (SE)، بجلی کا بہاؤ (PF)، اور اضطراری تجزیہ (CA) کو نظام کے متطور گراف پر مؤثر طریقے سے نافذ کیا جاتا ہے تاکہ ایک اعلی کارکردگی والے EMS تجزیہ کا ڈھانچہ تشکیل دیا جا سکے۔ اس کی معلوماتی کارکردگی کا تجربہ چین کے صوبہ سیچوان میں 2749 بسز پر مشتمل بجلی کے نظام کے ذریعے میدان میں کیا گیا۔ نتائج سے ظاہر ہوتا ہے کہ پیش کردہ EMS معلوماتی کارکردگی میں نمایاں اضافہ کرتا ہے اور حقیقی وقت میں بجلی کے نظام کے تجزیہ کے مقصد کو حاصل کرتا ہے۔
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ur
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A critical discussion of the present status of the CERN experiments on charm dynamics and hadron collective flow is given. We emphasize the importance of the flow excitation function from 1 to 50 A$\cdot$GeV: here the hydrodynamic model has predicted the collapse of the $v_1$-flow and of the $v_2$-flow at $\sim 10$ A$\cdot$GeV; at 40 A$\cdot$GeV it has been recently observed by the NA49 collaboration. Since hadronic rescattering models predict much larger flow than observed at this energy we interpret this observation as potential evidence for a first order phase transition at high baryon density $\rho_B$. A detailed discussion of the collective flow as a barometer for the equation of state (EoS) of hot dense matter at RHIC follows. Additionally, detailed transport studies show that the away-side jet suppression can only partially ($<$ 50%) be due to hadronic rescattering. We, finally, propose upgrades and second generation experiments at RHIC which inspect the first order phase transition in the fragmentation region, i.e. at $\mu_B \approx 400$ MeV ($y \approx 4-5$), where the collapse of the proton flow should be seen in analogy to the 40 A$\cdot$GeV data. The study of Jet-Wake-riding potentials and Bow shocks -- caused by jets in the QGP formed at RHIC -- can give further information on the equation of state (EoS) and transport coefficients of the Quark Gluon Plasma (QGP).
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Şu anda CERN'de yapılan charmon dinamikleri ve hadron kolektif akışı deneylerinin durumu eleştirel bir şekilde tartışılıyor. 1 ile 50 A$\cdot$GeV arasındaki akış uyarım fonksiyonunun önemine vurgu yapılıyor: hidrodinamik model, $v_1$-akışının ve $v_2$-akışının yaklaşık 10 A$\cdot$GeV'de çökmesini öngörmüştü; bu çökme yaklaşık 40 A$\cdot$GeV'de yakın zamanda NA49 işbirliği tarafından gözlemlendi. Hadronik yeniden saçılma modelleri bu enerjide gözlemlenen akıştan çok daha büyük akış öngördüğü için, bu gözlemi yüksek baryon yoğunluğu $\rho_B$'da birinci dereceden bir faz geçişinin olası kanıtı olarak yorumluyoruz. Daha sonra RHIC'te sıcak ve yoğun maddenin hal denklemi (EoS) için bir barometre olarak kolektif akış ayrıntılı biçimde tartışılıyor. Ayrıca ayrıntılı taşıma çalışmaları, karşıt taraftaki jet baskılanmasının yalnızca kısmen (< %50) hadronik yeniden saçılma nedeniyle olabileceğini gösteriyor. Son olarak, bozunum bölgesinde, yani $\mu_B \approx 400$ MeV ($y \approx 4-5$) civarında, 40 A$\cdot$GeV verilerinde olduğu gibi proton akışının çökmesinin gözleneceği, birinci dereceden faz geçişini inceleyecek RHIC'te iyileştirmeler ve ikinci nesil deneyler öneriyoruz. RHIC'te oluşan Kuark Gluon Plazmasında (QGP) jetlerin oluşturduğu Jet-Uyanık-Potansiyellerin ve Püskürtme Şoklarının incelenmesi, Kuark Gluon Plazmasının (QGP) hal denklemi (EoS) ve taşıma katsayıları hakkında ek bilgi sağlayabilir.
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tr
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A recent publication provides the network graph for a neocortical microcircuit comprising 8 million connections between 31,000 neurons (H. Markram, et al., Reconstruction and simulation of neocortical microcircuitry, Cell, 163 (2015) no. 2, 456-492). Since traditional graph-theoretical methods may not be sufficient to understand the immense complexity of such a biological network, we explored whether methods from algebraic topology could provide a new perspective on its structural and functional organization. Structural topological analysis revealed that directed graphs representing connectivity among neurons in the microcircuit deviated significantly from different varieties of randomized graph. In particular, the directed graphs contained in the order of $10^7$ simplices {\DH} groups of neurons with all-to-all directed connectivity. Some of these simplices contained up to 8 neurons, making them the most extreme neuronal clustering motif ever reported. Functional topological analysis of simulated neuronal activity in the microcircuit revealed novel spatio-temporal metrics that provide an effective classification of functional responses to qualitatively different stimuli. This study represents the first algebraic topological analysis of structural connectomics and connectomics-based spatio-temporal activity in a biologically realistic neural microcircuit. The methods used in the study show promise for more general applications in network science.
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Sebuah publikasi terbaru menyajikan grafik jaringan untuk mikrosirkuit neokortikal yang terdiri dari 8 juta koneksi antara 31.000 neuron (H. Markram, dkk., Rekonstruksi dan simulasi mikrosirkuit neokortikal, Cell, 163 (2015) no. 2, 456-492). Karena metode teori grafik tradisional mungkin tidak cukup untuk memahami kompleksitas luar biasa dari jaringan biologis semacam ini, kami mengeksplorasi apakah metode dari topologi aljabar dapat memberikan perspektif baru terhadap organisasi struktural dan fungsionalnya. Analisis topologis struktural mengungkapkan bahwa grafik terarah yang merepresentasikan konektivitas antar neuron dalam mikrosirkuit menyimpang secara signifikan dari berbagai jenis grafik acak. Secara khusus, grafik terarah tersebut mengandung sekitar $10^7$ simplices {\DH} kelompok neuron dengan konektivitas terarah semua-ke-semua. Beberapa simplices ini mengandung hingga 8 neuron, menjadikannya motif pengelompokan neuron paling ekstrem yang pernah dilaporkan. Analisis topologis fungsional terhadap aktivitas neuron yang disimulasikan dalam mikrosirkuit mengungkap metrik spasial-temporal yang baru dan mampu mengklasifikasikan secara efektif respons fungsional terhadap rangsangan yang secara kualitatif berbeda. Penelitian ini merupakan analisis topologi aljabar pertama terhadap konektomika struktural dan aktivitas spasial-temporal berbasis konektomika dalam mikrosirkuit saraf yang realistis secara biologis. Metode yang digunakan dalam penelitian ini menunjukkan potensi untuk aplikasi yang lebih luas dalam ilmu jaringan.
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id
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One of the major targets for next-generation cosmic microwave background (CMB) experiments is the detection of the primordial B-mode signal. Planning is under way for Stage-IV experiments that are projected to have instrumental noise small enough to make lensing and foregrounds the dominant source of uncertainty for estimating the tensor-to-scalar ratio $r$ from polarization maps. This makes delensing a crucial part of future CMB polarization science. In this paper we present a likelihood method for estimating the tensor-to-scalar ratio $r$ from CMB polarization observations, which combines the benefits of a full-scale likelihood approach with the tractability of the quadratic delensing technique. This method is a pixel space, all order likelihood analysis of the quadratic delensed B modes, and it essentially builds upon the quadratic delenser by taking into account all order lensing and pixel space anomalies. Its tractability relies on a crucial factorization of the pixel space covariance matrix of the polarization observations which allows one to compute the full Gaussian approximate likelihood profile, as a function of $r$, at the same computational cost of a single likelihood evaluation.
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পরবর্তী প্রজন্মের মহাজাগতিক মাইক্রোতরঙ্গ পটভূমি (সিএমবি) পরীক্ষাগুলির মধ্যে একটি প্রধান লক্ষ্য হল প্রাথমিক বি-মোড সংকেতের সনাক্তকরণ। চতুর্থ পর্যায়ের পরীক্ষার জন্য পরিকল্পনা চলছে যা এমন যন্ত্রের শব্দ থাকার কথা যা যথেষ্ট ক্ষুদ্র হবে, যাতে বহুমুখীকরণ এবং পূর্বভাগীয় উপাদানগুলিকে টেন্সর-টু-স্কেলার অনুপাত $r$ অনুমানের জন্য প্রধান অনিশ্চয়তার উৎস হিসাবে প্রতিষ্ঠিত করা যায় যা ধ্রুবীকরণ মানচিত্র থেকে পাওয়া যায়। এটি ভবিষ্যতের সিএমবি ধ্রুবীকরণ বিজ্ঞানের জন্য বহুমুখীকরণ অপসারণকে অত্যন্ত গুরুত্বপূর্ণ করে তোলে। এই প্রবন্ধে, আমরা সিএমবি ধ্রুবীকরণ পর্যবেক্ষণ থেকে টেন্সর-টু-স্কেলার অনুপাত $r$ অনুমানের জন্য একটি সম্ভাব্যতা পদ্ধতি উপস্থাপন করি, যা কোয়াড্র্যাটিক বহুমুখীকরণ অপসারণ কৌশলের বাস্তবায়নের সুবিধার সাথে একটি পূর্ণাঙ্গ সম্ভাব্যতা পদ্ধতির সুবিধাগুলি একত্রিত করে। এই পদ্ধতিটি কোয়াড্র্যাটিক বহুমুখীকরণ অপসারণ করা বি-মোডগুলির পিক্সেল স্থানের সমস্ত ক্রমের সম্ভাব্যতা বিশ্লেষণ এবং এটি মূলত কোয়াড্র্যাটিক বহুমুখীকরণ অপসারণকারীকে সমস্ত ক্রমের বহুমুখীকরণ এবং পিক্সেল স্থানের অস্বাভাবিকতা বিবেচনায় নেওয়ার মাধ্যমে গঠিত। এর বাস্তবায়নের উপর নির্ভরশীল একটি গুরুত্বপূর্ণ বিষয় হল ধ্রুবীকরণ পর্যবেক্ষণের পিক্সেল স্থানের ভেদাঙ্ক ম্যাট্রিক্সের একটি গুণন, যা একক সম্ভাব্যতা মূল্যায়নের সমান গাণিতিক খরচে $r$-এর ফাংশন হিসাবে পূর্ণ গাউসীয় আসন্ন সম্ভাব্যতা প্রোফাইল গণনা করার অনুমতি দেয়।
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bn
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An interpretable system for open-domain reasoning needs to express its reasoning process in a transparent form. Natural language is an attractive representation for this purpose -- it is both highly expressive and easy for humans to understand. However, manipulating natural language statements in logically consistent ways is hard: models must cope with variation in how meaning is expressed while remaining precise. In this paper, we describe ParaPattern, a method for building models to generate deductive inferences from diverse natural language inputs without direct human supervision. We train BART-based models (Lewis et al., 2020) to generate the result of applying a particular logical operation to one or more premise statements. Crucially, we develop a largely automated pipeline for constructing suitable training examples from Wikipedia. We evaluate our models using out-of-domain sentence compositions from the QASC (Khot et al., 2020) and EntailmentBank (Dalvi et al., 2021) datasets as well as targeted perturbation sets. Our results show that our models are substantially more accurate and flexible than baseline systems. ParaPattern achieves 85% validity on examples of the 'substitution' operation from EntailmentBank without the use of any in-domain training data, matching the performance of a model fine-tuned for EntailmentBank. The full source code for our method is publicly available.
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کھلے شعبے کے استدلال کے لیے ایک تشریح کی جا سکنے والی نظام کو اپنے استدلال کے عمل کو شفاف شکل میں ظاہر کرنے کی ضرورت ہوتی ہے۔ اس مقصد کے لیے قدرتی زبان ایک پرکشش نمائندگی ہے -- یہ نہ صرف انتہائی اظہاری ہوتی ہے بلکہ انسانوں کے لیے سمجھنا بھی آسان ہوتی ہے۔ تاہم، قدرتی زبان کے بیانات کو منطقی طور پر مسلّط انداز میں استعمال کرنا مشکل ہوتا ہے: ماڈلز کو معنی کے اظہار میں ہونے والی تنوع کا سامنا کرتے ہوئے بھی درست رہنا ہوتا ہے۔ اس مقالے میں، ہم پیراپیٹرن کا تفصیلی جائزہ پیش کرتے ہیں، جو براہ راست انسانی نگرانی کے بغیر مختلف قدرتی زبان کے ادخالات سے منطقی نتائج اخذ کرنے والے ماڈلز تیار کرنے کا ایک طریقہ ہے۔ ہم بارٹ پر مبنی ماڈلز (لیوس و دیگر، 2020) کو ایک یا ایک سے زیادہ اصل بیانات پر ایک خاص منطقی عمل کو لاگو کرنے کا نتیجہ پیدا کرنے کے لیے تربیت دیتے ہیں۔ اہم بات یہ ہے کہ ہم ویکیپیڈیا سے مناسب تربیت کے مثالوں کی تعمیر کے لیے ایک زیادہ تر خودکار پائپ لائن تیار کرتے ہیں۔ ہم اپنے ماڈلز کا اطلاق QASC (کھوت و دیگر، 2020) اور انٹیلمنٹ بینک (دلّوی و دیگر، 2021) ڈیٹا سیٹس سے خارجِ شعبہ جملوں کی تشکیل کے علاوہ ہدف بنائے گئے تغیرات کے سیٹس کے ذریعے جانچتے ہیں۔ ہمارے نتائج ظاہر کرتے ہیں کہ ہمارے ماڈلز بنیادی نظاموں کے مقابلے میں کافی زیادہ درست اور لچکدار ہیں۔ پیراپیٹرن بغیر کسی داخلِ شعبہ تربیتی ڈیٹا کے انٹیلمنٹ بینک کے 'تبدیلی' کے عمل کی مثالوں پر 85 فیصد درستگی حاصل کرتا ہے، جو انٹیلمنٹ بینک کے لیے مخصوص طور پر فائن ٹیون کیے گئے ماڈل کی کارکردگی کے برابر ہے۔ ہمارے طریقہ کا مکمل سورس کوڈ عوامی طور پر دستیاب ہے۔
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ur
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New algorithms for efficient decoding of polar codes (which may be CRC-augmented), transmitted over either a binary erasure channel (BEC) or an additive white Gaussian noise channel (AWGNC), are presented. We start by presenting a new efficient exact maximum likelihood decoding algorithm for the BEC based on inactivation decoding and analyze its computational complexity. This algorithm applies a matrix triangulation process on a sparse polar code parity check matrix, followed by solving a small size linear system over GF(2). We then consider efficient decoding of polar codes, transmitted over the AWGNC. The algorithm applies CRC-aided belief propagation list (CBPL) decoding, followed by ordered statistics decoding (OSD) of low order. Even when the reprocessing order of the OSD is as low as one, the new decoder is shown to significantly improve on plain CBPL. To implement the OSD efficiently, we adapt the matrix triangulation algorithm from the BEC case. We also indicate how the decoding algorithms can be implemented in parallel for low latency decoding. Numerical simulations are used to evaluate the performance and computational complexity of the new algorithms.
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ပေါလာကုဒ်များ (CRC ဖြင့် တိုးချဲ့ထားနိုင်သည်) ကို ဒွိဖျက်သိမ်းရေးချိန် (BEC) သို့မဟုတ် ထည့်သွင်းအသုံးပြုသည့် အဖြူရောင်ဂေါ့စီယန်း အသံဆူညံမှု ချိန် (AWGNC) တို့ပေါ်တွင် ထုတ်လွှတ်သည့်အခါ ထိရောက်စွာ ဒီကုဒ်ဖြေရန် အတွက် အယ်လ်ဂိုရီသမ်များကို တင်ပြသည်။ အင်အားကောင်းသော မဟုတ်ပါက ဒီကုဒ်ဖြေခြင်းအတွက် အသစ်ဖြစ်ပြီး ထိရောက်သော တိကျသည့် အများဆုံးဖြစ်နိုင်ခြေ ဒီကုဒ်ဖြေခြင်း အယ်လ်ဂိုရီသမ်ကို မိတ်ဆက်ပြီး ၎င်း၏ တွက်ချက်မှု ရှုပ်ထွေးမှုကို ဆန်းစစ်သည်။ ဤအယ်လ်ဂိုရီသမ်သည် ပေါလာကုဒ်၏ မျှော်လင့်ချက်စစ်ဆေးမှု မက်ထရစ် တစ်ခုကို အသုံးပြု၍ မက်ထရစ် တြိဂံဖြစ်အောင် လုပ်ပြီးနောက် GF(2) အပေါ်တွင် အရွယ်အစားသေးငယ်သော လီနီယာစနစ်ကို ဖြေရှင်းခြင်းဖြစ်သည်။ ထို့နောက် AWGNC ပေါ်တွင် ထုတ်လွှတ်သည့် ပေါလာကုဒ်များ၏ ထိရောက်သော ဒီကုဒ်ဖြေခြင်းကို စဉ်းစားသည်။ အယ်လ်ဂိုရီသမ်သည် CRC ကူညီသော ယုံကြည်မှု ပျံ့နှံ့မှု စာရင်း (CBPL) ဒီကုဒ်ဖြေခြင်းကို အသုံးပြုပြီး နိမ့်ကျသော အဆင့်အတန်း စီထားသည့် စာရင်းဒီကုဒ်ဖြေခြင်း (OSD) ကို ဆက်လက်အသုံးပြုသည်။ OSD ၏ ပြန်လည်လုပ်ဆောင်မှု အဆင့်သည် တစ်ခုသာဖြစ်သော်လည်း အသစ်သော ဒီကုဒ်ဖြေစက်သည် ရိုးရိုး CBPL ကို သိသိသာသာ မြှင့်တင်ပေးကြောင်း ပြသထားသည်။ OSD ကို ထိရောက်စွာ အကောင်အထည်ဖော်ရန်အတွက် BEC အခြေအနေမှ မက်ထရစ် တြိဂံဖြစ်အောင်လုပ်သည့် အယ်လ်ဂိုရီသမ်ကို အသုံးပြုပြောင်းလဲသည်။ နိမ့်ကျသော နှောင့်နှေးမှု ဒီကုဒ်ဖြေခြင်းအတွက် ဒီကုဒ်ဖြေခြင်း အယ်လ်ဂိုရီသမ်များကို အပြိုင်အလုံးစုံ အကောင်အထည်ဖော်နိုင်ကြောင်းကိုလည်း ညွှန်ပြသည်။ အသစ်သော အယ်လ်ဂိုရီသမ်များ၏ စွမ်းဆောင်ရည်နှင့် တွက်ချက်မှု ရှုပ်ထွေးမှုကို အကဲဖြတ်ရန် ကိန်းဂဏန်း စမ်းသပ်မှုများကို အသုံးပြုသည်။
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my
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A phenomenological analysis of lifetimes of bottom and charmed hadrons within the framework of the heavy quark expansion is performed. The baryon matrix element is evaluated using the bag model and the nonrelativistic quark model. We find that bottom-baryon lifetimes follow the pattern $\tau(\Omega_b)\simeq\tau(\Xi_b^-)>\tau(\Lambda_b)\simeq\tau(\Xi_b^0)$. However, neither the lifetime ratio $\tau(\Lambda_b)/\tau( B_d)$ nor the absolute decay rates of the $\Lambda_b$ baryon and $B$ mesons can be explained. One way of solving both difficulties is to allow the presence of linear $1/m_Q$ corrections by scaling the inclusive nonleptonic width with the fifth power of the hadron mass $m_{H_Q}$ rather than the heavy quark mass $m_Q$. The hierarchy of bottom baryon lifetimes is dramatically modified to $\tau(\Lambda_b)>\tau(\Xi_b^-)>\tau(\Xi_b^0)>\tau( \Omega_b)$: The longest-lived $\Omega_b$ among bottom baryons in the OPE prescription now becomes shortest-lived. The replacement of $m_Q$ by $m_{H_Q}$ in nonleptonic widths is natural and justified in the PQCD-based factorization approach formulated in terms of hadron-level kinematics. For inclusive charmed baryon decays, we argue that since the heavy quark expansion does not converge, local duality cannot be tested in this case. We show that while the ansatz of substituting the heavy quark mass by the hadron mass provides a much better description of the charmed-baryon lifetime {\it ratios}, it appears unnatural and unpredictive for describing the {\it absolute} inclusive decay rates of charmed baryons, contrary to the bottom case.
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在重夸克展开的框架内，对底夸克和粲夸克强子的寿命进行了唯象分析。重子矩阵元通过袋模型和非相对论夸克模型进行计算。我们发现，底重子寿命呈现出 $\tau(\Omega_b)\simeq\tau(\Xi_b^-)>\tau(\Lambda_b)\simeq\tau(\Xi_b^0)$ 的模式。然而，无论是 $\tau(\Lambda_b)/\tau( B_d)$ 的寿命比，还是 $\Lambda_b$ 重子与 $B$ 介子的绝对衰变率，都无法得到解释。解决这两个困难的一种方法是引入线性的 $1/m_Q$ 修正项，即在非轻子衰变宽度中使用强子质量 $m_{H_Q}$ 的五次方代替重夸克质量 $m_Q$ 进行标度。这一修正显著改变了底重子寿命的层级关系，变为 $\tau(\Lambda_b)>\tau(\Xi_b^-)>\tau(\Xi_b^0)>\tau( \Omega_b)$：在OPE方案中原先寿命最长的 $\Omega_b$ 底重子，现在变为寿命最短的。在基于PQCD的因子化方法中，以强子层次运动学表述时，将非轻子衰变宽度中的 $m_Q$ 替换为 $m_{H_Q}$ 是自然且合理的。对于包含粲重子的衰变，我们认为由于重夸克展开在此情况下不收敛，因而无法检验局域对偶性。我们指出，尽管用强子质量替代重夸克质量的假设能更好地描述粲重子寿命的比值，但与底夸克情况相反，这种方法在描述粲重子包含衰变的绝对衰变率时显得不自然且缺乏预测能力。
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zh
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We present ALMA and ACA [CI]$^{3}P_{1}-^{3}P_{0}$ ([CI](1-0)) observations of NGC6240, which we combine with ALMA CO(2-1) and IRAM PdBI CO(1-0) data to study the physical properties of the massive molecular (H$_2$) outflow. We discover that the receding and approaching sides of the H$_2$ outflow, aligned east-west, exceed 10 kpc in their total extent. High resolution ($0.24"$) [CI](1-0) line images surprisingly reveal that the outflow emission peaks between the two AGNs, rather than on either of the two, and that it dominates the velocity field in this nuclear region. We combine the [CI](1-0) and CO(1-0) data to constrain the CO-to-H$_2$ conversion factor ($\alpha_{\rm CO}$) in the outflow, which is on average $2.1\pm1.2~\rm M_{\odot} (K~km~s^{-1}~pc^2)^{-1}$. We estimate that $60\pm20$ % of the total H$_2$ gas reservoir of NGC6240 is entrained in the outflow, for a resulting mass-loss rate of $\dot{M}_{\rm out}=2500\pm1200~M_{\odot}~yr^{-1}$ $\equiv 50\pm30$ SFR. This energetics rules out a solely star formation-driven wind, but the puzzling morphology challenges a classic radiative-mode AGN feedback scenario. For the quiescent gas we compute $\langle\alpha_{\rm CO}\rangle = 3.2\pm1.8~\rm M_{\odot} (K~km~s^{-1}~pc^2)^{-1}$, which is at least twice the value commonly employed for (U)LIRGs. We observe a tentative trend of increasing $r_{21}\equiv L^{\prime}_{\rm CO(2-1)}/L^{\prime}_{\rm CO(1-0)}$ ratios with velocity dispersion and measure $r_{21}>1$ in the outflow, whereas $r_{21}\simeq1$ in the quiescent gas. We propose that molecular outflows are the location of the warmer, strongly unbound phase that partially reduces the opacity of the CO lines in (U)LIRGs, hence driving down their global $\alpha_{\rm CO}$ and increasing their $r_{21}$ values.
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Presentiamo osservazioni ALMA e ACA della transizione [CI]$^{3}P_{1}-^{3}P_{0}$ ([CI](1-0)) di NGC6240, che combiniamo con dati ALMA della linea CO(2-1) e dati IRAM PdBI della linea CO(1-0) per studiare le proprietà fisiche dell'outflow molecolare massiccio (H$_2$). Scopriamo che i lati in recessione e in avvicinamento dell'outflow di H$_2$, allineati est-ovest, superano complessivamente un'estensione di 10 kpc. Immagini ad alta risoluzione ($0.24"$) della linea [CI](1-0) rivelano in modo sorprendente che l'emissione dell'outflow presenta un massimo tra i due AGN, piuttosto che su uno dei due, e che domina il campo di velocità in questa regione nucleare. Combiniamo i dati [CI](1-0) e CO(1-0) per vincolare il fattore di conversione da CO ad H$_2$ ($\alpha_{\rm CO}$) nell'outflow, il cui valore medio è $2.1\pm1.2~\rm M_{\odot} (K~km~s^{-1}~pc^2)^{-1}$. Stimiamo che il $60\pm20$ % dell'intero serbatoio di gas H$_2$ di NGC6240 sia coinvolto nell'outflow, con un tasso di perdita di massa risultante di $\dot{M}_{\rm out}=2500\pm1200~M_{\odot}~yr^{-1}$ $\equiv 50\pm30$ SFR. Questa energetica esclude un vento generato esclusivamente dalla formazione stellare, ma la morfologia enigmatica contrasta con uno scenario classico di retroazione AGN in modalità radiativa. Per il gas tranquillo calcoliamo $\langle\alpha_{\rm CO}\rangle = 3.2\pm1.8~\rm M_{\odot} (K~km~s^{-1}~pc^2)^{-1}$, valore almeno doppio rispetto a quello comunemente utilizzato per le (U)LIRG. Osserviamo una tendenza indicativa di aumenti del rapporto $r_{21}\equiv L^{\prime}_{\rm CO(2-1)}/L^{\prime}_{\rm CO(1-0)}$ con la dispersione di velocità e misuriamo $r_{21}>1$ nell'outflow, mentre $r_{21}\simeq1$ nel gas tranquillo. Proponiamo che gli outflow molecolari siano la sede della fase più calda e fortemente non legata che riduce parzialmente l'opacità delle linee CO nelle (U)LIRG, determinando così una diminuzione del loro $\alpha_{\rm CO}$ globale e un aumento dei valori di $r_{21}$.
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it
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We show that typical behaviors of market participants at the high frequency scale generate leverage effect and rough volatility. To do so, we build a simple microscopic model for the price of an asset based on Hawkes processes. We encode in this model some of the main features of market microstructure in the context of high frequency trading: high degree of endogeneity of market, no-arbitrage property, buying/selling asymmetry and presence of metaorders. We prove that when the first three of these stylized facts are considered within the framework of our microscopic model, it behaves in the long run as a Heston stochastic volatility model, where leverage effect is generated. Adding the last property enables us to obtain a rough Heston model in the limit, exhibiting both leverage effect and rough volatility. Hence we show that at least part of the foundations of leverage effect and rough volatility can be found in the microstructure of the asset.
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আমরা দেখাই যে উচ্চ ফ্রিকোয়েন্সি স্কেলে বাজারের অংশগ্রহণকারীদের সাধারণ আচরণ লিভারেজ প্রভাব এবং রাফ অস্থিরতা তৈরি করে। এটি করার জন্য, আমরা হকস প্রক্রিয়ার উপর ভিত্তি করে একটি সম্পদের দামের জন্য একটি সাধারণ সূক্ষ্ম মডেল তৈরি করি। উচ্চ ফ্রিকোয়েন্সি ট্রেডিংয়ের প্রেক্ষাপটে বাজারের সূক্ষ্ম কাঠামোর কিছু প্রধান বৈশিষ্ট্য আমরা এই মডেলে অন্তর্ভুক্ত করি: বাজারের উচ্চ মাত্রার অন্তর্জাতিকতা, নো-আরবিট্রাজ বৈশিষ্ট্য, ক্রয়/বিক্রয় অসমতা এবং মেটাঅর্ডারের উপস্থিতি। আমরা প্রমাণ করি যে যখন এই ধরনের স্টাইলাইজড তথ্যগুলির প্রথম তিনটি আমাদের সূক্ষ্ম মডেলের কাঠামোতে বিবেচনা করা হয়, তখন দীর্ঘমেয়াদে এটি একটি হেস্টন স্টোকাস্টিক ভলাটিলিটি মডেলের মতো আচরণ করে, যেখানে লিভারেজ প্রভাব তৈরি হয়। শেষ বৈশিষ্ট্যটি যোগ করলে আমরা সীমাতে একটি রাফ হেস্টন মডেল পাই, যেখানে লিভারেজ প্রভাব এবং রাফ অস্থিরতা উভয়ই দেখা যায়। তাই আমরা দেখাই যে লিভারেজ প্রভাব এবং রাফ অস্থিরতার অন্তত অংশবিশেষের ভিত্তি সম্পদের সূক্ষ্ম কাঠামোতে পাওয়া যায়।
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bn
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We present a new family of zero-field Ising models over $N$ binary variables/spins obtained by consecutive "gluing" of planar and $O(1)$-sized components and subsets of at most three vertices into a tree. The polynomial-time algorithm of the dynamic programming type for solving exact inference (computing partition function) and exact sampling (generating i.i.d. samples) consists in a sequential application of an efficient (for planar) or brute-force (for $O(1)$-sized) inference and sampling to the components as a black box. To illustrate the utility of the new family of tractable graphical models, we first build a polynomial algorithm for inference and sampling of zero-field Ising models over $K_{3,3}$-minor-free topologies and over $K_{5}$-minor-free topologies -- both are extensions of the planar zero-field Ising models -- which are neither genus - nor treewidth-bounded. Second, we demonstrate empirically an improvement in the approximation quality of the NP-hard problem of inference over the square-grid Ising model in a node-dependent non-zero "magnetic" field.
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เราเสนอตระกูลใหม่ของโมเดลไอซิงแบบสนามศูนย์ (zero-field Ising models) ที่มีตัวแปร/สปินแบบไบนารีจำนวน $N$ ตัว ซึ่งได้มาจากการ "ต่อกัน" อย่างต่อเนื่องขององค์ประกอบที่มีลักษณะระนาบและองค์ประกอบขนาด $O(1)$ รวมถึงชุดย่อยที่มีจุดสุดยอดไม่เกินสามจุดเข้าด้วยกันในรูปแบบต้นไม้ อัลกอริธึมแบบพหุนามที่ใช้การเขียนโปรแกรมแบบพลวัต (dynamic programming) สำหรับการอนุมานแบบแม่นยำ (การคำนวณฟังก์ชันพาร์ติชัน) และการสุ่มตัวอย่างแบบแม่นยำ (การสร้างตัวอย่างที่เป็นอิสระและเหมือนกัน) ประกอบด้วยการประยุกต์ใช้ขั้นตอนวิธีการอนุมานและการสุ่มตัวอย่างที่มีประสิทธิภาพ (สำหรับกรณีระนาบ) หรือแบบแรงดิบ (brute-force) (สำหรับกรณีขนาด $O(1)$) กับแต่ละองค์ประกอบอย่างต่อเนื่อง โดยถือองค์ประกอบเหล่านั้นเป็นกล่องดำ (black box) เพื่อแสดงให้เห็นถึงประโยชน์ของตระกูลโมเดลเชิงกราฟที่สามารถจัดการได้นี้ เราได้สร้างอัลกอริธึมแบบพหุนามสำหรับการอนุมานและการสุ่มตัวอย่างของโมเดลไอซิงแบบสนามศูนย์บนโครงสร้างที่ไม่มีไมเนอร์ $K_{3,3}$ และบนโครงสร้างที่ไม่มีไมเนอร์ $K_{5}$ ซึ่งทั้งสองกรณีเป็นการขยายจากโมเดลไอซิงแบบสนามศูนย์ที่มีลักษณะระนาบ โดยโครงสร้างดังกล่าวไม่อยู่ในขอบเขตที่จำกัดด้วยพันธุกรรม (genus) หรือความกว้างของต้นไม้ (treewidth) ต่อมา เราได้แสดงให้เห็นโดยการทดลองถึงการปรับปรุงคุณภาพของการประมาณผลสำหรับปัญหาการอนุมานซึ่งเป็นปัญหาแบบ NP-hard บนโมเดลไอซิงที่มีโครงข่ายรูปสี่เหลี่ยมจัตุรัสภายใต้สนาม "แม่เหล็ก" ที่ไม่เป็นศูนย์และขึ้นอยู่กับโหนด
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th
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We develop a robust coarse-grained model for single and double stranded DNA by representing each nucleotide by three interaction sites (TIS) located at the centers of mass of sugar, phosphate, and base. The resulting TIS model includes base-stacking, hydrogen bond, and electrostatic interactions as well as bond-stretching and bond angle potentials that account for the polymeric nature of DNA. The choices of force constants for stretching and the bending potentials were guided by a Boltzmann inversion procedure using a large representative set of DNA structures extracted from the Protein Data Bank. Some of the parameters in the stacking interactions were calculated using a learning procedure, which ensured that the experimentally measured melting temperatures of dimers are faithfully reproduced. Without any further adjustments, the calculations based on the TIS model reproduces the experimentally measured salt and sequence dependence of the size of single stranded DNA (ssDNA), as well as the persistence lengths of poly(dA) and poly(dT) chains. Interestingly, upon application of mechanical force the extension of poly(dA) exhibits a plateau, which we trace to the formation of stacked helical domains. In contrast, the force-extension curve (FEC) of poly(dT) is entropic in origin, and could be described by a standard polymer model. We also show that the persistence length of double stranded DNA is consistent with the prediction based on the worm-like chain. The persistence length, which decreases with increasing salt concentration, is in accord with the Odijk-Skolnick-Fixman theory intended for stiff polyelectrolyte chains near the rod limit. The range of applications, which did not require adjusting any parameter after the initial construction based solely on PDB structures and melting profiles of dimers, attests to the transferability and robustness of the TIS model for ssDNA and dsDNA.
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Tek ve çift iplikli DNA için, her nükleotidi şeker, fosfat ve bazın kütle merkezlerinde yer alan üç etkileşim bölgesiyle (TIS) temsil ederek sağlam bir kaba tanecikli model geliştiriyoruz. Elde edilen TIS modeli, DNA'nın polimerik yapısını hesaba katan bağ uzama ve bağ açısı potansiyellerinin yanı sıra, baz yığılma, hidrojen bağı ve elektrostatik etkileşimleri de içerir. Uzama ve bükülme potansiyelleri için seçilen kuvvet sabitleri, Protein Veri Bankası'ndan çıkarılan büyük bir temsili DNA yapı seti kullanılarak Boltzmann tersine çevrim yöntemiyle belirlenmiştir. Yığılma etkileşimlerindeki bazı parametreler, dimerlerin deneysel olarak ölçülen erime sıcaklıklarının doğru bir şekilde yeniden üretildiğini garanti eden bir öğrenme yöntemiyle hesaplanmıştır. Herhangi bir ek ayarlamaya gerek kalmadan, TIS modeline dayalı hesaplamalar, tek iplikli DNA'nın (ssDNA) boyutunun tuz ve dizi bağımlılığını deneysel olarak ölçülen değerlerle uyumlu şekilde yeniden üretir. Ayrıca, poli(dA) ve poli(dT) zincirlerinin kırılma uzunlukları da doğru şekilde verilir. İlginç bir şekilde, mekanik kuvvet uygulandığında poli(dA)'nın uzaması bir plaто gösterir ve bu durumu yığılmış heliks alanlarının oluşumuna bağlarız. Buna karşılık, poli(dT)'nin kuvvet-uzama eğrisi (FEC) entropik kökenlidir ve standart bir polimer modeliyle tanımlanabilir. Ayrıca, çift iplikli DNA'nın kırılma uzunluğunun solucan-benzeri zincir modelinin öngörüsüyle tutarlı olduğunu gösteriyoruz. Tuz konsantrasyonu arttıkça azalan kırılma uzunluğu, çubuk sınırına yakın sert polielektrolit zincirler için tasarlanan Odijk-Skolnick-Fixman teorisiyle uyumludur. Modelin uygulama alanları, başlangıçta yalnızca PDB yapıları ve dimerlerin erime profilleri temel alınarak oluşturulduktan sonra herhangi bir parametrenin ayarlanmamasına rağmen geniş bir başarım sergilemiş olup, TIS modelinin ssDNA ve dsDNA için taşıyabilirliğini ve sağlam yapısını kanıtlamaktadır.
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tr
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Pyrochlore systems ($A_{2}B_{2}O_{7}$) with $A$-site rare-earth local moments and $B$-site $5d$ conduction electrons offer excellent material platforms for the discovery of exotic quantum many-body ground states. Notable examples include U(1) quantum spin liquid of the local moments and semimetallic non-Fermi liquid of the conduction electrons. Here we investigate emergent quantum phases and their transitions driven by the Kondo lattice coupling between such highly entangled quantum ground states. Using the renormalization group method, it is shown that weak Kondo lattice coupling is irrelevant, leading to a fractionalized semimetal phase with decoupled local moments and conduction electrons. Upon increasing the Kondo lattice coupling, this phase is unstable to the formation of broken symmetry states. Particularly important is the opposing influence of the Kondo lattice coupling and long-range Coulomb interaction. The former prefers to break the particle-hole symmetry while the latter tends to restore it. The characteristic competition leads to possibly multiple phase transitions, first from a fractionalized semimetal phase to a fractionalized Fermi surface state with particle-hole pockets, followed by the second transition to a fractionalized ferromagnetic state. Multiscale quantum critical behaviors appear at nonzero temperatures and with external magnetic field near such quantum phase transitions. We discuss the implication of these results to the experiments on Pr$_2$Ir$_2$O$_7$.
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Пирохлорные системы ($A_{2}B_{2}O_{7}$) с локальными магнитными моментами редкоземельных элементов на позициях $A$ и проводящими электронами $5d$ на позициях $B$ представляют собой превосходные материальные платформы для обнаружения экзотических квантовых многотельных основных состояний. Среди примечательных примеров — спиновая жидкость с симметрией U(1) локальных моментов и полуметаллическая неФерми-жидкость проводящих электронов. В данной работе мы исследуем возникающие квантовые фазы и их переходы, вызванные решётчатой связью Кондо между такими сильно запутанными квантовыми основными состояниями. С помощью метода ренормгруппы показано, что слабая решётчатая связь Кондо является нерелевантной, что приводит к фракционализованной полуметаллической фазе с разъединёнными локальными моментами и проводящими электронами. При увеличении решётчатой связи Кондо эта фаза становится неустойчивой по отношению к образованию состояний с нарушенной симметрией. Особую важность представляет противоположное влияние решётчатой связи Кондо и дальнодействующего кулоновского взаимодействия. Первое стремится нарушить симметрию частица-дырка, в то время как второе, напротив, стремится восстановить её. Характерная конкуренция приводит к возможному наличию нескольких фазовых переходов: сначала от фракционализованной полуметаллической фазы к состоянию с фракционализованной ферми-поверхностью, содержащей карманы частиц и дырок, а затем ко второму переходу — в фракционализованное ферромагнитное состояние. Многошкальное квантовое критическое поведение проявляется при ненулевых температурах и во внешнем магнитном поле вблизи таких квантовых фазовых переходов. Обсуждаются последствия полученных результатов для экспериментов на Pr$_2$Ir$_2$O$_7$.
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ru
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We study quantum correlations and discord in a bipartite continuous variable hybrid system formed by linear combinations of coherent states $|\alpha\rangle$ and single photon added coherent states (SPACS) of the form $|\psi\rangle_{\text{dp(pa)}}= \mathcal{N}/\sqrt{2} (\hat{a}^\dagger |\alpha\rangle_a |\alpha\rangle_b \pm \hat{b}^\dagger |\alpha\rangle_a |\alpha\rangle_b)$. We stablish a relationship between the quantum discord with a local observable (the quadrature variance for one sub-system) under the influence of scattering and phase fluctuation noise. For the pure states the quantum correlations are characterized by means of measurement induced disturbance (MID) with simultaneous quadrature measurements. In a scenario where homodyne conditional measurements are available we show that the MID provides an easy way to select optimal phases to obtain information of the maximal correlations in the channels. The quantum correlations of these entangled states with channel losses are quantitatively characterized with the quantum discord (QD) with a displaced qubit projector. We observe that as scattering increases, QD decreases monotonically. At the same time for the state $|\psi\rangle_{\text{dp}}$, QD is more resistant to high phase fluctuations when the average photon number $n_0$ is bigger than zero, but if phase fluctuations are low, QD is more resistant if $n_0=0$. For the dp model with scattering, we obtain an analytical expression of the QD as a function of the observable quadrature variance in a local sub-system. This relation allows us to have a way to obtain the degree of QD in the channel by just measuring a local property observable such as the quadrature variance. For the other model this relation still exists but is explored numerically. This relation is an important result that allows to identify quantum processing capabilities in terms of just local observables.
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Studujeme kvantové korelace a diskord v bipartitním hybridním systému s nepřetržitými proměnnými, který je tvořen lineárními kombinacemi koherentních stavů $|\alpha\rangle$ a koherentních stavů s přidaným jedním fotonem (SPACS) ve tvaru $|\psi\rangle_{\text{dp(pa)}}= \mathcal{N}/\sqrt{2} (\hat{a}^\dagger |\alpha\rangle_a |\alpha\rangle_b \pm \hat{b}^\dagger |\alpha\rangle_a |\alpha\rangle_b)$. Stanovíme vztah mezi kvantovým diskordem a lokální pozorovatelnou veličinou (rozptylem kvadratury pro jeden podsystém) za přítomnosti šumu způsobeného rozptylem a fluktuacemi fáze. Pro čisté stavy jsou kvantové korelace charakterizovány pomocí poruchy vyvolané měřením (MID) při současných měřeních kvadratur. Ve scénáři, kdy jsou k dispozici homodyně podmíněná měření, ukazujeme, že MID poskytuje jednoduchý způsob výběru optimálních fází pro získání informace o maximálních korelacích v kanálech. Kvantové korelace těchto provázaných stavů za přítomnosti ztrát v kanále jsou kvantitativně charakterizovány kvantovým diskordem (QD) pomocí posunutého qubitového projektoru. Pozorujeme, že s rostoucím rozptylem QD monotónně klesá. Současně pro stav $|\psi\rangle_{\text{dp}}$ je QD odolnější vůči vysokým fázovým fluktuacím, když střední počet fotonů $n_0$ je větší než nula, ale pokud jsou fázové fluktuace nízké, je QD odolnější při $n_0=0$. Pro dp model s rozptylem získáme analytický výraz pro QD jako funkci pozorovatelného rozptylu kvadratury v lokálním podsystému. Tento vztah umožňuje určit míru QD v kanále pouhým měřením lokální pozorovatelné veličiny, jako je rozptyl kvadratury. Pro druhý model tento vztah rovněž existuje, ale je prozkoumán numericky. Tento vztah je důležitým výsledkem, který umožňuje identifikovat kvantové zpracovatelské schopnosti pouze na základě lokálních pozorovatelných veličin.
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cs
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We present a systematic derivation of a model based on the central moment lattice Boltzmann equation that rigorously maintains Galilean invariance of forces to simulate inertial frame independent flow fields. In this regard, the central moments, i.e. moments shifted by the local fluid velocity, of the discrete source terms of the lattice Boltzmann equation are obtained by matching those of the continuous full Boltzmann equation of various orders. This results in an exact hierarchical identity between the central moments of the source terms of a given order and the components of the central moments of the distribution functions and sources of lower orders. The corresponding source terms in velocity space are then obtained from an exact inverse transformation due to a suitable choice of orthogonal basis for moments. Furthermore, such a central moment based kinetic model is further extended by incorporating reduced compressibility effects to represent incompressible flow. Moreover, the description and simulation of fluid turbulence for full or any subset of scales or their averaged behavior should remain independent of any inertial frame of reference. Thus, based on the above formulation, a new approach in lattice Boltzmann framework to incorporate turbulence models for simulation of Galilean invariant statistical averaged or filtered turbulent fluid motion is discussed.
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Isinasalarawan namin ang isang sistematikong pagkuha ng isang modelo batay sa lattice Boltzmann equation na gumagamit ng central moment na mahigpit na nagpapanatili ng Galilean invariance ng mga puwersa upang masimulan ang mga field ng daloy na malaya sa inertial na balangkas. Sa ganitong pagtingin, ang mga central moment, iyon ay, mga moment na nailipat batay sa lokal na bilis ng likido, ng diskretong mga terminong pinagmulan ng lattice Boltzmann equation ay natutukoy sa pamamagitan ng pagtutugma sa mga katumbas nito mula sa tuloy-tuloy na buong Boltzmann equation sa iba't ibang mga order. Nagreresulta ito sa isang eksaktong hierarkikal na pagkakakilanlan sa pagitan ng mga central moment ng mga terminong pinagmulan sa isang partikular na order at ang mga bahagi ng mga central moment ng mga function ng pamamahagi at mga pinagmulan sa mas mababang order. Ang mga koresponding terminong pinagmulan sa espasyo ng bilis ay natutukoy naman sa pamamagitan ng isang eksaktong pagbabalik ng transpormasyon dahil sa angkop na pagpili ng orthogonal na basehan para sa mga moment. Higit pa rito, ang naturang modelo ng central moment na batay sa kinetic ay karagdagang pinapalawak sa pamamagitan ng pagsasama ng mga epekto ng nabawasang compressibility upang kumatawan sa daloy na hindi mapaparami. Bukod dito, ang paglalarawan at pagsimula ng turbulensiya ng likido para sa buong o anumang subset ng mga sukat o ang kanilang nai-averagyong pag-uugali ay dapat manatiling malaya sa anumang inertial na balangkas ng sanggunian. Samakatuwid, batay sa nabanggit na pormulasyon, isang bagong pamamaraan sa loob ng lattice Boltzmann framework upang isama ang mga modelo ng turbulensiya para sa pagsimula ng Galilean invariant na nai-averagyong estadistika o nafilter na turbulenteng kilusan ng likido ay talakayin.
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tl
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Large amounts of labeled training data are one of the main contributors to the great success that deep models have achieved in the past. Label acquisition for tasks other than benchmarks can pose a challenge due to requirements of both funding and expertise. By selecting unlabeled examples that are promising in terms of model improvement and only asking for respective labels, active learning can increase the efficiency of the labeling process in terms of time and cost. In this work, we describe combinations of an incremental learning scheme and methods of active learning. These allow for continuous exploration of newly observed unlabeled data. We describe selection criteria based on model uncertainty as well as expected model output change (EMOC). An object detection task is evaluated in a continuous exploration context on the PASCAL VOC dataset. We also validate a weakly supervised system based on active and incremental learning in a real-world biodiversity application where images from camera traps are analyzed. Labeling only 32 images by accepting or rejecting proposals generated by our method yields an increase in accuracy from 25.4% to 42.6%.
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Grandes quantidades de dados rotulados para treinamento são um dos principais fatores responsáveis pelo grande sucesso que os modelos profundos alcançaram no passado. A obtenção de rótulos para tarefas que não sejam benchmarks pode representar um desafio devido aos requisitos de financiamento e expertise. Ao selecionar exemplos não rotulados promissores em termos de melhoria do modelo e solicitar apenas os rótulos correspondentes, o aprendizado ativo pode aumentar a eficiência do processo de rotulagem em termos de tempo e custo. Neste trabalho, descrevemos combinações de um esquema de aprendizado incremental e métodos de aprendizado ativo. Essas combinações permitem a exploração contínua de novos dados não rotulados observados. Descrevemos critérios de seleção baseados na incerteza do modelo, bem como na mudança esperada na saída do modelo (EMOC). Uma tarefa de detecção de objetos é avaliada em um contexto de exploração contínua no conjunto de dados PASCAL VOC. Também validamos um sistema de supervisão fraca baseado em aprendizado ativo e incremental em uma aplicação real de biodiversidade, na qual imagens de armadilhas fotográficas são analisadas. Rotular apenas 32 imagens, aceitando ou rejeitando propostas geradas pelo nosso método, resulta em um aumento na precisão de 25,4% para 42,6%.
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pt
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Making use of both MUSE observations of 85 galaxies from the survey GASP (GAs Stripping Phenomena in galaxies with MUSE) and a large sample from MaNGA (Mapping Nearby Galaxies at Apache Point Observatory survey) we investigate the distribution of gas metallicity gradients as a function of stellar mass, for local cluster and field galaxies. Overall, metallicity profiles steepen with increasing stellar mass up to $10^{10.3}\,{\rm M_\odot}$ and flatten out at higher masses. Combining the results from the metallicity profiles and the stellar mass surface density gradients, we propose that the observed steepening is a consequence of local metal enrichment due to in-situ star formation during the inside-out formation of disk galaxies. The metallicity gradient-stellar mass relation is characterized by a rather large scatter, especially for $10^{9.8}<{\rm M_\star/M_\odot}<10^{10.5}$, and we demonstrate that metallicity gradients anti-correlate with the galaxy gas fraction. Focusing on the galaxy environment, at any given stellar mass, cluster galaxies have systematically flatter metallicity profiles than their field counterparts. Many sub-populations coexist in clusters: galaxies with shallower metallicity profiles appear to have fallen into their present host halo sooner and have experienced the environmental effects for a longer time than cluster galaxies with steeper metallicity profiles. Recent galaxy infallers, like galaxies currently undergoing ram-pressure stripping, show metallicity gradients more similar to those of field galaxies, suggesting they have not felt the effect of the cluster yet.
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GASP (GAs Stripping Phenomena in galaxies with MUSE) জরিপ থেকে 85টি ছায়াপথের MUSE পর্যবেক্ষণ এবং MaNGA (Mapping Nearby Galaxies at Apache Point Observatory জরিপ) থেকে একটি বৃহৎ নমুনার উপর ভিত্তি করে আমরা স্থানীয় গুচ্ছ ও ক্ষেত্রের ছায়াপথগুলির জন্য তারকীয় ভরের ফাংশন হিসাবে গ্যাস ধাতবতা ঢালের বন্টন নিয়ে গবেষণা করি। মোটের উপর, ধাতবতার প্রোফাইলগুলি $10^{10.3}\,{\rm M_\odot}$ পর্যন্ত তারকীয় ভর বৃদ্ধির সাথে সাথে খাড়া হয় এবং উচ্চতর ভরে সমতল হয়ে যায়। ধাতবতা প্রোফাইল এবং তারকীয় ভর পৃষ্ঠের ঘনত্ব ঢালের ফলাফলগুলি একত্রিত করে, আমরা প্রস্তাব করি যে পর্যবেক্ষিত খাড়া হওয়াটি চাকতি আকৃতির ছায়াপথগুলির অভ্যন্তরীণ থেকে বাহিরের দিকে গঠনের সময় স্থানীয় তারকার গঠনের ফলে স্থানীয় ধাতব সমৃদ্ধির ফলাফল। ধাতবতা ঢাল-তারকীয় ভর সম্পর্কটি বিশেষত $10^{9.8}<{\rm M_\star/M_\odot}<10^{10.5}$ এর জন্য বেশ বড় ছড়ানোর দ্বারা চিহ্নিত করা হয়, এবং আমরা দেখাই যে ধাতবতা ঢালগুলি ছায়াপথ গ্যাস ভগ্নাংশের সাথে বিপরীত সম্পর্ক দেখায়। ছায়াপথ পরিবেশের দিকে মনোনিবেশ করে, যেকোনো নির্দিষ্ট তারকীয় ভরের জন্য গুচ্ছ ছায়াপথগুলির ধাতবতার প্রোফাইল তাদের ক্ষেত্রের সদৃশ ছায়াপথগুলির তুলনায় সিস্টেম্যাটিকভাবে সমতল। গুচ্ছগুলিতে অনেক উপ-জনসংখ্যা একসাথে বাস করে: কম ঢালযুক্ত ধাতবতা প্রোফাইল সহ ছায়াপথগুলি মনে হয় তাদের বর্তমান হোস্ট হ্যালোতে আগে পড়েছে এবং খাড়া ধাতবতা প্রোফাইল সহ গুচ্ছ ছায়াপথগুলির তুলনায় দীর্ঘতর সময় ধরে পরিবেশগত প্রভাব অনুভব করেছে। সদ্য ছায়াপথ অনুপ্রবেশকারীরা, যেমন বর্তমানে র্যাম-চাপ স্ট্রিপিংয়ের মুখোমুখি ছায়াপথগুলি, ক্ষেত্র ছায়াপথগুলির সাথে আরও মিল রাখে এমন ধাতবতা ঢাল দেখায়, যা ইঙ্গিত দেয় যে তারা এখনও গুচ্ছের প্রভাব অনুভব করেনি।
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bn
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We present results from the zeroth-order imaging of a Chandra HETGS observation of the nearby Seyfert 2 galaxy Circinus. Twelve X-ray sources were detected in the ACIS-S image of the galaxy, embedded in diffuse X-ray emission. The latter shows a prominent (~18arcsec) soft ``plume'' in the N-W direction, coincident with the [OIII] ionization cone. The radial profiles of the brightest X-ray source at various energies are consistent with an unresolved (FWHM ~0.8arcsec) component, which we identify as the active nucleus, plus two extended components with FWHMs ~ 2.3arcsec and 18arcsec, respectively. In a radius of 3arcsec, the nucleus contributes roughly the same flux as the extended components at the softest energies (< 2 keV). However, at harder energies (> 2 keV), the contribution of the nucleus is dominant. The zeroth-order ACIS spectrum of the nucleus exhibits emission lines at both soft and hard X-rays, including a prominent Fe Kalpha line at 6.4 keV, showing that most of the X-ray lines previously detected with ASCA originate in a compact region (<15 pc). Based on its X-ray spectrum, we argue that the 2.3arcsec extended component is scattered nuclear radiation from nearby ionized gas. The large-scale extended component includes the emission from the N-W plume and possibly from the outer starburst ring.
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Біз жақын орналасқан Сейферт 2 галактикасы — Циркуль бойынша Chandra HETGS бақылауының нөлдік ретті бейнелеу нәтижелерін ұсынамыз. Галактиканың ACIS-S бейнесінде диффузиялық рентген сәулесінің ортасында он екі рентген көзі табылды. Соңғысы солтүстік-батыс бағытта [OIII] иондау конусымен сәйкес келетін бір айқын (≈18arcsec) жұмсақ «желбіршекті» көрсетеді. Әртүрлі энергиялардағы ең жарық рентген көзінің радиалдық профилдері шешілмеген (FWHM ≈0,8arcsec) компонентпен, сондай-ақ FWHM-і шамамен 2,3arcsec және 18arcsec болатын екі кеңейтілген компонентпен сәйкес келеді, олардың бірін біз белсенді ядро ретінде анықтаймыз. 3arcsec радиусында ядро жұмсақтығы ең төмен энергияларда (< 2 кэВ) кеңейтілген компоненттермен шамамен бірдей ағын үлесін қосады. Алайда, қаттырақ энергияларда (> 2 кэВ) ядроның үлесі басым болады. Ядроның нөлдік ретті ACIS спектрі жұмсақ және қатты рентген сәулелерінде, соның ішінде 6,4 кэВ-тағы айқын Fe Kalpha сызығында шығару сызықтарын көрсетеді, бұл ASCA-мен бұрын анықталған рентген сызықтарының көбі компактты аймақта (<15 пк) пайда болғанын көрсетеді. Оның рентген спектрі негізінде біз 2,3arcsec кеңейтілген компоненті жақын иондалған газдан шашыраған ядролық сәулелену екенін болжаймыз. Үлкен масштабты кеңейтілген компонент солтүстік-батыс желбіршегінің шығаруын және, мүмкін, сыртқы жұлдызды жарқыл сақинасын қамтиды.
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kk
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Fast Radio Bursts (FRBs) are bright enigmatic radio pulses of roughly millisecond duration that come from extragalactic distances. As part of the MeerTRAP project, we use the MeerKAT telescope array in South Africa to search for and localise those bursts to high precision in real-time. We aim to pinpoint FRBs to their host galaxies and, thereby, to understand how they are created. However, the transient nature of FRBs presents various challenges, e.g. in system design, raw compute power and real-time communication, where the real-time requirements are reasonably strict (a few tens of seconds). Rapid data processing is essential for us to be able to retain high-resolution data of the bursts, to localise them, and to minimise the delay for follow-up observations. We give a short overview of the data analysis pipeline, describe the challenges faced, and elaborate on our initial design and implementation of a real-time triggering infrastructure for FRBs at the MeerKAT telescope.
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Ledakan Radio Pantas (FRB) adalah denyutan radio terang yang penuh teka-teki dengan tempoh kira-kira milisaat yang berasal dari jarak luar galaksi. Sebagai sebahagian daripada projek MeerTRAP, kami menggunakan tatasusunan teleskop MeerKAT di Afrika Selatan untuk mencari dan menentukan lokasi denyutan tersebut secara tepat dalam masa sebenar. Matlamat kami adalah untuk menentukan lokasi tepat FRB ke galaksi perumahnya dan dengan itu memahami bagaimana ia terbentuk. Namun begitu, sifat sementara FRB membawa pelbagai cabaran, seperti dalam reka bentuk sistem, kuasa pengiraan kasar dan komunikasi masa sebenar, di mana keperluan masa sebenar adalah agak ketat (beberapa puluh saat). Pemprosesan data yang pantas adalah penting bagi kami untuk dapat mengekalkan data resolusi tinggi denyutan tersebut, menentukan lokasinya, dan meminimumkan kelewatan bagi pemerhatian susulan. Kami memberikan gambaran ringkas tentang paip talian analisis data, menghuraikan cabaran-cabaran yang dihadapi, serta menerangkan secara terperinci rekabentuk awal dan pelaksanaan infrastruktur pencetus masa sebenar untuk FRB di teleskop MeerKAT.
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ms
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Using the density-matrix renormalization group technique, we study a one-dimensional spin-$\frac{1}{2}$ Heisenberg chain consisting of coupled tetramers as an effective spin model for copper vanadate CuInVO$_5$. We obtain the ground-state phase diagram as a function of intra-tetramer and inter-tetramer exchange interactions, exhibiting two multimerized valence-bond-solid (VBS) phases : one is characterized by the formation of tetramer-singlet units; the other by the formation of dimer-singlet pairs. We show that the finite spin gaps in both the VBS phases smoothly vanish at the phase boundary: a second order phase transition defining a quantum critical point (QCP). The phase boundary is also captured by the fact that the central charge is unity at the phase boundary and zero otherwise in the thermodynamic limit. We further demonstrate that the experimental magnetization curve (which starts increasing with zero or tiny field) can be reasonably explained only by assuming the exchange parameters of CuInVO$_5$ to be very close to the phase boundary. Thus, we argue that CuInVO$_5$ may be a first example material which at ambient pressure stands near a QCP between two VBS phases. By varying the balance of exchange interactions with pressure, a transition from N\'eel to either of the VBS phases could be observed.
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ঘনত্ব-ম্যাট্রিক্স পুনঃসামান্যকরণ গ্রুপ কৌশল ব্যবহার করে, আমরা কপার ভ্যানাডেট CuInVO$_5$-এর জন্য একটি কার্যকর স্পিন মডেল হিসাবে যুক্ত টেট্রামারগুলির গঠনকারী এক-মাত্রিক স্পিন-$\frac{1}{2}$ হেইজেনবার্গ শৃঙ্খলের অধ্যয়ন করি। আমরা টেট্রামার-অভ্যন্তরীণ এবং টেট্রামার-মধ্যবর্তী বিনিময় মিথস্ক্রিয়ার ফাংশন হিসাবে ভূমি-অবস্থার পর্যায় চিত্র পাই, যা দুটি বহুলকীকৃত ভ্যালেন্স-বন্ড-সলিড (VBS) পর্যায় প্রদর্শন করে: একটি টেট্রামার-সিঙ্গলেট এককের গঠনের দ্বারা চিহ্নিত হয়; অন্যটি ডাইমার-সিঙ্গলেট জোড়ের গঠনের দ্বারা। আমরা দেখাই যে উভয় VBS পর্যায়ে সসীম স্পিন ফাঁকগুলি পর্যায় সীমানায় মসৃণভাবে শূন্যে পরিণত হয়: একটি দ্বিতীয় ক্রমের পর্যায় রূপান্তর যা একটি কোয়ান্টাম সমালোচনা বিন্দু (QCP) নির্ধারণ করে। তাপগতীয় সীমায় পর্যায় সীমানায় কেন্দ্রীয় চার্জের একক এবং অন্যত্র শূন্য হওয়ার তথ্যটি দ্বারাও পর্যায় সীমানাটি ধরা পড়ে। আমরা আরও দেখাই যে পরীক্ষালব্ধ চৌম্বকীকরণ বক্ররেখা (যা শূন্য বা অতি ক্ষুদ্র ক্ষেত্রের সাথে বৃদ্ধি পায়) কেবলমাত্র CuInVO$_5$-এর বিনিময় পরামিতির পর্যায় সীমানার খুব কাছাকাছি থাকার ধারণা করলেই যুক্তিযুক্তভাবে ব্যাখ্যা করা যায়। সুতরাং, আমরা যুক্তি দেই যে CuInVO$_5$ প্রথম উদাহরণের উপাদান হতে পারে যা স্বাভাবিক চাপে দুটি VBS পর্যায়ের মধ্যে একটি QCP-এর কাছাকাছি অবস্থান করে। চাপের সাথে বিনিময় মিথস্ক্রিয়ার ভারসাম্য পরিবর্তন করে N\'eel থেকে যে কোনো একটি VBS পর্যায়ে রূপান্তর পর্যবেক্ষণ করা যেতে পারে।
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bn
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We made a supplemental study of the superoutbursts and superhumps in SU UMa stars by using the recently released Kepler public data of V1504 Cyg and V344 Lyr. One of the superoutbursts in V1504 Cyg was preceded by a precursor normal outburst which was well separated from the main superoutburst. The superhump first appeared during the descending branch of the precursor normal outburst and it continued into quiescence (the deep dip between the precursor and the main superoutburst), and it began to grow in amplitude with the growth of the main superoutburst after quiescence ended. A similar phenomenon was also observed in V344 Lyr. This observation demonstrates very clearly that the superoutburst was triggered by the superhump (i.e., by the tidal instability), supporting the thermal-tidal instability model. Smak (2013, Acta Astron., 63, 109, arXiv:1301.0187) criticized our previous paper (Osaki and Kato, 2013, PASJ, 65, 50, arXiv:1212.1516) and challenged our main conclusion that various observational lines of evidence of V1504 Cyg support the thermal-tidal instability model for the superoutbursts of SU UMa stars. We present our detailed accounts to all of his criticisms by offering clear explanations. We conclude that the thermal-tidal instability model is after all only the viable model for the superoutbursts and superhumps in SU UMa stars.
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Realizamos um estudo complementar das supererupções e superprotuberâncias em estrelas SU UMa utilizando dados públicos recentemente disponibilizados pelo Kepler de V1504 Cyg e V344 Lyr. Uma das supererupções em V1504 Cyg foi precedida por uma erupção normal precursora, bem separada da supererupção principal. A superprotuberância apareceu pela primeira vez durante o ramo decrescente da erupção normal precursora e continuou durante a quiescência (o declínio acentuado entre a precursora e a supererupção principal), começando a aumentar em amplitude com o crescimento da supererupção principal após o fim da quiescência. Um fenômeno semelhante também foi observado em V344 Lyr. Essa observação demonstra muito claramente que a supererupção foi desencadeada pela superprotuberância (ou seja, pela instabilidade tidal), apoiando o modelo de instabilidade térmico-tidal. Smak (2013, Acta Astron., 63, 109, arXiv:1301.0187) criticou nosso artigo anterior (Osaki e Kato, 2013, PASJ, 65, 50, arXiv:1212.1516) e contestou nossa principal conclusão de que várias evidências observacionais de V1504 Cyg apoiam o modelo de instabilidade térmico-tidal para as supererupções de estrelas SU UMa. Apresentamos nossas respostas detalhadas a todas as suas críticas, oferecendo explicações claras. Concluímos que, afinal, o modelo de instabilidade térmico-tidal é o único modelo viável para as supererupções e superprotuberâncias em estrelas SU UMa.
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The Supernova Cosmology Project has discovered over twenty-eight supernovae (SNe) at 0.35 <z < 0.65 in an ongoing program that uses Type Ia SNe as high-redshift distance indicators. Here we present measurements of the ratio between the locally observed and global Hubble constants, H_0^L/H_0^G, based on the first 7 SNe of this high-redshift data set compared with 18 SNe at z <= 0.1 from the Calan/Tololo survey. If Omega_M <= 1, then light-curve-width corrected SN magnitudes yield H_0^L/H_0^G < 1.10 (95% confidence level) in both a Lambda=0 and a flat universe. The analysis using the SNe Ia as standard candles without a light-curve-width correction yields similar results. These results rule out the hypothesis that the discrepant ages of the Universe derived from globular clusters and recent measurements of the Hubble constant are attributable to a locally underdense bubble. Using the Cepheid-distance-calibrated absolute magnitudes for SNe Ia of Sandage (1996}, we can also measure the global Hubble constant, H_0^G. If Omega_M >= 0.2, we find that H_0^G < 70 km/s/Mpc in a Lambda=0 universe and H_0^G < 78 km/s/Mpc in a flat universe, correcting the distant and local SN apparent magnitudes for light curve width. Lower results for H_0^G are obtained if the magnitudes are not width corrected.
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Dự án Thiên văn học Siêu tân tinh đã phát hiện hơn hai mươi tám siêu tân tinh (SNe) ở dải 0,35 <z < 0,65 trong một chương trình đang tiếp tục sử dụng các siêu tân tinh loại Ia như những chỉ báo khoảng cách ở độ dịch đỏ cao. Ở đây chúng tôi trình bày các phép đo tỷ số giữa hằng số Hubble quan sát tại chỗ và hằng số Hubble toàn cục, H_0^L/H_0^G, dựa trên bảy siêu tân tinh đầu tiên trong tập dữ liệu độ dịch đỏ cao này so sánh với 18 siêu tân tinh ở z <= 0,1 từ khảo sát Calan/Tololo. Nếu Omega_M <= 1, thì các độ sáng đã hiệu chỉnh theo bề rộng đường cong ánh sáng của siêu tân tinh cho ra H_0^L/H_0^G < 1,10 (mức tin cậy 95%) trong cả vũ trụ có Lambda=0 và vũ trụ phẳng. Phân tích sử dụng siêu tân tinh Ia như những ngọn nến chuẩn mà không hiệu chỉnh bề rộng đường cong ánh sáng cũng cho kết quả tương tự. Những kết quả này loại trừ giả thuyết rằng sự khác biệt về tuổi của vũ trụ suy ra từ các cụm sao cầu và các phép đo gần đây về hằng số Hubble là do một bong bóng mật độ thấp tại địa phương. Sử dụng các độ sáng tuyệt đối đã được hiệu chuẩn theo khoảng cách Cepheid đối với siêu tân tinh Ia của Sandage (1996), chúng tôi cũng có thể đo hằng số Hubble toàn cục, H_0^G. Nếu Omega_M >= 0,2, chúng tôi thấy rằng H_0^G < 70 km/s/Mpc trong vũ trụ có Lambda=0 và H_0^G < 78 km/s/Mpc trong vũ trụ phẳng, khi đã hiệu chỉnh độ sáng biểu kiến của siêu tân tinh xa và gần theo bề rộng đường cong ánh sáng. Các giá trị thấp hơn đối với H_0^G thu được nếu các độ sáng không được hiệu chỉnh theo bề rộng.
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Let $\mathcal{P}({\bf N})$ be the power set of $\bf N$. An upper density (on $\bf N$) is a non\-decreasing and subadditive function $\mu^\ast: \mathcal{P}({\bf N})\to\bf R$ such that $\mu^\ast({\bf N}) = 1$ and $\mu^\ast(k \cdot X + h) = \frac{1}{k} \mu^\ast(X)$ for all $X \subseteq \bf N$ and $h,k \in {\bf N}^+$, where $k \cdot X + h := \{kx + h: x \in X\}$. The upper asymptotic, upper Banach, upper logarithmic, upper Buck, upper P\'olya, and upper analytic densities are examples of upper densities. We show that every upper density $\mu^\ast$ has the strong Darboux property, and so does the associated lower density, where a function $f: \mathcal P({\bf N}) \to \bf R$ is said to have the strong Darboux property if, whenever $X \subseteq Y \subseteq \bf N$ and $a \in [f(X),f(Y)]$, there is a set $A$ such that $X\subseteq A\subseteq Y$ and $f(A)=a$. In fact, we prove the above under the assumption that the monotonicity of $\mu^\ast$ is relaxed to the weaker condition that $\mu^\ast(X) \le 1$ for every $X \subseteq \bf N$.
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Nechť $\mathcal{P}({\bf N})$ značí potenční množinu množiny $\bf N$. Horní hustota (na $\bf N$) je neklesající a subaditivní funkce $\mu^\ast: \mathcal{P}({\bf N})\to\bf R$, pro kterou platí $\mu^\ast({\bf N}) = 1$ a $\mu^\ast(k \cdot X + h) = \frac{1}{k} \mu^\ast(X)$ pro všechny množiny $X \subseteq \bf N$ a čísla $h,k \in {\bf N}^+$, kde $k \cdot X + h := \{kx + h: x \in X\}$. Příklady horních hustot jsou horní asymptotická, horní Banachova, horní logaritmická, horní Buckova, horní Pólyova a horní analytická hustota. Ukazujeme, že každá horní hustota $\mu^\ast$ má silnou Darbouxovu vlastnost, stejně tak i příslušná dolní hustota, přičemž říkáme, že funkce $f: \mathcal P({\bf N}) \to \bf R$ má silnou Darbouxovu vlastnost, jestliže pro každé $X \subseteq Y \subseteq \bf N$ a každé $a \in [f(X),f(Y)]$ existuje množina $A$ taková, že $X\subseteq A\subseteq Y$ a $f(A)=a$. Ve skutečnosti dokazujeme výše uvedené tvrzení za předpokladu, že podmínka monotonie funkce $\mu^\ast$ je oslabena na slabší podmínku, že $\mu^\ast(X) \le 1$ pro každou množinu $X \subseteq \bf N$.
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cs
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General relativity can be formulated equivalently with a non-Riemannian geometry that associates with an affine connection of nonzero nonmetricity $Q$ but vanishing curvature $R$ and torsion $T$. Modification based on this description of gravity generates the $f(Q)$ gravity. In this work we explore the application of $f(Q)$ gravity to the spherically symmetric configurations. We discuss the gauge fixing and connections in this setting. We demonstrate the effects of $f(Q)$ by considering the external and internal solutions of compact stars. The external background solutions for any regular form of $f(Q)$ coincide with the corresponding solutions in general relativity, i.e., the Schwarzschild-de Sitter solution and the Reissner-Nordstr\"om-de Sitter solution with an electromagnetic field. For internal structure, with a simple model $f(Q)=Q+\alpha Q^2$ and a polytropic equation of state, we find that a negative modification ($\alpha<0$) provides support to more stellar masses while a positive one ($\alpha>0$) reduces the amount of matter of the star.
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Obecnou teorii relativity lze formulovat ekvivalentně pomocí neřímanovské geometrie, která je spojena s afinní konexí s nenulovou nenulovou nemetrickostí $Q$, ale s mizivou křivostí $R$ a torzí $T$. Modifikace založená na tomto popisu gravitace vede na gravitaci $f(Q)$. V této práci prozkoumáváme aplikaci gravitace $f(Q)$ na sféricky symetrické konfigurace. Diskutujeme fixaci kalibračního pole a konexe v tomto kontextu. Ukazujeme vliv $f(Q)$ na vnější a vnitřní řešení kompaktních hvězd. Vnější řešení na pozadí pro jakoukoli regulární formu $f(Q)$ souhlasí s odpovídajícími řešeními obecné teorie relativity, tj. Schwarzschildovým-de Sitterovým řešením a Reissner-Nordströmovým-de Sitterovým řešením s elektromagnetickým polem. Pro vnitřní strukturu s jednoduchým modelem $f(Q)=Q+\alpha Q^2$ a polytropní stavovou rovnicí zjišťujeme, že záporná modifikace ($\alpha<0$) umožňuje existenci větších hmot hvězd, zatímco kladná modifikace ($\alpha>0$) snižuje množství hmoty hvězdy.
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cs
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Learning a graph topology to reveal the underlying relationship between data entities plays an important role in various machine learning and data analysis tasks. Under the assumption that structured data vary smoothly over a graph, the problem can be formulated as a regularised convex optimisation over a positive semidefinite cone and solved by iterative algorithms. Classic methods require an explicit convex function to reflect generic topological priors, e.g. the $\ell_1$ penalty for enforcing sparsity, which limits the flexibility and expressiveness in learning rich topological structures. We propose to learn a mapping from node data to the graph structure based on the idea of learning to optimise (L2O). Specifically, our model first unrolls an iterative primal-dual splitting algorithm into a neural network. The key structural proximal projection is replaced with a variational autoencoder that refines the estimated graph with enhanced topological properties. The model is trained in an end-to-end fashion with pairs of node data and graph samples. Experiments on both synthetic and real-world data demonstrate that our model is more efficient than classic iterative algorithms in learning a graph with specific topological properties.
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ການຮຽນຮູ້ໂຄງສ້າງຂອງເຄືອຂ່າຍເພື່ອເປີດເຜີຍຄວາມສຳພັນທີ່ແທ້ຈິງລະຫວ່າງຂໍ້ມູນຂອງຂໍ້ມູນມີບົດບາດສຳຄັນໃນການວຽກງານດ້ານການຮຽນຮູ້ຂອງເຄື່ອງຈັກ ແລະ ການວິເຄາະຂໍ້ມູນຕ່າງໆ. ໂດຍອີງໃສ່ຂໍ້ສົມມຸດວ່າຂໍ້ມູນທີ່ມີໂຄງສ້າງປ່ຽນແປງຢ່າງລຽບລຽນໄປຕາມເຄືອຂ່າຍ, ບັນຫາດັ່ງກ່າວສາມາດຖືກຈັດໃຫ້ເປັນບັນຫາການເພີ່ມປະສິດທິພາບໂຄງສ້າງທີ່ເປັນເອກະພາບໃນຂອບເຂດຂອງເຄືອຂ່າຍທີ່ເປັນບວກ ແລະ ສາມາດແກ້ໄຂໄດ້ໂດຍການໃຊ້ຂະບວນການຊ້ຳ. ວິທີການດັ້ງເດີມຕ້ອງການຟັງຊັ່ນໂຄງສ້າງທີ່ຊັດເຈນເພື່ອສະທ້ອນໃຫ້ເຫັນເຖິງຂໍ້ຮູ້ທົ່ວໄປກ່ຽວກັບໂຄງສ້າງ, ຕົວຢ່າງເຊັ່ນ ການລົງໂທດ $\ell_1$ ເພື່ອຮັກສາຄວາມຫ່າງ, ຊຶ່ງຈຳກັດຄວາມຍືດຫຍຸ່ນ ແລະ ຄວາມສາມາດໃນການສະແດງອອກເຖິງໂຄງສ້າງທີ່ສັບຊ້ອນຫຼາຍ. ພວກເຮົາຂໍສະເໜີການຮຽນຮູ້ການແຜນທີ່ຈາກຂໍ້ມູນຂອງຈຸດໝາຍ (node data) ໄປຫາໂຄງສ້າງຂອງເຄືອຂ່າຍໂດຍອີງໃສ່ແນວຄິດຂອງ "ການຮຽນຮູ້ເພື່ອເພີ່ມປະສິດທິພາບ" (L2O). ໂດຍສະເພາະ, ລະບົບຂອງພວກເຮົາຈະຄ່ອຍໆປ່ຽນຂະບວນການແບ່ງສ່ວນຂັ້ນຕອນທີ່ຊ້ຳໆໃຫ້ເປັນເຄືອຂ່າຍປັນຍາປະດິດ. ການໂຄ້ດຄ້າງໂຄງສ້າງສຳຄັນຈະຖືກປ່ຽນແທນດ້ວຍ variational autoencoder ທີ່ຊ່ວຍປັບປຸງຄວາມຖືກຕ້ອງຂອງເຄືອຂ່າຍທີ່ຖືກຄາດຄະເນຂຶ້ນ ໂດຍເພີ່ມຄຸນສົມບັດທາງໂຄງສ້າງໃຫ້ດີຂຶ້ນ. ລະບົບຖືກຝຶກໂດຍໃຊ້ຂໍ້ມູນຂອງຈຸດໝາຍ ແລະ ຕົວຢ່າງຂອງເຄືອຂ່າຍໃນຮູບແບບຄູ່ ແລະ ໂດຍການຝຶກແບບທັງໝົດຈາກຕົ້ນຫາເຖິງທ້າຍທາງ. ການທົດລອງກ່ຽວກັບຂໍ້ມູນທີ່ສ້າງຂຶ້ນ ແລະ ຂໍ້ມູນຈິງທີ່ເກີດຂຶ້ນໃນໂລກຈິງສະແດງໃຫ້ເຫັນວ່າລະບົບຂອງພວກເຮົາມີປະສິດທິພາບດີກວ່າຂະບວນການຊ້ຳດັ້ງເດີມໃນການຮຽນຮູ້ເຄືອຂ່າຍທີ່ມີຄຸນສົມບັດທາງໂຄງສ້າງທີ່ຊັດເຈນ.
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lo
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A critical discussion of the present status of the CERN experiments on charm dynamics and hadron collective flow is given. We emphasize the importance of the flow excitation function from 1 to 50 A$\cdot$GeV: here the hydrodynamic model has predicted the collapse of the $v_1$-flow and of the $v_2$-flow at $\sim 10$ A$\cdot$GeV; at 40 A$\cdot$GeV it has been recently observed by the NA49 collaboration. Since hadronic rescattering models predict much larger flow than observed at this energy we interpret this observation as potential evidence for a first order phase transition at high baryon density $\rho_B$. A detailed discussion of the collective flow as a barometer for the equation of state (EoS) of hot dense matter at RHIC follows. Additionally, detailed transport studies show that the away-side jet suppression can only partially ($<$ 50%) be due to hadronic rescattering. We, finally, propose upgrades and second generation experiments at RHIC which inspect the first order phase transition in the fragmentation region, i.e. at $\mu_B \approx 400$ MeV ($y \approx 4-5$), where the collapse of the proton flow should be seen in analogy to the 40 A$\cdot$GeV data. The study of Jet-Wake-riding potentials and Bow shocks -- caused by jets in the QGP formed at RHIC -- can give further information on the equation of state (EoS) and transport coefficients of the Quark Gluon Plasma (QGP).
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Diskusi kritis mengenai status saat ini eksperimen CERN tentang dinamika keanggunan (charm) dan aliran kolektif hadron diberikan. Kami menekankan pentingnya fungsi eksitasi aliran dari 1 hingga 50 A$\cdot$GeV: di sini model hidrodinamika telah memprediksi runtuhnya aliran $v_1$ dan aliran $v_2$ pada sekitar 10 A$\cdot$GeV; pada 40 A$\cdot$GeV hal ini baru-baru ini diamati oleh kolaborasi NA49. Karena model hamburan ulang hadron memprediksi aliran yang jauh lebih besar daripada yang diamati pada energi ini, kami menafsirkan pengamatan ini sebagai bukti potensial adanya transisi fasa orde pertama pada rapatan barion tinggi $\rho_B$. Diskusi terperinci mengenai aliran kolektif sebagai barometer untuk persamaan keadaan (EoS) materi panas dan pekat di RHIC disajikan selanjutnya. Selain itu, studi transpor terperinci menunjukkan bahwa penekanan jet sisi-jauh hanya dapat sebagian kecil (< 50%) disebabkan oleh hamburan ulang hadron. Kami akhirnya mengusulkan peningkatan fasilitas dan eksperimen generasi kedua di RHIC yang mengamati transisi fasa orde pertama di wilayah fragmentasi, yaitu pada $\mu_B \approx 400$ MeV ($y \approx 4-5$), di mana runtuhnya aliran proton seharusnya dapat diamati secara analog dengan data pada 40 A$\cdot$GeV. Studi mengenai potensial Jet-Wake-riding dan kejutan haluan (bow shocks) -- yang disebabkan oleh jet dalam QGP yang terbentuk di RHIC -- dapat memberikan informasi tambahan mengenai persamaan keadaan (EoS) dan koefisien transport plasma kuark-gluon (QGP).
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id
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We study the implications of Ultra-High Energy Cosmic Ray (UHECR) data from the Pierre Auger Observatory for potential accelerator candidates and cosmogenic neutrino fluxes for different combinations of nuclear disintegration and air-shower models. We exploit the most recent spectral and mass composition data (2017) with a new, computationally very efficient simulation code PriNCe. We extend the systematic framework originally developed by the Pierre Auger Collaboration with the cosmological source evolution as an additional free parameter. In this framework, an ensemble of generalized UHECR accelerators is characterized by a universal spectral index (equal for all injection species), a maximal rigidity, and the normalizations for five nuclear element groups. We find that the 2017 data favor a small but constrained contribution of heavy elements (iron) at the source. We demonstrate that the results moderately depend on the nuclear disintegration (PSB, Peanut, or Talys) model, and more strongly on the air-shower (EPOS-LHC, Sibyll-2.3, or QGSjet-II-04) model. Variations of these models result in different source evolutions and spectral indices, limiting the interpretation in terms of a particular class of cosmic accelerators. Better constrained parameters include the maximal rigidity and the mass composition at the source. Hence, the cosmogenic neutrino flux can be robustly predicted, since it originates from interactions with the cosmic infrared background and peaks at $10^8 \, \mathrm{GeV}$. Depending on the source evolution at high redshifts the flux is likely out of reach of future neutrino observatories in most cases, and a minimal cosmogenic neutrino flux cannot be claimed from data without assuming a cosmological distribution of the sources.
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ພວກເຮົາສຶກສາຜົນກະທົບຂອງຂໍ້ມູນລັງສີຈາກຈັກກະວານພະລັງງານສູງຫຼາຍ (UHECR) ຈາກສະຖານີດຳເນີນການ Pierre Auger ສຳລັບຜູ້ສະໜອງພະລັງງານທີ່ເປັນໄປໄດ້ ແລະ ຄວາມເຂັ້ມຂອງນິວຕຣິໂນທີ່ເກີດຈາກຈັກກະວານ ໂດຍອີງໃສ່ການປະສົມປະສານທີ່ແຕກຕ່າງກັນຂອງຮູບແບບການແຍກນິວເຄຍ ແລະ ຮູບແບບຂອງເຫດການລັງສີໃນອາກາດ. ພວກເຮົານຳໃຊ້ຂໍ້ມູນລ້າສຸດດ້ານສະເປັກຕຼັມ ແລະ ປະກອບສ່ວນຂອງມວນ (2017) ຮ່ວມກັບລະຫັດການສຳລັບການຈຳລອງທີ່ມີປະສິດທິພາບສູງໃນດ້ານຄອມພິວເຕີ້ຊື່ວ່າ PriNCe. ພວກເຮົາຂະຫຍາຍຂອບເຂດການສຶກສາທີ່ພັດທະນາຂຶ້ນເດີມໂດຍກຸ່ມງານ Pierre Auger ໂດຍເພີ່ມການພັດທະນາຂອງແຫຼ່ງກຳເນີດໃນຈັກກະວານເປັນຕົວແປເສລີເພີ່ມເຕີມ. ໃນຂອບເຂດນີ້, ກຸ່ມຂອງເຄື່ອງເຮັດໃຫ້ເກີດພະລັງງານ UHECR ທີ່ກວ້າງຂວາງຖືກອະທິບາຍດ້ວຍດັດສະນີສະເປັກຕຼັມສາກົນ (ເທົ່າກັນສຳລັບທຸກສະເປຊີທີ່ຖືກສົ່ງເຂົ້າ), ຄວາມແຂງແຮງສູງສຸດ, ແລະ ການປັບຄ່າປົກກະຕິສຳລັບກຸ່ມຂອງອົງປະກອບນິວເຄຍຈຳນວນຫ້າກຸ່ມ. ພວກເຮົາພົບວ່າຂໍ້ມູນປີ 2017 ສະແດງໃຫ້ເຫັນເຖິງການມີສ່ວນຮ່ວມຂອງອົງປະກອບໜັກ (ເຫຼັກ) ທີ່ແຫຼ່ງກຳເນີດທີ່ນ້ອຍແຕ່ຖືກຈຳກັດ. ພວກເຮົາສະແດງໃຫ້ເຫັນວ່າຜົນໄດ້ຮັບຂຶ້ນກັບຮູບແບບການແຍກນິວເຄຍ (PSB, Peanut, ຫຼື Talys) ໃນລະດັບປານກາງ, ແລະ ຂຶ້ນກັບຮູບແບບຂອງເຫດການລັງສີໃນອາກາດ (EPOS-LHC, Sibyll-2.3, ຫຼື QGSjet-II-04) ໃນລະດັບທີ່ແຂງແຮງກວ່າ. ການປ່ຽນແປງຂອງຮູບແບບເຫຼົ່ານີ້ນຳໄປສູ່ການພັດທະນາຂອງແຫຼ່ງກຳເນີດ ແລະ ດັດສະນີສະເປັກຕຼັມທີ່ແຕກຕ່າງກັນ, ເຊິ່ງຈຳກັດການຕີຄວາມໝາຍໃນແງ່ຂອງກຸ່ມຂອງເຄື່ອງເຮັດໃຫ້ເກີດພະລັງງານຈາກຈັກກະວານໃດໜຶ່ງ. ຕົວແປທີ່ຖືກຈຳກັດຢ່າງດີແມ່ນຄວາມແຂງແຮງສູງສຸດ ແລະ ປະກອບສ່ວນຂອງມວນທີ່ແຫຼ່ງກຳເນີດ. ດັ່ງນັ້ນ, ຄວາມເຂັ້ມຂອງນິວຕຣິໂນທີ່ເກີດຈາກຈັກກະວານສາມາດຄາດຄະເນໄດ້ຢ່າງໜັກແໜ້ນ, ເນື່ອງຈາກມັນເກີດຈາກການມີສ່ວນຮ່ວມກັບພື້ນຖານລັງສີແດງຈາກຈັກກະວານ ແລະ ມີຈຸດສູງສຸດຢູ່ທີ່ $10^8 \, \mathrm{GeV}$. ຂຶ້ນກັບການພັດທະນາຂອງແຫຼ່ງກຳເນີດໃນເຂດທີ່ມີການເລື່ອນສີແດງສູງ, ຄວາມເຂັ້ມຂອງນີ້ມັກຈະຢູ່ນອກຂອບເຂດຂອງສະຖານີດຳເນີນການສຳຫຼັບນິວຕຣິໂນໃນອະນາຄົດໃນສ່ວນໃຫຍ່ຂອງກໍລະນີ, ແລະ ຄວາມເຂັ້ມຂອງນິວຕຣິໂນທີ່ເກີດຈາກຈັກກະວານຕ່ຳສຸດບໍ່ສາມາດຖືກຢືນຢັນຈາກຂໍ້ມູນໄດ້ໂດຍບໍ່ຕ້ອງການຖ້າຫາກບໍ່ມີການສົມມຸດວ່າແຫຼ່ງກຳເນີດມີການແຜ່ກະຈາຍໃນຈັກກະວານ.
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lo
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In the last decade, several works have focused on exploring the material and electrical properties of $\text{GeTe/Sb}_{2}\text{Te}_{3}$ superlattices (SLs) in particular because of some first device implementations demonstrating interesting performances such as fast switching speed, low energy consumption, and non-volatility. However, the switching mechanism in such SL-based devices remains under debate. In this work, we investigate the prototype $\text{GeTe/Sb}_{2}\text{Te}_{3}$ SLs, to analyze fundamentally their electronic and thermal properties by ab initio methods. We find that the resistive contrast is small among the different phases of $\text{GeTe/Sb}_{2}\text{Te}_{3}$ because of a small electronic gap (about 0.1 eV) and a consequent semi-metallic-like behavior. At the same time the out-of-plane lattice thermal conductivity is rather small, while varying up to four times among the different phases, from 0.11 to 0.45 W/m$^{-1}$K$^{-1}$, intimately related to the number of Van der Waals (VdW) gaps in a unit block. Such findings confirm the importance of the thermal improvement achievable in $\text{GeTe/Sb}_{2}\text{Te}_{3}$ super-lattices devices, highlighting the impact of the material stacking and the role of VdW gaps on the thermal engineering of the Phase-Change Memory cell.
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ក្នុងទសវត្សរ៍ចុងក្រោយ ការងារជាច្រើនបានផ្តោតលើការស្វែងយល់អំពីលក្ខណៈវត្ថុធាតុ និងលក្ខណៈអគ្គិសនីរបស់ស៊ុបភើឡាតតិច (SLs) $\text{GeTe/Sb}_{2}\text{Te}_{3}$ ជាពិសេស ដោយសារតែការអនុវត្តន៍ឧបករណ៍ជាលើកដំបូងមួយចំនួនបានបង្ហាញពីសមត្ថភាពគួរឱ្យចាប់អារម្មណ៍ ដូចជាល្បឿនប្តូររហ័ស ការប្រើប្រាស់ថាមពលទាប និងលក្ខណៈមិនចងចាំ។ ទោះជាយ៉ាងណាក៏ដោយ មេកានិចប្តូររបស់ឧបករណ៍ដែលផ្អែកលើស៊ុបភើឡាតតិចទាំងនេះនៅតែជាប្រធានបទនៃការជជែកវែកញែក។ ក្នុងការងារនេះ យើងស្វែងយល់អំពីស៊ុបភើឡាតតិច $\text{GeTe/Sb}_{2}\text{Te}_{3}$ ដើម្បីវិភាគដោយជម្រៅអំពីលក្ខណៈអេឡិចត្រូនិច និងលក្ខណៈកំដៅរបស់វាដោយប្រើវិធីសាស្ត្រ ab initio។ យើងរកឃើញថា ភាពខុសគ្នានៃភាពធន់នៅក្នុងរាល់ដំណាក់កាលផ្សេងៗគ្នានៃ $\text{GeTe/Sb}_{2}\text{Te}_{3}$ គឺតូច ដោយសារតែគម្លាតអេឡិចត្រូនិចតូច (ប្រហែល 0.1 eV) និងឥរិយាបថបែបស៊ីមីមេតាលីកដែលកើតឡើង។ ក្នុងពេលដំណាលគ្នានោះ ការដំណើរកំដៅតាមទិសផ្ដេកនៃផ្នែកគ្រីស្តាល់គឺតូច ខណៈដែលវាអាចប្រែប្រួលដល់ទៅបួនដងក្នុងរាល់ដំណាក់កាលផ្សេងៗ ពី 0.11 ទៅ 0.45 W/m$^{-1}$K$^{-1}$ ដែលពាក់ព័ន្ធយ៉ាងជិតស្និតទៅនឹងចំនួនគម្លាតវ៉ាន់ដែវវ៉ាល (VdW) នៅក្នុងប្លុកឯកតា។ ការស្វែងរកទាំងនេះបញ្ជាក់ពីសារៈសំខាន់នៃការកែលម្អកំដៅដែលអាចសម្រេចបានក្នុងឧបករណ៍ស៊ុបភើឡាតតិច $\text{GeTe/Sb}_{2}\text{Te}_{3}$ ដោយបំភ្លឺនូវផលប៉ះពាល់នៃការតម្រៀបសម្ភារៈ និងតួនាទីរបស់គម្លាត VdW លើវិស្វកម្មកំដៅនៃកោសិកាមេម៉ូរីផ្លាស់ប្តូរដំណាក់កាល។
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In this work we present the main atmospheric parameters, carbon, nitrogen and oxygen abundances, and 12C/13C ratios determined in a sample of 28 Galactic clump stars. Abundances of carbon were studied using the C2 band at 5086.2 {\AA}. The wavelength interval 7980-8130 {\AA} with strong CN features was analysed in order to determine nitrogen abundances and 12C/13C isotope ratios. The oxygen abundances were determined from the [O I] line at 6300 {\AA}. The mean abundances of C, N and O abundances in the investigated clump stars support our previous estimations that, compared to the Sun and dwarf stars of the Galactic disc, carbon is depleted by about 0.2 dex, nitrogen is enhanced by 0.2 dex and oxygen is close to abundances in dwarfs. The 12C/13C and C/N ratios for galactic red clump stars analysed were compared to the evolutionary models of extra-mixing. The steeper drop of 12C/13C ratio in the model of thermohaline mixing by Charbonnel & Lagarde better reflects the observational data at low stellar masses than the more shallow model of cool bottom processing by Boothroyd & Sackmann. For stars of about 2 Msun masses a modelling of rotationally induced mixing should be considered with rotation of about 250 km s-1 at the time when a star was at the hydrogen-core-burning stage.
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En este trabajo presentamos los principales parámetros atmosféricos, las abundancias de carbono, nitrógeno y oxígeno, y las relaciones 12C/13C determinadas en una muestra de 28 estrellas gigantes rojas del racimo galáctico. Las abundancias de carbono se estudiaron utilizando la banda de C2 en 5086,2 {\AA}. Se analizó el intervalo de longitud de onda 7980-8130 {\AA}, que contiene fuertes características de CN, con el fin de determinar las abundancias de nitrógeno y las relaciones isotópicas 12C/13C. Las abundancias de oxígeno se determinaron a partir de la línea [O I] en 6300 {\AA}. Las abundancias medias de C, N y O en las estrellas del racimo investigadas respaldan nuestras estimaciones previas de que, en comparación con el Sol y las estrellas enanas del disco galáctico, el carbono está disminuido en aproximadamente 0,2 dex, el nitrógeno está aumentado en 0,2 dex y el oxígeno es cercano a las abundancias en estrellas enanas. Las relaciones 12C/13C y C/N para las estrellas gigantes rojas del racimo galáctico analizadas se compararon con modelos evolutivos de mezcla adicional. La caída más pronunciada de la relación 12C/13C en el modelo de mezcla termohalina de Charbonnel & Lagarde refleja mejor los datos observacionales en estrellas de baja masa que el modelo menos pronunciado de procesamiento en la parte fría inferior de Boothroyd & Sackmann. Para estrellas de aproximadamente 2 masas solares, debería considerarse un modelo de mezcla inducida por rotación, con una rotación de aproximadamente 250 km s-1 en la etapa de combustión del núcleo de hidrógeno de la estrella.
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The multiscale approach to N-body systems is generalized to address the broad continuum of long time and length scales associated with collective behaviors. A technique is developed based on the concept of an uncountable set of time variables and of order parameters (OPs) specifying major features of the system. We adopt this perspective as a natural extension of the commonly used discrete set of timescales and OPs which is practical when only a few, widely-separated scales exist. The existence of a gap in the spectrum of timescales for such a system (under quasiequilibrium conditions) is used to introduce a continuous scaling and perform a multiscale analysis of the Liouville equation. A functional-differential Smoluchowski equation is derived for the stochastic dynamics of the continuum of Fourier component order parameters. A continuum of spatially non-local Langevin equations for the OPs is also derived. The theory is demonstrated via the analysis of structural transitions in a composite material, as occurs for viral capsids and molecular circuits.
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N-বডি তন্ত্রগুলির জন্য মাল্টিস্কেল পদ্ধতিকে সমষ্টিগত আচরণগুলির সাথে সম্পর্কিত দীর্ঘ সময় ও দৈর্ঘ্যের প্রসারিত ক্রমে প্রয়োগ করা হয়। সময়ের গণনাতীত চলরাশি এবং তন্ত্রের প্রধান বৈশিষ্ট্যগুলি নির্দিষ্ট করে এমন অর্ডার প্যারামিটারগুলির (OPs) ধারণা ভিত্তিক একটি কৌশল বিকশিত করা হয়। কেবলমাত্র কয়েকটি সুস্পষ্টভাবে পৃথক স্কেল বিদ্যমান হলে যা ব্যবহারিক হয়, সেই ক্ষেত্রে সাধারণত ব্যবহৃত সময়সীমার এবং OPs-এর বিচ্ছিন্ন সেটের একটি স্বাভাবিক সম্প্রসারণ হিসাবে আমরা এই দৃষ্টিভঙ্গি গ্রহণ করি। এমন একটি তন্ত্রের জন্য সময়সীমার বর্ণালির মধ্যে (কোয়াসি-সাম্যাবস্থার অধীনে) একটি বিভাজনের অস্তিত্ব ব্যবহার করে একটি অবিচ্ছিন্ন স্কেলিং চালু করা হয় এবং লিওভিল সমীকরণের একটি মাল্টিস্কেল বিশ্লেষণ করা হয়। ফুরিয়ার উপাদান অর্ডার প্যারামিটারগুলির স্টোকাস্টিক গতিবিদ্যার জন্য একটি ফাংশন-অন্তরকলনীয় স্মোলুখোভস্কি সমীকরণ প্রতিষ্ঠা করা হয়। OPs-এর জন্য স্থানিকভাবে অ-স্থানীয় ল্যানজেভিন সমীকরণগুলির একটি ক্রমও প্রতিষ্ঠা করা হয়। ভাইরাল ক্যাপসিড এবং আণবিক সার্কিটগুলিতে যেমন ঘটে তেমন একটি সমন্বিত উপাদানে গাঠনিক রূপান্তরের বিশ্লেষণের মাধ্যমে তত্ত্বটি প্রদর্শিত হয়।
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Artificial ice systems have been designed to replicate paradigmatic phenomena observed in frustrated spin systems. Here we present a detailed theoretical analysis based on Monte-Carlo simulations of the low energy phases in an artificial colloidal ice system, a recently introduced ice system where an ensemble of repulsive colloids are two-dimensionally confined by gravity to a lattice of double wells at a one-to-one filling. Triggered by recent results obtained by Brownian dynamics simulations [A. Lib\'al et al, Phys. Rev. Lett. 120, 027204 (2018)], we analyze the energetics and the phase transitions that occur in the honeycomb geometry (realizing the analogue of a spin ice system on a kagome lattice) when decreasing the temperature. When the particles are restricted to occupy the two minima of the potential well, we recover the same phase diagram as the dipolar spin ice system, with a long range ordered chiral ground state. In contrast, when considering the particle motion and their relaxation within the traps, we observe ferromagnetic ordering at low temperature. This observation highlights the fundamental role played by the continuous motion of the colloids in artificial ice systems.
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কৃত্রিম বরফ ব্যবস্থাগুলি হতাশাজনক স্পিন ব্যবস্থাগুলিতে পর্যবেক্ষিত প্যারাডাইম্যাটিক ঘটনাগুলির অনুকরণ করার জন্য তৈরি করা হয়েছে। এখানে আমরা কৃত্রিম কোলয়েডাল বরফ ব্যবস্থার নিম্ন শক্তি অবস্থাগুলির মন্টে কার্লো অনুকলনের ভিত্তিতে একটি বিস্তারিত তাত্ত্বিক বিশ্লেষণ উপস্থাপন করছি, যা সম্প্রতি চালু করা হয়েছে এমন একটি বরফ ব্যবস্থা যেখানে বিকর্ষণমূলক কোলয়েডগুলির একটি সমষ্টিকে মাধ্যাকর্ষণের দ্বারা দ্বৈত কূপের একটি ল্যাটিসে দ্বি-মাত্রিকভাবে আবদ্ধ করা হয় এবং এক-এর-এক পূরণে রাখা হয়। ব্রাউনিয়ান গতিবিদ্যার অনুকলনের মাধ্যমে প্রাপ্ত সম্প্রতি প্রাপ্ত ফলাফলগুলির [A. Lib\'al et al, Phys. Rev. Lett. 120, 027204 (2018)] প্রেরণায়, আমরা তাপমাত্রা হ্রাসের সময় ষড়ভুজাকার জ্যামিতির মধ্যে (একটি কাগোমি ল্যাটিসে স্পিন বরফ ব্যবস্থার সদৃশ বাস্তবায়ন) ঘটে যাওয়া শক্তি এবং পর্যায় পরিবর্তনগুলির বিশ্লেষণ করি। যখন কণাগুলি সম্ভাব্য কূপের দুটি সর্বনিম্ন অবস্থানে অবস্থান করার জন্য সীমাবদ্ধ থাকে, তখন আমরা ডাইপোলার স্পিন বরফ ব্যবস্থার মতো একই পর্যায় চিত্র পাই, যেখানে একটি দীর্ঘ পরিসর ক্রমবিন্যাসের কাইরাল ভূমি অবস্থা থাকে। তদ্বিপরীতে, যখন কণাগুলির গতি এবং তাদের ফাঁদগুলির মধ্যে শিথিলতার বিষয়টি বিবেচনা করা হয়, তখন আমরা নিম্ন তাপমাত্রায় ফেরোম্যাগনেটিক ক্রমবিন্যাস লক্ষ্য করি। এই পর্যবেক্ষণটি কৃত্রিম বরফ ব্যবস্থাগুলিতে কোলয়েডগুলির অবিরত গতির দ্বারা প্রদত্ত মৌলিক ভূমিকাটি তুলে ধরে।
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By using dark nebulae as opaque outer screens, the luminosity function of white dwarfs and M dwarfs has been studied. High-extinction areas towards the Orion A, Serpens and rho Oph cloud complexes were observed, covering a volume corresponding to 464 pc3 in the solar neighbourhood, complete to Mv=16.5. Foreground stars were selected by VRI photometry and photometric parallaxes. The resulting foreground sample consists of 21 M dwarfs and 7 white dwarfs. The derived M-dwarf luminosity function is consistent with previous studies, showing no substantial upturn beyond Mv=16. The 7 white dwarfs imply a local density of 0.013(+-0.005)Msun/pc3 (~15% of the dynamical mass in the solar neighbourhood) supporting other recent results but obtained with a completely different method. For the clouds, foreground-star data were used to derive independent cloud distances, while the background stars and a simple model of the Milky Way gave reliable cloud extinctions.
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利用暗星云作为不透明的外部屏幕，已对白矮星和M型矮星的光度函数进行了研究。观测了朝向猎户座A、巨蛇座和蛇夫座ρ云复合体的高消光区域，覆盖了太阳邻域内相当于464 pc³的体积，完备至Mv=16.5。通过VRI测光和光度视差法选出了前景恒星。最终得到的前景星样本包含21颗M型矮星和7颗白矮星。所导出的M型矮星光度函数与以往研究结果一致，在Mv=16以上未显示出显著的上升趋势。这7颗白矮星意味着局部质量密度为0.013(±0.005)Msun/pc³（约为太阳邻域动力学质量的15%），这一结果支持其他近期研究结论，但采用的是完全不同的方法。对于这些云团，利用前景恒星数据推导出各自独立的云团距离，同时结合背景恒星和一个简单的银河系模型，获得了可靠的云团消光值。
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This paper investigates the use of bootstrap-based bias correction of semi-parametric estimators of the long memory parameter in fractionally integrated processes. The re-sampling method involves the application of the sieve bootstrap to data pre-filtered by a preliminary semi-parametric estimate of the long memory parameter. Theoretical justification for using the bootstrap techniques to bias adjust log-periodogram and semi-parametric local Whittle estimators of the memory parameter is provided. Simulation evidence comparing the performance of the bootstrap bias correction with analytical bias correction techniques is also presented. The bootstrap method is shown to produce notable bias reductions, in particular when applied to an estimator for which analytical adjustments have already been used. The empirical coverage of confidence intervals based on the bias-adjusted estimators is very close to the nominal, for a reasonably large sample size, more so than for the comparable analytically adjusted estimators. The precision of inferences (as measured by interval length) is also greater when the bootstrap is used to bias correct rather than analytical adjustments.
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В данной статье исследуется использование основанной на бутстрепе коррекции смещения полупараметрических оценок параметра долгой памяти в дробно-интегрированных процессах. Метод повторного сэмплирования предполагает применение решетчатого бутстрепа к данным, предварительно отфильтрованным с использованием предварительной полупараметрической оценки параметра долгой памяти. Приводится теоретическое обоснование применения бутстреп-методов для коррекции смещения логпериодограммных и полупараметрических локальных оценок Уиттла для параметра памяти. Также представлены результаты имитационного моделирования, сравнивающие эффективность бутстреп-коррекции смещения с аналитическими методами коррекции. Показано, что бутстреп-метод обеспечивает значительное уменьшение смещения, особенно при применении к оценкам, для которых уже использовались аналитические корректировки. Эмпирическое покрытие доверительных интервалов, построенных на основе скорректированных оценок, очень близко к номинальному уровню при достаточно большом объёме выборки, что превосходит аналогичные показатели для аналитически скорректированных оценок. Точность выводов (измеряемая длиной интервалов) также выше при использовании бутстреп-коррекции смещения по сравнению с аналитическими корректировками.
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In this paper, we provide non-parametric statistical tools to test stationarity of microstructure noise in general hidden Ito semimartingales, and discuss how to measure liquidity risk using high frequency financial data. In particular, we investigate the impact of non-stationary microstructure noise on some volatility estimators, and design three complementary tests by exploiting edge effects, information aggregation of local estimates and high-frequency asymptotic approximation. The asymptotic distributions of these tests are available under both stationary and non-stationary assumptions, thereby enable us to conservatively control type-I errors and meanwhile ensure the proposed tests enjoy the asymptotically optimal statistical power. Besides it also enables us to empirically measure aggregate liquidity risks by these test statistics. As byproducts, functional dependence and endogenous microstructure noise are briefly discussed. Simulation with a realistic configuration corroborates our theoretical results, and our empirical study indicates the prevalence of non-stationary microstructure noise in New York Stock Exchange.
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Trong bài báo này, chúng tôi cung cấp các công cụ thống kê phi tham số để kiểm định tính dừng của nhiễu vi cấu trúc trong các bán martingale Ito ẩn tổng quát, đồng thời thảo luận cách đo lường rủi ro thanh khoản bằng dữ liệu tài chính tần suất cao. Cụ thể, chúng tôi nghiên cứu tác động của nhiễu vi cấu trúc không dừng lên một số ước lượng biến động, đồng thời xây dựng ba kiểm định bổ trợ lẫn nhau bằng cách khai thác các hiệu ứng rìa, sự tích hợp thông tin từ các ước lượng cục bộ và xấp xỉ tiệm cận tần suất cao. Các phân phối tiệm cận của các kiểm định này đều có sẵn dưới cả giả thiết dừng và không dừng, do đó cho phép chúng tôi kiểm soát một cách thận trọng sai số loại I và đồng thời đảm bảo các kiểm định đề xuất đạt được sức mạnh thống kê tiệm cận tối ưu. Ngoài ra, điều này còn cho phép chúng tôi đo lường thực nghiệm rủi ro thanh khoản tổng hợp thông qua các thống kê kiểm định này. Là các kết quả phụ, sự phụ thuộc hàm và nhiễu vi cấu trúc nội sinh được thảo luận sơ lược. Mô phỏng với cấu hình thực tế xác nhận các kết quả lý thuyết của chúng tôi, và nghiên cứu thực nghiệm cho thấy hiện tượng nhiễu vi cấu trúc không dừng phổ biến trên Sở Giao dịch Chứng khoán New York.
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The advantages of adaptivity and feedback are of immense interest in signal processing and communication with many positive and negative results. Although it is established that adaptivity does not offer substantial reductions in minimax mean square error for a fixed number of measurements, existing results have shown several advantages of adaptivity in complexity of reconstruction, accuracy of support detection, and gain in signal-to-noise ratio, under constraints on sensing energy. Sensing energy has often been measured in terms of the Frobenius Norm of the sensing matrix. This paper uses a different metric that we call the $l_0$ cost of a sensing matrix-- to quantify the complexity of sensing. Thus sparse sensing matrices have a lower cost. We derive information-theoretic lower bounds on the $l_0$ cost that hold for any non-adaptive sensing strategy. We establish that any non-adaptive sensing strategy must incur an $l_0$ cost of $\Theta\left( N \log_2(N)\right) $ to reconstruct an $N$-dimensional, one--sparse signal when the number of measurements are limited to $\Theta\left(\log_2 (N)\right)$. In comparison, bisection-type adaptive strategies only require an $l_0$ cost of at most $\mathcal{O}(N)$ for an equal number of measurements. The problem has an interesting interpretation as a sphere packing problem in a multidimensional space, such that all the sphere centres have minimum non-zero co-ordinates. We also discuss the variation in $l_0$ cost as the number of measurements increase from $\Theta\left(\log_2 (N)\right)$ to $\Theta\left(N\right)$.
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Преимущества адаптивности и обратной связи представляют большой интерес в области обработки сигналов и связи, и по этому вопросу имеется множество как положительных, так и отрицательных результатов. Хотя установлено, что адаптивность не обеспечивает существенного снижения минимаксной среднеквадратичной ошибки при фиксированном числе измерений, существующие результаты показали ряд преимуществ адаптивности в отношении сложности реконструкции, точности обнаружения носителя сигнала и выигрыша по отношению сигнал/шум при ограничениях на энергию зондирования. Энергия зондирования часто измерялась с помощью нормы Фробениуса матрицы зондирования. В данной работе используется другая метрика, которую мы называем стоимостью $l_0$ матрицы зондирования — для оценки сложности процесса зондирования. Таким образом, разреженные матрицы зондирования имеют меньшую стоимость. Мы выводим информационно-теоретические нижние границы стоимости $l_0$, справедливые для любой неадаптивной стратегии зондирования. Устанавливается, что любая неадаптивная стратегия зондирования обязана понести стоимость $l_0$, равную $\Theta\left( N \log_2(N)\right) $, чтобы восстановить $N$-мерный одноразреженный сигнал, когда число измерений ограничено величиной $\Theta\left(\log_2 (N)\right)$. В сравнении, адаптивные стратегии типа деления пополам требуют стоимости $l_0$, не превышающей $\mathcal{O}(N)$, при одинаковом числе измерений. Данная задача имеет интересную интерпретацию как задача упаковки сфер в многомерном пространстве, при которой все центры сфер имеют минимальные ненулевые координаты. Мы также обсуждаем изменение стоимости $l_0$ при увеличении числа измерений от $\Theta\left(\log_2 (N)\right)$ до $\Theta\left(N\right)$.
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We provide the first direct observations of interstellar H+ and He+ pickup ions in the solar wind from 22 AU to 38 AU. We use the Vasyliunas and Siscoe model functional form to quantify the pickup ion distributions, and while the fit parameters generally lie outside their physically expected ranges, this form allows fits that quantify variations in the pickup H+ properties with distance. By ~20 AU, the pickup ions already provide the dominant internal pressure in the solar wind. We determine the radial trends and extrapolate them to the termination shock at ~90 AU, where the pickup H+ to core solar wind density reaches ~0.14. The pickup H+ temperature and thermal pressure increase from 22-38 AU, indicating additional heating of the pickup ions. This produces very large extrapolated ratios of pickup H+ to solar wind temperature and pressure and an extrapolated ratio of the pickup ion pressure to the solar wind dynamic pressure at the termination shock of ~0.16. Such a large ratio has profound implications for moderating the termination shock and the overall outer heliospheric interaction. We also identify suprathermal tails in the H+ spectra and complex features in the He+ spectra, likely indicating variations in the pickup ion history and processing. Finally, we discover enhancements in both H+ and He+ populations just below their cutoff energies, which may be associated with enhanced local pickup. This study serves to document the release and as the citable reference of these pickup ion data for broad community use and analysis.
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เราได้ให้ข้อมูลการสังเกตโดยตรงครั้งแรกเกี่ยวกับไอออนที่ถูกดูดเข้ามา (pickup ions) ของ H+ และ He+ จากอวกาศระหว่างดวงดาว ซึ่งอยู่ในลมสุริยะตั้งแต่ 22 AU ถึง 38 AU เราใช้รูปแบบฟังก์ชันของโมเดล Vasyliunas และ Siscoe เพื่อวัดการแจกแจงของไอออนที่ถูกดูดเข้ามา และถึงแม้ว่าพารามิเตอร์ที่ได้จากการประมาณค่าจะอยู่นอกช่วงที่คาดไว้ตามหลักฟิสิกส์โดยทั่วไป แต่รูปแบบนี้ก็ยังสามารถใช้ประมาณค่าเพื่อวัดความแปรผันของคุณสมบัติของไอออน H+ ที่ถูกดูดเข้ามาตามระยะทางได้ ที่ระยะประมาณ 20 AU ไอออนที่ถูกดูดเข้ามาก็ให้แรงดันภายในที่เป็นองค์ประกอบหลักในลมสุริยะแล้ว เราได้กำหนดแนวโน้มตามแนวรัศมีและประมาณค่าต่อไปยังช็อกที่สิ้นสุด (termination shock) ที่ประมาณ 90 AU ซึ่งอัตราส่วนความหนาแน่นของไอออน H+ ที่ถูกดูดเข้ามาต่อความหนาแน่นของลมสุริยะหลักมีค่าประมาณ 0.14 อุณหภูมิและความดันความร้อนของไอออน H+ ที่ถูกดูดเข้ามาเพิ่มขึ้นระหว่าง 22 ถึง 38 AU ซึ่งบ่งชี้ถึงการให้ความร้อนเพิ่มเติมแก่ไอออนที่ถูกดูดเข้ามา สิ่งนี้ทำให้เกิดอัตราส่วนที่ประมาณค่าได้สูงมากของอุณหภูมิและความดันระหว่างไอออน H+ ที่ถูกดูดเข้ามากับลมสุริยะ และให้อัตราส่วนที่ประมาณค่าได้ของความดันไอออนที่ถูกดูดเข้ามาต่อความดันจลน์ของลมสุริยะที่ช็อกที่สิ้นสุดมีค่าประมาณ 0.16 อัตราส่วนที่สูงมากเช่นนี้มีนัยสำคัญอย่างยิ่งต่อการปรับลักษณะของช็อกที่สิ้นสุดและการมีปฏิสัมพันธ์โดยรวมในเฮลิโอสเฟียร์ด้านนอก นอกจากนี้ เรายังพบหางพลังงานสูงกว่าปกติ (suprathermal tails) ในสเปกตรัมของ H+ และลักษณะซับซ้อนในสเปกตรัมของ He+ ซึ่งน่าจะบ่งชี้ถึงความแปรผันในประวัติและการเปลี่ยนแปลงของไอออนที่ถูกดูดเข้ามา สุดท้าย เราค้นพบการเพิ่มขึ้นของจำนวนประชากรทั้ง H+ และ He+ ที่พลังงานต่ำกว่าค่าพลังงานตัดขาด (cutoff energies) เล็กน้อย ซึ่งอาจเกี่ยวข้องกับการเพิ่มขึ้นของการดูดซับในพื้นที่ใกล้เคียง การศึกษานี้จัดทำขึ้นเพื่อบันทึกการเปิดเผยข้อมูลและเป็นแหล่งอ้างอิงที่สามารถอ้างถึงได้สำหรับข้อมูลไอออนที่ถูกดูดเข้ามาเหล่านี้ เพื่อการใช้งานและการวิเคราะห์ในวงกว้างของชุมชนวิชาการ
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th
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Fast Radio Bursts (FRBs) are bright enigmatic radio pulses of roughly millisecond duration that come from extragalactic distances. As part of the MeerTRAP project, we use the MeerKAT telescope array in South Africa to search for and localise those bursts to high precision in real-time. We aim to pinpoint FRBs to their host galaxies and, thereby, to understand how they are created. However, the transient nature of FRBs presents various challenges, e.g. in system design, raw compute power and real-time communication, where the real-time requirements are reasonably strict (a few tens of seconds). Rapid data processing is essential for us to be able to retain high-resolution data of the bursts, to localise them, and to minimise the delay for follow-up observations. We give a short overview of the data analysis pipeline, describe the challenges faced, and elaborate on our initial design and implementation of a real-time triggering infrastructure for FRBs at the MeerKAT telescope.
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Les sursauts radio rapides (FRB) sont des impulsions radio brillantes et énigmatiques d'une durée d'environ une milliseconde provenant de distances extragalactiques. Dans le cadre du projet MeerTRAP, nous utilisons le réseau de télescopes MeerKAT en Afrique du Sud pour détecter et localiser en temps réel ces sursauts avec une grande précision. Notre objectif est de localiser les FRB jusqu'à leurs galaxies hôtes afin de comprendre leur mécanisme de formation. Toutefois, la nature transitoire des FRB pose divers défis, par exemple en matière de conception du système, de puissance de calcul brute et de communication en temps réel, où les exigences temporelles sont assez strictes (quelques dizaines de secondes). Un traitement rapide des données est essentiel pour nous permettre de conserver des données haute résolution des sursauts, de les localiser avec précision et de minimiser le délai pour les observations complémentaires. Nous présentons un bref aperçu du pipeline d'analyse des données, décrivons les difficultés rencontrées et détaillons notre conception initiale et la mise en œuvre d'une infrastructure de déclenchement en temps réel pour les FRB au télescope MeerKAT.
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fr
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We investigate the Coma cluster galaxy luminosity function (GLF) at faint magnitudes, in particular in the u* band by applying photometric redshift techniques applied to deep u*, B, V, R, I images covering a region of ~1deg2 (R 24). Global and local GLFs in the B, V, R and I bands obtained with photometric redshift selection are consistent with our previous results based on a statistical background subtraction. In the area covered only by the u* image, the GLF was also derived after applying a statistical background subtraction. The GLF in the u* band shows an increase of the faint end slope towards the outer regions of the cluster (from alpha~1 in the cluster center to alpha~2 in the cluster periphery). This could be explained assuming a short burst of star formation in these galaxies when entering the cluster. The analysis of the multicolor type spatial distribution reveals that late type galaxies are distributed in clumps in the cluster outskirts, where X-ray substructures are also detected and where the GLF in the u* band is steeper.
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우리는 약 ~1deg²(R 24)의 영역을 덮는 깊은 u*, B, V, R, I 영상에 광도 적색편이 기법을 적용하여, 특히 u* 대역에서 흐린 등급까지의 성운자리 은하단 은하 등급함수(GLF)를 조사한다. 광도 적색편이 선택을 통해 얻은 B, V, R, I 대역의 전역적 및 지역적 GLF는 통계적 배경 감산에 기반한 이전의 결과들과 일치한다. u* 영상만 덮인 영역에서는 통계적 배경 감산을 수행한 후 GLF를 도출하였다. u* 대역의 GLF는 은하단 중심부에서의 알파값 약 1에서 외곽부로 갈수록 알파값 약 2로 완만한 쪽에서 급경사로 변화하는 경향을 보인다. 이는 이러한 은하들이 은하단에 진입할 때 짧은 시기의 별 형성 활동을 겪었다고 가정하면 설명될 수 있다. 다중색상 유형의 공간 분포 분석 결과, 후기형 은하들은 X선 하위구조도 검출되는 은하단 외각부의 덩어리 형태로 분포하며, 이 지역에서 u* 대역의 GLF가 더욱 급경사임을 보여준다.
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ko
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The recently-discovered stellar system in Canis Major is analysed using He-burning Red Clump stars as tracers. Canis Major turns out to be the strongest and most spatially confined overdensity of the whole Galactic Disc, both in terms of number density and of statistical significance. When projected onto the Galactic Plane, it appears as an elongated and compact overdensity extending from l ~ 200 to l ~ 280 with a roundish core toward l ~ 240. We find that the main body of the system has an integrated absolute magnitude M_V=-14.4 +/- 0.8, a central surface brightness \mu_{V,0} = 24.0 +/- 0.6 mag/arcsec^2 and a line-of-sight profile peaked at D_{sun}=7.2 +/- 1.0 kpc with Half Width at Half Maximum ~ 2.0 kpc, in excellent agreement with the results obtained with widely different tracers (M giants and Main Sequence stars) in previous analyses. The mean distance to the main body of Canis Major is observed to increase with increasing Galactic longitude, from D_{sun} ~ 6.3 kpc at l ~ 225, to D_{sun} ~ 9.3 kpc at l ~ 265, in good agreement with the predictions of our more recent N-body simulation that models CMa as a dwarf galaxy being accreted in a planar orbit onto the disc of the Milky Way. We confirm that the Canis Major system has all the characteristics of the relic of a dwarf galaxy seen on top of a large-scale overdensity that we detect all over the third and fourth Galactic quadrants (180<l<360, with a strong maximum around l=290 and b> -5) that is identified as the stellar component of the southern Galactic Warp... (Abridged)....
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ប្រព័ន្ធផ្កាយថ្មីៗដែលត្រូវបានរកឃើញនៅក្នុងតំបន់ Canis Major ត្រូវបានវិភាគដោយប្រើផ្កាយ Red Clump ដែលកំពុងឆេះ He ជាសញ្ញាបណ្តាញ។ Canis Major បានបង្ហាញថាជាកន្លែងដែលមានការកើនឡើងខ្លាំងបំផុត និងមានការបំពេញក្នុងតំបន់តូចបំផុតនៅលើឌីសកាឡាក់ទិចទាំងមូល ទាំងពីទិដ្ឋភាពដង់ស៊ីតេចំនួន និងពីភាពសំខាន់ផ្នែកស្ថិតិ។ នៅពេលដែលគេគូរវាលើផ្ទៃកាឡាក់ទិច វាបង្ហាញថាជាកន្លែងកើនឡើងដែលមានរាងវែង និងមានលក្ខណៈតូចចង្អៀត ហើយពង្រីកពី l ~ 200 ទៅ l ~ 280 ដោយមានផ្នែកកណ្តាលមូលនៅជិត l ~ 240។ យើងរកឃើញថាផ្នែកចម្បងនៃប្រព័ន្ធនេះមានម៉ាញ៉ូទីវដ្តអាប់សូលុយត់សរុប M_V=-14.4 +/- 0.8 ភាពភ្លឺនៅផ្ទៃកណ្តាល \mu_{V,0} = 24.0 +/- 0.6 mag/arcsec^2 និងក្រាហ្វិកបណ្តោយបន្ទាត់មើលដែលមានកំពូលនៅ D_{sun}=7.2 +/- 1.0 kpc ដោយមានទទឹងកន្លះនៅកំពូលកន្លះ ~ 2.0 kpc ដែលស្របនឹងលទ្ធផលដែលបានរកឃើញពីការសិក្សាមុនៗដោយប្រើសញ្ញាបណ្តាញខុសគ្នាយ៉ាងច្រើន (ផ្កាយ M ដ៏ធំ និងផ្កាយនៅលើស៊េរៀចម្បង)។ ចម្ងាយមធ្យមទៅផ្នែកចម្បងនៃ Canis Major ត្រូវបានសង្កេតឃើញថាកើនឡើងតាមរយៈរយៈបណ្តោយកាឡាក់ទិច ពី D_{sun} ~ 6.3 kpc នៅ l ~ 225 ទៅ D_{sun} ~ 9.3 kpc នៅ l ~ 265 ដែលស្របនឹងការទស្សន៍ទាយពីការធ្វើម៉ូដែល N-body ថ្មីៗបំផុតរបស់យើង ដែលធ្វើម៉ូដែល CMa ថាជាកាឡាក់ទិចតូចមួយកំពុងត្រូវបានទាញចូលតាមគន្លងរាបស្មើទៅកាន់ឌីសនៃកាឡាក់ទិច Milky Way។ យើងបញ្ជាក់ថាប្រព័ន្ធ Canis Major មានលក្ខណៈគ្រប់យ៉ាងរបស់សល់សៅរបស់កាឡាក់ទិចតូចមួយ ដែលបានឃើញនៅលើការកើនឡើងនៃទំហំធំមួយដែលយើងរកឃើញនៅគ្រប់ផ្នែកចតុកោណទីបី និងទីបួនរបស់កាឡាក់ទិច (180<l<360 ដោយមានកំពូលខ្លាំងនៅជិត l=290 និង b> -5) ដែលត្រូវបានកំណត់អត្តសញ្ញាណថាជាធាតុផ្កាយនៃការកោងខាងត្បូងរបស់កាឡាក់ទិច... (កាត់ខ្លី)....
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km
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Astrophotonics is the application of versatile photonic technologies to channel, manipulate, and disperse guided light from one or more telescopes to achieve scientific objectives in astronomy in an efficient and cost-effective way. The developments and demands from the telecommunication industry have driven a major boost in photonic technology and vice versa in the last 40 years. The photonic platform of guided light in fibers and waveguides has opened the doors to next-generation instrumentation for both ground- and space-based telescopes in optical and near/mid-IR bands, particularly for the upcoming extremely large telescopes (ELTs). The large telescopes are pushing the limits of adaptive optics to reach close to a near-diffraction-limited performance. The photonic devices are ideally suited for capturing this AO-corrected light and enabling new and exciting science such as characterizing exoplanet atmospheres. The purpose of this white paper is to summarize the current landscape of astrophotonic devices and their scientific impact, highlight the key issues, and outline specific technological and organizational approaches to address these issues in the coming decade and thereby enable new discoveries as we embark on the era of extremely large telescopes.
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ອາສໂตรຟໂຕນິກ ແມ່ນການນຳໃຊ້ເຕັກໂນໂລຊີຟໂຕນິກທີ່ມີຄວາມຫຼາກຫຼາຍເຂົ້າໃນການນຳທາງ, ຈັດການ ແລະ ກະຈາຍແສງທີ່ຖືກນຳທາງຈາກໜຶ່ງຫຼືຫຼາຍໆໂທລະສະກົບ ເພື່ອບັນລຸເປົ້າໝາຍດ້ານວິທະຍາສາດໃນດ້ານດາລາສາດ ໃນທາງທີ່ມີປະສິດທິພາບ ແລະ ຄຸ້ມຄ່າ. ການພັດທະນາ ແລະ ຄວາມຕ້ອງການຈາກອຸດສາຫະກຳການສື່ສານໄດ້ຂັບເຄື່ອນໃຫ້ເກີດການກ້າວໜ້າຢ່າງໃຫຍ່ຫຼວງໃນເຕັກໂນໂລຊີຟໂຕນິກ ແລະ ກົງກັນຂ້າມໃນໄລຍະ 40 ປີຜ່ານມາ. ແຜນການຟໂຕນິກທີ່ນຳທາງແສງໃນເສັ້ນໄຍ ແລະ ທາງນຳທາງ ໄດ້ເປີດປະຕູໄປສູ່ເຄື່ອງມືຮຸ່ນໃໝ່ສຳລັບໂທລະສະກົບທີ່ຕັ້ງຢູ່ດິນ ແລະ ຢູ່ໃນອາວະກາດ ໃນຊ່ວງຄວາມຍາວຄື້ນແສງທີ່ມອງເຫັນ ແລະ ໃກ້/ກາງ-IR, ໂດຍສະເພາະສຳລັບໂທລະສະກົບທີ່ໃຫຍ່ເປັນຢ່າງຍິ່ງໃນອະນາຄົດ (ELTs). ໂທລະສະກົບທີ່ໃຫຍ່ເຫຼົ່ານີ້ ກຳລັງກົດດັນຂອດຈຳກັດຂອງເຕັກໂນໂລຊີອັດຕາປັບຕົວ (adaptive optics) ເພື່ອໃຫ້ສາມາດເຂົ້າໃກ້ກັບປະສິດທິພາບທີ່ຖືກຈຳກັດໂດຍການເບື່ອງເບອນ (diffraction-limited). ເຄື່ອງມືຟໂຕນິກເຫຼົ່ານີ້ ເໝາະສົມຢ່າງຍິ່ງໃນການຈັບແສງທີ່ຖືກປັບຕົວໂດຍ AO ແລະ ເຮັດໃຫ້ເກີດວິທະຍາສາດໃໝ່ໆທີ່ຫນ້າຕື່ນເຕັ້ນ ເຊັ່ນ: ການຄຸນລັກສະນະຂອງບັນດາດວງອາທິດນອກລະບົບ. ຈຸດປະສົງຂອງເອກະສານຂາວນີ້ ແມ່ນເພື່ອສະຫຼຸບສະພາບການປັດຈຸບັນຂອງເຄື່ອງມືອາສໂຕຟໂຕນິກ ແລະ ຜົນກະທົບດ້ານວິທະຍາສາດຂອງມັນ, ຊີ້ໃຫ້ເຫັນບັນຫາສຳຄັນໆ, ແລະ ກຳນົດທາງເລືອກດ້ານເຕັກໂນໂລຊີ ແລະ ການຈັດຕັ້ງທີ່ເປັນຮູບປະທຳ ເພື່ອຈັດການກັບບັນຫາເຫຼົ່ານີ້ໃນທົດສະວັດໜ້າ ແລະ ສະນັ້ນຈຶ່ງເຮັດໃຫ້ການຄົ້ນພົບໃໝ່ໆເປັນໄປໄດ້ ໃນຂະນະທີ່ພວກເຮົາກຳລັງກ້າວເຂົ້າສູ່ຍຸກຂອງໂທລະສະກົບທີ່ໃຫຍ່ເປັນຢ່າງຍິ່ງ.
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lo
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The time-evolution of the maximum and the width of exact analytic wave packet (WP) solutions of the time-dependent Schr\"odinger equation (SE) represents the particle and wave aspects, respectively, of the quantum system. The dynamics of the maximum, located at the mean value of position, is governed by the Newtonian equation of the corresponding classical problem. The width, which is directly proportional to the position uncertainty, obeys a complex nonlinear Riccati equation which can be transformed into a real nonlinear Ermakov equation. The coupled pair of these equations yields a dynamical invariant which plays a key role in our investigation. It can be expressed in terms of a complex variable that linearizes the Riccati equation. This variable also provides the time-dependent parameters that characterize the Green's function, or Feynman kernel, of the corresponding problem. From there, also the relation between the classical and quantum dynamics of the systems can be obtained. Furthermore, the close connection between the Ermakov invariant and the Wigner function will be shown. Factorization of the dynamical invariant allows for comparison with creation/annihilation operators and supersymmetry where the partner potentials fulfil (real) Riccati equations. This provides the link to a nonlinear formulation of time-independent quantum mechanics in terms of an Ermakov equation for the amplitude of the stationary state wave functions combined with a conservation law. Comparison with SUSY and the time-dependent problems concludes our analysis.
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Zaman-bağımlı Schrödinger denkleminin (SE) tam analitik dalga paketi (DP) çözümlerinin maksimumunun ve genişliğinin zamanla değişim evrimi, sırasıyla kuantum sisteminin parçacık ve dalga yönlerini temsil eder. Ortalama konum değerinde yer alan maksimumun dinamiği, ilgili klasik problemin Newton denklemi tarafından belirlenir. Konum belirsizliğiyle doğrudan orantılı olan genişlik ise, gerçek doğrusal olmayan Ermakov denklemine dönüştürülebilen karmaşık doğrusal olmayan Riccati denklemine uyar. Bu iki denklemin oluşturduğu eşlenmiş sistemi, incelememizde önemli bir rol oynayan dinamik bir invaryant verir. Bu invaryant, Riccati denklemini doğrusallaştıran karmaşık bir değişken cinsinden ifade edilebilir. Bu değişken aynı zamanda ilgili problemin Green fonksiyonunun ya da Feynman çekirdeğinin karakterize edilmesinde kullanılan zaman-bağımlı parametreleri sağlar. Buradan, sistemin klasik ve kuantum dinamikleri arasındaki ilişki de elde edilebilir. Ayrıca, Ermakov invaryantı ile Wigner fonksiyonu arasındaki yakın ilişki gösterilecektir. Dinamik invaryantın çarpanlara ayrılması, yaratım/yoketme operatörleri ve süpersimetri ile karşılaştırma yapılmasına olanak tanır; burada eş potansiyeller (gerçek) Riccati denklemlerini sağlar. Bu durum, durum dalga fonksiyonlarının genliği için bir Ermakov denklemi ile bir korunum yasasının birleşiminden oluşan, zamandan bağımsız kuantum mekaniğinin doğrusal olmayan bir formülasyonuna bağlantı sağlar. Süpersimetri (SUSY) ve zaman-bağımlı problemlerle karşılaştırma analizimizi tamamlar.
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Superfluidity and superconductivity are remarkable manifestations of quantum coherence at a macroscopic scale. The dynamics of superfluids has dominated the study of these systems for decades now, but a comprehensive theoretical framework is still lacking. We introduce a local extension of the time-dependent density functional theory to describe the dynamics of fermionic superfluids. Within this approach one can correctly represent vortex quantization, generation, and dynamics, the transition from a superfluid to a normal phase and a number of other large amplitude collective modes which are beyond the scope of two-fluid hydrodynamics, Ginzburg-Landau and/or Gross-Pitaevskii approaches. We illustrate the power of this approach by studying the generation of quantized vortices, vortex rings, vortex reconnection, and transition from a superfluid to a normal state in real time for a unitary Fermi gas. We predict the emergence of a new qualitative phenomenon in superfluid dynamics of gases, the existence of stable superfluidity when the systems are stirred with velocities significantly exceeding the nominal Landau critical velocity in these systems.
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초유동성과 초전도성은 거시적 규모에서 양자 일관성이 나타나는 놀라운 예이다. 수십 년 동안 초유체의 역학이 이러한 시스템 연구를 주도해 왔으나, 여전히 포괄적인 이론 체계가 부족한 실정이다. 우리는 페르미온 초유체의 역학을 기술하기 위해 시간의존 밀도범함수 이론의 국소적 확장을 제안한다. 이 접근법을 통해 와동자 양자화, 생성 및 역학, 초유체에서 정상상으로의 전이, 그리고 이중유체 유체역학, 기나이부-란다우 및/또는 그로스-피타예프스키 접근법의 범위를 벗어난 여러 가지 큰 진폭 집단 모드들을 정확하게 표현할 수 있다. 우리는 단위 페르미 기체에 대해 양자화된 와동자, 와동 고리, 와동 재연결, 그리고 초유체에서 정상상으로의 전이를 실시간으로 연구함으로써 이 접근법의 강력함을 보여준다. 우리는 이러한 시스템에서 명목상의 란다우 임계 속도를 상당히 초과하는 속도로 교반될 때 안정적인 초유동성이 존재한다는 새로운 질적 현상이 초유체 기체 역학에서 나타날 수 있음을 예측한다.
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ko
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Superfluidity and superconductivity are remarkable manifestations of quantum coherence at a macroscopic scale. The dynamics of superfluids has dominated the study of these systems for decades now, but a comprehensive theoretical framework is still lacking. We introduce a local extension of the time-dependent density functional theory to describe the dynamics of fermionic superfluids. Within this approach one can correctly represent vortex quantization, generation, and dynamics, the transition from a superfluid to a normal phase and a number of other large amplitude collective modes which are beyond the scope of two-fluid hydrodynamics, Ginzburg-Landau and/or Gross-Pitaevskii approaches. We illustrate the power of this approach by studying the generation of quantized vortices, vortex rings, vortex reconnection, and transition from a superfluid to a normal state in real time for a unitary Fermi gas. We predict the emergence of a new qualitative phenomenon in superfluid dynamics of gases, the existence of stable superfluidity when the systems are stirred with velocities significantly exceeding the nominal Landau critical velocity in these systems.
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La superfluidez y la superconductividad son manifestaciones notables de la coherencia cuántica a escala macroscópica. La dinámica de los superfluidos ha dominado el estudio de estos sistemas durante décadas, pero aún carece de un marco teórico completo. Introducimos una extensión local de la teoría del funcional de la densidad dependiente del tiempo para describir la dinámica de superfluidos fermiónicos. Mediante este enfoque se puede representar correctamente la cuantización, generación y dinámica de vórtices, la transición de un estado superfluido a uno normal y una serie de otros modos colectivos de gran amplitud que están fuera del alcance de las aproximaciones de hidrodinámica de dos fluidos, Ginzburg-Landau y/o Gross-Pitaevskii. Ilustramos el poder de este enfoque estudiando en tiempo real la generación de vórtices cuantizados, anillos de vórtice, reconexión de vórtices y la transición de un estado superfluido a uno normal en un gas fermiónico unitario. Predecimos la aparición de un nuevo fenómeno cualitativo en la dinámica superfluida de gases: la existencia de una superfluidez estable cuando los sistemas son agitados con velocidades que superan significativamente la velocidad crítica nominal de Landau en estos sistemas.
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es
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Kundt spacetimes are of great importance in general relativity in 4 dimensions and have a number of topical applications in higher dimensions in the context of string theory. The degenerate Kundt spacetimes have many special and unique mathematical properties, including their invariant curvature structure and their holonomy structure. We provide a rigorous geometrical kinematical definition of the general Kundt spacetime in 4 dimensions; essentially a Kundt spacetime is defined as one admitting a null vector that is geodesic, expansion-free, shear-free and twist-free. A Kundt spacetime is said to be degenerate if the preferred kinematic and curvature null frames are all aligned. The degenerate Kundt spacetimes are the only spacetimes in 4 dimensions that are not $\mathcal{I}$-non-degenerate, so that they are not determined by their scalar polynomial curvature invariants. We first discuss the non-aligned Kundt spacetimes, and then turn our attention to the degenerate Kundt spacetimes. The degenerate Kundt spacetimes are classified algebraically by the Riemann tensor and its covariant derivatives in the aligned kinematic frame; as an example, we classify Riemann type D degenerate Kundt spacetimes in which $\nabla(Riem),\nabla^{(2)}(Riem)$ are also of type D. We discuss other local characteristics of the degenerate Kundt spacetimes. Finally, we discuss degenerate Kundt spacetimes in higher dimensions.
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クンドの時空は4次元の一般相対性理論において非常に重要であり、弦理論の文脈における高次元での多くの注目すべき応用を持っている。退化したクンドの時空は、不変な曲率構造やホロノミー構造など、多くの特別で一意的な数学的性質を持つ。我々は4次元における一般クンド時空に対して、幾何学的かつ運動学的な厳密な定義を与える。本質的に、クンド時空とは、測地的かつ膨張なし、せん断なし、ねじれのないヌルベクトルを許容する時空として定義される。クンド時空が退化しているとは、好ましい運動学的ヌルフレームと曲率ヌルフレームがすべて整列している場合を指す。退化したクンド時空は、4次元において唯一の $\mathcal{I}$-非退化でない時空であり、スカラー多項式曲率不変量によっては一意に決定されない。まず、非整列なクンド時空について議論し、その後、退化したクンド時空に注目する。退化したクンド時空は、整列した運動学的フレームにおけるリーマンテンソルおよびその共変微分によって代数的に分類される。例として、$\nabla(Riem)$ および $\nabla^{(2)}(Riem)$ もタイプDであるようなリーマンタイプDの退化クンド時空を分類する。さらに、退化したクンド時空の他の局所的特徴についても議論する。最後に、高次元における退化クンド時空について考察する。
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ja
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In this paper, we provide non-parametric statistical tools to test stationarity of microstructure noise in general hidden Ito semimartingales, and discuss how to measure liquidity risk using high frequency financial data. In particular, we investigate the impact of non-stationary microstructure noise on some volatility estimators, and design three complementary tests by exploiting edge effects, information aggregation of local estimates and high-frequency asymptotic approximation. The asymptotic distributions of these tests are available under both stationary and non-stationary assumptions, thereby enable us to conservatively control type-I errors and meanwhile ensure the proposed tests enjoy the asymptotically optimal statistical power. Besides it also enables us to empirically measure aggregate liquidity risks by these test statistics. As byproducts, functional dependence and endogenous microstructure noise are briefly discussed. Simulation with a realistic configuration corroborates our theoretical results, and our empirical study indicates the prevalence of non-stationary microstructure noise in New York Stock Exchange.
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En este artículo, proporcionamos herramientas estadísticas no paramétricas para probar la estacionariedad del ruido microestructural en semimartingalas de Itô ocultas generales, y discutimos cómo medir el riesgo de liquidez utilizando datos financieros de alta frecuencia. En particular, investigamos el impacto del ruido microestructural no estacionario sobre algunos estimadores de volatilidad, y diseñamos tres pruebas complementarias explotando efectos de borde, agregación de información de estimaciones locales y aproximaciones asintóticas de alta frecuencia. Las distribuciones asintóticas de estas pruebas están disponibles tanto bajo supuestos de estacionariedad como de no estacionariedad, lo que nos permite controlar de forma conservadora los errores tipo I y garantizar al mismo tiempo que las pruebas propuestas poseen potencia estadística asintóticamente óptima. Además, esto también nos permite medir empíricamente los riesgos agregados de liquidez mediante estos estadísticos de prueba. Como resultados secundarios, se discuten brevemente la dependencia funcional y el ruido microestructural endógeno. Una simulación con una configuración realista corrobora nuestros resultados teóricos, y nuestro estudio empírico indica la prevalencia del ruido microestructural no estacionario en la Bolsa de Nueva York.
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es
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We investigate the limitations that emerge in thermodynamic tasks as a result of having local control only over the components of a thermal machine. These limitations are particularly relevant for devices composed of interacting many-body systems. Specifically, we study protocols of work extraction that employ a many-body system as a working medium whose evolution can be driven by tuning the on-site Hamiltonian terms. This provides a restricted set of thermodynamic operations, giving rise to novel bounds for the performance of engines. Our findings show that those limitations in control render it in general impossible to reach Carnot efficiency; in its extreme ramification it can even forbid to reach a finite efficiency of work per particle. We focus on the 1D Ising model in the thermodynamic limit as a case study. We show that in the limit of strong interactions the ferromagnetic case becomes useless for work extraction, while the anti-ferromagnetic improves its performance with the strength of the couplings, reaching Carnot in the limit of arbitrary strong interactions. Our results provide a promising connection between the study of quantum control and thermodynamics and introduce a more realistic set of physical operations well suited to capture current experimental scenarios.
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ကျွန်ုပ်တို့သည် အပူစက်၏ အစိတ်အပိုင်းများကိုသာ ဒေသဆိုင်ရာ ထိန်းချုပ်မှုရှိခြင်းကြောင့် ပေါ်ပေါက်လာသော စွမ်းအင်ဖြန့်ဖြူးရေး လုပ်ငန်းများတွင် ရှိသည့် ကန့်သတ်ချက်များကို စူးစမ်းစစ်ဆေးကြသည်။ ထိုကန့်သတ်ချက်များသည် အပြန်အလှန် လုပ်ဆောင်နေသော စုပေါင်းစနစ်များဖြင့် ဖွဲ့စည်းထားသည့် ကိရိယာများအတွက် အထူးသင့်လျော်ပါသည်။ သီးသန့်ဆိုလျှင်၊ ကျွန်ုပ်တို့သည် နေရာတစ်ခုစီရှိ ဟမ်မီလ်တိုးနီးယန်း ကို ညှိခြင်းဖြင့် မောင်းနှင်နိုင်သော စွမ်းအင်ပြောင်းလဲမှုကို ဖြစ်ပေါ်စေသည့် စုပေါင်းစနစ်တစ်ခုကို အလုပ်လုပ်ရန် အလုပ်သုံးအလှည့်အပြောင်းအဖြစ် အသုံးပြုသည့် စွမ်းအင်ထုတ်ယူမှု အလုပ်စဉ်များကို လေ့လာကြသည်။ ထိုသို့သော အလုပ်စဉ်များသည် စွမ်းအင်ဖြန့်ဖြူးရေး လုပ်ဆောင်ချက်များ၏ ကန့်သတ်ထားသော အစုအမှုတ်ကို ပေးပို့ပြီး စက်များ၏ စွမ်းဆောင်ရည်အတွက် အသစ်အဆန်း ကန့်သတ်ချက်များကို ဖြစ်ပေါ်စေသည်။ ကျွန်ုပ်တို့၏ ရလဒ်များအရ ထိန်းချုပ်မှု၏ ထိုကန့်သတ်ချက်များကြောင့် ကာနို ထိရောက်မှုကို ရရှိရန် ယေဘုယျအားဖြင့် မဖြစ်နိုင်ကြောင်း ပြသပါသည်။ ထို၏ အဆုံးစွန်သော ရလဒ်အနေဖြင့် အမှုန်တစ်လုံးချင်းစီအတွက် စွမ်းအင်ထုတ်ယူမှု၏ အကန့်အသတ်ရှိသော ထိရောက်မှုကိုပင် ရရှိရန် တားမြစ်နိုင်ပါသည်။ ကျွန်ုပ်တို့သည် စူးစမ်းစစ်ဆေးမှုတစ်ခုအဖြစ် စွမ်းအင်ဖြန့်ဖြူးရေး နယ်ပယ်တွင် ၁ မျဉ်း အိုင်စင်း မော်ဒယ်ကို အာရုံစိုက်လေ့လာကြသည်။ အပြန်အလှန် လုပ်ဆောင်မှုများ အလွန်ပြင်းထန်သည့် နယ်ပယ်တွင် သံလိုက်ဖော်ရွေ အမျိုးအစားသည် စွမ်းအင်ထုတ်ယူမှုအတွက် အသုံးမဝင်တော့ပေ၊ သို့သော် ဆန့်ကျင်သံလိုက်ဖော်ရွေ အမျိုးအစားသည် ချိတ်ဆက်မှုများ၏ အားကို ပိုမိုကောင်းမွန်စေပြီး အလွန်ပြင်းထန်သော အပြန်အလှန်လုပ်ဆောင်မှုများ၏ နယ်ပယ်တွင် ကာနိုသို့ ရောက်ရှိသည်။ ကျွန်ုပ်တို့၏ ရလဒ်များသည် ကွမ်တမ် ထိန်းချုပ်မှုနှင့် စွမ်းအင်ဖြန့်ဖြူးရေး လေ့လာမှုများကြား ကတိကဝတ်ပြုသော ဆက်သွယ်မှုကို ပေးပို့ပြီး လက်ရှိ စမ်းသပ်မှုများ၏ အခြေအနေများကို ဖမ်းယူရန် သင့်တော်သော ရူပဗေဒ လုပ်ဆောင်မှုများ၏ ပိုမိုသင့်လျော်သော အစုအမှုတ်ကို မိတ်ဆက်ပေးပါသည်။
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my
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The Supernova Cosmology Project has discovered over twenty-eight supernovae (SNe) at 0.35 <z < 0.65 in an ongoing program that uses Type Ia SNe as high-redshift distance indicators. Here we present measurements of the ratio between the locally observed and global Hubble constants, H_0^L/H_0^G, based on the first 7 SNe of this high-redshift data set compared with 18 SNe at z <= 0.1 from the Calan/Tololo survey. If Omega_M <= 1, then light-curve-width corrected SN magnitudes yield H_0^L/H_0^G < 1.10 (95% confidence level) in both a Lambda=0 and a flat universe. The analysis using the SNe Ia as standard candles without a light-curve-width correction yields similar results. These results rule out the hypothesis that the discrepant ages of the Universe derived from globular clusters and recent measurements of the Hubble constant are attributable to a locally underdense bubble. Using the Cepheid-distance-calibrated absolute magnitudes for SNe Ia of Sandage (1996}, we can also measure the global Hubble constant, H_0^G. If Omega_M >= 0.2, we find that H_0^G < 70 km/s/Mpc in a Lambda=0 universe and H_0^G < 78 km/s/Mpc in a flat universe, correcting the distant and local SN apparent magnitudes for light curve width. Lower results for H_0^G are obtained if the magnitudes are not width corrected.
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Il Supernova Cosmology Project ha scoperto oltre ventotto supernove (SNe) con 0,35 <z < 0,65 nell'ambito di un programma in corso che utilizza le SNe di tipo Ia come indicatori di distanza ad alto redshift. Presentiamo qui misure del rapporto tra la costante di Hubble osservata localmente e quella globale, H_0^L/H_0^G, basate sulle prime 7 SNe di questo insieme di dati ad alto redshift, confrontate con 18 SNe con z <= 0,1 provenienti dal sondaggio Calan/Tololo. Se Omega_M <= 1, le magnitudini delle SNe corrette per l'ampiezza della curva di luce forniscono H_0^L/H_0^G < 1,10 (livello di confidenza del 95%) sia in un universo con Lambda=0 sia in un universo piatto. L'analisi che utilizza le SNe Ia come candele standard senza correzione per l'ampiezza della curva di luce produce risultati simili. Questi risultati escludono l'ipotesi che le discrepanze tra le età dell'Universo derivate dagli ammassi globulari e le recenti misure della costante di Hubble siano attribuibili a una bolla localmente sottodensa. Utilizzando le magnitudini assolute calibrate tramite distanze Cefeidi per le SNe Ia di Sandage (1996), possiamo inoltre misurare la costante di Hubble globale, H_0^G. Se Omega_M >= 0,2, troviamo che H_0^G < 70 km/s/Mpc in un universo con Lambda=0 e H_0^G < 78 km/s/Mpc in un universo piatto, correggendo le magnitudini apparenti delle SNe locali e distanti per l'ampiezza della curva di luce. Risultati inferiori per H_0^G si ottengono se le magnitudini non sono corrette per l'ampiezza.
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it
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Spelling error correction is one of topics which have a long history in natural language processing. Although previous studies have achieved remarkable results, challenges still exist. In the Vietnamese language, a state-of-the-art method for the task infers a syllable's context from its adjacent syllables. The method's accuracy can be unsatisfactory, however, because the model may lose the context if two (or more) spelling mistakes stand near each other. In this paper, we propose a novel method to correct Vietnamese spelling errors. We tackle the problems of mistyped errors and misspelled errors by using a deep learning model. The embedding layer, in particular, is powered by the byte pair encoding technique. The sequence to sequence model based on the Transformer architecture makes our approach different from the previous works on the same problem. In the experiment, we train the model with a large synthetic dataset, which is randomly introduced spelling errors. We test the performance of the proposed method using a realistic dataset. This dataset contains 11,202 human-made misspellings in 9,341 different Vietnamese sentences. The experimental results show that our method achieves encouraging performance with 86.8% errors detected and 81.5% errors corrected, which improves the state-of-the-art approach 5.6% and 2.2%, respectively.
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ការកែតម្រូវកំហុសអក្ខរាវិរុទ្ធ គឺជាប្រធានបទមួយក្នុងចំណោមប្រធានបទជាច្រើនដែលមានប្រវត្តិវែងឆ្ងាយក្នុងការដំណើរការភាសាធម្មជាតិ។ ទោះបីជាការសិក្សាមុនៗបានសម្រេចលទ្ធផលគួរឱ្យកត់សម្គាល់ក៏ដោយ ក៏នៅតែមានបញ្ហាប្រឈមជាច្រើនដែលត្រូវដោះស្រាយ។ ក្នុងភាសាវៀតណាម វិធីសាស្ត្រដ៏ទាន់សម័យបំផុតសម្រាប់បេសកកម្មនេះ គឺការសន្និដ្ឋានបរិបទនៃព្យញ្ជនៈមួយពីព្យញ្ជនៈដែលនៅជាប់គ្នា។ ទោះជាយ៉ាងណាក៏ដោយ ភាពត្រឹមត្រូវរបស់វិធីសាស្ត្រនេះអាចមិនគ្រប់គ្រាន់ ពីព្រោះគំរូអាចបាត់បរិបទ ប្រសិនបើកំហុសអក្ខរាវិរុទ្ធពីរ (ឬច្រើនជាងនេះ) កើតឡើងនៅក្បែរគ្នា។ ក្នុងឯកសារនេះ យើងខ្ញុំស្នើវិធីសាស្ត្រថ្មីមួយសម្រាប់កែតម្រូវកំហុសអក្ខរាវិរុទ្ធភាសាវៀតណាម។ យើងខ្ញុំដោះស្រាយបញ្ហាកំហុសវាយអក្សរ និងកំហុសអក្ខរាវិរុទ្ធដោយប្រើគំរូរៀនជ្រៅ។ ជាពិសេស ស្រទាប់បញ្ចូលអក្សរត្រូវបានបំពាក់ដោយបច្ចេកទេសបំបែកគូប៊ីត។ គំរូបន្តទៅបន្តដែលផ្អែកលើស្ថាបត្យកម្មត្រាស្វើម៉ា ធ្វើឱ្យវិធីសាស្ត្ររបស់យើងខុសពីការងារមុនៗលើបញ្ហាដូចគ្នានេះ។ ក្នុងការពិសោធន៍ យើងខ្ញុំបានបណ្តុះគំរូជាមួយទិន្នន័យសំយោគធំមួយ ដែលមានកំហុសអក្ខរាវិរុទ្ធត្រូវបានបញ្ចូលចេញពីការចៃដន្យ។ យើងខ្ញុំធ្វើតេស្តលើប្រសិទ្ធភាពវិធីសាស្ត្រដែលបានស្នើឡើងដោយប្រើទិន្នន័យដែលពិតប្រាកដ។ ទិន្នន័យនេះមានកំហុសអក្ខរាវិរុទ្ធដែលធ្វើដោយមនុស្សចំនួន 11,202 ក្នុងប្រយោគវៀតណាមខុសៗគ្នាចំនួន 9,341។ លទ្ធផលពិសោធន៍បង្ហាញថា វិធីសាស្ត្ររបស់យើងខ្ញុំសម្រេចបាននូវលទ្ធផលគួរឱ្យកត់សម្គាល់ ដោយកំហុសត្រូវបានរកឃើញ 86.8% និងកំហុសត្រូវបានកែតម្រូវ 81.5% ដែលធ្វើឱ្យវិធីសាស្ត្រទាន់សម័យបំផុតមុននេះ កើនឡើង 5.6% និង 2.2% តាមលំដាប់។
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km
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We investigate the Coma cluster galaxy luminosity function (GLF) at faint magnitudes, in particular in the u* band by applying photometric redshift techniques applied to deep u*, B, V, R, I images covering a region of ~1deg2 (R 24). Global and local GLFs in the B, V, R and I bands obtained with photometric redshift selection are consistent with our previous results based on a statistical background subtraction. In the area covered only by the u* image, the GLF was also derived after applying a statistical background subtraction. The GLF in the u* band shows an increase of the faint end slope towards the outer regions of the cluster (from alpha~1 in the cluster center to alpha~2 in the cluster periphery). This could be explained assuming a short burst of star formation in these galaxies when entering the cluster. The analysis of the multicolor type spatial distribution reveals that late type galaxies are distributed in clumps in the cluster outskirts, where X-ray substructures are also detected and where the GLF in the u* band is steeper.
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Kami mengkaji fungsi kecerahan galaksi dalam gugusan Coma (GLF) pada magnitud malap, khususnya dalam jalur u*, dengan menggunakan teknik pergeseran merah fotometrik yang dikenakan ke imej u*, B, V, R, I yang dalam yang meliputi kawasan ~1darjah2 (R 24). GLF global dan setempat dalam jalur B, V, R dan I yang diperoleh melalui pemilihan pergeseran merah fotometrik adalah konsisten dengan keputusan kami sebelumnya yang berdasarkan penolakan latar belakang secara statistik. Dalam kawasan yang diliputi hanya oleh imej u*, GLF juga diterbitkan setelah penolakan latar belakang secara statistik dilakukan. GLF dalam jalur u* menunjukkan peningkatan kecerunan hujung malap ke arah kawasan luar gugusan (daripada alpha~1 di pusat gugusan kepada alpha~2 di periferal gugusan). Ini boleh diterangkan dengan mengandaikan ledakan pembentukan bintang yang singkat dalam galaksi-galaksi ini apabila memasuki gugusan. Analisis taburan ruang jenis pelbagai warna mendedahkan bahawa galaksi jenis lewat diedarkan secara kelompok di kawasan pinggir gugusan, iaitu di mana substruktur sinar-X juga dikesan dan di mana GLF dalam jalur u* adalah lebih curam.
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ms
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During the early 1830's Bernard Bolzano, working in Prague, wrote a manuscript giving a foundational account of numbers and their properties. In the final section of his work he described what he called `infinite number expressions' and `measurable numbers'. This work was evidently an attempt to provide an improved proof of the sufficiency of the criterion usually known as the `Cauchy criterion' for the convergence of an infinite sequence. Bolzano had in fact published this criterion four years earlier than Cauchy who, in his work of 1821, made no attempt at a proof. Any such proof required the construction or definition of real numbers and this, in essence, was what Bolzano achieved in his work on measurable numbers. It therefore pre-dates the well-known constructions of Dedekind, Cantor and many others by several decades. Bolzano's manuscript was partially published in 1962 and more fully published in 1976. We give an account of measurable numbers, the properties Bolzano proved about them, and the controversial reception they have prompted since their publication.
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V počátcích 30. let 19. století Bernard Bolzano, pracující v Praze, napsal rukopis, ve kterém podal základní výklad čísel a jejich vlastností. Ve svém posledním oddílu popsal to, čemu říkal „nekonečné číselné výrazy“ a „měřitelná čísla“. Tato práce byla zjevně pokusem o poskytnutí lepšího důkazu postačující podmínky obvykle známé jako „Cauchyho kritérium“ pro konvergenci nekonečné posloupnosti. Bolzano ve skutečnosti publikoval toto kritérium o čtyři roky dříve než Cauchy, který ve své práci z roku 1821 žádný pokus o důkaz nepodnikl. Každý takový důkaz vyžadoval konstrukci nebo definici reálných čísel a to, v podstatě, bylo to, čeho Bolzano ve své práci o měřitelných číslech dosáhl. Tato práce tedy předchází známým konstrukcím Dedekinda, Cantora a mnoha dalších o několik desetiletí. Bolzanův rukopis byl částečně publikován v roce 1962 a podstatně úplněji v roce 1976. Podáváme výklad měřitelných čísel, vlastností, které o nich Bolzano dokázal, a kontroverzní reakce, které vyvolaly od jejich zveřejnění.
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cs
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The advantages of adaptivity and feedback are of immense interest in signal processing and communication with many positive and negative results. Although it is established that adaptivity does not offer substantial reductions in minimax mean square error for a fixed number of measurements, existing results have shown several advantages of adaptivity in complexity of reconstruction, accuracy of support detection, and gain in signal-to-noise ratio, under constraints on sensing energy. Sensing energy has often been measured in terms of the Frobenius Norm of the sensing matrix. This paper uses a different metric that we call the $l_0$ cost of a sensing matrix-- to quantify the complexity of sensing. Thus sparse sensing matrices have a lower cost. We derive information-theoretic lower bounds on the $l_0$ cost that hold for any non-adaptive sensing strategy. We establish that any non-adaptive sensing strategy must incur an $l_0$ cost of $\Theta\left( N \log_2(N)\right) $ to reconstruct an $N$-dimensional, one--sparse signal when the number of measurements are limited to $\Theta\left(\log_2 (N)\right)$. In comparison, bisection-type adaptive strategies only require an $l_0$ cost of at most $\mathcal{O}(N)$ for an equal number of measurements. The problem has an interesting interpretation as a sphere packing problem in a multidimensional space, such that all the sphere centres have minimum non-zero co-ordinates. We also discuss the variation in $l_0$ cost as the number of measurements increase from $\Theta\left(\log_2 (N)\right)$ to $\Theta\left(N\right)$.
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Las ventajas de la adaptabilidad y la retroalimentación son de gran interés en el procesamiento de señales y las comunicaciones, con muchos resultados positivos y negativos. Aunque está establecido que la adaptabilidad no ofrece reducciones sustanciales en el error cuadrático medio minimax para un número fijo de mediciones, los resultados existentes han mostrado varias ventajas de la adaptabilidad en cuanto a la complejidad de la reconstrucción, la precisión en la detección del soporte y la ganancia en la relación señal-ruido, bajo restricciones en la energía de sensado. La energía de sensado frecuentemente se ha medido en términos de la norma de Frobenius de la matriz de sensado. Este artículo utiliza una métrica diferente que llamamos el costo $l_0$ de una matriz de sensado, para cuantificar la complejidad del sensado. Así, las matrices de sensado dispersas tienen un costo menor. Derivamos cotas inferiores de teoría de la información sobre el costo $l_0$ que son válidas para cualquier estrategia de sensado no adaptativa. Establecemos que cualquier estrategia de sensado no adaptativa debe incurrir en un costo $l_0$ de $\Theta\left( N \log_2(N)\right) $ para reconstruir una señal unidimensionalmente dispersa de dimensión $N$ cuando el número de mediciones está limitado a $\Theta\left(\log_2 (N)\right)$. En comparación, estrategias adaptativas del tipo de bisección solo requieren un costo $l_0$ de a lo sumo $\mathcal{O}(N)$ con un número igual de mediciones. El problema tiene una interpretación interesante como un problema de empaquetamiento de esferas en un espacio multidimensional, de tal manera que todos los centros de las esferas tengan coordenadas mínimas no nulas. También discutimos la variación del costo $l_0$ cuando el número de mediciones aumenta desde $\Theta\left(\log_2 (N)\right)$ hasta $\Theta\left(N\right)$.
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es
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This paper investigates the use of bootstrap-based bias correction of semi-parametric estimators of the long memory parameter in fractionally integrated processes. The re-sampling method involves the application of the sieve bootstrap to data pre-filtered by a preliminary semi-parametric estimate of the long memory parameter. Theoretical justification for using the bootstrap techniques to bias adjust log-periodogram and semi-parametric local Whittle estimators of the memory parameter is provided. Simulation evidence comparing the performance of the bootstrap bias correction with analytical bias correction techniques is also presented. The bootstrap method is shown to produce notable bias reductions, in particular when applied to an estimator for which analytical adjustments have already been used. The empirical coverage of confidence intervals based on the bias-adjusted estimators is very close to the nominal, for a reasonably large sample size, more so than for the comparable analytically adjusted estimators. The precision of inferences (as measured by interval length) is also greater when the bootstrap is used to bias correct rather than analytical adjustments.
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In diesem Artikel wird die Anwendung einer auf dem Bootstrap-Verfahren basierenden Bias-Korrektur für semiparametrische Schätzer des Langgedächtnisparameters in fraktional integrierten Prozessen untersucht. Die Resampling-Methode besteht darin, das Sieve-Bootstrap-Verfahren auf Daten anzuwenden, die zuvor mittels einer vorläufigen semiparametrischen Schätzung des Langgedächtnisparameters gefiltert wurden. Es wird eine theoretische Begründung für die Verwendung von Bootstrap-Techniken zur Bias-Korrektur von Log-Periodogramm- und semiparametrischen lokalen Whittle-Schätzern des Gedächtnisparameters geliefert. Außerdem werden Simulationsergebnisse vorgestellt, die die Leistungsfähigkeit der Bootstrap-Bias-Korrektur im Vergleich zu analytischen Bias-Korrekturverfahren bewerten. Es zeigt sich, dass das Bootstrap-Verfahren deutliche Bias-Reduktionen erzielt, insbesondere wenn es auf einen Schätzer angewendet wird, für den bereits analytische Korrekturen verwendet wurden. Die empirische Überdeckungswahrscheinlichkeit von Konfidenzintervallen, die auf den biasbereinigten Schätzern basieren, liegt bei angemessen großem Stichprobenumfang sehr nahe am Nominalwert, und zwar genauer als bei vergleichbaren analytisch korrigierten Schätzern. Die Präzision der Schlussfolgerungen (gemessen an der Intervalllänge) ist ebenfalls höher, wenn die Bias-Korrektur mittels Bootstrap anstatt durch analytische Anpassungen erfolgt.
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Superfluidity and superconductivity are remarkable manifestations of quantum coherence at a macroscopic scale. The dynamics of superfluids has dominated the study of these systems for decades now, but a comprehensive theoretical framework is still lacking. We introduce a local extension of the time-dependent density functional theory to describe the dynamics of fermionic superfluids. Within this approach one can correctly represent vortex quantization, generation, and dynamics, the transition from a superfluid to a normal phase and a number of other large amplitude collective modes which are beyond the scope of two-fluid hydrodynamics, Ginzburg-Landau and/or Gross-Pitaevskii approaches. We illustrate the power of this approach by studying the generation of quantized vortices, vortex rings, vortex reconnection, and transition from a superfluid to a normal state in real time for a unitary Fermi gas. We predict the emergence of a new qualitative phenomenon in superfluid dynamics of gases, the existence of stable superfluidity when the systems are stirred with velocities significantly exceeding the nominal Landau critical velocity in these systems.
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La superfluidité et la supraconductivité sont des manifestations remarquables de la cohérence quantique à une échelle macroscopique. L'étude de la dynamique des superfluides a dominé la recherche sur ces systèmes depuis des décennies, mais un cadre théorique complet fait encore défaut. Nous introduisons une extension locale de la théorie de la fonctionnelle de la densité dépendante du temps afin de décrire la dynamique des superfluides fermioniques. Cette approche permet de représenter correctement la quantification, la génération et la dynamique des vortex, la transition entre un état superfluide et un état normal, ainsi qu'un certain nombre d'autres modes collectifs d'amplitude importante qui échappent au cadre de l'hydrodynamique à deux fluides, de l'approche de Ginzburg-Landau et/ou de Gross-Pitaevskii. Nous illustrons la puissance de cette approche en étudiant, en temps réel, la génération de vortex quantifiés, d'anneaux de vortex, la reconnexion de vortex, et la transition entre un état superfluide et un état normal dans un gaz de Fermi unitaire. Nous prédisons l'apparition d'un nouveau phénomène qualitatif en dynamique des superfluides gazeux, à savoir l'existence d'une superfluidité stable lorsque les systèmes sont agités à des vitesses nettement supérieures à la vitesse critique de Landau nominale dans ces systèmes.
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fr
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In this work we present the main atmospheric parameters, carbon, nitrogen and oxygen abundances, and 12C/13C ratios determined in a sample of 28 Galactic clump stars. Abundances of carbon were studied using the C2 band at 5086.2 {\AA}. The wavelength interval 7980-8130 {\AA} with strong CN features was analysed in order to determine nitrogen abundances and 12C/13C isotope ratios. The oxygen abundances were determined from the [O I] line at 6300 {\AA}. The mean abundances of C, N and O abundances in the investigated clump stars support our previous estimations that, compared to the Sun and dwarf stars of the Galactic disc, carbon is depleted by about 0.2 dex, nitrogen is enhanced by 0.2 dex and oxygen is close to abundances in dwarfs. The 12C/13C and C/N ratios for galactic red clump stars analysed were compared to the evolutionary models of extra-mixing. The steeper drop of 12C/13C ratio in the model of thermohaline mixing by Charbonnel & Lagarde better reflects the observational data at low stellar masses than the more shallow model of cool bottom processing by Boothroyd & Sackmann. For stars of about 2 Msun masses a modelling of rotationally induced mixing should be considered with rotation of about 250 km s-1 at the time when a star was at the hydrogen-core-burning stage.
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Trong nghiên cứu này, chúng tôi trình bày các thông số khí quyển chính, hàm lượng carbon, nitơ và oxy, cũng như các tỷ số 12C/13C xác định trong một mẫu gồm 28 ngôi sao cụm đỏ thuộc Ngân Hà. Hàm lượng carbon được nghiên cứu bằng cách sử dụng dải C2 tại 5086,2 {\AA}. Khoảng bước sóng 7980–8130 {\AA} chứa các đặc trưng CN mạnh đã được phân tích nhằm xác định hàm lượng nitơ và các tỷ số đồng vị 12C/13C. Hàm lượng oxy được xác định từ vạch [O I] tại 6300 {\AA}. Các hàm lượng trung bình của C, N và O trong các ngôi sao cụm được khảo sát cho thấy kết quả tương tự các đánh giá trước đây của chúng tôi rằng, so với Mặt Trời và các ngôi sao lùn trong đĩa Ngân Hà, carbon bị suy giảm khoảng 0,2 dex, nitơ tăng khoảng 0,2 dex, còn oxy gần bằng hàm lượng trong các ngôi sao lùn. Các tỷ số 12C/13C và C/N của các ngôi sao cụm đỏ Ngân Hà được phân tích đã được so sánh với các mô hình tiến hóa về trộn thêm. Sự giảm mạnh hơn của tỷ số 12C/13C trong mô hình trộn nhiệt phân capillary của Charbonnel & Lagarde phản ánh tốt hơn dữ liệu quan sát ở khối lượng sao thấp hơn so với mô hình dốc nhẹ hơn của quá trình đáy nguội (cool bottom processing) của Boothroyd & Sackmann. Đối với các ngôi sao có khối lượng khoảng 2 M☉, cần xem xét mô hình trộn do quay gây ra với vận tốc quay khoảng 250 km s⁻¹ tại thời điểm ngôi sao ở giai đoạn đốt cháy hydro trong lõi.
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vi
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The current early stage in the investigation of the stability of the Kerr metric is characterized by the study of appropriate model problems. Particularly interesting is the problem of the stability of the solutions of the Klein-Gordon equation, describing the propagation of a scalar field in the background of a rotating (Kerr-) black hole. Results suggest that the stability of the field depends crucially on its mass $\mu$. Among others, the paper provides an improved bound for $\mu$ above which the solutions of the reduced, by separation in the azimuth angle in Boyer-Lindquist coordinates, Klein-Gordon equation are stable. Finally, it gives new formulations of the reduced equation, in particular, in form of a time-dependent wave equation that is governed by a family of unitarily equivalent positive self-adjoint operators. The latter formulation might turn out useful for further investigation. On the other hand, it is proved that from the abstract properties of this family alone it cannot be concluded that the corresponding solutions are stable.
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ការសិក្សាបឋមនាពេលបច្ចុប្បន្ននៃស្ថេរភាពនៃគំរូ Kerr ត្រូវបានគេចាត់ទុកថាជាការសិក្សាលើបញ្ហាគំរូដែលសមស្រប។ បញ្ហាដែលគួរឱ្យចាប់អារម្មណ៍ជាពិសេសគឺបញ្ហាស្ថេរភាពនៃដំណោះស្រាយនៃសមីការ Klein-Gordon ដែលពិពណ៌នាអំពីការរីករាយរបស់វាលស្កាលែរនៅក្នុងបរិបទនៃរន្ធខ្មៅបង្វិល (Kerr-)។ លទ្ធផលបង្ហាញថា ស្ថេរភាពនៃវាលពឹងផ្អែកយ៉ាងខ្លាំងទៅតាមម៉ាសរបស់វា $\mu$។ ក្នុងចំណោមផ្សេងៗ ការងារនេះផ្តល់នូវដែនកំណត់ប្រសើរឡើងសម្រាប់ $\mu$ ដែលខាងលើដែនកំណត់នេះ ដំណោះស្រាយនៃសមីការ Klein-Gordon ដែលបានកាត់បន្ថយដោយការបំបែកតាមមុំអាស៊ីមុតក្នុងកូអរដោនេ Boyer-Lindquist គឺស្ថិតក្នុងស្ថានភាពស្ថេរ។ ទីបំផុត វាផ្តល់នូវទម្រង់ថ្មីនៃសមីការដែលបានកាត់បន្ថយ ជាពិសេស ក្រោមទម្រង់នៃសមីការរលកអាស្រ័យពេល ដែលត្រូវបានគ្រប់គ្រងដោយគ្រួសារនៃប្រមាណវិធីខ្លួនឯងប៉ះពាល់វិជ្ជមានដែលមានលក្ខណៈស្មើគ្នាតាមអ៊ីក្វាលង់។ ទម្រង់ចុងក្រោយនេះអាចប្រើបានសម្រាប់ការសិក្សាបន្ថែម។ ផ្ទុយទៅវិញ វាត្រូវបានបញ្ជាក់ថា ពីលក្ខណៈទូទៅរបស់គ្រួសារនេះតែមួយគត់ គេមិនអាចសន្និដ្ឋានបានថាដំណោះស្រាយដែលត្រូវគ្នាគឺស្ថិតក្នុងស្ថានភាពស្ថេរទេ។
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km
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A recent publication provides the network graph for a neocortical microcircuit comprising 8 million connections between 31,000 neurons (H. Markram, et al., Reconstruction and simulation of neocortical microcircuitry, Cell, 163 (2015) no. 2, 456-492). Since traditional graph-theoretical methods may not be sufficient to understand the immense complexity of such a biological network, we explored whether methods from algebraic topology could provide a new perspective on its structural and functional organization. Structural topological analysis revealed that directed graphs representing connectivity among neurons in the microcircuit deviated significantly from different varieties of randomized graph. In particular, the directed graphs contained in the order of $10^7$ simplices {\DH} groups of neurons with all-to-all directed connectivity. Some of these simplices contained up to 8 neurons, making them the most extreme neuronal clustering motif ever reported. Functional topological analysis of simulated neuronal activity in the microcircuit revealed novel spatio-temporal metrics that provide an effective classification of functional responses to qualitatively different stimuli. This study represents the first algebraic topological analysis of structural connectomics and connectomics-based spatio-temporal activity in a biologically realistic neural microcircuit. The methods used in the study show promise for more general applications in network science.
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Eine kürzlich erschienene Publikation liefert den Netzwerkgraphen eines neokortikalen Mikrozirkuits, der 8 Millionen Verbindungen zwischen 31.000 Neuronen umfasst (H. Markram et al., Reconstruction and simulation of neocortical microcircuitry, Cell, 163 (2015), Nr. 2, 456–492). Da traditionelle graphentheoretische Methoden möglicherweise nicht ausreichen, um die immense Komplexität eines solchen biologischen Netzwerks zu verstehen, untersuchten wir, ob Methoden der algebraischen Topologie einen neuen Blickwinkel auf seine strukturelle und funktionale Organisation ermöglichen könnten. Die strukturelle topologische Analyse ergab, dass gerichtete Graphen, die die Konnektivität zwischen Neuronen im Mikrozirkuit darstellen, signifikant von verschiedenen Arten zufälliger Graphen abweichen. Insbesondere enthielten die gerichteten Graphen in der Größenordnung von $10^7$ Simplizes – also Gruppen von Neuronen mit allzu-all gerichteter Konnektivität. Einige dieser Simplizes enthielten bis zu acht Neuronen und stellen damit das extremste neuronale Clustering-Motiv dar, das bisher berichtet wurde. Die funktionelle topologische Analyse der simulierten neuronalen Aktivität im Mikrozirkuit offenbarte neuartige räumlich-zeitliche Metriken, die eine effektive Klassifizierung funktioneller Reaktionen auf qualitativ unterschiedliche Reize ermöglichen. Diese Studie stellt die erste algebraisch-topologische Analyse der strukturellen Connectomik und der auf Connectomik basierenden räumlich-zeitlichen Aktivität in einem biologisch realistischen neuronalen Mikrozirkuit dar. Die in der Studie verwendeten Methoden zeigen vielversprechende Ansätze für allgemeinere Anwendungen in der Netzwerkforschung.
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de
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Background. When selecting predictive tools, clinicians and healthcare professionals are challenged with an overwhelming number of tools, most of which have never been evaluated for comparative effectiveness. To overcome this challenge, the authors developed and validated an evidence-based framework for grading and assessment of predictive tools (GRASP), based on the critical appraisal of published evidence. Methods. To examine GRASP impact on professionals decisions, a controlled experiment was conducted through an online survey. Randomising two groups of tools and two scenarios; participants were asked to select the best tools; most validated or implemented, with and without GRASP. A wide group of international participants were invited. Task completion time, rate of correct decisions, rate of objective vs subjective decisions, and level of decisional conflict were measured. Results. Valid responses received were 194. Compared to not using the framework, GRASP significantly increased correct decisions by 64% (T=8.53, p<0.001), increased objective decision making by 32% (T=9.24, p<0.001), and decreased subjective decision making; based on guessing and based on prior knowledge or experience by 20% (T=-5.47, p<0.001) and 8% (T=-2.99, p=0.003) respectively. GRASP significantly decreased decisional conflict; increasing confidence and satisfaction of participants with their decisions by 11% (T=4.27, p<0.001) and 13% (T=4.89, p<0.001) respectively. GRASP decreased task completion time by 52% (T=-0.87, p=0.384). The average system usability scale of GRASP was very good; 72.5%, and 88% of participants found GRASP useful. Discussion and Conclusions. Using GRASP has positively supported and significantly improved evidence-based decision making and increased accuracy and efficiency of selecting predictive tools.
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Úvod. Při výběru prediktivních nástrojů se lékaři a zdravotničtí pracovníci potýkají s přetížením velkým počtem dostupných nástrojů, z nichž většina nikdy nebyla posouzena z hlediska srovnatelné účinnosti. Za účelem překonání této výzvy autoři vyvinuli a ověřili důkazem založený rámec pro hodnocení a posuzování prediktivních nástrojů (GRASP) na základě kritické analýzy publikovaných důkazů. Metody. Za účelem zkoumání vlivu GRASP na rozhodování odborníků byl proveden kontrolovaný experiment prostřednictvím online dotazníku. Účastníci byli náhodně rozděleni do dvou skupin nástrojů a dvou scénářů a bylo od nich požadováno vybrat nejlepší nástroje – nejvíce ověřené nebo implementované – s použitím a bez použití GRASP. Byla pozvána široká mezinárodní skupina účastníků. Měřily se doba dokončení úkolu, míra správných rozhodnutí, míra objektivních versus subjektivních rozhodnutí a úroveň rozhodovacího konfliktu. Výsledky. Bylo přijato 194 platných odpovědí. Ve srovnání s nepoužitím rámce GRASP významně zvýšil správná rozhodnutí o 64 % (T=8,53, p<0,001), zvýšil objektivní rozhodování o 32 % (T=9,24, p<0,001) a snížil subjektivní rozhodování – založené na hádání a založené na dřívějších znalostech nebo zkušenostech – o 20 % (T=-5,47, p<0,001) a 8 % (T=-2,99, p=0,003) v uvedeném pořadí. GRASP významně snížil rozhodovací konflikt; zvýšil sebevědomí a spokojenost účastníků se svými rozhodnutími o 11 % (T=4,27, p<0,001) a 13 % (T=4,89, p<0,001). GRASP snížil dobu dokončení úkolu o 52 % (T=-0,87, p=0,384). Průměrné skóre systémové uživatelské přívětivosti (SUS) pro GRASP bylo velmi dobré – 72,5 % a 88 % účastníků považovalo GRASP za užitečný. Diskuze a závěry. Použití GRASP pozitivně podpořilo a významně zlepšilo rozhodování založené na důkazech a zvýšilo přesnost a efektivitu výběru prediktivních nástrojů.
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cs
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We develop a robust coarse-grained model for single and double stranded DNA by representing each nucleotide by three interaction sites (TIS) located at the centers of mass of sugar, phosphate, and base. The resulting TIS model includes base-stacking, hydrogen bond, and electrostatic interactions as well as bond-stretching and bond angle potentials that account for the polymeric nature of DNA. The choices of force constants for stretching and the bending potentials were guided by a Boltzmann inversion procedure using a large representative set of DNA structures extracted from the Protein Data Bank. Some of the parameters in the stacking interactions were calculated using a learning procedure, which ensured that the experimentally measured melting temperatures of dimers are faithfully reproduced. Without any further adjustments, the calculations based on the TIS model reproduces the experimentally measured salt and sequence dependence of the size of single stranded DNA (ssDNA), as well as the persistence lengths of poly(dA) and poly(dT) chains. Interestingly, upon application of mechanical force the extension of poly(dA) exhibits a plateau, which we trace to the formation of stacked helical domains. In contrast, the force-extension curve (FEC) of poly(dT) is entropic in origin, and could be described by a standard polymer model. We also show that the persistence length of double stranded DNA is consistent with the prediction based on the worm-like chain. The persistence length, which decreases with increasing salt concentration, is in accord with the Odijk-Skolnick-Fixman theory intended for stiff polyelectrolyte chains near the rod limit. The range of applications, which did not require adjusting any parameter after the initial construction based solely on PDB structures and melting profiles of dimers, attests to the transferability and robustness of the TIS model for ssDNA and dsDNA.
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نطور نموذجًا خشنًا قويًا للحمض النووي أحادي وثنائي السلسلة من خلال تمثيل كل نوكليوتيد بثلاثة مواقع تفاعل (TIS) تقع عند مراكز الكتلة للسكر والفوسفات والقاعدة. ويشمل النموذج الناتج (TIS) تفاعلات التراص القاعدي، وروابط الهيدروجين، والتفاعلات الكهروستاتيكية، إضافة إلى جهود تمدد الروابط وزوايا الروابط التي تأخذ في الاعتبار الطبيعة البلمرية للحمض النووي. وقد استُخدمت إجراءات عكس بولتزمان، بالاعتماد على مجموعة كبيرة وممثلة لهياكل الحمض النووي المستمدة من قاعدة بيانات البروتين (PDB)، لتوجيه اختيار ثوابت القوة الخاصة بجهود التمدد والانحناء. كما تم حساب بعض المعلمات الخاصة بتفاعلات التراص باستخدام إجراء تعلّمي، مما كفل إعادة إنتاج درجات حرارة الانصهار المقاسة تجريبيًا للأزواج الثنائية بدقة. ودون الحاجة إلى أي تعديلات إضافية، تُعيد الحسابات المستندة إلى نموذج TIS إنتاج الاعتماد التجريبي للملوحة والتسلسل على حجم الحمض النووي أحادي السلسلة (ssDNA)، وكذلك أطوال الاستقامة لسلاسل poly(dA) وpoly(dT). ومن المثير للاهتمام أن امتداد سلسلة poly(dA) عند تطبيق قوة ميكانيكية يُظهر منسوبًا ثابتًا، يمكننا عزو ذلك إلى تشكل نطاقات لولبية مرصوصة. على النقيض من ذلك، فإن منحنى القوة مقابل الامتداد (FEC) لسلسلة poly(dT) له طبيعة إنتروبية، ويمكن وصفه بنموذج بوليمر قياسي. ونُبيّن أيضًا أن طول الاستقامة للحمض النووي ثنائي السلسلة يتماشى مع التنبؤ المستند إلى نموذج السلسلة الشبيهة بالدودة (worm-like chain). وطول الاستقامة هذا، الذي يقل مع زيادة تركيز الملح، يتماشى مع نظرية أوديج-سكولنيك-فيكسمان المخصصة للسلاسل البوليإلكتروليتية الصلبة القريبة من حد العصا. ويشهد مدى التطبيقات الواسع، الذي لم يتطلب تعديل أي معلمة بعد البناء الأولي القائم فقط على هياكل PDB وملفات درجات انصهار الأزواج الثنائية، على قابلية النقل والمتانة لنموذج TIS الخاص بالحمض النووي أحادي وثنائي السلسلة.
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Late-Babylonian mathematics (450-100 BC), represented by some 60 cuneiform tablets from Babylon and Uruk, is incompletely known compared to its abundantly preserved, well-studied Old-Babylonian predecessor (1800-1600 BC). With the present paper, 16 fragments from Babylon, probably belonging to 13 different tablets, are added to this corpus. Two remarkable tablets represent a hitherto unknown class of very large factorization tables that can be adequately described as Babylonian examples of number crunching (Section I). In these tables a very large sexagesimal number representing a small factor (9 or 12) raised to a high power, or a product of such numbers, is repeatedly divided by its constituent factors (9 or 12), very likely until 1 is reached. In Text A the initial number is a 25-digit number equivalent to 9 to the power 46; in Text B it is a 30-digit number equivalent to 9 to the power 11 times 12 to the power 39 - the longest number attested in ancient Mesopotamia and, probably, in all antiquity. Most other fragments belong to tables with reciprocals (Section II) and squares (Section III). Finally, two fragments contain multiplications of one kind or another (Section IV).
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晚巴比伦数学（公元前450年–前100年）的资料仅由来自巴比伦和乌尔克的大约60块楔形文字泥板代表，与大量保存且研究充分的古巴比伦时期数学（公元前1800年–前1600年）相比，其内容尚不完整。本文新增了来自巴比伦的16块残片，可能属于13块不同的泥板，将其纳入这一文献体系。其中两块显著的泥板代表了一类此前未知的极大因数分解表，可恰当地视为巴比伦“数值计算”的实例（第一节）。在这些表格中，一个极大的六十进制数——表示一个小因数（9或12）的高次幂，或若干此类数的乘积——被其组成因数（9或12）反复除法，极有可能一直除到结果为1为止。在文本A中，初始数是一个相当于9的46次方的25位数；在文本B中，初始数是一个相当于9的11次方乘以12的39次方的30位数——这是迄今在古代美索不达米亚，乃至整个古代世界中所发现的最长的数字。其余大多数残片属于倒数表（第二节）和平方表（第三节）。最后，两块残片包含某种形式的乘法运算（第四节）。
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In this work we present the main atmospheric parameters, carbon, nitrogen and oxygen abundances, and 12C/13C ratios determined in a sample of 28 Galactic clump stars. Abundances of carbon were studied using the C2 band at 5086.2 {\AA}. The wavelength interval 7980-8130 {\AA} with strong CN features was analysed in order to determine nitrogen abundances and 12C/13C isotope ratios. The oxygen abundances were determined from the [O I] line at 6300 {\AA}. The mean abundances of C, N and O abundances in the investigated clump stars support our previous estimations that, compared to the Sun and dwarf stars of the Galactic disc, carbon is depleted by about 0.2 dex, nitrogen is enhanced by 0.2 dex and oxygen is close to abundances in dwarfs. The 12C/13C and C/N ratios for galactic red clump stars analysed were compared to the evolutionary models of extra-mixing. The steeper drop of 12C/13C ratio in the model of thermohaline mixing by Charbonnel & Lagarde better reflects the observational data at low stellar masses than the more shallow model of cool bottom processing by Boothroyd & Sackmann. For stars of about 2 Msun masses a modelling of rotationally induced mixing should be considered with rotation of about 250 km s-1 at the time when a star was at the hydrogen-core-burning stage.
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Sa gawaing ito, iniharap namin ang pangunahing mga atmosperikong parameter, mga abundance ng carbon, nitrogen, at oxygen, at mga rasyo ng 12C/13C na natukoy sa isang sample na binubuo ng 28 Galactic clump stars. Ang mga abundance ng carbon ay sinuri gamit ang C2 band sa 5086.2 {\AA}. Ang wavelength interval na 7980-8130 {\AA} na may malalakas na CN feature ay nilikhang upang matukoy ang mga abundance ng nitrogen at mga rasyo ng isotope ng 12C/13C. Ang mga abundance ng oxygen ay natukoy mula sa [O I] na linya sa 6300 {\AA}. Ang mga karaniwang abundance ng C, N, at O sa mga sinuri na clump stars ay sumusuporta sa aming nakaraang mga pagtataya na, kung ihahambing sa Araw at mga dwarf stars ng Galactic disc, ang carbon ay nabawasan ng humigit-kumulang 0.2 dex, ang nitrogen ay nadagdagan ng 0.2 dex, at ang oxygen ay malapit sa mga abundance sa mga dwarf. Ang mga rasyo ng 12C/13C at C/N para sa mga sinuri na galactic red clump stars ay kinumpara sa mga modelo ng ebolusyon ng extra-mixing. Ang mas matarik na pagbaba ng rasyo ng 12C/13C sa modelo ng thermohaline mixing ni Charbonnel & Lagarde ay mas tumutukoy sa mga datos ng obserbasyon sa mababang masa ng bituin kumpara sa mas mababaw na modelo ng cool bottom processing ni Boothroyd & Sackmann. Para sa mga bituin na may humigit-kumulang 2 Msun na masa, dapat isaalang-alang ang pagmomodelo ng rotationally induced mixing na may bilis ng pag-ikot na humigit-kumulang 250 km s-1 noong nasa hydrogen-core-burning stage pa ang bituin.
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tl
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Many academics have called for increasing attention to theory in software engineering. Consequently, this paper empirically evaluates two dissimilar software development process theories - one expressing a more traditional, methodical view (FBS) and one expressing an alternative, more improvisational view (SCI). A primarily quantitative survey of more than 1300 software developers is combined with four qualitative case studies to achieve a simultaneously broad and deep empirical evaluation. Case data analysis using a closed-ended, a priori coding scheme based on the two theories strongly supports SCI, as does analysis of questionnaire response distributions (p<0.001; chi-square goodness of fit test). Furthermore, case-questionnaire triangulation found no evidence that support for SCI varied by participants' gender, education, experience, nationality or the size or nature of their projects. This suggests that instead of iteration between weakly-coupled phases (analysis, design, coding, testing), it is more accurate and useful to conceptualize development as ad hoc oscillation between organizing perceptions of the project context (Sensemaking), simultaneously improving mental pictures of the context and design artifact (Coevolution) and constructing, debugging and deploying software artifacts (Implementation).
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بہت سے ماہرین تعلیم نے سافٹ ویئر انجینئرنگ میں نظریات پر توجہ بڑھانے کی اپیل کی ہے۔ نتیجے کے طور پر، اس مقالے میں دو مختلف قسم کے سافٹ ویئر ترقی کے عمل کے نظریات کا تجرباتی جائزہ لیا گیا ہے - ایک روایتی، منظم نقطہ نظر (FBS) کو ظاہر کرتا ہے اور دوسرا ایک متبادل، زیادہ تخلیقی نقطہ نظر (SCI) کو بیان کرتا ہے۔ ایک وسیع پیمانے پر کمیتی جائزہ جس میں 1300 سے زائد سافٹ ویئر ڈویلپرز کو شامل کیا گیا ہے، چار معیاری کیس اسٹڈیز کے ساتھ ملایا گیا ہے تاکہ ایک ہی وقت میں وسیع اور گہرا تجرباتی جائزہ حاصل کیا جا سکے۔ دونوں نظریات پر مبنی بند الفاظ، از قبل کوڈنگ اسکیم کا استعمال کرتے ہوئے کیس ڈیٹا کے تجزیہ سے SCI کی واضح حمایت ہوتی ہے، جس کی تصدیق سروے کے جوابات کے تقسیم کے تجزیہ سے بھی ہوتی ہے (p<0.001؛ کائی اسکوائر گڈنس آف فِٹ ٹیسٹ)۔ مزید برآں، کیس اور سروے کے جائزہ کے امتزاج سے یہ ثابت ہوا کہ SCI کی حمایت شرکاء کی جنس، تعلیم، تجربہ، قومیت یا ان کے منصوبوں کی بڑے پن یا نوعیت کے لحاظ سے مختلف نہیں ہوتی۔ اس سے یہ نتیجہ اخذ کیا جا سکتا ہے کہ کمزور طور پر جڑے مراحل (تحلیل، ڈیزائن، کوڈنگ، ٹیسٹنگ) کے درمیان بار بار عمل کرنے کے بجائے، ترقی کو منصوبے کے تناظر کی تنظیم کے بارے ادھوچ طور پر آبادی (سینسمیکنگ)، تناظر اور ڈیزائن کی دماغی تصویروں کو ایک ساتھ بہتر بنانا (کوایولوشن) اور سافٹ ویئر آرٹیفیکٹس کی تعمیر، ڈی باگنگ اور تشکیل دینے (ایمپلیمنٹیشن) کے درمیان لہر دار حرکت کے طور پر سمجھنا زیادہ درست اور مفید ہے۔
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In this paper, we provide non-parametric statistical tools to test stationarity of microstructure noise in general hidden Ito semimartingales, and discuss how to measure liquidity risk using high frequency financial data. In particular, we investigate the impact of non-stationary microstructure noise on some volatility estimators, and design three complementary tests by exploiting edge effects, information aggregation of local estimates and high-frequency asymptotic approximation. The asymptotic distributions of these tests are available under both stationary and non-stationary assumptions, thereby enable us to conservatively control type-I errors and meanwhile ensure the proposed tests enjoy the asymptotically optimal statistical power. Besides it also enables us to empirically measure aggregate liquidity risks by these test statistics. As byproducts, functional dependence and endogenous microstructure noise are briefly discussed. Simulation with a realistic configuration corroborates our theoretical results, and our empirical study indicates the prevalence of non-stationary microstructure noise in New York Stock Exchange.
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Neste artigo, fornecemos ferramentas estatísticas não paramétricas para testar a estacionariedade do ruído de microestrutura em semimartingales de Itô ocultos gerais, e discutimos como medir o risco de liquidez utilizando dados financeiros de alta frequência. Em particular, investigamos o impacto do ruído de microestrutura não estacionário sobre alguns estimadores de volatilidade, e desenvolvemos três testes complementares explorando efeitos de borda, agregação de informações de estimativas locais e aproximação assintótica em alta frequência. As distribuições assintóticas desses testes estão disponíveis tanto sob hipóteses estacionárias quanto não estacionárias, permitindo-nos controlar conservadoramente os erros do tipo I e garantir ao mesmo tempo que os testes propostos possuam potência estatística assintoticamente ótima. Além disso, isso nos permite medir empiricamente riscos agregados de liquidez por meio dessas estatísticas de teste. Como subprodutos, dependência funcional e ruído de microestrutura endógeno são brevemente discutidos. Uma simulação com uma configuração realista corrobora nossos resultados teóricos, e nosso estudo empírico indica a prevalência de ruído de microestrutura não estacionário na Bolsa de Valores de Nova York.
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With the aim of better understanding the class of 4D theories generated by compactifications of 6D superconformal field theories (SCFTs), we study the structure of N = 1 supersymmetric punctures for class S_Gamma theories, namely the 6D SCFTs obtained from M5-branes probing an ADE singularity. For M5-branes probing a C^2 / Z_k singularity, the punctures are governed by a dynamical system in which evolution in time corresponds to motion to a neighboring node in an affine A-type quiver. Classification of punctures reduces to determining consistent initial conditions which produce periodic orbits. The study of this system is particularly tractable in the case of a single M5-brane. Even in this "simple" case, the solutions exhibit a remarkable level of complexity: Only specific rational values for the initial momenta lead to periodic orbits, and small perturbations in these values lead to vastly different late time behavior. Another difference from half BPS punctures of class S theories includes the appearance of a continuous complex "zero mode" modulus in some puncture solutions. The construction of punctures with higher order poles involves a related set of recursion relations. The resulting structures also generalize to systems with multiple M5-branes as well as probes of D- and E-type orbifold singularities.
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Dengan tujuan memahami lebih baik kelas teori 4D yang dihasilkan dari kompaktifikasi teori medan superkonformal 6D (SCFTs), kami mempelajari struktur lubang supersimetri N = 1 untuk teori kelas S_Gamma, yaitu SCFT 6D yang diperoleh dari M5-brana yang menelusuri singularitas ADE. Untuk M5-brana yang menelusuri singularitas C^2 / Z_k, struktur lubang diatur oleh suatu sistem dinamis di mana perkembangan dalam waktu sesuai dengan perpindahan ke simpul tetangga dalam kuiver tipe-A afine. Klasifikasi lubang direduksi menjadi penentuan kondisi awal yang konsisten yang menghasilkan orbit periodik. Studi terhadap sistem ini menjadi lebih mudah ditangani dalam kasus satu M5-brana. Bahkan dalam kasus yang "sederhana" ini, solusi menunjukkan tingkat kompleksitas yang luar biasa: hanya nilai-nilai rasional tertentu untuk momentum awal yang menghasilkan orbit periodik, dan gangguan kecil terhadap nilai-nilai tersebut menghasilkan perilaku jangka panjang yang sangat berbeda. Perbedaan lain dari lubang setengah BPS pada teori kelas S termasuk munculnya modulus modus nol kompleks kontinu dalam beberapa solusi lubang. Konstruksi lubang dengan kutub orde lebih tinggi melibatkan himpunan relasi rekursif terkait. Struktur yang dihasilkan juga dapat digeneralisasi ke sistem dengan banyak M5-brana serta penelusur singularitas orifold tipe-D dan tipe-E.
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id
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Let A be a C*-algebra and A** its enveloping von Neumann algebra. C. Akemann suggested a kind of non-commutative topology in which certain projections in A** play the role of open sets. The adjectives "open", "closed", "compact", and "relatively compact" all can be applied to projections in A**. Two operator inequalities were used by Akemann in connection with compactness. Both of these inequalities are equivalent to compactness for a closed projection in A**, but only one is equivalent to relative compactness for a general projection. A third operator inequality, also related to compactness, was used by the author. It turns out that the study of all three inequalities can be unified by considering a numerical invariant which is equivalent to the distance of a projection from the set of relatively compact projections. Since the subject concerns the relation between a projection and its closure, Tomita's concept of regularity of projections seems relevant, and some results and examples on regularity are also given. A few related results on semicontinuity are also included.
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Cho A là một C*-đại số và A** là đại số von Neumann bao của nó. C. Akemann đã đề xuất một dạng tô pô không giao hoán trong đó một số phép chiếu nhất định trong A** đóng vai trò như các tập mở. Các tính từ "mở", "đóng", "compact" và "compact tương đối" đều có thể áp dụng cho các phép chiếu trong A**. Akemann đã sử dụng hai bất đẳng thức toán tử liên quan đến tính compact. Cả hai bất đẳng thức này đều tương đương với tính compact đối với một phép chiếu đóng trong A**, nhưng chỉ một trong hai tương đương với tính compact tương đối đối với một phép chiếu tổng quát. Tác giả đã sử dụng một bất đẳng thức toán tử thứ ba, cũng liên quan đến tính compact. Hóa ra việc nghiên cứu cả ba bất đẳng thức này có thể được thống nhất thông qua việc xét một bất biến số học tương đương với khoảng cách từ một phép chiếu đến tập hợp các phép chiếu compact tương đối. Vì chủ đề liên quan đến quan hệ giữa một phép chiếu và bao đóng của nó, nên khái niệm tính chính quy của các phép chiếu do Tomita đề xuất dường như có liên quan, và một số kết quả cùng các ví dụ về tính chính quy cũng được trình bày. Một vài kết quả liên quan đến tính nửa liên tục cũng được đưa vào.
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vi
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With the aim of better understanding the class of 4D theories generated by compactifications of 6D superconformal field theories (SCFTs), we study the structure of N = 1 supersymmetric punctures for class S_Gamma theories, namely the 6D SCFTs obtained from M5-branes probing an ADE singularity. For M5-branes probing a C^2 / Z_k singularity, the punctures are governed by a dynamical system in which evolution in time corresponds to motion to a neighboring node in an affine A-type quiver. Classification of punctures reduces to determining consistent initial conditions which produce periodic orbits. The study of this system is particularly tractable in the case of a single M5-brane. Even in this "simple" case, the solutions exhibit a remarkable level of complexity: Only specific rational values for the initial momenta lead to periodic orbits, and small perturbations in these values lead to vastly different late time behavior. Another difference from half BPS punctures of class S theories includes the appearance of a continuous complex "zero mode" modulus in some puncture solutions. The construction of punctures with higher order poles involves a related set of recursion relations. The resulting structures also generalize to systems with multiple M5-branes as well as probes of D- and E-type orbifold singularities.
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Com o objetivo de compreender melhor a classe de teorias 4D geradas por compactificações de teorias de campo superconformes 6D (SCFTs), estudamos a estrutura de punções supersimétricas com N = 1 para teorias da classe S_Gamma, ou seja, as SCFTs 6D obtidas a partir de branas M5 sondando uma singularidade ADE. Para branas M5 sondando uma singularidade C^2 / Z_k, as punções são governadas por um sistema dinâmico no qual a evolução no tempo corresponde ao movimento para um nó vizinho em um quiver afim do tipo A. A classificação de punções reduz-se à determinação de condições iniciais consistentes que produzam órbitas periódicas. O estudo desse sistema é particularmente tratável no caso de uma única brana M5. Mesmo nesse caso "simples", as soluções exibem um nível notável de complexidade: apenas valores racionais específicos para os momentos iniciais levam a órbitas periódicas, e pequenas perturbações nesses valores conduzem a comportamentos drasticamente diferentes em tempos posteriores. Outra diferença em relação às punções meia-BPS de teorias da classe S inclui o aparecimento de um módulo contínuo complexo de "modo zero" em algumas soluções de punções. A construção de punções com polos de ordem superior envolve um conjunto relacionado de relações de recorrência. As estruturas resultantes também se generalizam para sistemas com múltiplas branas M5, bem como para sondas de singularidades orbifold dos tipos D e E.
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We derive mass functions (MF) for halo red dwarfs (the faintest hydrogen burning stars) and then extrapolate to place limits on the total mass of halo brown dwarfs (stars not quite massive enough to burn hydrogen). The mass functions are obtained from the luminosity function of a sample of 114 local halo stars in the USNO parallax survey (Dahn \etal 1995). We use stellar models of Alexander \etal (1996) and make varying assumptions about metallicity and about possible unresolved binaries in the sample. We find that the MF for halo red dwarfs cannot rise more quickly than $1/m^2$ as one approaches the hydrogen burning limit. Using recent results from star formation theory, we extrapolate the MF into the brown-dwarf regime. We see that likely extrapolations imply that the total mass of brown dwarfs in the halo is less than $\sim 3\%$ of the local mass density of the halo ($\sim 0.3\%$ for the more realistic models we consider). Our limits apply to brown dwarfs in the halo that come from the same stellar population as the red dwarfs.
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Obtemos funções de massa (FM) para anãs vermelhas do halo (as estrelas que queimam hidrogênio mais fracas) e, em seguida, extrapolamos para estabelecer limites sobre a massa total de anãs marrons do halo (estrelas que não são suficientemente massivas para queimar hidrogênio). As funções de massa são obtidas a partir da função de luminosidade de uma amostra de 114 estrelas locais do halo no levantamento de paralaxe do USNO (Dahn \etal 1995). Utilizamos modelos estelares de Alexander \etal (1996) e fazemos diferentes suposições sobre metalicidade e sobre possíveis binárias não resolvidas na amostra. Descobrimos que a FM para anãs vermelhas do halo não pode crescer mais rapidamente do que $1/m^2$ à medida que se aproxima do limite de queima de hidrogênio. Usando resultados recentes da teoria da formação estelar, extrapolamos a FM para o regime de anãs marrons. Observamos que extrapolações prováveis implicam que a massa total de anãs marrons no halo é inferior a $\sim 3\%$ da densidade local de massa do halo ($\sim 0,3\%$ para os modelos mais realistas que consideramos). Nossos limites aplicam-se a anãs marrons no halo que provêm da mesma população estelar das anãs vermelhas.
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The cosmic microwave background (CMB) temperature anisotropies exhibit a large-scale dipolar power asymmetry. To determine whether this is due to a real, physical modulation or is simply a large statistical fluctuation requires the measurement of new modes. Here we forecast how well CMB polarization data from \Planck\ and future experiments will be able to confirm or constrain physical models for modulation. Fitting several such models to the \Planck\ temperature data allows us to provide predictions for polarization asymmetry. While for some models and parameters \Planck\ polarization will decrease error bars on the modulation amplitude by only a small percentage, we show, importantly, that cosmic-variance-limited (and in some cases even \Planck) polarization data can decrease the errors by considerably better than the expectation of $\sqrt 2$ based on simple $\ell$-space arguments. We project that if the primordial fluctuations are truly modulated (with parameters as indicated by \Planck\ temperature data) then \Planck\ will be able to make a 2$\sigma$ detection of the modulation model with 20--75\% probability, increasing to 45--99\% when cosmic-variance-limited polarization is considered. We stress that these results are quite model dependent. Cosmic variance in temperature is important: combining statistically isotropic polarization with temperature data will spuriously increase the significance of the temperature signal with 30\% probability for \Planck.
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Ang mga anisotropiya ng temperatura ng cosmic microwave background (CMB) ay nagpapakita ng malawakang dipolar na hindi pagkakapantay ng lakas. Upang matukoy kung ito ay dahil sa tunay na pisikal na modulasyon o simpleng malaking statistical fluctuation ay nangangailangan ng pagsukat ng mga bagong mode. Dito, hinuhulaan namin kung gaano kahusay ang CMB polarization data mula sa \Planck\ at mga susunod pang eksperimento na magagawa upang mapatunayan o mapanghawakan ang mga pisikal na modelo para sa modulasyon. Ang pagsasama ng ilang ganitong modelo sa \Planck\ temperature data ay nagbibigay-daan sa amin na magbigay ng mga hula para sa polarization asymmetry. Bagaman para sa ilang modelo at parameter ang \Planck\ polarization ay babawasan lamang ng kaunti ang error bars sa amplitude ng modulasyon, ipinapakita namin, na mahalaga, na ang cosmic-variance-limited (at sa ilang kaso kahit ang \Planck) polarization data ay maaaring bawasan ang mga error nang mas mahusay kaysa sa inaasahang $\sqrt 2$ batay sa simpleng $\ell$-space na argumento. Inihahayag namin na kung ang mga paunang pagbabago ay talagang modulated (na may parameter na ipinakita ng \Planck\ temperature data), ang \Planck\ ay may kakayahang makagawa ng 2$\sigma$ na deteksyon ng modelo ng modulasyon na may 20–75\% na posibilidad, na tataas sa 45–99\% kapag isinasaalang-alang ang cosmic-variance-limited polarization. Binibigyang-diin namin na ang mga resulta ay lubhang nakadepende sa modelo. Mahalaga ang cosmic variance sa temperatura: ang pagsasama ng statistically isotropic polarization sa datos ng temperatura ay magpapataas nang maling paraan sa kahalagahan ng temperatura na signal nang 30\% na posibilidad para sa \Planck.
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tl
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