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Majorana neutrinos in the seesaw model can have sizable mixings through which they can be produced at the Large Hadron Collider (LHC) and show a remarkable Lepton Number Violating (LNV) signature. In this article we study the LNV decay of the W boson via two almost degenerate heavy on-shell Majorana neutrinos $N_j$, into three charged leptons and a light neutrino. We consider the scenario where the heavy neutrino masses are within $1$ GeV $\leq M_N \leq 10$ GeV. We evaluated the possibility to measure a LNV oscillation process in such a scenario, namely, the modulation of the quantity $d \Gamma/d L$ for the process at the LHC where $W^{\pm} \to \mu^{\pm} N \to \mu^{\pm} \tau^{\pm} W^{\mp *}$ $ \to \mu^{\pm} \tau^{\pm} e^{\mp} \nu_e$. $L$ is the distance within the detector between the two vertices of the process. We found out some realistic conditions under which such a modulation could be probed at the LHC.
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ในแบบจำลองซีซอว์ นิวตริโนแบบมาโจราณาอาจมีการผสมผสานกันในระดับที่สังเกตได้ ซึ่งทำให้สามารถผลิตอนุภาคเหล่านี้ที่เครื่องชนอนุภาคขนาดใหญ่ (LHC) และแสดงลายเซ็นที่โดดเด่นของการฝ่าฝืนกฎจำนวนเลปตอน (LNV) ได้ ในบทความนี้ เราศึกษาการสลายตัวแบบ LNV ของโบซอน W ผ่านนิวตริโนมาโจราณาหนักสองตัวที่เกือบมีมวลซ้อนทับกัน $N_j$ ไปเป็นเลปตอนมีประจุสามตัวและนิวตริโนเบา เราพิจารณาสถานการณ์ที่มวลของนิวตริโนหนักอยู่ในช่วง $1$ จิกะอิเล็กตรอนโวลต์ $\leq M_N \leq 10$ จิกะอิเล็กตรอนโวลต์ เราประเมินความเป็นไปได้ในการวัดกระบวนการสั่นของ LNV ในสถานการณ์ดังกล่าว โดยเฉพาะการเปลี่ยนแปลงของขนาด $d \Gamma/d L$ สำหรับกระบวนการที่ LHC ซึ่ง $W^{\pm} \to \mu^{\pm} N \to \mu^{\pm} \tau^{\pm} W^{\mp *}$ $ \to \mu^{\pm} \tau^{\pm} e^{\mp} \nu_e$ โดย $L$ คือระยะทางภายในเครื่องตรวจจับระหว่างจุดกำเนิดสองจุดของกระบวนการ เราพบเงื่อนไขบางประการที่เป็นจริงได้ ซึ่งสามารถใช้ตรวจสอบการเปลี่ยนแปลงดังกล่าวที่ LHC ได้
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th
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We present high-resolution, high-sensitivity radio images of the ultra-luminous infrared galaxy (ULIRG) IRAS 23365+3604. We performed contemporaneous observations at 1.7 and 5.0 GHz, in three epochs separated by one year from each other, with the European very long baseline interferometry Network (EVN). We also present complementary Multi-Element Radio Linked Interferometry Network (MERLIN) at 1.6 and 5.0 GHz, and archival Very Large Array (VLA) data, taken at 1.4 and 4.9 GHz. We find that the emission at ~5.0 GHz remains quite compact as seen at different resolutions, whereas at ~1.7 GHz, high resolution imaging reveals some extended structure. The nuclear region has an approximate linear size of 200 pc and shows the presence of two main emission components: i) one with a composite spectrum due to ongoing non-thermal activity (probably due to recently exploded supernovae and AGN activity), ii) another one with a steep spectrum, likely dominated by an old population of radio emitters, such as supernova remnants (SNRs). Radiative losses are important, so re-acceleration or replenishment of new electrons is necessary. We estimate a magnetic field strength of 18 \mu G at galactic, and 175 \mu G at nuclear scales, which are typical for galaxies in advanced mergers.
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Představujeme radiové snímky ultra-jasné infračervené galaxie (ULIRG) IRAS 23365+3604 s vysokým rozlišením a citlivostí. Provedli jsme současné pozorování na frekvencích 1,7 a 5,0 GHz ve třech epizodách, vzájemně vzdálených o jeden rok, pomocí Evropské sítě velmi dlouhých základen (EVN). Dále prezentujeme doplňující data z Multi-Element Radio Linked Interferometry Network (MERLIN) na frekvencích 1,6 a 5,0 GHz a archivní data z Very Large Array (VLA) pořízená na frekvencích 1,4 a 4,9 GHz. Zjistili jsme, že záření na frekvenci přibližně 5,0 GHz zůstává poměrně kompaktní při různých rozlišeních, zatímco na frekvenci přibližně 1,7 GHz odhaluje zobrazování s vysokým rozlišením určitou rozšířenou strukturu. Jádrová oblast má přibližnou lineární velikost 200 pc a vykazuje přítomnost dvou hlavních složek záření: i) jedné se složeným spektrem způsobeným probíhající netepelnou aktivitou (pravděpodobně v důsledku nedávných explozí supernov a AGN aktivitou), ii) druhé se strmým spektrem, která je pravděpodobně ovlivněna starší populací radiových zdrojů, jako jsou pozůstatky po supernovách (SNR). Radiativní ztráty jsou významné, proto je nutné znovunabíjení nebo doplňování nových elektronů. Odhadujeme intenzitu magnetického pole na 18 μG na galaktické úrovni a 175 μG na úrovni jádra, což je typické pro galaxie v pokročilé fázi srážky.
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cs
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In this paper, we analyze a composite decode-and-forward scheme for the two-way relay channel with a direct link. During transmission, our scheme combines both block Markov coding and an independent coding scheme similar to network coding at the relay. The main contribution of this work is to examine how link state impacts the allocation of power between these two distinct techniques, which in turn governs the necessity of each technique in achieving the largest transmission rate region. We analytically determine the link-state regimes and associated relaying techniques. Our results illustrate an interesting trend: when the user-to-relay link is marginally stronger than the direct link, it is optimal to use only independent coding. In this case, the relay need not use full power. However, for larger user-to-relay link gains, the relay must supplement independent coding with block Markov coding to achieve the largest rate region. These link-state regimes are important for the application of two-way relaying in 5G networks, such as in D2D mode or relay-aided transmission.
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In questo articolo, analizziamo uno schema composito di tipo decode-and-forward per il canale di relè bidirezionale con collegamento diretto. Durante la trasmissione, il nostro schema combina sia la codifica block Markov sia uno schema di codifica indipendente simile alla network coding presso il relè. Il contributo principale di questo lavoro consiste nello studio di come lo stato del collegamento influisca sull'allocazione della potenza tra queste due tecniche distinte, il che a sua volta determina la necessità di ciascuna tecnica per raggiungere la massima regione di velocità trasmissiva. Determiniamo analiticamente i regimi di stato del collegamento e le tecniche di relè associate. I nostri risultati evidenziano una tendenza interessante: quando il collegamento da utente a relè è marginalmente più forte del collegamento diretto, è ottimale utilizzare soltanto la codifica indipendente. In questo caso, il relè non deve utilizzare tutta la potenza disponibile. Tuttavia, per guadagni maggiori del collegamento da utente a relè, il relè deve affiancare alla codifica indipendente anche la codifica block Markov per raggiungere la massima regione di velocità. Questi regimi di stato del collegamento sono importanti per l'applicazione del relè bidirezionale nelle reti 5G, come ad esempio nella modalità D2D o nella trasmissione assistita da relè.
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it
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Binary black holes on quasicircular orbits with spins aligned with their orbital angular momentum have been testbeds for analytic and numerical relativity for decades, not least because symmetry ensures that such configurations are equilibrium solutions to the spin-precession equations. In this work, we show that these solutions can be unstable when the spin of the higher-mass black hole is aligned with the orbital angular momentum and the spin of the lower-mass black hole is anti-aligned. Spins in these configurations are unstable to precession to large misalignment when the binary separation $r$ is between the values $r_{\rm ud\pm}= (\sqrt{\chi_1} \pm \sqrt{q \chi_2})^4 (1-q)^{-2} M$, where $M$ is the total mass, $q \equiv m_2/m_1$ is the mass ratio, and $\chi_1$ ($\chi_2$) is the dimensionless spin of the more (less) massive black hole. This instability exists for a wide range of spin magnitudes and mass ratios and can occur in the strong-field regime near merger. We describe the origin and nature of the instability using recently developed analytical techniques to characterize fully generic spin precession. This instability provides a channel to circumvent astrophysical spin alignment at large binary separations, allowing significant spin precession prior to merger affecting both gravitational-wave and electromagnetic signatures of stellar-mass and supermassive binary black holes.
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Lubang hitam dedua perduaan pada orbit hampir membulat dengan putaran selari dengan momentum sudut orbit mereka telah menjadi landasan ujian kepada kerelativan analitik dan berangka selama beberapa dekad, tidak kurang kerana simetri memastikan bahawa konfigurasi sedemikian merupakan penyelesaian keseimbangan kepada persamaan praesusi putaran. Dalam karya ini, kami menunjukkan bahawa penyelesaian ini boleh menjadi tidak stabil apabila putaran lubang hitam yang lebih berjisim adalah selari dengan momentum sudut orbit dan putaran lubang hitam yang kurang berjisim adalah bertentangan arah. Putaran dalam konfigurasi ini tidak stabil terhadap praesusi kepada ketidakselarasan besar apabila pemisahan dedua $r$ berada di antara nilai-nilai $r_{\rm ud\pm}= (\sqrt{\chi_1} \pm \sqrt{q \chi_2})^4 (1-q)^{-2} M$, dengan $M$ ialah jisim keseluruhan, $q \equiv m_2/m_1$ ialah nisbah jisim, dan $\chi_1$ ($\chi_2$) ialah putaran tanpa dimensi bagi lubang hitam yang lebih (kurang) berjisim. Ketidakstabilan ini wujud bagi julat yang luas magnitud putaran dan nisbah jisim dan boleh berlaku dalam kawasan medan kuat berhampiran peleburan. Kami menerangkan asal usul dan sifat ketidakstabilan ini menggunakan teknik analitik yang baru dibangunkan untuk mewatakkan sepenuhnya praesusi putaran generik. Ketidakstabilan ini menyediakan satu saluran untuk mengelakkan penyelarasan putaran astrophizikal pada pemisahan dedua yang besar, membolehkan praesusi putaran yang ketara sebelum peleburan yang memberi kesan kepada isyarat gelombang graviti dan elektromagnet bagi dedua lubang hitam berjisim bintang dan supermasif.
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ms
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Gerhard had recently analyzed the data on seven dwarf spheroidals, and concluded that these disagree with the predictions of MOND. We contend that this conclusion is anything but correct. With new data for three of the dwarfs the observations of all dwarfs are in compelling agreement with the predictions of MOND. Gerhard found MOND M/L values that fall around a few solar units, as expected if MOND is a valid alternative to dark matter. His sole cause for complaint was that some of his MOND M/L values were still outside the range of ``reasonable'' stellar values. This, we say, was easily attributable to uncertainties in the data, such as in the velocity dispersions, luminosities, core radii, etc., and in the assumptions that underlie the analysis, such as isotropic velocity distribution, light-distribution fits, etc.. There are now new, much improved determinations of the velocity dispersions for three of the dwarfs, in particular for the two dwarfs for which Gerhard found high MOND M/L values. In fact, within just the quoted errors on the velocity dispersions and the luminosities, the MOND M/L values for all seven dwarfs are now perfectly consistent with stellar values, with no need for dark matter.
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เกอร์ฮาร์ดได้วิเคราะห์ข้อมูลจากกาแล็กซีแคระรูปทรงกลมเจ็ดแห่งเมื่อไม่นานมานี้ และสรุปว่าข้อมูลเหล่านี้ขัดแย้งกับการทำนายของทฤษฎี MOND เราขอโต้แย้งว่าข้อสรุปดังกล่าวไม่ถูกต้องอย่างยิ่ง ด้วยข้อมูลใหม่สำหรับกาแล็กซีแคระสามแห่ง ข้อมูลสังเกตการณ์ของกาแล็กซีแคระทั้งหมดกลับสอดคล้องกับการทำนายของ MOND อย่างน่าประทับใจ เกอร์ฮาร์ดได้ค่ามวลต่อความสว่าง (M/L) ภายใต้ MOND ที่อยู่ในระดับไม่กี่หน่วยของค่าสุริยะ ซึ่งเป็นไปตามที่คาดไว้หาก MOND เป็นทางเลือกที่ถูกต้องแทนสสารมืด สิ่งเดียวที่เขาติดใจคือค่า M/L ภายใต้ MOND บางค่ายังอยู่นอกช่วงของค่ามวลต่อความสว่างจากดาวฤกษ์ที่ถือว่า "สมเหตุสมผล" ซึ่งเราขอชี้แจงว่าสาเหตุนี้สามารถอธิบายได้ง่ายว่าเกิดจากความไม่แน่นอนของข้อมูล เช่น ความคลาดเคลื่อนของการกระจายความเร็ว ความสว่าง รัศมีแกนกลาง ฯลฯ และข้อสมมติที่ใช้ในการวิเคราะห์ เช่น การกระจายความเร็วแบบไอโซทรอปิก การประมาณรูปแบบการกระจายของแสง ฯลฯ ขณะนี้มีข้อมูลใหม่ที่แม่นยำกว่ามากสำหรับค่าการกระจายความเร็วของกาแล็กซีแคระสามแห่ง โดยเฉพาะสองแห่งที่เกอร์ฮาร์ดพบค่า M/L ภายใต้ MOND สูงมาก ที่จริงแล้ว แม้เพียงพิจารณาความคลาดเคลื่อนที่รายงานไว้ของค่าการกระจายความเร็วและความสว่าง ค่า M/L ภายใต้ MOND สำหรับกาแล็กซีแคระทั้งเจ็ดแห่งก็สอดคล้องอย่างสมบูรณ์กับค่าที่คาดไว้จากดาวฤกษ์ โดยไม่จำเป็นต้องอ้างถึงสสารมืดอีกต่อไป
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th
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Nonadiabatic geometric phases are only dependent on the evolution path of a quantum system but independent of the evolution details, and therefore quantum computation based on nonadiabatic geometric phases is robust against control errors. To realize nonadiabatic geometric quantum computation, it is necessary to ensure that the quantum system undergoes a cyclic evolution and the dynamical phases are removed from the total phases. To satisfy these conditions, the evolution paths in previous schemes are usually restricted to some special forms, e.g, orange-slice-shaped loops, which make the paths unnecessarily long in general. In this paper, we put forward an approach to the realization of nonadiabatic geometric quantum computation by which a universal set of nonadiabatic geometric gates can be realized with any desired evolution paths. Our approach makes it possible to realize geometric quantum computation with an economical evolution time so the influence of environment noises on the quantum gates can be minimized further.
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Các pha hình học không đoạn nhiệt chỉ phụ thuộc vào quỹ đạo tiến hóa của một hệ lượng tử mà không phụ thuộc vào các chi tiết tiến hóa, do đó phép tính lượng tử dựa trên các pha hình học không đoạn nhiệt có độ bền cao trước các lỗi điều khiển. Để thực hiện phép tính lượng tử hình học không đoạn nhiệt, cần đảm bảo rằng hệ lượng tử trải qua một quá trình tiến hóa tuần hoàn và các pha động lực học bị loại bỏ khỏi các pha toàn phần. Để thỏa mãn các điều kiện này, các quỹ đạo tiến hóa trong các phương án trước đây thường bị giới hạn ở một số dạng đặc biệt, ví dụ như các vòng tròn hình múi cam, điều này thường khiến các quỹ đạo trở nên dài hơn mức cần thiết. Trong bài báo này, chúng tôi đề xuất một phương pháp thực hiện phép tính lượng tử hình học không đoạn nhiệt, cho phép thực hiện một tập đầy đủ các cổng hình học không đoạn nhiệt với bất kỳ quỹ đạo tiến hóa mong muốn nào. Phương pháp của chúng tôi làm cho việc thực hiện phép tính lượng tử hình học với thời gian tiến hóa tiết kiệm hơn trở nên khả thi, nhờ đó ảnh hưởng của nhiễu môi trường lên các cổng lượng tử có thể được giảm thiểu thêm.
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vi
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We report the thermoelectric (TE) properties of (1-x)LaCoO3.xLa0.7Sr0.3MnO3 (0 < x < 0.10) composite in a temperature range 320-800 K. Addition of La0.7Sr0.3MnO3 to LaCoO3 in small amount (5 weight %) improves the overall Seebeck coefficient ({\alpha}) at higher temperatures. The electrical conductivity, however, decreases due to a decrease in carrier concentration of the composite. The decrease in electrical conductivity of the composite at high temperature may be attributed to the insulating nature of the LSMO above room temperature. Thermal conductivity (\k{appa}) of all the samples increases with an increase in the temperature but decreases with increasing LSMO content. We also report the local variation of the Seebeck coefficient across the composite samples measured using a precision Seebeck measurement system. A maximum value of 0.09 for the figure of merit (ZT) is obtained for 0.95LaCoO3.0.05La0.7Sr0.3MnO3 at 620 K which is significantly higher than the ZT of either of LaCoO3 or La0.7Sr0.3MnO3 at 620 K. This suggests the potential for enhancement of operating temperatures of hitherto well known low-temperature thermoelectric materials through suitable compositing approach.
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ہم (1-x)LaCoO3.xLa0.7Sr0.3MnO3 (0 < x < 0.10) مرکب کی حرارت برقی (TE) خصوصیات کی رپورٹ 320-800 K درجہ حرارت کی حد میں پیش کرتے ہیں۔ لاکوO3 میں چھوٹی مقدار (5 فیصد وزنی) La0.7Sr0.3MnO3 کے اضافے سے زیادہ درجہ حرارت پر مجموعی سیبیک کوائفیشنٹ ({\alpha}) میں بہتری آتی ہے۔ تاہم، برقی موصلیت کم ہوجاتی ہے کیونکہ مرکب کی حاملہ تعداد کم ہوجاتی ہے۔ اونچے درجہ حرارت پر مرکب کی برقی موصلیت میں کمی کی وجہ کمرے کے درجہ حرارت سے اوپر LSMO کی عُزلت خصوصیت ہوسکتی ہے۔ تمام نمونوں کی حرارتی موصلیت (\k{appa}) درجہ حرارت میں اضافے کے ساتھ بڑھتی ہے لیکن LSMO کی مقدار میں اضافے کے ساتھ کم ہوتی ہے۔ ہم مرکب نمونوں کے سراسر سیبیک کوائفیشنٹ کی مقامی تغیرات کی رپورٹ بھی پیش کرتے ہیں جو ایک درست سیبیک پیمائش سسٹم کے ذریعہ ماپی گئی تھی۔ 0.95LaCoO3.0.05La0.7Sr0.3MnO3 کے لیے 620 K پر معیاری عدد (ZT) کی زیادہ سے زیادہ قیمت 0.09 حاصل ہوئی، جو 620 K پر لاکوO3 یا La0.7Sr0.3MnO3 دونوں کے ZT سے کافی زیادہ ہے۔ اس سے پتہ چلتا ہے کہ مناسب مرکب بنانے کے طریقہ کار کے ذریعہ اب تک جانے جانے والے کم درجہ حرارت والے حرارت برقی مواد کے کام کرنے کے درجہ حرارت میں بہتری کی صلاحیت موجود ہے۔
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ur
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Efficient exploration remains a challenging problem in reinforcement learning, especially for those tasks where rewards from environments are sparse. A commonly used approach for exploring such environments is to introduce some "intrinsic" reward. In this work, we focus on model uncertainty estimation as an intrinsic reward for efficient exploration. In particular, we introduce an implicit generative modeling approach to estimate a Bayesian uncertainty of the agent's belief of the environment dynamics. Each random draw from our generative model is a neural network that instantiates the dynamic function, hence multiple draws would approximate the posterior, and the variance in the future prediction based on this posterior is used as an intrinsic reward for exploration. We design a training algorithm for our generative model based on the amortized Stein Variational Gradient Descent. In experiments, we compare our implementation with state-of-the-art intrinsic reward-based exploration approaches, including two recent approaches based on an ensemble of dynamic models. In challenging exploration tasks, our implicit generative model consistently outperforms competing approaches regarding data efficiency in exploration.
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Etkin keşif, özellikle çevreden gelen ödüllerin seyrek olduğu görevlerde, pekiştirmeli öğrenmede zorlu bir problem olmaya devam etmektedir. Böyle ortamları keşfetmek için yaygın olarak kullanılan bir yaklaşım bazı "içsel" ödüller eklemektir. Bu çalışmada, etkin keşif için içsel ödül olarak model belirsizliği tahmini üzerinde odaklanıyoruz. Özellikle, ajanın çevre dinamiklerine dair inancının Bayesçi belirsizliğini tahmin etmek amacıyla örtük bir üretici modelleme yaklaşımı sunuyoruz. Üretici modelimizden yapılan her rastgele çekiliş, dinamik fonksiyonu somutlaştıran bir sinir ağıdır; bu nedenle birden fazla çekiliş, posterior dağılımı yaklaşık olarak verir ve bu posterior dağılıma dayalı gelecekteki tahminlerdeki varyans, keşif için içsel bir ödül olarak kullanılır. Üretici modelimiz için amortismanlı Stein Varyasyonel Gradyan İnişine dayalı bir eğitim algoritması tasarladık. Deneylerde, son zamanlarda dinamik modellerin birleşimine dayalı iki yaklaşımı da içeren, içsel ödüle dayalı en ileri düzey keşif yöntemleriyle uygulamamızı karşılaştırıyoruz. Zorlu keşif görevlerinde, örtük üretici modelimiz keşifte veri verimliliği açısından rakip yaklaşımları tutarlı bir şekilde geride bırakmaktadır.
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tr
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It was shown recently that the anomalous scaling of simultaneous correlation functions in turbulence is intimately related to the breaking of temporal scale invariance, which is equivalent to the appearance of infinitely many times scales in the time dependence of time-correlation functions. In this paper we derive a continued fraction representation of turbulent time correlation functions which is exact and in which the multiplicity of time scales is explicit. We demonstrate that this form yields precisely the same scaling laws for time derivatives and time integrals as the "multi-fractal" representation that was used before. Truncating the continued fraction representation yields the "best" estimates of time correlation functions if the given information is limited to the scaling exponents of the simultaneous correlation functions up to a certain, finite order. It is worth noting that the derivation of a continued fraction representation obtained here for an operator which is not Hermitian or anti-Hermitian may be of independent interest.
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Gần đây đã chỉ ra rằng sự thay đổi thang đo bất thường của các hàm tương quan đồng thời trong dòng chảy hỗn loạn có liên quan mật thiết đến sự phá vỡ tính bất biến thang đo thời gian, điều này tương đương với sự xuất hiện của vô số thang thời gian trong sự phụ thuộc thời gian của các hàm tương quan theo thời gian. Trong bài báo này, chúng tôi suy ra một biểu diễn phân số liên tục của các hàm tương quan theo thời gian trong dòng chảy hỗn loạn, biểu diễn này là chính xác và trong đó sự đa dạng của các thang thời gian được thể hiện rõ ràng. Chúng tôi chứng minh rằng dạng này cho ra các quy luật thay đổi thang đo đối với đạo hàm theo thời gian và tích phân theo thời gian hoàn toàn giống như biểu diễn "đa phân số" đã được sử dụng trước đây. Việc cắt ngắn biểu diễn phân số liên tục sẽ cho ra các ước lượng "tốt nhất" của các hàm tương quan theo thời gian nếu thông tin đã biết bị giới hạn ở các số mũ thay đổi thang đo của các hàm tương quan đồng thời đến một bậc hữu hạn nhất định. Cần lưu ý rằng việc suy ra biểu diễn phân số liên tục ở đây đối với một toán tử không phải là Hermit hay phản Hermit có thể mang ý nghĩa độc lập.
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Ultra-high-energy cosmic rays (UHECRs) are the highest energy messengers in the universe, with energies up to $10^{20}$ eV. Studies of astrophysical particles (nuclei, electrons, neutrinos and photons) at their highest observed energies have implications for fundamental physics as well as astrophysics. The primary particles interact in the atmosphere (or in the Earth) and generate extensive air showers. Analysis of those showers enables one not only to estimate the energy, direction and most probable mass of the primary cosmic particles, but also to obtain information about the properties of their hadronic interactions at energies more than one order of magnitude above that accessible with the current highest energy human-made accelerator. The Pierre Auger Observatory, located in the province of Mendoza, Argentina, is the largest cosmic ray experiment ever built. The observatory was designed as a hybrid detector covering an area of 3000 km$^2$ and has been taking data for almost twenty years. In this paper, a selection of the latest results is presented: the cosmic ray energy spectrum, studies of hadronic physics, searches for a directional anisotropy and studies of mass composition (including the photon and neutrino searches). Finally, the current upgrade ("AugerPrime") of the observatory, which is mostly aimed at improving the sensitivity to the particle type and mass of ultra-high energy cosmic rays, is described.
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초고에너지 우주선(UHECRs)은 최대 $10^{20}$ eV의 에너지를 가진, 우주에서 가장 높은 에너지를 지닌 정보 전달자이다. 관측된 가장 높은 에너지를 가진 천체물리학적 입자(원자핵, 전자, 중성미자 및 광자)에 대한 연구는 천체물리학뿐 아니라 기본 물리학에도 중요한 시사점을 제공한다. 초기 입자들은 대기 중(또는 지구 내)에서 상호작용하며 광범위한 대기 캐스케이드(에어 샤워)를 생성한다. 이러한 캐스케이드의 분석을 통해 초기 우주선 입자의 에너지, 방향, 가장 가능성 높은 질량을 추정할 수 있을 뿐 아니라, 현재 인간이 만든 가장 높은 에너지 가속기에서 달성 가능한 에너지보다 한 차수 이상 높은 에너지 영역에서의 강입자 상호작용 특성에 관한 정보도 얻을 수 있다. 아르헨티나 멘도사 주에 위치한 피에르 오귀르 관측소는 지금까지 건설된 가장 큰 우주선 실험 시설이다. 이 관측소는 3000 km$^2$의 면적을 커버하는 하이브리드 탐지기로 설계되었으며, 거의 20년 동안 데이터를 수집해 왔다. 본 논문에서는 최신 결과들 중 일부를 소개한다. 즉, 우주선 에너지 스펙트럼, 강입자 물리학 연구, 방향성 비등방성 탐색, 질량 조성 연구(광자 및 중성미자 탐색 포함) 등을 다룬다. 마지막으로, 초고에너지 우주선의 입자 종류 및 질량에 대한 감도 향상에 주로 목표를 둔 관측소의 현재 업그레이드 사업("AugerPrime")에 대해서도 설명한다.
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Massive rotating single stars with an initial metal composition appropriate for the dwarf galaxy I Zw 18 ([Fe/H]=$-$1.7) are modelled during hydrogen burning for initial masses of 9-300 M$_{\odot}$ and rotational velocities of 0-900 km s$^{-1}$. Internal mixing processes in these models were calibrated based on an observed sample of OB-type stars in the Magellanic Clouds. Even moderately fast rotators, which may be abundant at this metallicity, are found to undergo efficient mixing induced by rotation resulting in quasi chemically-homogeneous evolution. These homogeneously-evolving models reach effective temperatures of up to 90 kK during core hydrogen burning. This, together with their moderate mass-loss rates, make them Transparent Wind Ultraviolet INtense stars (TWUIN star), and their expected numbers might explain the observed HeII ionizing photon flux in I Zw 18 and other low-metallicity HeII galaxies. Our slowly rotating stars above $\sim$80 M$_{\odot}$ evolve into late B- to M-type supergiants during core hydrogen burning, with visual magnitudes up to 19$^{\mathrm{m}}$ at the distance of I Zw 18. Both types of stars, TWUIN stars and luminous late-type supergiants, are only predicted at low metallicity. Massive star evolution at low metallicity is shown to differ qualitatively from that in metal-rich environments. Our grid can be used to interpret observations of local star-forming dwarf galaxies and high-redshift galaxies, as well as the metal-poor components of our Milky Way and its globular clusters.
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I Zw 18 cüce galaksisi için uygun olan başlangıç metalik bileşime ([Fe/H]=$-$1.7) sahip, 9-300 M$_{\odot}$ başlangıç kütleleri ve 0-900 km s$^{-1}$ dönme hızları için hidrojen yanması sürecindeki büyük dönen tek yıldızlar modellenmiştir. Bu modellerdeki iç karışım süreçleri, Büyük ve Küçük Macellan Bulutları'ndaki gözlemlenen OB-tipi yıldız örnekleri temel alınarak kalibre edilmiştir. Bu metalik düzeyde bol miktarda bulunabilecek orta derecede hızlı dönen yıldızların, dönmenin etkisiyle verimli karışım gösterdiği ve neredeyse kimyasal olarak homojen evrim geçirdiği bulunmuştur. Bu homojen evrilen modeller, çekirdek hidrojen yanması sırasında etkin sıcaklıklarını 90 kK'ye kadar çıkarabilmektedir. Bu durum, bunların aynı zamanda orta düzeydeki kütle kaybı oranlarıyla birlikte, Şeffaf Rüzgar Ultraviyole Yoğun yıldızlar (TWUIN yıldızı) olmalarına neden olur ve beklenen sayıları, I Zw 18 ve diğer düşük metalik HeII galaksilerinde gözlenen HeII iyonlaştırıcı foton akısını açıklayabilir. I Zw 18'in uzaklığında, $\sim$80 M$_{\odot}$ üzerindeki yavaş dönen yıldızlarımız çekirdek hidrojen yanması sırasında geç B- ve M-tipi süperdevler haline gelir ve görünür büyüklükleri 19$^{\mathrm{m}}$'ye kadar çıkar. Hem TWUIN yıldızları hem de parlak geç tip süperdevler yalnızca düşük metalik düzeylerde öngörülmektedir. Düşük metalikteki büyük yıldız evriminin, yüksek metalikli ortamlardakinden niteliksel olarak farklı olduğu gösterilmiştir. Bu model ağı, yerel yıldız oluşumlu cüce galaksilerin, yüksek kırmızıya kayma gösteren galaksilerin yanı sıra Samanyolu'muzun ve globüler kümelerinin metal-fakir bileşenlerinin gözlemlerini yorumlamak için kullanılabilir.
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While large-scale language models (LMs) are able to imitate the distribution of natural language well enough to generate realistic text, it is difficult to control which regions of the distribution they generate. This is especially problematic because datasets used for training large LMs usually contain significant toxicity, hate, bias, and negativity. We propose GeDi as an efficient method for using smaller LMs as generative discriminators to guide generation from large LMs to make them safer and more controllable. GeDi guides generation at each step by computing classification probabilities for all possible next tokens via Bayes rule by normalizing over two class-conditional distributions; one conditioned on the desired attribute, or control code, and another conditioned on the undesired attribute, or anti control code. We find that GeDi gives stronger controllability than the state of the art method while also achieving generation speeds more than 30 times faster. Additionally, training GeDi on only four topics allows us to controllably generate new topics zero-shot from just a keyword, unlocking a new capability that previous controllable generation methods do not have. Lastly, we show that GeDi can make GPT-2 (1.5B parameters) significantly less toxic without sacrificing linguistic quality, making it by far the most practical existing method for detoxifying large language models while maintaining a fast generation speed.
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ទោះបីជាម៉ូដែលភាសាល្បឿនធំៗ (LMs) អាចចម្លងចែកចាយភាសាធម្មជាតិបានគ្រប់គ្រាន់ដើម្បីបង្កើតអត្ថបទដែលមើលទៅដូចជាពិតក៏ដោយ ក៏វាពិបាកក្នុងការគ្រប់គ្រងថាតើតំបន់ណាមួយនៃចែកចាយនោះដែលពួកវាបង្កើត។ នេះគឺជាបញ្ហាជាពិសេសដោយសារតែទិន្នន័យដែលប្រើសម្រាប់បណ្តុះបណ្តាល LMs ធំៗ ជាទូទៅមានភាពអាក្រក់ ភាពអ័ព្ទ អំពើលំអៀង និងភាពអវិជ្ជមានយ៉ាងខ្លាំង។ យើងស្នើ GeDi ជាវិធីសាស្ត្រដ៏មានប្រសិទ្ធភាពសម្រាប់ប្រើ LMs តូចៗជាអង្គភាពបែងចែកបង្កើត ដើម្បីដឹកនាំការបង្កើតពី LMs ធំៗ ដើម្បីធ្វើឱ្យពួកវាមានសុវត្ថិភាព និងគ្រប់គ្រងបានច្រើនជាងមុន។ GeDi ដឹកនាំការបង្កើតនៅរាល់ជំហានតាមរយៈការគណនាប្រូបាបប្រភេទសម្រាប់សញ្ញាបន្ទាប់ទាំងអស់ដែលអាចកើតមានតាមរយៈច្បាប់ប៉ៃយ៉េ ដោយធ្វើឱ្យមានលក្ខណៈធម្មតាលើចែកចាយលក្ខណៈពីរ មួយដែលអនុវត្តលើលក្ខណៈដែលចង់បាន ឬកូដគ្រប់គ្រង ហើយមួយទៀតដែលអនុវត្តលើលក្ខណៈដែលមិនចង់បាន ឬកូដប្រឆាំងគ្រប់គ្រង។ យើងរកឃើញថា GeDi ផ្តល់នូវការគ្រប់គ្រងបានខ្លាំងជាងវិធីសាស្ត្រដែលមានស្រាប់ ខណៈពេលដែលវាក៏សម្រេចបានល្បឿនបង្កើតលឿនជាង 30 ដង។ លើសពីនេះទៀត ការបណ្តុះបណ្តាល GeDi លើប្រធានបទតែបួនប្រធានបទ អនុញ្ញាតឱ្យយើងបង្កើតប្រធានបទថ្មីៗដោយគ្មានគំរូ ពីគ្រាប់ចុចមួយគ្រាប់ប៉ុណ្ណោះ ដែលបើកដំណើរការសមត្ថភាពថ្មីមួយដែលវិធីសាស្ត្របង្កើតដែលគ្រប់គ្រងបានមុនៗមិនមាន។ ចុងក្រោយ យើងបង្ហាញថា GeDi អាចធ្វើឱ្យ GPT-2 (1.5B ប៉ារ៉ាម៉ែត្រ) មានភាពអាក្រក់តិចជាងមុន ដោយមិនបាត់បង់គុណភាពភាសា ដែលធ្វើឱ្យវាក្លាយជាវិធីសាស្ត្រដែលអនុវត្តបានច្រើនបំផុតក្នុងចំណោមវិធីសាស្ត្រដែលមានស្រាប់សម្រាប់ធ្វើឱ្យម៉ូដែលភាសាធំៗមានសុវត្ថិភាព ខណៈពេលដែលរក្សាល្បឿនបង្កើតលឿន។
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The prompt optical emission of GRB 990123 was uncorrelated to the gamma-ray light-curve and exhibited temporal properties similar to those of the steeply-decaying, early X-ray emission observed by Swift at the end of many bursts. These facts suggest that the optical counterpart of GRB 990123 was the large-angle emission released during (the second pulse of) the burst. If the optical and gamma-ray emissions of GRB 990123 have, indeed, the same origin then their properties require that (i) the optical counterpart was synchrotron emission and the gamma-rays arose from inverse-Compton scatterings ("synchrotron self-Compton model"), (ii) the peak-energy of the optical-synchrotron component was at ~20 eV, and (iii) the burst emission was produced by a relativistic outflow moving at Lorentz factor > 450 and at a radius > 10^{15} cm, which is comparable to the outflow deceleration radius. Because the spectrum of GRB 990123 was optically thin above 2 keV, the magnetic field behind the shock must have decayed on a length-scale of <1% of the thickness of the shocked gas, which corresponds to 10^6-10^7 plasma skin-depths. Consistency of the optical counterpart decay rate and its spectral slope (or that of the burst, if they represent different spectral components) with the expectations for the large-angle burst emission represents the most direct test of the unifying picture proposed here for GRB 990123.
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Ang prompt na optical emission ng GRB 990123 ay hindi nauugnay sa gamma-ray light-curve at nagpakita ng mga temporal na katangian na katulad ng mga steeply-decaying, maagang X-ray emission na naitala ng Swift sa katapusan ng maraming pagsabog. Ang mga katotohanang ito ay nagmumungkahi na ang optical counterpart ng GRB 990123 ay ang large-angle emission na nailabas noong (ikalawang pulso ng) pagsabog. Kung ang optical at gamma-ray emissions ng GRB 990123 ay may iisang pinagmulan nga, kung gayon ang kanilang mga katangian ay nangangailangan na (i) ang optical counterpart ay synchrotron emission at ang gamma-ray ay nagmula sa inverse-Compton scatterings ("synchrotron self-Compton model"), (ii) ang peak-energy ng optical-synchrotron na bahagi ay nasa ~20 eV, at (iii) ang emission ng pagsabog ay nabuo ng isang relativistic outflow na gumalaw sa Lorentz factor na higit sa 450 at sa radius na higit sa 10^{15} cm, na katumbas ng outflow deceleration radius. Dahil ang spectrum ng GRB 990123 ay optically thin sa itaas ng 2 keV, ang magnetic field sa likod ng shock ay dapat nag-decay sa isang habang sukat na mas mababa sa 1% ng kapal ng nasugatang gas, na tumutugma sa 10^6-10^7 plasma skin-depths. Ang pagkakatugma ng decay rate ng optical counterpart at ng spectral slope nito (o ng pagsabog, kung sila ay kumakatawan sa iba't ibang spectral component) sa mga inaasahan para sa large-angle burst emission ang siyang pinakadirektang pagsusuri sa nag-iisang larawan na ipinapangako rito para sa GRB 990123.
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On November 23, 2021, the Einstein-Besso manuscript on the perihelion motion of Mercury will be auctioned at Christie's. Expected to fetch around $3M, it promises to be the most expensive scientific manuscript ever sold at auction. In this preprint, we present the parts of our forthcoming book, How Einstein Found His Field Equations. Sources and Interpretation (Springer, 2021) dealing with Einstein's attempts, in 1913 and in 1915, to account for the anomalous advance of Mercury's perihelion. In 1913, as documented in the Einstein-Besso manuscript, Einstein and his friend Michele Besso found that the Einstein-Grossmann or Entwurf (= outline or draft) theory, a preliminary version of general relativity, could only account for 18 of the 43 seconds-of-arc-per-century discrepancy between Newtonian theory and observation. In November 1915, however, putting the techniques developed in his collaboration with Besso to good use, Einstein showed that his new general theory of relativity could account for all missing 43 seconds of arc. After a brief introduction, we provide an annotated transcription of the key pages of the Einstein-Besso manuscript and an annotated new translation of the November 1915 perihelion paper.
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၂၀၂၁ ခုနှစ်၊ နိုဝင်ဘာလ ၂၃ ရက်နေ့တွင် မာကျူရီဂြိုဟ်၏ နေအနီးဆုံးအမှတ် ရွေ့လျားမှုနှင့်ပတ်သက်သော အိုင်းစတိုင်း-ဘက်ဆို မူရင်းစာရွက်များကို ခရစ္စတီးကရိပ်တွင် လေလံခတ်မည်ဖြစ်သည်။ အလျားလိုက် ၃ သန်းခန့်ရရှိမည်ဟု မျှော်လင့်ထားပြီး လေလံခေါ်ရောင်းချမည့် သိပ္ပံနည်းကျ မူရင်းစာရွက်များအနက် အကုန်အကျအများဆုံးဖြစ်လာမည်ဟု မျှော်လင့်ရသည်။ ဤကြိုတင်ထုတ်ဝေမှုတွင် ကျွန်ုပ်တို့၏ မကြာမီထွက်ရှိမည့်စာအုပ်ဖြစ်သော အိုင်းစတိုင်းသည် သူ၏ကွင်းညီများကို မည်သို့ရှာဖွေခဲ့သနည်း။ မူရင်းအရင်းအမြစ်များနှင့် အနက်ကောက်ယူမှုများ (စပရင်ဂါ၊ ၂၀၂၁) မှ မာကျူရီဂြိုဟ်၏ နေအနီးဆုံးအမှတ် အလွဲသွားသော ရှေ့ဆက်တိုးတက်မှုကို ၁၉၁၃ ခုနှစ်နှင့် ၁၉၁၅ ခုနှစ်တို့တွင် အိုင်းစတိုင်းကြိုးပမ်းခဲ့ပုံများကို တင်ပြထားသည်။ ၁၉၁၃ ခုနှစ်တွင် အိုင်းစတိုင်း-ဘက်ဆို မူရင်းစာရွက်များတွင် မှတ်တမ်းတင်ထားသည့်အတိုင်း အိုင်းစတိုင်းနှင့် သူ၏မိတ်ဆွေ မိုက်ချယ်လ် ဘက်ဆိုတို့သည် ယေဘုယျ ဆွဲငင်အားဆိုင်ရာ သီအိုရီ၏ ကနဦးဗားရှင်းဖြစ်သော အိုင်းစတိုင်း-ဂရော့စ်မန်း သို့မဟုတ် အင်တွာ့ဖ် (= မူကွဲ သို့မဟုတ် ကြိုတင်မူကွဲ) သီအိုရီကို အသုံးပြု၍ နယူတန်၏သီအိုရီနှင့် လေ့လာမှုအကြား တစ်ရာစုလျှင် စက္ကန့် ၄၃ ပိုင်းခွဲ ကွာခြားမှုအနက် စက္ကန့် ၁၈ ပိုင်းခွဲသာ ရှင်းပြနိုင်ကြောင်း တွေ့ရှိခဲ့ကြသည်။ သို့ရာတွင် ၁၉၁၅ ခုနှစ် နိုဝင်ဘာလတွင် ဘက်ဆိုနှင့် ပူးပေါင်းကာ ဖွံ့ဖြိုးတိုးတက်စေခဲ့သော နည်းလမ်းများကို အကျိုးရှိစွာ အသုံးချကာ အိုင်းစတိုင်းသည် သူ၏ ယေဘုယျ ဆွဲငင်အားဆိုင်ရာ သီအိုရီသစ်ဖြင့် ပျောက်ဆုံးနေသော စက္ကန့် ၄၃ ပိုင်းခွဲအားလုံးကို ရှင်းပြနိုင်ကြောင်း ပြသခဲ့သည်။ အကျဉ်းချုပ် မိတ်ဆက်ချက်အပြီးတွင် အိုင်းစတိုင်း-ဘက်ဆို မူရင်းစာရွက်များ၏ အဓိကစာမျက်နှာများကို မှတ်စုဖြင့်တွဲဖက်ထားသော မှတ်တမ်းတင်မှုနှင့် နိုဝင်ဘာ ၁၉၁၅ ခုနှစ်က နေအနီးဆုံးအမှတ် စာတမ်းကို မှတ်စုဖြင့်တွဲဖက်ထားသော မူလဘာသာပြန်သစ်ကို ပေးအပ်ထားပါသည်။
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my
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Let R be the set of isomorphism classes of ideals in the Weyl algebra $A=A_{1}$, and let C be the set of isomorphism classes of triples (V; X, Y), where V is a finite-dimensional (complex) vector space, and X, Y are endomorphisms of V such that [X,Y]+I has rank 1. Following a suggestion of L. Le Bruyn, we define a map $\theta: R \to C$ by appropriately extending an ideal of A to a sheaf over a quantum projective plane, and then using standard methods of homological algebra. We prove that $\theta$ is inverse to a bijection $\omega: C \to R$ constructed in \cite{BW} by a completely different method. The main step in the proof is to show that $\theta$ is equivariant with respect to natural actions of the group G=Aut(A) on R and C: for that we have to study also the extensions of an ideal to certain weighted quantum projective planes. Along the way, we find an elementary description of \theta.
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Payagan ang R na maging hanay ng mga klase ng isomorphism ng mga ideal sa alhebrang Weyl $A=A_{1}$, at payagan ang C na maging hanay ng mga klase ng isomorphism ng mga triple (V; X, Y), kung saan ang V ay isang may hangganang-dimensyonal (kompleks) na espasyong bektor, at ang X, Y ay mga endomorphism ng V kung saan ang [X,Y]+I ay may ranggo na 1. Sumusunod sa isang iminungkahing kay L. Le Bruyn, inilalarawan namin ang isang paglilipat $\theta: R \to C$ sa pamamagitan ng angkop na pagpapalawig ng isang ideal ng A sa isang sheaf sa ibabaw ng isang quantum na planong proyektibo, at pagkatapos ay gumagamit ng karaniwang pamamaraan ng homological na alhebra. Pinatutunayan namin na ang $\theta$ ay kabaligtaran ng isang bijeksyon $\omega: C \to R$ na itinayo sa \cite{BW} sa pamamagitan ng isang ganap na iba't ibang pamamaraan. Ang pangunahing hakbang sa patunay ay ipakita na ang $\theta$ ay equivariant kaugnay ng mga likas na aksyon ng grupo G=Aut(A) sa R at C: para doon, kailangan din naming pag-aralan ang mga pagpapalawig ng isang ideal sa ilang partikular na may-timbang na quantum na mga planong proyektibo. Sa pagitan, natagpuan namin ang isang pang-elementong deskripsyon ng \theta.
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tl
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We present a large sample of infrared-luminous candidate active galactic nuclei (AGNs) that lack X-ray detections in Chandra, XMM-Newton, and NuSTAR fields. We selected all optically detected SDSS sources with redshift measurements, combined additional broadband photometry from WISE, UKIDSS, 2MASS, and GALEX, and modeled the spectral energy distributions (SEDs) of our sample sources. We parameterize nuclear obscuration in our SEDs with $E(B\!-\!V)_{\text{AGN}}$ and uncover thousands of powerful obscured AGNs that lack X-ray counterparts, many of which are identified as AGN candidates based on straightforward WISE photometric criteria. Using the observed luminosity correlation between restframe 2-10 keV ($L_{\text{X}}$) and restframe AGN 6 $\mu{\text{m}}$ ($L_{\text{MIR}}$), we estimate the intrinsic X-ray luminosities of our sample sources and combine these data with flux limits from X-ray catalogs to determine lower limits on nuclear obscuration. Using the ratio of intrinsic-to-observed X-ray luminosity ($R_{L_{\text{X}}}$), we find a significant fraction of sources with column densities approaching $N_{\text{H}}>$ 10$^{\text{24}}$ cm$^{-{\text{2}}}$, suggesting that multiwavelength observations are necessary to account for the population of heavily obscured AGNs. We simulate the underlying $N_{\text{H}}$ distribution for the X-ray non-detected sources in our sample through survival analysis, and confirm the presence of AGN activity via X-ray stacking. Our results point to a considerable population of extremely obscured AGNs undetected by current X-ray observatories.
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ہم انفراریڈ روشن امیدوار فعال سَیاروی ہستیوں (ای جی این ایز) کا ایک بڑا نمونہ پیش کرتے ہیں جن میں چاندرہ، ایکس ایم ایم نیوٹن اور نو اسٹار کے میدانوں میں ایکس رے کا کوئی انکشاف نہیں ہوتا۔ ہم نے سپیکٹرو سکوپک سروے کے تمام نظری طور پر دریافت شدہ ذرائع کو سرخ فاصلہ کے پیمائش کے ساتھ منتخب کیا، وائیس، یو کے آئی ڈی ایس ایس، 2ایم اے ایم ایس اور گیلیکس سے مزید وسیع پیمانے پر فوٹومیٹری شامل کی، اور اپنے نمونہ ذرائع کے سپیکٹرل انرجی تقسیم (ایس ای ڈی) کی ماڈلنگ کی۔ ہم اپنے ایس ای ڈی میں نیوکلیئر پردہ داری کی وضاحت $E(B\!-\!V)_{\text{AGN}}$ کے ذریعہ کرتے ہیں اور ہزاروں طاقتور پردہ دار ای جی این ایز کو دریافت کرتے ہیں جن کے ایکس رے کے ہم منصبدار نہیں ہوتے، جن میں سے بہت سے صرف وائیس فوٹومیٹری معیارات کی بنیاد پر ای جی این ای امیدوار کے طور پر شناخت کیے گئے ہیں۔ باقی 2-10 کے وی ($L_{\text{X}}$) اور باقی ای جی این ای 6 $\mu{\text{m}}$ ($L_{\text{MIR}}$) کے درمیان مشاہدہ شدہ روشنی کے تعلق کا استعمال کرتے ہوئے، ہم اپنے نمونہ ذرائع کی ذاتی ایکس رے روشنی کا اندازہ لگاتے ہیں اور ان ڈیٹا کو ایکس رے کیٹلاگز کے پار ہونے کی حد کے ساتھ ملاتے ہیں تاکہ نیوکلیئر پردہ داری کی کم از کم حد معلوم کی جا سکے۔ ذاتی اور مشاہدہ شدہ ایکس رے روشنی کے تناسب ($R_{L_{\text{X}}}$) کا استعمال کرتے ہوئے، ہم ایسے ذرائع کی ایک قابل ذکر تعداد کو تلاش کرتے ہیں جن کے کالم کی کثافت $N_{\text{H}}>$ 10$^{\text{24}}$ cm$^{-{\text{2}}}$ کی طرف بڑھ رہی ہوتی ہے، جس سے ظاہر ہوتا ہے کہ شدید پردہ دار ای جی این ایز کی آبادی کو شامل کرنے کے لیے متعدد طول موج کی مشاہدات ضروری ہیں۔ ہم اپنے نمونہ میں ایکس رے کی عدم دریافت شدہ ذرائع کے لیے بنیادی $N_{\text{H}}$ تقسیم کی شبیہ کشی بقا تجزیہ کے ذریعہ کرتے ہیں، اور ایکس رے اسٹیکنگ کے ذریعہ ای جی این ای سرگرمی کی موجودگی کی تصدیق کرتے ہیں۔ ہمارے نتائج اس بات کی طرف اشارہ کرتے ہیں کہ موجودہ ایکس رے رصد گاہوں کے ذریعہ دریافت نہ ہونے والے انتہائی پردہ دار ای جی این ایز کی ایک قابل ذکر آبادی موجود ہے۔
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ur
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We employ the Schwinger boson mean-field approach to study the effects of arbitrary frustrated bonds and plaquettes (formed from four frustrated bonds) in two-dimensional ferro- and antiferromagnets on the spin-wave spectrum and the correlation length at finite temperatures. We distinguish between strongly frustrated bonds (plaquettes), when the frustrated coupling $J^\prime$ exceeds the spin canting threshold $J_c$, and weakly frustrated bonds (plaquettes), with $J^\prime <J_c, (J_c-J^\prime)/J_c\sim 1$. It is shown that in antiferromagnets the amplitude of spin-wave scattering on strongly frustrated bonds or plaquettes grows with the decrease of the temperature. A small amount of such defects reduces significantly the spin-wave stiffness and the correlation length at low temperatures. As a result, the quasi-2D N\'eel temperature is sharply suppressed. Quantum fluctuations are also considered and their effect on the spin-wave spectrum is shown to be of the order of $(2S)^{-2}\ln^{-1}2S$ in the large spin limit. For weakly frustrated (nonfrustrated) defect bonds (plaquettes) the spin-wave stiffness renormalization is of the order of the dopant concentration and does not depend on the temperature. The results account for the observed properties of doped quasi-2D $La_2CuO_{4+x}$.
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Kami menggunakan pendekatan medan purata boson Schwinger untuk mengkaji kesan ikatan terpenun dan petak-petak (yang terbentuk daripada empat ikatan terpenun) yang sewenang-wenang dalam ferromagnet dan antiferromagnet dua dimensi terhadap spektrum gelombang spin dan panjang berkorelasi pada suhu terhingga. Kami membezakan antara ikatan terpenun (petak-petak) yang sangat kuat, apabila pasangan terpenun $J^\prime$ melebihi ambang kecondongan spin $J_c$, dan ikatan terpenun (petak-petak) yang lemah, dengan $J^\prime <J_c, (J_c-J^\prime)/J_c\sim 1$. Ditunjukkan bahawa dalam antiferromagnet, amplitud serakan gelombang spin pada ikatan atau petak yang sangat terpenun bertambah dengan penurunan suhu. Jumlah kecil cacat sedemikian mengurangkan secara ketara kekukuhan gelombang spin dan panjang berkorelasi pada suhu rendah. Akibatnya, suhu N\'eel quasi-2D ditekan secara mendadak. Fluktuasi kuantum turut dipertimbangkan dan kesannya terhadap spektrum gelombang spin ditunjukkan berada dalam tertib $(2S)^{-2}\ln^{-1}2S$ dalam had spin besar. Bagi ikatan cacat (petak-petak) yang terpenun lemah (tidak terpenun), pembetulan kekukuhan gelombang spin adalah dalam tertib kepekatan pendopan dan tidak bergantung kepada suhu. Keputusan ini menerangkan sifat-sifat yang dicerap dalam $La_2CuO_{4+x}$ quasi-2D yang didop.
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ms
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We investigate dust entrainment by photoevaporative winds in protoplanetary discs using dusty smoothed particle hydrodrodynamics (SPH). We use unequal-mass particles to resolve more than five orders of magnitude in disc/outflow density and a one-fluid formulation to efficiently simulate an equivalent magnitude range in drag stopping time. We find that only micron sized dust grains and smaller can be entrained in EUV driven winds. The maximum grain size is set by dust settling in the disc rather than aerodynamic drag in the wind. More generally, there is a linear relationship between the base flow density and the maximum entrainable grain size in the wind. A pileup of micron sized dust grains can occur in the upper atmosphere at critical radii in the disc as grains decouple from the low-density wind. Entrainment is a strong function of location in the disc, resulting in a size sorting of grains in the outflow---the largest grain being carried out between $10$--$20\,$AU. The peak dust density for each grain size occurs at the inner edge of its own entrainment region.
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우리는 성운 원반에서 광증발성 바람에 의한 먼지 혼입 현상을 먼지가 포함된 평활입자유체역학(SPH)을 사용하여 조사한다. 원반/유출 밀도에서 5차 이상의 크기 범위를 해석하기 위해 불균등한 질량을 가진 입자를 사용하였으며, 드래그 정지 시간의 동등한 크기 범위를 효율적으로 시뮬레이션하기 위해 일체유체(one-fluid) 공식을 적용하였다. 우리는 EUV에 의해 유도된 바람에서는 미크론 크기 이하의 먼지 입자만이 혼입될 수 있음을 발견하였다. 최대 입자 크기는 바람 내 공기역학적 드래그보다는 원반 내 먼지 침강에 의해 결정된다. 보다 일반적으로, 바람 내에서 혼입 가능한 최대 입자 크기와 기저 유동 밀도 사이에는 선형 관계가 존재한다. 입자들이 저밀도 바람으로부터 분리되면서, 원반의 임계 반경에서 상층 대기부에 미크론 크기의 먼지 입자들이 축적될 수 있다. 혼입은 원반 내 위치에 따라 크게 달라지며, 이로 인해 유출 내에서 입자 크기별로 정렬되는 현상이 발생하는데, 가장 큰 입자는 $10$–$20\,$AU 사이에서 유출된다. 각 입자 크기에 대한 최대 먼지 밀도는 각자의 혼입 영역의 내부 경계에서 발생한다.
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ko
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Over cosmic time, galaxies grow through the hierarchical merging of smaller galaxies. However, the bright region of the galaxy luminosity function is incompatible with the simplest version of hierarchical merging, and it is believed that feedback from the central black hole in the host galaxies reduces the number of bright galaxies and regulates the co-evolution of black hole and host galaxy. Numerous simulations of galaxy evolution have attempted to include the physical effects of such feedback with a resolution usually exceeding a kiloparsec. However, interactions between jets and the interstellar medium involve processes occurring on less than kiloparsec scales. In order to further the understanding of processes occurring on such scales, we present a suite of simulations of relativistic jets interacting with a fractal two-phase interstellar medium with a resolution of two parsecs and a largest scale of one kiloparsec. The transfer of energy and momentum to the interstellar medium is considerable, and we find that jets with powers in the range of 10^43-10^46 erg s^-1 can inhibit star formation through the dispersal of dense gas in the galaxy core. We determine the effectiveness of this process as a function of the ratio of the jet power to the Eddington luminosity of the black hole, the pressure of the interstellar medium and the porosity of the dense gas.
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মহাজাগতিক সময়ের মধ্য দিয়ে ছোট ছোট ছায়াপথের পদানুক্রমিক সংযুক্তির মাধ্যমে ছায়াপথগুলি বৃদ্ধি পায়। তবে ছায়াপথের দীপ্তি অপেক্ষকের উজ্জ্বল অংশটি পদানুক্রমিক সংযুক্তির সরলতম সংস্করণের সাথে অসামঞ্জস্যপূর্ণ, এবং এটি বিশ্বাস করা হয় যে আশ্রয়কারী ছায়াপথগুলির কেন্দ্রীয় কৃষ্ণগহ্বর থেকে উৎসরিত প্রতিক্রিয়া উজ্জ্বল ছায়াপথের সংখ্যা হ্রাস করে এবং কৃষ্ণগহ্বর ও আশ্রয়কারী ছায়াপথের সহ-বিবর্তনকে নিয়ন্ত্রণ করে। ছায়াপথের বিবর্তনের অসংখ্য সিমুলেশন সাধারণত এক কিলোপারসেকের বেশি রেজোলিউশন নিয়ে এমন প্রতিক্রিয়ার ভৌত প্রভাব অন্তর্ভুক্ত করার চেষ্টা করেছে। তবুও, জেট এবং আন্তঃনাক্ষত্রিক মাধ্যমের মধ্যে মিথস্ক্রিয়া এক কিলোপারসেকের কম স্কেলে ঘটিত প্রক্রিয়াগুলির সাথে জড়িত। এমন স্কেলে ঘটিত প্রক্রিয়াগুলি সম্পর্কে আরও ভালোভাবে বোঝার জন্য, আমরা দুই পারসেক রেজোলিউশন এবং এক কিলোপারসেক পর্যন্ত সর্বোচ্চ স্কেল নিয়ে একটি ফ্র্যাকটাল দ্বিপর্যায় আন্তঃনাক্ষত্রিক মাধ্যমের সাথে আপেক্ষিকতাজনিত জেটগুলির মিথস্ক্রিয়ার সিমুলেশনের একটি সেট উপস্থাপন করি। আন্তঃনাক্ষত্রিক মাধ্যমে শক্তি ও ভরবেগের স্থানান্তর উল্লেখযোগ্য, এবং আমরা দেখতে পাই যে 10^43-10^46 আর্গ সেকেন্ড^-1 পরিসরের ক্ষমতা বিশিষ্ট জেটগুলি ছায়াপথের কেন্দ্রে ঘন গ্যাস ছড়িয়ে দেওয়ার মাধ্যমে তারকা গঠনকে বাধা দিতে পারে। আমরা জেটের ক্ষমতা এবং কৃষ্ণগহ্বরের এডিংটন দীপ্তির অনুপাত, আন্তঃনাক্ষত্রিক মাধ্যমের চাপ এবং ঘন গ্যাসের সরুত্বের উপর ভিত্তি করে এই প্রক্রিয়ার কার্যকারিতা নির্ধারণ করি।
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bn
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We perform numerical simulations of a two-dimensional bidisperse granular packing subjected to both a static confining pressure and a sinusoidal dynamic forcing applied by a wall on one edge of the packing. We measure the response experienced by a wall on the opposite edge of the packing and obtain the resonant frequency of the packing as the static or dynamic pressures are varied. Under increasing static pressure, the resonant frequency increases, indicating a velocity increase of elastic waves propagating through the packing. In contrast, when the dynamic amplitude is increased for fixed static pressure, the resonant frequency decreases, indicating a decrease in the wave velocity. This occurs both for compressional and for shear dynamic forcing, and is in agreement with experimental results. We find that the average contact number $Z_c$ at the resonant frequency decreases with increasing dynamic amplitude, indicating that the elastic softening of the packing is associated with a reduced number of grain-grain contacts through which the elastic waves can travel. We image the excitations created in the packing and show that there are localized disturbances or soft spots that become more prevalent with increasing dynamic amplitude. Our results are in agreement with experiments on glass bead packings and earth materials such as sandstone and granite, and may be relevant to the decrease in elastic wave velocities that has been observed to occur near fault zones after strong earthquakes, in surficial sediments during strong ground motion, and in structures during earthquake excitation.
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Realizamos simulações numéricas de um empacotamento granular bidisperso bidimensional submetido a uma pressão de confinamento estática e a uma força dinâmica senoidal aplicada por uma parede em uma das bordas do empacotamento. Medimos a resposta experimentada por uma parede na borda oposta do empacotamento e obtemos a frequência de ressonância do empacotamento à medida que as pressões estática ou dinâmica são variadas. Com o aumento da pressão estática, a frequência de ressonância aumenta, indicando um aumento na velocidade de ondas elásticas que se propagam através do empacotamento. Em contraste, quando a amplitude dinâmica é aumentada para uma pressão estática fixa, a frequência de ressonância diminui, indicando uma redução na velocidade da onda. Isso ocorre tanto para forçamento dinâmico compressional quanto para forçamento de cisalhamento, e está de acordo com resultados experimentais. Descobrimos que o número médio de contatos \(Z_c\) na frequência de ressonância diminui com o aumento da amplitude dinâmica, indicando que o amolecimento elástico do empacotamento está associado a um número reduzido de contatos entre grãos pelos quais as ondas elásticas podem se propagar. Visualizamos as excitações geradas no empacotamento e mostramos que existem perturbações localizadas ou pontos moles que se tornam mais prevalentes com o aumento da amplitude dinâmica. Nossos resultados estão de acordo com experimentos realizados em empacotamentos de microesferas de vidro e materiais terrestres como arenito e granito, e podem ser relevantes para a diminuição das velocidades das ondas elásticas observada em zonas próximas a falhas após terremotos fortes, em sedimentos superficiais durante movimentos fortes do solo e em estruturas durante excitação sísmica.
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pt
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When there exists a malicious attacker in the network, we need to consider the possibilities of eavesdropping and the contamination simultaneously. Under an acyclic broadcast network, the optimality of linear codes was shown when Eve is allowed to attack any $r$ edges. The optimality of linear codes is not shown under a different assumption for Eve. As a typical example of an acyclic unicast network, we focus on the one-hop relay network under the single transmission scheme by assuming that Eve attacks only one edge in each level. Surprisingly, as a result, we find that a non-linear code significantly improves the performance on the one-hop relay network over linear codes. That is, a non-liner code realizes the imperfect security on this model that cannot be realized by linear codes. This kind of superiority of a linear code still holds even with considering the effect of sequential error injection on information leakage.
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ເມື່ອມີຜູ້ໂຈມຕີທີ່ມີເຈດຕະນາຮ້າຍໃນເຄືອຂ່າຍ, ພວກເຮົາຈຳເປັນຕ້ອງພິຈາລະນາຄວາມເປັນໄປໄດ້ຂອງການດັກຟັງ ແລະ ການປົນເປື້ອນພ້ອມກັນ. ໃນເຄືອຂ່າຍຖ່າຍໂທລະສາບທີ່ບໍ່ມີວົງຈອນ, ຄວາມເປັນທີ່ດີທີ່ສຸດຂອງລະຫັດເສັ້ນຊື່ໄດ້ຖືກສະແດງໃຫ້ເຫັນເມື່ອ Eve ໄດ້ຮັບອະນຸຍາດໃຫ້ໂຈມຕີທຸກໆ $r$ ແຖວ. ຄວາມເປັນທີ່ດີທີ່ສຸດຂອງລະຫັດເສັ້ນຊື່ຍັງບໍ່ໄດ້ຖືກສະແດງໃນຂໍ້ສົມມຸດຖານອື່ນໆຂອງ Eve. ເປັນຕົວຢ່າງທົ່ວໄປຂອງເຄືອຂ່າຍ unicast ທີ່ບໍ່ມີວົງຈອນ, ພວກເຮົາມຸ່ງເນັ້ນໄປທີ່ເຄືອຂ່າຍ relay ຫນຶ່ງຂັ້ນພາຍໃຕ້ແຜນການຖ່າຍໂທລະສາບດຽວໂດຍສົມມຸດວ່າ Eve ໂຈມຕີພຽງແຖວດຽວໃນແຕ່ລະຂັ້ນ. ຢ່າງຫນ້າປະຫລາດໃຈ, ຜົນໄດ້ຮັບພວກເຮົາພົບວ່າລະຫັດທີ່ບໍ່ແມ່ນເສັ້ນຊື່ປັບປຸງປະສິດທິພາບຢ່າງຫຼວງຫຼາຍໃນເຄືອຂ່າຍ relay ຫນຶ່ງຂັ້ນເມື່ອທຽບກັບລະຫັດເສັ້ນຊື່. ນັ້ນກໍຄື, ລະຫັດທີ່ບໍ່ແມ່ນເສັ້ນຊື່ສາມາດບັນລຸຄວາມປອດໄພທີ່ບໍ່ສົມບູນໃນຮູບແບບນີ້ ເຊິ່ງບໍ່ສາມາດບັນລຸໄດ້ໂດຍລະຫັດເສັ້ນຊື່. ຄວາມເອກະສິດຂອງລະຫັດເສັ້ນຊື່ແບບນີ້ຍັງຄົງຢູ່ເຖິງແມ່ນວ່າຈະພິຈາລະນາຜົນກະທົບຂອງການສອດແນມຂໍ້ມູນຕິດຕໍ່ກັນຕໍ່ການຮົ່ວໄຫຼຂອງຂໍ້ມູນ.
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lo
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In this paper, we analyze a composite decode-and-forward scheme for the two-way relay channel with a direct link. During transmission, our scheme combines both block Markov coding and an independent coding scheme similar to network coding at the relay. The main contribution of this work is to examine how link state impacts the allocation of power between these two distinct techniques, which in turn governs the necessity of each technique in achieving the largest transmission rate region. We analytically determine the link-state regimes and associated relaying techniques. Our results illustrate an interesting trend: when the user-to-relay link is marginally stronger than the direct link, it is optimal to use only independent coding. In this case, the relay need not use full power. However, for larger user-to-relay link gains, the relay must supplement independent coding with block Markov coding to achieve the largest rate region. These link-state regimes are important for the application of two-way relaying in 5G networks, such as in D2D mode or relay-aided transmission.
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In dieser Arbeit analysieren wir ein zusammengesetztes Decode-and-Forward-Verfahren für den bidirektionalen Relaiskanal mit direkter Verbindung. Während der Übertragung kombiniert unser Verfahren Block-Markov-Codierung und ein unabhängiges Codierungsverfahren, das der Netzwerkcodierung am Relais ähnelt. Der Hauptbeitrag dieser Arbeit besteht darin, zu untersuchen, wie der Zustand der Verbindung die Aufteilung der Sendeleistung zwischen diesen beiden unterschiedlichen Techniken beeinflusst, was wiederum bestimmt, inwieweit jede Technik notwendig ist, um den größtmöglichen Übertragungsratebereich zu erreichen. Wir ermitteln analytisch die Zustandsbereiche der Verbindungen und die zugehörigen Relaisverfahren. Unsere Ergebnisse zeigen eine interessante Tendenz: Wenn die Benutzer-zu-Relais-Verbindung geringfügig stärker ist als die direkte Verbindung, ist es optimal, ausschließlich unabhängige Codierung zu verwenden. In diesem Fall muss das Relais nicht die volle Leistung nutzen. Bei größeren Gewinnen der Benutzer-zu-Relais-Verbindung muss das Relais jedoch die unabhängige Codierung durch Block-Markov-Codierung ergänzen, um den größtmöglichen Ratenbereich zu erreichen. Diese Zustandsbereiche der Verbindungen sind wichtig für die Anwendung des bidirektionalen Relaisbetriebs in 5G-Netzen, beispielsweise im D2D-Modus oder bei relaisunterstützter Übertragung.
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de
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In the setting of a Gaussian channel without power constraints, proposed by Poltyrev, the codewords are points in an n-dimensional Euclidean space (an infinite constellation) and the tradeoff between their density and the error probability is considered. The capacity in this setting is the highest achievable normalized log density (NLD) with vanishing error probability. This capacity as well as error exponent bounds for this setting are known. In this work we consider the optimal performance achievable in the fixed blocklength (dimension) regime. We provide two new achievability bounds, and extend the validity of the sphere bound to finite dimensional infinite constellations. We also provide asymptotic analysis of the bounds: When the NLD is fixed, we provide asymptotic expansions for the bounds that are significantly tighter than the previously known error exponent results. When the error probability is fixed, we show that as n grows, the gap to capacity is inversely proportional (up to the first order) to the square-root of n where the proportion constant is given by the inverse Q-function of the allowed error probability, times the square root of 1/2. In an analogy to similar result in channel coding, the dispersion of infinite constellations is 1/2nat^2 per channel use. All our achievability results use lattices and therefore hold for the maximal error probability as well. Connections to the error exponent of the power constrained Gaussian channel and to the volume-to-noise ratio as a figure of merit are discussed. In addition, we demonstrate the tightness of the results numerically and compare to state-of-the-art coding schemes.
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گاوسی چینل کے اس تناظر میں جس میں طاقت کی کوئی حد نہیں ہوتی، جو پولٹیریف کے ذریعہ تجویز کیا گیا تھا، کوڈلفاظ n-بُعدی یوقلڈی فضا میں نقاط ہوتے ہیں (امحدود تراکیب) اور ان کی کثافت اور غلطی کے امکان کے درمیان تعلق کا جائزہ لیا جاتا ہے۔ اس تنظیم میں صلاحیت سے مراد غیر معمولی غلطی کے امکان کے ساتھ حاصل کی جا سکنے والی زیادہ سے زیادہ نارملائزڈ لاگ کثافت (NLD) ہے۔ اس صلاحیت کے علاوہ اس تنظیم کے لیے غلطی کے اُسّی حدود بھی معلوم ہیں۔ اس کام میں ہم فکسڈ بلاک لمبائی (بُعد) کے دائرہ کار میں حاصل کی جا سکنے والی بہترین کارکردگی پر غور کرتے ہیں۔ ہم دو نئی حصولیت کی حدود فراہم کرتے ہیں، اور سفیر باؤنڈ کی وضاحت کو محدود بُعدی امحدود تراکیب تک وسعت دیتے ہیں۔ ہم حدود کا متشکل تجزیہ بھی فراہم کرتے ہیں: جب NLD کو فکسڈ رکھا جاتا ہے، تو ہم ایسے متشکل توسیعات فراہم کرتے ہیں جو پہلے سے معلوم غلطی کے اُسّی نتائج کے مقابلے میں کافی زیادہ مضبوط ہوتے ہیں۔ جب غلطی کا امکان فکسڈ ہو، تو ہم دکھاتے ہیں کہ جیسے جیسے n بڑھتا ہے، صلاحیت سے فرق n کی مربع جڑ کے الٹ تناسب پر منحصر ہوتا ہے (پہلے درجے تک)، جہاں تناسب کا دائمی عدد مجاز غلطی کے امکان کا معکوس Q-فنکشن ہوتا ہے، جسے 1/2 کی مربع جڑ سے ضرب دیا جاتا ہے۔ چینل کوڈنگ میں اسی قسم کے نتیجے کی طرح، امحدود تراکیب کی تقسیم 1/2 نیٹ² فی چینل استعمال ہوتی ہے۔ تمام حصولیت کے نتائج جالیوں کا استعمال کرتے ہیں اور اس لیے زیادہ سے زیادہ غلطی کے امکان کے لیے بھی درست ہوتے ہیں۔ طاقت پابندی والے گاوسی چینل کے غلطی کے اُسّی اور نویز تناسب کے حوالے سے حجم کو فائدہ مندی کے معیار کے طور پر تعلق پر بحث کی گئی ہے۔ اس کے علاوہ، ہم نتائج کی تنگی کو عددی طور پر ظاہر کرتے ہیں اور ان کا موازنہ موجودہ دور کی کوڈنگ اسکیموں سے کرتے ہیں۔
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ur
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We study the response of confining gauge theory to the external electric field by using holographic Yang-Mills theories in the large $N_c$ limit. Although the theories are in the confinement phase, we find a transition from the insulator to the conductor phase when the electric field exceeds its critical value. Then, the baryon number current is generated in the conductor phase. At the same time, in this phase, the meson melting is observed through the quasi-normal modes of meson spectrum. Possible ideas are given for the string state corresponding to the melted mesons, and they lead to the idea that the source of this current may be identified with the quarks and anti-quarks supplied by the melted mesons. We also discuss about other possible carriers. Furthermore, from the analysis of the massless quark, chiral symmetry restoration is observed at the insulator-conductor transition point by studying a confining theory in which the chiral symmetry is broken.
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Pinag-aaralan natin ang tugon ng confining gauge theory sa panlabas na electric field sa pamamagitan ng paggamit ng holographic na mga teorya ng Yang-Mills sa hangganan ng malaking $N_c$. Bagaman ang mga teorya ay nasa yugto ng confinement, natagpuan natin ang isang transisyon mula sa insulator tungo sa conductor phase kapag ang electric field ay lumampas sa kritikal nitong halaga. Pagkatapos, ang baryon number current ay nabubuo sa loob ng conductor phase. Kasabay nito, sa yugtong ito, ang pagkatunaw ng meson ay napagmasdan sa pamamagitan ng mga quasi-normal mode ng meson spectrum. Iba't ibang posibleng ideya ang ibinigay para sa string state na tumutugma sa mga natunaw na meson, at ito ay humahantong sa ideya na ang pinagmulan ng kasalukuyang ito ay maaaring maiugnay sa mga quark at anti-quark na ibinibigay ng mga natunaw na meson. Pinag-uusapan din natin ang tungkol sa iba pang posibleng mga tagapagdala. Bukod dito, mula sa pagsusuri sa massless na quark, ang pagbabalik ng chiral symmetry ay napagmasdan sa punto ng transisyon ng insulator-conductor sa pamamagitan ng pag-aaral ng isang confining theory kung saan nababali ang chiral symmetry.
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tl
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In this paper, we analyze a composite decode-and-forward scheme for the two-way relay channel with a direct link. During transmission, our scheme combines both block Markov coding and an independent coding scheme similar to network coding at the relay. The main contribution of this work is to examine how link state impacts the allocation of power between these two distinct techniques, which in turn governs the necessity of each technique in achieving the largest transmission rate region. We analytically determine the link-state regimes and associated relaying techniques. Our results illustrate an interesting trend: when the user-to-relay link is marginally stronger than the direct link, it is optimal to use only independent coding. In this case, the relay need not use full power. However, for larger user-to-relay link gains, the relay must supplement independent coding with block Markov coding to achieve the largest rate region. These link-state regimes are important for the application of two-way relaying in 5G networks, such as in D2D mode or relay-aided transmission.
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في هذا البحث، نقوم بتحليل نظام مركب لإعادة الترميز وإعادة الإرسال في قناة الترحيل ثنائية الاتجاه التي تتضمن اتصالاً مباشراً. أثناء الإرسال، يدمج نظامنا ترميز بلوكي من نوع ماركوف ونظام ترميز مستقل يشبه الترميز الشبكي في وحدة الترحيل. يكمن المساهمة الرئيسية لهذا العمل في دراسة تأثير حالة الاتصال على توزيع القدرة بين هاتين التقنيتين المختلفتين، والتي بدورها تحدد ضرورة استخدام كل تقنية لتحقيق أكبر منطقة ممكنة من معدلات الإرسال. قمنا بتحديد أنماط حالات الاتصال والتقنيات المرتبطة بالترحيل تحليلياً. وتُظهر نتائجنا اتجاهاً مثيراً للاهتمام: عندما يكون الاتصال بين المستخدم ووحدة الترحيل أقوى قليلاً من الاتصال المباشر، يكون من الأمثل استخدام الترميز المستقل فقط. وفي هذه الحالة، لا تحتاج وحدة الترحيل إلى استخدام كامل طاقتها. ومع ذلك، عند زيادة مكاسب الاتصال بين المستخدم ووحدة الترحيل، يجب على وحدة الترحيل دعم الترميز المستقل بترميز بلوكي من نوع ماركوف لتحقيق أكبر منطقة من معدلات الإرسال. إن أنماط حالات الاتصال هذه مهمة لتطبيق الترحيل ثنائي الاتجاه في شبكات الجيل الخامس، مثل الوضع المباشر بين الأجهزة (D2D) أو الإرسال المدعوم بالترحيل.
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We study classical and quantum hidden symmetries of a particle with electric charge $e$ in the background of a Dirac monopole of magnetic charge $g$ subjected to an additional central potential $V(r)=U(r) +(eg)^2/2mr^{2}$ with $U(r)=\tfrac{1}{2}m\omega^2r^2$, similar to that in the one-dimensional conformal mechanics model of de Alfaro, Fubini and Furlan (AFF). By means of a non-unitary conformal bridge transformation, we establish a relation of the quantum states and of all symmetries of the system with those of the system without harmonic trap, $U(r)=0$. Introducing spin degrees of freedom via a very special spin-orbit coupling, we construct the $\mathfrak{osp}(2,2)$ superconformal extension of the system with unbroken $\mathcal{N}=2$ Poincar\'e supersymmetry and show that two different superconformal extensions of the one-dimensional AFF model with unbroken and spontaneously broken supersymmetry have a common origin. We also show a universal relationship between the dynamics of a Euclidean particle in an arbitrary central potential $U(r)$ and the dynamics of a charged particle in a monopole background subjected to the potential $V(r)$.
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Studujeme klasické a kvantové skryté symetrie částice s elektrickým nábojem $e $ v poli Diracova monopolu s magnetickým nábojem $ g $, na kterou působí navíc centrální potenciál $ V(r)=U(r) +(eg)^2/2mr^{2} $, kde $ U(r)=\tfrac{1}{2}m\omega^2r^2 $, podobně jako v jednorozměrném modelu konformní mechaniky de Alfara, Fubiniho a Furlana (AFF). Pomocí neunitární konformní můstkové transformace stanovíme vztah mezi kvantovými stavy a všemi symetriemi systému a systémem bez harmonické pasti, kdy $ U(r)=0 $. Zavedením stupňů volnosti spinu prostřednictvím velmi speciální spin-orbitální vazby sestrojíme superkonformní rozšíření $ \mathfrak{osp}(2,2) $ systému s neporušenou $ \mathcal{N}=2 $ Poincar\'eho supersymetrií a ukážeme, že dvě různé superkonformní rozšíření jednorozměrného modelu AFF s neporušenou a spontánně porušenou supersymetrií mají společný původ. Dále ukážeme univerzální vztah mezi dynamikou eukleidovské částice v libovolném centrálním potenciálu $ U(r) $ a dynamikou nabité částice v poli monopolu, na kterou působí potenciál $ V(r) $.
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cs
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It was shown recently that the anomalous scaling of simultaneous correlation functions in turbulence is intimately related to the breaking of temporal scale invariance, which is equivalent to the appearance of infinitely many times scales in the time dependence of time-correlation functions. In this paper we derive a continued fraction representation of turbulent time correlation functions which is exact and in which the multiplicity of time scales is explicit. We demonstrate that this form yields precisely the same scaling laws for time derivatives and time integrals as the "multi-fractal" representation that was used before. Truncating the continued fraction representation yields the "best" estimates of time correlation functions if the given information is limited to the scaling exponents of the simultaneous correlation functions up to a certain, finite order. It is worth noting that the derivation of a continued fraction representation obtained here for an operator which is not Hermitian or anti-Hermitian may be of independent interest.
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Yakın zamanda, türbülans içindeki eşzamanlı korelasyon fonksiyonlarının anormal ölçeklenmesinin, zamansal ölçek değişmezliğinin kırılmasıyla yakından ilişkili olduğu gösterilmiştir ve bu durum, zaman korelasyon fonksiyonlarının zaman bağımlılığında sonsuz sayıda zaman ölçeğinin ortaya çıkmasına eşdeğerdir. Bu makalede, türbülanslı zaman korelasyon fonksiyonları için kesintisiz bir kesir gösterimi elde ediyoruz ve bu gösterim tam doğrudur ve zaman ölçeklerinin çokluğu burada açıkça ortadadır. Bu formun, daha önce kullanılan "çoklu-fraktal" gösterimle tam olarak aynı zaman türevleri ve zaman integralleri için ölçekleme yasalarını verdiğini gösteriyoruz. Sürekli kesir gösterimini kesmek, verilen bilgi eşzamanlı korelasyon fonksiyonlarının ölçekleme üslerine belli, sonlu bir mertebe kadar sınırlıysa, zaman korelasyon fonksiyonları için "en iyi" tahminleri verir. Burada Hermityen ya da anti-Hermityen olmayan bir operatör için elde edilen sürekli kesir gösteriminin çıkarımı bağımsız olarak da ilgi çekebilir.
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tr
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One way to recognise an object is to study how the echo has been shaped during the interaction with the target. Wideband sonar allows the study of the energy distribution for a large range of frequencies. The frequency distribution contains information about an object, including its inner structure. This information is a key for automatic recognition. The scattering by a target can be quantitatively described by its Form Function. The Form Function can be calculated based on the data of the initial pulse, reflected pulse and parameters of a medium where the pulse is propagating. In this work spherical objects are classified based on their filler material - water or air. We limit the study to spherical 2 layered targets immersed in water. The Form Function is used as a descriptor and fed into a Neural Network classifier, Multilayer Perceptron (MLP). The performance of the classifier is compared with Support Vector Machine (SVM) and the Form Function descriptor is examined in contrast to the Time and Frequency Representation of the echo.
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Salah satu cara mengenali suatu objek adalah dengan mempelajari bagaimana gema terbentuk selama interaksi dengan target. Sonar lebar pita memungkinkan studi distribusi energi pada rentang frekuensi yang luas. Distribusi frekuensi berisi informasi mengenai suatu objek, termasuk struktur bagian dalamnya. Informasi ini merupakan kunci untuk pengenalan otomatis. Hamburan oleh suatu target dapat dijelaskan secara kuantitatif melalui Fungsi Bentuk (Form Function). Fungsi Bentuk dapat dihitung berdasarkan data pulsa awal, pulsa terpantul, dan parameter medium tempat pulsa merambat. Dalam penelitian ini, objek berbentuk bola diklasifikasikan berdasarkan material isinya—air atau udara. Kami membatasi studi pada target bola dua lapisan yang terendam dalam air. Fungsi Bentuk digunakan sebagai deskriptor dan dimasukkan ke dalam klasifikasi Jaringan Syaraf Tiruan, Perseptron Berlapis (Multilayer Perceptron/MLP). Kinerja klasifier dibandingkan dengan Mesin Vektor Pendukung (Support Vector Machine/SVM), dan deskriptor Fungsi Bentuk dianalisis berbanding dengan Representasi Waktu dan Frekuensi dari gema.
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id
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Eugenio Regazzini was born on August 12, 1946 in Cremona (Italy), and took his degree in 1969 at the University "L. Bocconi" of Milano. He has held positions at the universities of Torino, Bologna and Milano, and at the University "L. Bocconi" as assistant professor and lecturer from 1974 to 1980, and then professor since 1980. He is currently professor in probability and mathematical statistics at the University of Pavia. In the periods 1989-2001 and 2006-2009 he was head of the Institute for Applications of Mathematics and Computer Science of the Italian National Research Council (C.N.R.) in Milano and head of the Department of Mathematics at the University of Pavia, respectively. For twelve years between 1989 and 2006, he served as a member of the Scientific Board of the Italian Mathematical Union (U.M.I.). In 2007, he was elected Fellow of the IMS and, in 2001, Fellow of the "Istituto Lombardo---Accademia di Scienze e Lettere." His research activity in probability and statistics has covered a wide spectrum of topics, including finitely additive probabilities, foundations of the Bayesian paradigm, exchangeability and partial exchangeability, distribution of functionals of random probability measures, stochastic integration, history of probability and statistics. Overall, he has been one of the most authoritative developers of de Finetti's legacy. In the last five years, he has extended his scientific interests to probabilistic methods in mathematical physics; in particular, he has studied the asymptotic behavior of the solutions of equations, which are of interest for the kinetic theory of gases. The present interview was taken in occasion of his 65th birthday.
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Эвдженио Регаццини 1946 жылдың 12 тамызында Кремона (Италия) қаласында дүниеге келген және 1969 жылы Миландың «Л. Боккони» университетінде білім алған. Ол 1974-1980 жылдары Турино, Болонья, Милан және «Л. Боккони» университеттерінде ассистент және оқытушы болып жұмыс істеген, содан кейін 1980 жылдан бастап профессор болды. Қазіргі уақытта ол Павия университетінде ықтималдық пен математикалық статистика профессоры. 1989-2001 және 2006-2009 жылдар аралығында ол Миландағы Италия Ұлттық зерттеу кеңесінің (C.N.R.) Математиканың және компьютерлік ғылымның қолданылуы институтының жетекшісі және сәйкесінше Павия университетінің математика кафедрасының меңгерушісі болды. 1989 жылдан 2006 жылға дейін он екі жыл бойы ол Италия математикалық одағының (U.M.I.) ғылыми кеңесінің мүшесі болды. 2007 жылы ол IMS-тің Fellow мүшесіне, ал 2001 жылы «Иституто Ломбардо – Ғылымдар мен әдебиет академиясының» Fellow мүшесіне сайланды. Ықтималдық пен статистика саласындағы зерттеу жұмыстары әлдеқайда кең тақырыптарды қамтыды, оған шектеулі қосылатын ықтималдықтар, Байес парадигмасының негіздері, ауыстырымдылық пен жартылай ауыстырымдылық, кездейсоқ ықтималдық өлшемдерінің функционалдарының таралуы, стохастикалық интеграция, ықтималдық пен статистиканың тарихы жатады. Жалпы алғанда, ол де Финетти мұрасының ең авторитетті дамытушыларының бірі болды. Соңғы бес жылда ол ғылыми қызығушылығын математикалық физикадағы ықтималдық әдістеріне дейін кеңейтті; атап айтқанда, газдардың кинетикалық теориясы үшін маңызы бар теңдеулердің шешімдерінің асимптоталық мінез-құлқын зерттеді. Бұл сұхбат оның 65 жасқа толуына арналып алынды.
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kk
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We report new HI observations of four z$\sim$0.05 star-forming galaxies undertaken during the commissioning phase of the Five-hundred-meter Aperture Spherical Radio Telescope (FAST). FAST is the largest single-dish telescope with a 500 meter aperture and a 19-Beam receiver. Exploiting the unprecedented sensitivity provided by FAST, we aim to study the atomic gas, via the HI 21cm emission line, in low-$z$ star-forming galaxies taken from the Valpara\'iso ALMA/APEX Line Emission Survey (VALES) project. Together with previous ALMA CO($J=1-0$) observations, the HI data provides crucial information to measure the gas mass and dynamics. As a pilot HI survey, we targeted four local star-forming galaxies at $z\sim0.05$. In particular, one of them has already been detected in HI by the Arecibo Legacy Fast ALFA survey (ALFALFA), allowing a careful comparison. We use an ON-OFF observing approach that allowed us to reach an rms of 0.7mJy/beam at a 1.7km/s velocity resolution within only 20 minutes ON-target integration time. We demonstrate the great capabilities of the FAST 19-beam receiver for pushing the detectability of the HI emission line of extra-galactic sources. The HI emission line detected by FAST shows good consistency with the previous ALFALFA results. Our observations are put in context with previous multi-wavelength data to reveal the physical properties of these low-$z$ galaxies. We find that the CO($J=1-0$) and HI emission line profiles are similar. The dynamical mass estimated from the HI data is an order of magnitude higher than the baryon mass and the dynamical mass derived from the CO observations, implying that the mass probed by dynamics of HI is dominated by the dark matter halo. In one case, a target shows an excess of CO($J=1-0$) in the line centre, which can be explained by an enhanced CO($J=1-0$) emission induced by a nuclear starburst showing high velocity dispersion.
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យើងខ្ញុំរាយការណ៍អំពីការសង្កេត HI ថ្មីៗចំពោះហ្គាឡាក់ស៊ីបង្កើតផ្កាយចំនួនបួន នៅ z$\sim$0.05 ដែលបានអនុវត្តក្នុងដំណាក់កាលដំបូងនៃការដំឡើងទូរទស្សន៍វិទ្យុប្រឡាយធំប្រាំម៉ែត្រ (FAST)។ FAST គឺជាទូរទស្សន៍វិទ្យុប្រឡាយតែមួយដ៏ធំបំផុតដែលមានប្រឡាយ 500 ម៉ែត្រ និងអង់តែន 19 កាំ។ ដោយប្រើប្រាស់ភាពរសើបដ៏អស្ចារ្យដែលផ្តល់ដោយ FAST យើងខ្ញុំបានស្វែងយកការសិក្សាអំពីឧស្ម័នអាតូមិកតាមរយៈបន្ទាត់បញ្ចេញពន្លឺ HI 21cm នៅក្នុងហ្គាឡាក់ស៊ីបង្កើតផ្កាយនៅតំបន់ z ទាប ដែលបានយកពីគម្រោងស្ទង់រកបន្ទាត់បញ្ចេញពន្លឺ Valparaíso ALMA/APEX (VALES)។ រួមជាមួយទិន្នន័យសង្កេតពី ALMA លើ CO($J=1-0$) ការសង្កេតពី HI ផ្តល់ព័ត៌មានសំខាន់ៗដើម្បីវាស់ម៉ាសនិងសកម្មភាពរបស់ឧស្ម័ន។ ជាការស្ទង់ដំបូងអំពី HI យើងខ្ញុំបានគោលដៅទៅកាន់ហ្គាឡាក់ស៊ីបង្កើតផ្កាយនៅតំបន់នោះចំនួនបួន នៅ z$\sim0.05$។ ជាពិសេស មួយក្នុងចំណោមវាត្រូវបានរកឃើញក្នុង HI រួចហើយដោយការស្ទង់ Arecibo Legacy Fast ALFA (ALFALFA) ដែលអនុញ្ញាតឱ្យយើងធ្វើការប្រៀបធៀបដោយប្រុងប្រយ័ត្ន។ យើងខ្ញុំបានប្រើវិធីសាស្ត្រសង្កេត ON-OFF ដែលអនុញ្ញាតឱ្យយើងឈានដល់ rms 0.7mJy/beam នៅកម្រិតភាពប្រែប្រួលល្បឿន 1.7km/s ក្នុងរយៈពេលតែ 20 នាទីនៃពេលវេលាសង្កេត។ យើងខ្ញុំបានបង្ហាញពីសមត្ថភាពដ៏អស្ចារ្យរបស់អង់តែន 19 កាំរបស់ FAST ក្នុងការពង្រីកសមត្ថភាពរកឃើញបន្ទាត់បញ្ចេញពន្លឺ HI នៃប្រភពខាងក្រៅហ្គាឡាក់ស៊ី។ បន្ទាត់បញ្ចេញពន្លឺ HI ដែលរកឃើញដោយ FAST បង្ហាញពីភាពស៊ីសង្វាក់គ្នាយ៉ាងល្អជាមួយលទ្ធផល ALFALFA មុន។ ការសង្កេតរបស់យើងត្រូវបានដាក់បញ្ចូលក្នុងបរិបទជាមួយទិន្នន័យពហុរលកមុនដើម្បីបង្ហាញពីលក្ខណៈរូបវិទ្យារបស់ហ្គាឡាក់ស៊ីទាំងនេះនៅតំបន់ z ទាប។ យើងរកឃើញថាប្រវត្តិបន្ទាត់បញ្ចេញពន្លឺ CO($J=1-0$) និង HI មានលក្ខណៈស្រដៀងគ្នា។ ម៉ាសដែលបានប៉ាន់ស្មានពីទិន្នន័យ HI គឺខ្ពស់ជាងម៉ាសប៉័រ្យូន និងម៉ាសដែលបានប៉ាន់ស្មានពីការសង្កេត CO មួយកម្រិត ដែលបង្ហាញថាម៉ាសដែលត្រូវបានវាស់ដោយសកម្មភាពរបស់ HI គឺគ្រប់គ្រងដោយគ្រាប់ម៉ាសងងឹត។ ក្នុងករណីមួយ គោលដៅបង្ហាញពីការលើសនៃ CO($J=1-0$) នៅចំណុចកណ្តាលបន្ទាត់ ដែលអាចពន្យល់បានដោយការបង្កើនការបញ្ចេញពន្លឺ CO($J=1-0$) ដែលបណ្តាលមកពីការផ្ទះៗផ្កាយនៅកណ្តាលដែលបង្ហាញពីភាពប្រែប្រួលល្បឿនខ្ពស់។
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km
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Ultra-high-energy cosmic rays (UHECRs) are the highest energy messengers in the universe, with energies up to $10^{20}$ eV. Studies of astrophysical particles (nuclei, electrons, neutrinos and photons) at their highest observed energies have implications for fundamental physics as well as astrophysics. The primary particles interact in the atmosphere (or in the Earth) and generate extensive air showers. Analysis of those showers enables one not only to estimate the energy, direction and most probable mass of the primary cosmic particles, but also to obtain information about the properties of their hadronic interactions at energies more than one order of magnitude above that accessible with the current highest energy human-made accelerator. The Pierre Auger Observatory, located in the province of Mendoza, Argentina, is the largest cosmic ray experiment ever built. The observatory was designed as a hybrid detector covering an area of 3000 km$^2$ and has been taking data for almost twenty years. In this paper, a selection of the latest results is presented: the cosmic ray energy spectrum, studies of hadronic physics, searches for a directional anisotropy and studies of mass composition (including the photon and neutrino searches). Finally, the current upgrade ("AugerPrime") of the observatory, which is mostly aimed at improving the sensitivity to the particle type and mass of ultra-high energy cosmic rays, is described.
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Ультравысокоэнергетические космические лучи (УВЭКЛ) являются самыми высокоэнергетическими посланниками во Вселенной с энергиями до $10^{20}$ эВ. Исследования астрофизических частиц (ядер, электронов, нейтрино и фотонов) при их самых высоких наблюдаемых энергиях имеют значение как для фундаментальной физики, так и для астрофизики. Первичные частицы взаимодействуют в атмосфере (или в теле Земли) и порождают широкие атмосферные ливни. Анализ этих ливней позволяет не только оценить энергию, направление и наиболее вероятную массу первичных космических частиц, но и получить информацию о свойствах их адронных взаимодействий при энергиях, превышающих более чем на порядок величину, доступную на современных ускорителях с наибольшими энергиями. Обсерватория Пьера Ожера, расположенная в провинции Мендоса, Аргентина, является крупнейшим экспериментом по изучению космических лучей, когда-либо построенным. Обсерватория создана как гибридный детектор, охватывающий площадь 3000 км$^2$, и собирает данные уже почти двадцать лет. В данной статье представлен отбор новейших результатов: спектр космических лучей по энергии, исследования адронной физики, поиски направленной анизотропии и исследования состава по массе (включая поиски фотонов и нейтрино). Наконец, описывается текущая модернизация обсерватории («AugerPrime»), основная цель которой — повысить чувствительность к типу и массе ультравысокоэнергетических космических лучей.
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ru
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Road user behavior prediction is one of the most critical components in trajectory planning for autonomous driving, especially in urban scenarios involving traffic signals. In this paper, a hierarchical framework is proposed to predict vehicle behaviors at a signalized intersection, using the traffic signal information of the intersection. The framework is composed of two phases: a discrete intention prediction phase and a continuous trajectory prediction phase. In the discrete intention prediction phase, a Bayesian network is adopted to predict the vehicle's high-level intention, after that, maximum entropy inverse reinforcement learning is utilized to learn the human driving model offline; during the online trajectory prediction phase, a driver characteristic is designed and updated to capture the different driving preferences between human drivers. We applied the proposed framework to one of the most challenging scenarios in autonomous driving: the yellow light running scenario. Numerical experiment results are presented in the later part of the paper which show the viability of the method. The accuracy of the Bayesian network for discrete intention prediction is 91.1%, and the prediction results are getting more and more accurate as the yellow time elapses. The average Euclidean distance error in continuous trajectory prediction is only 0.85 m in the yellow light running scenario.
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ການຄາດເດົາພຶດຕິກຳຂອງຜູ້ໃຊ້ຖະໜົນຖືວ່າເປັນໜຶ່ງໃນອົງປະກອບທີ່ສຳຄັນທີ່ສຸດໃນການວາງແຜນເສັ້ນທາງສຳລັບການຂັບຂີ່ອັດຕະໂນມັດ, ໂດຍສະເພາະໃນສະຖານະການເມືອງທີ່ກ່ຽວຂ້ອງກັບສັນຍານຈາລະຈອນ. ໃນບົດຄວາມນີ້, ພວກເຮົາຂໍເອົາລະບົບແບບຊັ້ນຊອງມາໃຊ້ເພື່ອຄາດເດົາພຶດຕິກຳຂອງລົດໃນສີ່ແຍກທີ່ມີສັນຍານ, ໂດຍໃຊ້ຂໍ້ມູນຂ່າວສານຂອງສັນຍານຈາລະຈອນຂອງສີ່ແຍກ. ລະບົບດັ່ງກ່າວປະກອບດ້ວຍສອງຂັ້ນຕອນ: ຂັ້ນຕອນການຄາດເດົາເຈດຕະນາແບບແຍກຕ່າງຫາກ ແລະ ຂັ້ນຕອນການຄາດເດົາເສັ້ນທາງແບບຕໍ່ເນື່ອງ. ໃນຂັ້ນຕອນການຄາດເດົາເຈດຕະນາແບບແຍກຕ່າງຫາກ, ພວກເຮົານຳໃຊ້ເຄືອຂ່າຍເບເຍ (Bayesian network) ເພື່ອຄາດເດົາເຈດຕະນາຂອງລົດໃນລະດັບສູງ, ຕໍ່ມາຈະນຳໃຊ້ການຮຽນຮູ້ການເສີມອັນດັບສູງສຸດ (maximum entropy inverse reinforcement learning) ເພື່ອຮຽນຮູ້ຮູບແບບການຂັບຂີ່ຂອງມະນຸດຢ່າງອິດສະລະ; ໃນຂະນະທີ່ຂັ້ນຕອນການຄາດເດົາເສັ້ນທາງແບບຕໍ່ເນື່ອງ, ພວກເຮົາອອກແບບ ແລະ ອັບເດດລັກສະນະຂອງຜູ້ຂັບຂີ່ເພື່ອຈັບເອົາຄວາມຕ້ອງການໃນການຂັບຂີ່ທີ່ແຕກຕ່າງກັນລະຫວ່າງຜູ້ຂັບຂີ່. ພວກເຮົາໄດ້ນຳໃຊ້ລະບົບທີ່ສະເໜີນີ້ໃນໜຶ່ງໃນສະຖານະການທີ່ທ້າທາຍທີ່ສຸດໃນການຂັບຂີ່ອັດຕະໂນມັດ: ສະຖານະການຂັບຂີ່ໃຕ້ແສງເຫຼືອງ. ຜົນໄດ້ຮັບຈາກການທົດລອງເຊິ່ງສະແດງໃຫ້ເຫັນເຖິງຄວາມເປັນໄປໄດ້ຂອງວິທີການດັ່ງກ່າວຈະຖືກນຳມາສະເໜີໃນສ່ວນທ້າຍຂອງບົດຄວາມ. ຄວາມຖືກຕ້ອງຂອງເຄືອຂ່າຍເບເຍໃນການຄາດເດົາເຈດຕະນາແບບແຍກຕ່າງຫາກແມ່ນ 91.1%, ແລະ ຜົນການຄາດເດົາກໍຈະຍິ່ງມີຄວາມຖືກຕ້ອງຫຼາຍຂຶ້ນເມື່ອເວລາແສງເຫຼືອງຜ່ານໄປ. ຂໍ້ຜິດພາດໃນໄລຍະທາງອີວຄລິດ (Euclidean distance) ເສັ້ນທາງແບບຕໍ່ເນື່ອງສະເລ່ຍແມ່ນພຽງແຕ່ 0.85 ແມັດໃນສະຖານະການຂັບຂີ່ໃຕ້ແສງເຫຼືອງ.
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lo
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Massive rotating single stars with an initial metal composition appropriate for the dwarf galaxy I Zw 18 ([Fe/H]=$-$1.7) are modelled during hydrogen burning for initial masses of 9-300 M$_{\odot}$ and rotational velocities of 0-900 km s$^{-1}$. Internal mixing processes in these models were calibrated based on an observed sample of OB-type stars in the Magellanic Clouds. Even moderately fast rotators, which may be abundant at this metallicity, are found to undergo efficient mixing induced by rotation resulting in quasi chemically-homogeneous evolution. These homogeneously-evolving models reach effective temperatures of up to 90 kK during core hydrogen burning. This, together with their moderate mass-loss rates, make them Transparent Wind Ultraviolet INtense stars (TWUIN star), and their expected numbers might explain the observed HeII ionizing photon flux in I Zw 18 and other low-metallicity HeII galaxies. Our slowly rotating stars above $\sim$80 M$_{\odot}$ evolve into late B- to M-type supergiants during core hydrogen burning, with visual magnitudes up to 19$^{\mathrm{m}}$ at the distance of I Zw 18. Both types of stars, TWUIN stars and luminous late-type supergiants, are only predicted at low metallicity. Massive star evolution at low metallicity is shown to differ qualitatively from that in metal-rich environments. Our grid can be used to interpret observations of local star-forming dwarf galaxies and high-redshift galaxies, as well as the metal-poor components of our Milky Way and its globular clusters.
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Bintang tunggal berputar besar dengan komposisi logam awal yang sesuai untuk galaksi kerdil I Zw 18 ([Fe/H] = $-$1.7) dimodelkan semasa pembakaran hidrogen bagi jisim awal 9–300 M$_{\odot}$ dan halaju putaran 0–900 km s$^{-1}$. Proses pencampuran dalaman dalam model-model ini dikalibrasi berdasarkan sampel bintang jenis OB yang dicerap di Awan Magellan. Didapati bahawa pemutar yang agak pantas, yang mungkin banyak wujud pada metalisiti ini, mengalami pencampuran cekap yang diaruhkan oleh putaran, mengakibatkan evolusi yang hampir homogen secara kimia. Model-model yang berevolusi secara homogen ini mencapai suhu berkesan sehingga 90 kK semasa pembakaran hidrogen teras. Ini, bersama-sama dengan kadar kehilangan jisim sederhana mereka, menjadikan mereka bintang Angin Lutsinar Ultralegapan INTENS (bintang TWUIN), dan bilangan jangkaan mereka mungkin dapat menjelaskan fluks foton pengionan HeII yang dicerap dalam I Zw 18 dan galaksi HeII lain yang rendah metalisitinya. Bintang-bintang yang berputar perlahan milik kita di atas $\sim$80 M$_{\odot}$ berkembang menjadi raksasa super jenis B akhir hingga M semasa pembakaran hidrogen teras, dengan magnitud visual sehingga 19$^{\mathrm{m}}$ pada jarak I Zw 18. Kedua-dua jenis bintang ini, bintang TWUIN dan raksasa super jenis akhir bersinar, hanya diramalkan wujud pada metalisiti rendah. Evolusi bintang besar pada metalisiti rendah ditunjukkan berbeza secara kualitatif daripada evolusi dalam persekitaran yang kaya logam. Grid kita boleh digunakan untuk mentafsir pencerapan galaksi kerdil pembentuk bintang setempat dan galaksi beranjakan-merah tinggi, serta komponen-komponen yang kurang logam dalam Bima Sakti kita dan gugusan globularnya.
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ms
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Ultra-high-energy cosmic rays (UHECRs) are the highest energy messengers in the universe, with energies up to $10^{20}$ eV. Studies of astrophysical particles (nuclei, electrons, neutrinos and photons) at their highest observed energies have implications for fundamental physics as well as astrophysics. The primary particles interact in the atmosphere (or in the Earth) and generate extensive air showers. Analysis of those showers enables one not only to estimate the energy, direction and most probable mass of the primary cosmic particles, but also to obtain information about the properties of their hadronic interactions at energies more than one order of magnitude above that accessible with the current highest energy human-made accelerator. The Pierre Auger Observatory, located in the province of Mendoza, Argentina, is the largest cosmic ray experiment ever built. The observatory was designed as a hybrid detector covering an area of 3000 km$^2$ and has been taking data for almost twenty years. In this paper, a selection of the latest results is presented: the cosmic ray energy spectrum, studies of hadronic physics, searches for a directional anisotropy and studies of mass composition (including the photon and neutrino searches). Finally, the current upgrade ("AugerPrime") of the observatory, which is mostly aimed at improving the sensitivity to the particle type and mass of ultra-high energy cosmic rays, is described.
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Sinar kosmik tenaga ultra-tinggi (UHECRs) merupakan pembawa tenaga tertinggi di alam semesta, dengan tenaga sehingga $10^{20}$ eV. Kajian zarah astofizik (nukleus, elektron, neutrino dan foton) pada tenaga tertinggi yang diperhatikan mempunyai implikasi terhadap fizik asas serta astrofizik. Zarah primer ini berinteraksi dalam atmosfera (atau di dalam Bumi) dan menghasilkan hujan udara meluas. Analisis hujan-hujan tersebut membolehkan kita bukan sahaja menganggar tenaga, arah dan jisim yang paling berkemungkinan bagi zarah kosmik primer, tetapi juga memperoleh maklumat mengenai sifat-sifat interaksi hadronik mereka pada tenaga yang melebihi lebih daripada satu darab magnitud berbanding tenaga yang boleh dicapai oleh pemecut buatan manusia dengan tenaga tertinggi semasa ini. Pemerhatian Pierre Auger, yang terletak di wilayah Mendoza, Argentina, merupakan eksperimen sinar kosmik terbesar yang pernah dibina. Pemerhatian ini direka sebagai pengesan hibrid yang merangkumi kawasan seluas 3000 km$^2$ dan telah mengumpul data selama hampir dua puluh tahun. Dalam kertas ini, dipaparkan satu pemilihan keputusan terkini: spektrum tenaga sinar kosmik, kajian fizik hadronik, pencarian anisotropi mengikut arah dan kajian komposisi jisim (termasuk pencarian foton dan neutrino). Akhir sekali, dilaporkan tentang pengemaskinian semasa ("AugerPrime") pemerhatian ini, yang terutamanya bertujuan meningkatkan kepekaan terhadap jenis zarah dan jisim sinar kosmik tenaga ultra-tinggi.
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ms
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The formulation of the tensor virial equations is generalized to unrelaxed configurations, where virial equilibrium does not coincide with dynamical (or hydrostatic) equilibrium. Further investigation is devoted to special classes of homeoidally striated ellipsoids, defined as homeoidally striated, Jacobi ellipsoids. In particular, virial equilibrium configurations with constant anisotropy parameters are studied with more detail, including both flattened and elongated, triaxial configurations, and the determination of the related bifurcation points. The explicit expression of different rotation parameters is also determined. An application is made to dark matter haloes hosting giant, galaxies, with regard to assigned initial and final configuration, following and generalizing to many respects a procedure conceived by Thuan & Gott (1975). The dependence of the limiting axis ratios, below which no configuration is allowed for the sequence under consideration, on the change in mass, total energy, and angular momentum, during the evolution, is illustrated in some representative situations. The dependence of axis ratios and rotation parameters on an additional parameter, related to the initial conditions of the density perturbation, is analysed in connection with a few special cases. Within the range of Peebles (1969) rotation parameter, inferred from high-resolution numerical simulations, the shape of dark matter haloes is mainly decided by the amount of anisotropy in residual velocity distribution. On the other hand, the contribution of rotation has only a minor effect on the meridional plane, and no effect on the equatorial plane, as bifurcation points occur for larger values of Peebles (1969) rotation parameter. To this respect, dark matter haloes are found to resemble giant elliptical galaxies.
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تنسور وائریل مساوات کی تشکیل کو غیر متوازن ترتیبات تک وسیع کیا گیا ہے، جہاں وائریل توازن، دینامکی (یا ہائیڈرو اسٹیٹک) توازن کے ہم آہنگ نہیں ہوتا۔ مزید تحقیق ہومیوڈلی سٹریٹیفائیڈ الپسوائیڈز کی خاص اقسام کے لیے وقف ہے، جنہیں ہومیوڈلی سٹریٹیفائیڈ، جیکوبی الپسوائیڈز کے طور پر تعریف کیا گیا ہے۔ خاص طور پر، مسلسل اینیسوٹروپی پیرامیٹرز کے ساتھ وائریل توازن کی ترتیبات کا مطالعہ مزید تفصیل کے ساتھ کیا گیا ہے، جس میں چپٹی اور لمبی دونوں قسم کی تھری ایکسیل ترتیبات شامل ہیں، اور متعلقہ بائی فرکیشن پوائنٹس کا تعین بھی شامل ہے۔ مختلف گردش کے پیرامیٹرز کی صریح اظہار بھی متعین کی گئی ہے۔ بڑے درجے کی کہکشانوں کو اپنے اندر رکھنے والے ڈارک میٹر ہیلو کے لیے ایک درخواست پیش کی گئی ہے، مخصوص ابتدائی اور حتمی ترتیب کے حوالے سے، جو تھوان اور گاٹ (1975) کے تصور کردہ طریقہ کار کی پیروی کرتی ہے اور اس کی کئی پہلوؤں میں توسیع بھی کرتی ہے۔ ترتیبات کے مخصوص سلسلے کے لیے جن محور تناسب کی حدود کا تعین کیا گیا ہے، جس کے نیچے کوئی بھی ترتیب جائز نہیں ہوتی، اور جو مجموعی مادہ، کل توانائی، اور زاویائی حرکت میں تبدیلی کے ساتھ تبدیلی کے دوران منسلک ہوتی ہیں، کو کچھ نمائندہ صورتحال میں واضح کیا گیا ہے۔ محور تناسب اور گردش کے پیرامیٹرز کی ایک اضافی پیرامیٹر پر، جو کثافت میں ابتدائی خلل کی ابتدائی شرائط سے منسلک ہے، پر منحصر تجزیہ کچھ خاص صورتوں کے تناظر میں کیا گیا ہے۔ پیبلز (1969) کے گردش کے پیرامیٹر کی حدود کے اندر، جو ہائی ریزولوشن عددی محاکات سے استنباط کی گئی ہے، ڈارک میٹر ہیلو کی شکل خاص طور پر باقی ماندہ رفتار تقسیم میں اینیسوٹروپی کی مقدار پر منحصر ہوتی ہے۔ دوسری طرف، گردش کا مرکزی سطح پر صرف معمولی اثر پڑتا ہے، اور استوائی سطح پر کوئی اثر نہیں پڑتا، کیونکہ بائی فرکیشن پوائنٹس پیبلز (1969) گردش کے پیرامیٹر کی بڑی قیمتوں پر پیدا ہوتے ہیں۔ اس حوالے سے، ڈارک میٹر ہیلو بڑی بیضوی کہکشانوں کی مانند پائے گئے ہیں۔
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ur
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Context. The dynamical evolution of near-parabolic comets strongly depends on the starting values of the orbital elements derived from the positional observations. In addition, when drawing conclusions about the origin of these objects, it is crucial to control the uncertainties of orbital elements at each stage of the dynamical evolution. Aims. I apply a completely homogeneous approach to determine the cometary orbits and their uncertainties. The resulting catalogue is suitable for the investigation of the origin and future of near-parabolic comets. Methods. First, osculating orbits were determined on the basis of positional data. Second, the dynamical calculations were performed backwards and forwards up to 250 au from the Sun to derive original and future barycentric orbits for each comet. In the present investigation of dynamical evolution, the numerical calculations for a given object start from the swarm of virtual comets constructed using the previously determined osculating (nominal) orbit. In this way, the uncertainties of orbital elements were derived at the end of numerical calculations. Results. Homogeneous sets of orbital elements for osculating, original and future orbits are given. The catalogue of 119 cometary orbits constitutes about 70 per cent of all the first class so-called Oort spike comets discovered during the period of 1801-2010 and about 90 per cent of those discovered in 1951-2010, for which observations were completed at the end of 2013. Non-gravitational (NG) orbits are derived for 45 comets, including asymmetric NG~solution for six of them. Additionally, the new method for cometary orbit-quality assessment is applied for all these objects.
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প্রেক্ষাপট। অবস্থানগত পর্যবেক্ষণের ভিত্তিতে প্রাপ্ত কক্ষপথের আদি উপাদানগুলির আদি মানগুলির উপর প্রায়-পরাবৃত্তাকার ধূমকেতুগুলির গতিময় বিবর্তন খুব নির্ভরশীল। এছাড়াও, এই বস্তুগুলির উৎপত্তি সম্পর্কে সিদ্ধান্ত নেওয়ার সময়, গতিময় বিবর্তনের প্রতিটি পর্যায়ে কক্ষপথের উপাদানগুলির অনিশ্চয়তা নিয়ন্ত্রণ করা অত্যন্ত গুরুত্বপূর্ণ। উদ্দেশ্য। আমি ধূমকেতুর কক্ষপথ এবং তাদের অনিশ্চয়তা নির্ধারণের জন্য একটি সম্পূর্ণ সমসত পদ্ধতি প্রয়োগ করি। ফলাফলে প্রাপ্ত তালিকাটি প্রায়-পরাবৃত্তাকার ধূমকেতুগুলির উৎপত্তি এবং ভবিষ্যৎ তদন্তের জন্য উপযুক্ত। পদ্ধতি। প্রথমে, অবস্থানগত তথ্যের ভিত্তিতে অস্কুলেটিং কক্ষপথগুলি নির্ধারণ করা হয়েছিল। দ্বিতীয়ত, প্রতিটি ধূমকেতুর জন্য মূল এবং ভবিষ্যতের ব্যারিসেন্ট্রিক কক্ষপথ প্রাপ্ত করার জন্য সূর্য থেকে 250 এ.ইউ. পর্যন্ত পিছন এবং সামনের দিকে গতিময় গণনা করা হয়েছিল। গতিময় বিবর্তনের বর্তমান তদন্তে, পূর্বে নির্ধারিত অস্কুলেটিং (নমিনাল) কক্ষপথ ব্যবহার করে গঠিত ভার্চুয়াল ধূমকেতুগুলির ঝাঁক থেকে একটি নির্দিষ্ট বস্তুর জন্য সংখ্যাগত গণনাগুলি শুরু করা হয়। এই পদ্ধতিতে, সংখ্যাগত গণনার শেষে কক্ষপথের উপাদানগুলির অনিশ্চয়তা প্রাপ্ত হয়। ফলাফল। অস্কুলেটিং, মূল এবং ভবিষ্যতের কক্ষপথের জন্য কক্ষপথের উপাদানগুলির সমসত সেটগুলি দেওয়া হয়েছে। 119টি ধূমকেতুর কক্ষপথের তালিকাটি 1801-2010 সময়কালে আবিষ্কৃত সমস্ত প্রথম শ্রেণীর তথাকথিত ওর্ট স্পাইক ধূমকেতুগুলির প্রায় 70 শতাংশ এবং 1951-2010 সময়ে আবিষ্কৃত সেগুলির প্রায় 90 শতাংশ গঠন করে, যাদের পর্যবেক্ষণ 2013 এর শেষ পর্যন্ত সম্পন্ন হয়েছিল। 45টি ধূমকেতুর জন্য অ-মহাকর্ষীয় (এনজি) কক্ষপথগুলি প্রাপ্ত হয়েছে, যার মধ্যে ছয়টির জন্য অসম এনজি সমাধান অন্তর্ভুক্ত রয়েছে। এছাড়াও, ধূমকেতুর কক্ষপথের গুণমান মূল্যায়নের জন্য একটি নতুন পদ্ধতি এই সমস্ত বস্তুগুলির জন্য প্রয়োগ করা হয়।
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bn
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Let kappa be an uncountable regular cardinal. Call an equivalence relation on functions from kappa into 2 Sigma_1^1-definable over H(kappa) if there is a first order sentence F and a parameter R subseteq H(kappa) such that functions f,g:kappa --> 2 are equivalent iff for some h:kappa --> 2, the structure (H(kappa),in,R,f,g,h) satisfies F, where in, R, f, g, and h are interpretations of the symbols appearing in F. All the values mu, 1 leq mu leq kappa^+ or mu=2^kappa, are possible numbers of equivalence classes for such a Sigma_1^1-equivalence relation. Additionally, the possibilities are closed under unions of <=kappa-many cardinals and products of <kappa-many cardinals. We prove that, consistent wise, these are the only restrictions under the singular cardinal hypothesis. The result is that the possible numbers of equivalence classes of Sigma_1^1-equivalence relations might consistent wise be exactly those cardinals which are in a prearranged set, provided that the singular cardinal hypothesis holds and that some necessary conditions are fulfilled.
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设κ为一个不可数的正则基数。称一个从κ到2的函数上的等价关系是H(κ)上的Σ₁¹-可定义的，如果存在一个一阶句子F和一个参数R ⊆ H(κ)，使得函数f, g: κ → 2等价当且仅当存在某个h: κ → 2，使得结构(H(κ), ∈, R, f, g, h)满足F，其中∈、R、f、g和h分别是F中出现符号的解释。所有取值μ，其中1 ≤ μ ≤ κ⁺ 或 μ = 2^κ，都是此类Σ₁¹-等价关系的等价类个数的可能取值。此外，这些可能的取值在不超过κ个基数的并和少于κ个基数的乘积下是封闭的。我们证明，在一致性意义上，若奇数基数假设成立，则这些是唯一的限制条件。结果是，在奇数基数假设成立且某些必要条件满足的前提下，Σ₁¹-等价关系的等价类个数可能取到的基数恰好是某个预先设定集合中的那些基数，这在一致性意义上是可能的。
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zh
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We employ the Schwinger boson mean-field approach to study the effects of arbitrary frustrated bonds and plaquettes (formed from four frustrated bonds) in two-dimensional ferro- and antiferromagnets on the spin-wave spectrum and the correlation length at finite temperatures. We distinguish between strongly frustrated bonds (plaquettes), when the frustrated coupling $J^\prime$ exceeds the spin canting threshold $J_c$, and weakly frustrated bonds (plaquettes), with $J^\prime <J_c, (J_c-J^\prime)/J_c\sim 1$. It is shown that in antiferromagnets the amplitude of spin-wave scattering on strongly frustrated bonds or plaquettes grows with the decrease of the temperature. A small amount of such defects reduces significantly the spin-wave stiffness and the correlation length at low temperatures. As a result, the quasi-2D N\'eel temperature is sharply suppressed. Quantum fluctuations are also considered and their effect on the spin-wave spectrum is shown to be of the order of $(2S)^{-2}\ln^{-1}2S$ in the large spin limit. For weakly frustrated (nonfrustrated) defect bonds (plaquettes) the spin-wave stiffness renormalization is of the order of the dopant concentration and does not depend on the temperature. The results account for the observed properties of doped quasi-2D $La_2CuO_{4+x}$.
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Utilizamos a abordagem de campo médio de bósons de Schwinger para estudar os efeitos de ligações frustradas arbitrárias e plaquetas (formadas por quatro ligações frustradas) em ferro- e antiferromagnetos bidimensionais sobre o espectro de ondas de spin e o comprimento de correlação em temperaturas finitas. Distinguimos entre ligações (plaquetas) fortemente frustradas, quando o acoplamento frustrado $J^\prime$ excede o limiar de inclinação do spin $J_c$, e ligações (plaquetas) fracamente frustradas, com $J^\prime < J_c$, $(J_c - J^\prime)/J_c \sim 1$. Mostra-se que em antiferromagnetos a amplitude do espalhamento de ondas de spin em ligações ou plaquetas fortemente frustradas cresce com a diminuição da temperatura. Uma pequena quantidade desses defeitos reduz significativamente a rigidez da onda de spin e o comprimento de correlação em baixas temperaturas. Como resultado, a temperatura de Néel quase-2D é fortemente suprimida. As flutuações quânticas também são consideradas, e seu efeito sobre o espectro de ondas de spin mostra-se da ordem de $(2S)^{-2}\ln^{-1}2S$ no limite de spin grande. Para ligações (plaquetas) defeituosas fracamente frustradas (não frustradas), a renormalização da rigidez da onda de spin é da ordem da concentração do dopante e não depende da temperatura. Os resultados explicam as propriedades observadas em $La_2CuO_{4+x}$ quase-2D dopado.
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pt
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Multicomponent bilayer structures arise as the ubiquitous plasma membrane in cellular biology and as blends of amphiphilic copolymers used in electrolyte membranes, drug delivery, and emulsion stabilization within the context of synthetic chemistry. We develop the multicomponent functionalized Cahn-Hilliard (mFCH) free energy as a model which allows competition between bilayers with distinct composition and between bilayers and higher codimensional structures, such as co-dimension two filaments and co-dimension three micelles. We investigate the stability and slow geometric evolution of multicomponent bilayer interfaces within the context of gradient flows of the mFCH, addressing the impact of aspect ratio of the lipid/copolymer unit on the intrinsic curvature and the codimensional bifurcation. In particular we derive a Canham-Helfrich sharp interface energy whose intrinsic curvature arises through a Melnikov parameter associated to lipid aspect ratio. We construct asymmetric homoclinic bilayer profiles via a billiard limit potential and show that the dominant co-dimensional bifurcation mechanism is via the layer-by-layer pearling observed experimentally.
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다성분 이중층 구조는 세포 생물학에서 보편적인 세포막으로 나타나며, 합성 화학의 맥락에서 전해질막, 약물 전달 및 유화 안정화에 사용되는 양친매성 블록공중합체의 혼합물로도 나타난다. 본 연구에서는 서로 다른 조성을 지닌 이중층들 사이 또는 이중층과 2차원 잔여(codimension two) 실형 구조(filaments) 및 3차원 잔여(codimension three) 미셀과 같은 더 높은 잔여 차원 구조들 사이의 경쟁을 설명할 수 있도록 해주는 다성분 기능화 카한-힐리어드(mFCH) 자유에너지 모델을 개발한다. 우리는 mFCH의 기울기 흐름 맥락에서 다성분 이중층 계면의 안정성과 느린 기하학적 진화를 조사하며, 지질/공중합체 단위의 종횡비(aspect ratio)가 고유 곡률 및 잔여 차원 분기(codimensional bifurcation)에 미치는 영향을 분석한다. 특히, 지질의 종횡비에 관련된 멜니코프 파라미터를 통해 고유 곡률이 유도되는 캔햄-헬프리크(Canham-Helfrich) 날카로운 계면 에너지를 도출한다. 우리는 빌리어드 극한 퍼텐셜을 통해 비대칭 동질성 이중층 프로파일을 구성하고, 실험적으로 관찰된 층별 배 모양 펄링(layer-by-layer pearling)을 통해 지배적인 잔여 차원 분기 메커니즘이 작용함을 보인다.
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ko
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We propose an online visual tracking algorithm by learning discriminative saliency map using Convolutional Neural Network (CNN). Given a CNN pre-trained on a large-scale image repository in offline, our algorithm takes outputs from hidden layers of the network as feature descriptors since they show excellent representation performance in various general visual recognition problems. The features are used to learn discriminative target appearance models using an online Support Vector Machine (SVM). In addition, we construct target-specific saliency map by backpropagating CNN features with guidance of the SVM, and obtain the final tracking result in each frame based on the appearance model generatively constructed with the saliency map. Since the saliency map visualizes spatial configuration of target effectively, it improves target localization accuracy and enable us to achieve pixel-level target segmentation. We verify the effectiveness of our tracking algorithm through extensive experiment on a challenging benchmark, where our method illustrates outstanding performance compared to the state-of-the-art tracking algorithms.
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ကွန်ဗျူးလူးရှင်နယ် နျူရယ်နက်ဝပ် (CNN) ကို အသုံးပြု၍ ကွဲပြားခြားနားသော သတိထားမိမှု မြေပုံကို သင်ကြားခြင်းဖြင့် အွန်လိုင်း ပုံရိပ် ခြေရာခံမှု အယ်လ်ဂိုရီသမ်တစ်ခုကို ကျွန်ုပ်တို့ အဆိုပြုပါသည်။ အော့ဖ်လိုင်းတွင် ပုံရိပ် သိုလှောင်မှု အကြီးစားတစ်ခုပေါ်တွင် ကြိုတင်သင်ကြားထားသော CNN တစ်ခုအား ပေးထားပါက၊ ကျွန်ုပ်တို့၏ အယ်လ်ဂိုရီသမ်သည် ကွန်ဗျူးလူးရှင်နယ် နက်ဝပ်ဝှက်ခ်တွင် မှောင်သော အလွှာများမှ ရလဒ်များကို အင်္ဂါရပ် ဖော်ပြချက်များအဖြစ် ယူပါသည်။ အကြောင်းမှာ ၎င်းတို့သည် ယေဘုယျ ပုံရိပ် အသိအမှတ်ပြုမှု ပြဿနာများစွာတွင် ကောင်းမွန်သော ကိုယ်စားပြုမှု စွမ်းဆောင်ရည်ကို ပြသသောကြောင့် ဖြစ်ပါသည်။ အင်္ဂါရပ်များကို အွန်လိုင်း Support Vector Machine (SVM) ကို အသုံးပြု၍ ကွဲပြားခြားနားသော ပစ်မှတ်၏ ပေါ်လွင်မှု မော်ဒယ်များကို သင်ကြားရန် အသုံးပြုပါသည်။ ထပ်မံ၍ SVM ၏ လမ်းညွှန်မှုဖြင့် CNN အင်္ဂါရပ်များကို ပြန်လည် ပို့ဆောင်ခြင်းဖြင့် ပစ်မှတ်အထူးသီးသန့် သတိထားမိမှု မြေပုံကို တည်ဆောက်ပြီး၊ သတိထားမိမှု မြေပုံဖြင့် ဖန်တီးထားသော ပေါ်လွင်မှု မော်ဒယ်ကို အခြေခံ၍ တစ်ဖရိမ်ချင်းစီတွင် နောက်ဆုံး ခြေရာခံမှု ရလဒ်ကို ရယူပါသည်။ သတိထားမိမှု မြေပုံသည် ပစ်မှတ်၏ နေရာချထားမှု ဖွဲ့စည်းပုံကို ထိရောက်စွာ ပြသသောကြောင့် ပစ်မှတ်၏ တည်နေရာ တိကျမှုကို မြှင့်တင်ပေးပြီး ပစ်မှတ်၏ ပစ်ကယ် အဆင့် ကွဲပြားမှုကို ရယူနိုင်စေပါသည်။ ကျွန်ုပ်တို့၏ နည်းလမ်းသည် ခေတ်မီ ခြေရာခံမှု အယ်လ်ဂိုရီသမ်များနှင့် နှိုင်းယှဉ်ပါက ထင်ရှားသော စွမ်းဆောင်ရည်ကို ပြသသည့် စိန်ခေါ်မှုများပါဝင်သော စံပြစမ်းသပ်မှုတစ်ခုတွင် ကျွန်ုပ်တို့၏ ခြေရာခံမှု အယ်လ်ဂိုရီသမ်၏ ထိရောက်မှုကို စမ်းသပ် အတည်ပြုပါသည်။
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my
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In this thesis we consider the polarized deep inelastic scattering in the region of low values of Bjorken variable, $x$. We formulate the evolution equations for the unintegrated parton distributions which include a complete resummation of the double logarithmic contributions, $\ln^2(1/x)$. Afterwards, these equations are completed with the standard LO and NLO DGLAP evolution terms, in order to obtain the proper behaviour of the parton distributions at moderate and large values of $x$. The equations obtained are applied to the following observables and processes: (i) to the nucleon structure function, $g_1$, in the polarized deep inelastic scattering, (ii) to the structure function of the polarized photon, $g_1^{\gamma}$, in the scattering of a lepton on a polarized photon, and (iii) to the differential structure function, $x_J d^2g_1/dx_J dk_J^2$, in the polarized deep inelastic scattering accompanied by a forward jet. Case (iii) is proposed to be a test process for the presence and the magnitude of the $\ln^2(1/x)$ contributions. For each process the consequences of including the logarithmic corrections are studied in a detail. After integrating out the structure function, $g_1$, the moments of the nucleon structure function are obtained. The contribution of the region of low $x$ to these moments is estimated, and then discussed in the context of the spin sum rules. Finally, some predictions for the observables, the asymmetry and the cross sections, in the processes (i)-(iii) are given. They are important to planned experiments with the polarized HERA and linear colliders, which will probe the region of low values of Bjorken $x$.
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នៅក្នុងប្រធានបទនេះ យើងពិចារណាលើការរាវរកជម្រៅដែលមានការបំបែកគោលកម្មវិធីនៅក្នុងតំបន់ដែលតម្លៃអថេរ Bjorken មានតម្លៃទាប $x$។ យើងបង្កើតសមីការវិវត្តន៍សម្រាប់ការចែកចាយផ្នែកដែលមិនបានបញ្ចូលដែលរួមបញ្ចូលការបូកសរុបពេញលេញនៃចំណែកដែលមានកត្តាកំណត់ $\ln^2(1/x)$។ បន្ទាប់មក សមីការទាំងនេះត្រូវបានបំពេញដោយចំណែកវិវត្តន៍ DGLAP ស្តង់ដារ LO និង NLO ដើម្បីទទួលបានឥរិយាបថត្រឹមត្រូវនៃការចែកចាយផ្នែកនៅតម្លៃមធ្យមនិងធំនៃ $x$។ សមីការដែលទទួលបានត្រូវបានអនុវត្តចំពោះតម្លៃដែលអាចសង្កេតបាននិងដំណើរការដូចខាងក្រោម៖ (i) ចំពោះមុខងាររចនាសម្ព័ន្ធនូគ្លេអុង $g_1$ នៅក្នុងការរាវរកជម្រៅដែលមានការបំបែកគោលកម្មវិធី (ii) ចំពោះមុខងាររចនាសម្ព័ន្ធនៃផូតុងដែលមានគោលកម្មវិធី $g_1^{\gamma}$ នៅក្នុងការរាវរកអេឡិចត្រុងលើផូតុងដែលមានគោលកម្មវិធី និង (iii) ចំពោះមុខងាររចនាសម្ព័ន្ធឌីផែរ៉ង់ស្យែល $x_J d^2g_1/dx_J dk_J^2$ នៅក្នុងការរាវរកជម្រៅដែលមានការបំបែកគោលកម្មវិធីដែលបន្ថែមដោយកាំមុខ។ ករណី (iii) ត្រូវបានស្នើឱ្យជាដំណើរការសាកល្បងសម្រាប់ភាពមាននិងទំហំនៃចំណែក $\ln^2(1/x)$។ សម្រាប់ដំណើរការនីមួយៗ ការសិក្សាលម្អិតអំពីផលប៉ះពាល់នៃការបញ្ចូលកំហាប់កត្តាកំណត់ត្រូវបានធ្វើឡើង។ បន្ទាប់ពីធ្វើប្រមាណវិធីបញ្ចូលមុខងាររចនាសម្ព័ន្ធ $g_1$ គេទទួលបានម៉ូម៉ង់នៃមុខងាររចនាសម្ព័ន្ធនូគ្លេអុង។ ចំណែកនៃតំបន់ $x$ ទាបចំពោះម៉ូម៉ង់ទាំងនេះត្រូវបានប៉ាន់ស្មាន ហើយបន្ទាប់មកពិភាក្សាក្នុងបរិបទនៃច្បាប់បូកស្ពែន។ ទីបំផុត ការព្យាករណ៍ខ្លះអំពីតម្លៃដែលអាចសង្កេតបាន អាស៊ីម៉េទ្រី និងកាត់កាត់ត្រូវបានផ្តល់ឱ្យក្នុងដំណើរការ (i)-(iii)។ ពួកវាសំខាន់ចំពោះការពិសោធន៍ដែលមានគម្រោងជាមួយម៉ាស៊ីនបំបែកគោលកម្មវិធី HERA និងម៉ាស៊ីនបុកបំបែកបន្ទាត់ ដែលនឹងស្វែងរកតំបន់ដែលមានតម្លៃទាបនៃ Bjorken $x$។
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Massive rotating single stars with an initial metal composition appropriate for the dwarf galaxy I Zw 18 ([Fe/H]=$-$1.7) are modelled during hydrogen burning for initial masses of 9-300 M$_{\odot}$ and rotational velocities of 0-900 km s$^{-1}$. Internal mixing processes in these models were calibrated based on an observed sample of OB-type stars in the Magellanic Clouds. Even moderately fast rotators, which may be abundant at this metallicity, are found to undergo efficient mixing induced by rotation resulting in quasi chemically-homogeneous evolution. These homogeneously-evolving models reach effective temperatures of up to 90 kK during core hydrogen burning. This, together with their moderate mass-loss rates, make them Transparent Wind Ultraviolet INtense stars (TWUIN star), and their expected numbers might explain the observed HeII ionizing photon flux in I Zw 18 and other low-metallicity HeII galaxies. Our slowly rotating stars above $\sim$80 M$_{\odot}$ evolve into late B- to M-type supergiants during core hydrogen burning, with visual magnitudes up to 19$^{\mathrm{m}}$ at the distance of I Zw 18. Both types of stars, TWUIN stars and luminous late-type supergiants, are only predicted at low metallicity. Massive star evolution at low metallicity is shown to differ qualitatively from that in metal-rich environments. Our grid can be used to interpret observations of local star-forming dwarf galaxies and high-redshift galaxies, as well as the metal-poor components of our Milky Way and its globular clusters.
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Stelle singole massicce in rotazione con una composizione iniziale di metalli appropriata per la galassia nana I Zw 18 ([Fe/H]=$-$1,7) sono state modellizzate durante la fase di combustione dell'idrogeno per masse iniziali comprese tra 9 e 300 M$_{\odot}$ e velocità di rotazione comprese tra 0 e 900 km s$^{-1}$. I processi di mescolamento interno in questi modelli sono stati calibrati sulla base di un campione osservato di stelle di tipo OB nelle Nubi di Magellano. Si è riscontrato che anche rotatori moderatamente veloci, che potrebbero essere abbondanti a questa metallicità, subiscono un efficiente mescolamento indotto dalla rotazione, risultando in un'evoluzione quasi chimicamente omogenea. Questi modelli con evoluzione omogenea raggiungono temperature efficaci fino a 90 kK durante la combustione dell'idrogeno nel nucleo. Ciò, unito ai loro tassi moderati di perdita di massa, li rende stelle Transparent Wind Ultraviolet INtense (stelle TWUIN), e il loro numero previsto potrebbe spiegare il flusso osservato di fotoni ionizzanti HeII in I Zw 18 e in altre galassie HeII a bassa metallicità. Le nostre stelle lentamente rotanti con masse superiori a $\sim$80 M$_{\odot}$ evolvono in supergiganti di tipo B tardo fino a tipo M durante la combustione dell'idrogeno nel nucleo, con magnitudini visibili fino a 19$^{\mathrm{m}}$ alla distanza di I Zw 18. Entrambi i tipi di stelle, le stelle TWUIN e le supergiganti luminose di tipo spettrale tardo, sono previsti soltanto a bassa metallicità. Si dimostra che l'evoluzione delle stelle massicce a bassa metallicità differisce qualitativamente da quella in ambienti ricchi di metalli. La nostra griglia può essere utilizzata per interpretare osservazioni di galassie nane con formazione stellare locale e galassie ad alto redshift, nonché le componenti povere di metalli della nostra Via Lattea e dei suoi ammassi globulari.
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We study the dynamical evolution of spiral structure in the stellar disks of isolated galaxies using high resolution Smoothed Particle Hydrodynamics (SPH) simulations that treat the evolution of gas, stars, and dark matter self-consistently. We focus this study on the question of self-excited spiral structure in the stellar disk and investigate the dynamical coupling between the cold, dissipative gaseous component and the stellar component. We find that angular momentum transport from the gas to the stars inside of corotation leads to a roughly time-steady spiral structure in the stellar disk. To make this point clear, we contrast these results with otherwise identical simulations that do not include a cold gaseous component that is able to cool radiatively and dissipate energy, and find that spiral structure, when it is incipient, dies out more rapidly in simulations that do not include gas. We also employ a standard star formation prescription to convert gas into stars and find that our results hold for typical gas consumption time scales that are in accord with the Kennicutt-Schmidt relation. We therefore attribute the long-lived roughly time steady spiral structure in the stellar disk to the dynamical coupling between the gas and the stars and the resultant torques that the self-gravitating gaseous disk is able to exert on the stars due to an azimuthal phase shift between the collisionless and dissipative components.
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យើងសិក្សាអំពីវិវត្តន៍ដែលមានចលនារបស់រចនាសម្ព័ន្ធសព្វរន្ធ (spiral structure) នៅក្នុងថាសផ្កាយរបស់ហ្គាឡាក់ស៊ីដាច់ដោយឡែក ដោយប្រើការធ្វើម៉ូដែលដែលមានកម្រិតលម្អិតខ្ពស់ដោយប្រើវិធីសាស្ត្រ Smoothed Particle Hydrodynamics (SPH) ដែលពិចារណាពីវិវត្តន៍របស់ឧស្ម័ន ផ្កាយ និងសារធាតុងងឹតដោយស៊ីសង្វាក់គ្នា។ យើងផ្តោតការសិក្សានេះលើសំណួរអំពីរចនាសម្ព័ន្ធសព្វរន្ធដែលបង្កើតឡើងដោយខ្លួនវាផ្ទាល់នៅក្នុងថាសផ្កាយ ហើយសិក្សាអំពីការភ្ជាប់គ្នាដោយចលនារវាងគ្រាប់ផ្កាយដែលមានសីតុណ្ហភាពទាប និងមានលក្ខណៈរាវនៃឧស្ម័ន និងគ្រាប់ផ្កាយ។ យើងរកឃើញថាការផ្ទេរចលនាថាមពលពីឧស្ម័នទៅផ្កាយនៅខាងក្នុងតំបន់ corotation បណ្តាលឱ្យមានរចនាសម្ព័ន្ធសព្វរន្ធដែលស្ថិតក្នុងស្ថានភាពស្ថិតស្ថេរប្រហែលថេរតាមពេលវេលានៅក្នុងថាសផ្កាយ។ ដើម្បីបញ្ជាក់ចំណុចនេះឱ្យកាន់តែច្បាស់ យើងធ្វើការប្រៀបធៀបលទ្ធផលទាំងនេះជាមួយការធ្វើម៉ូដែលដែលស្រដៀងគ្នាប៉ុន្តែដោយគ្មានគ្រាប់ឧស្ម័នដែលអាចត្រជាក់តាមរយៈការរេដៀក់ និងរាវថាមពលបាន ហើយរកឃើញថារចនាសម្ព័ន្ធសព្វរន្ធ នៅពេលដែលវាចាប់ផ្តើម វារលាយបាត់យ៉ាងរហ័សក្នុងការធ្វើម៉ូដែលដែលគ្មានឧស្ម័ន។ យើងក៏ប្រើវិធីសាស្ត្រស្តង់ដារក្នុងការបង្កើតផ្កាយដើម្បីបំលែងឧស្ម័នទៅជាផ្កាយ ហើយរកឃើញថាលទ្ធផលរបស់យើងនៅតែជាក់ស្តែងសម្រាប់រយៈពេលប្រើប្រាស់ឧស្ម័នធម្មតា ដែលស័ក្តិសមនឹងទំនាក់ទំនងKennicutt-Schmidt។ ដូច្នេះ យើងសន្មត់ថារចនាសម្ព័ន្ធសព្វរន្ធដែលរស់រានមានអាយុវែង និងស្ថិតក្នុងស្ថានភាពស្ថិតស្ថេរប្រហែលថេរតាមពេលវេលានៅក្នុងថាសផ្កាយ គឺដោយសារការភ្ជាប់គ្នាដោយចលនារវាងឧស្ម័ន និងផ្កាយ និងដោយសារកម្លាំងបង្វិលដែលថាសឧស្ម័នដែលមានទំនាញខ្លួនឯងអាចបង្កើតបានលើផ្កាយ ដោយសារការផ្លាស់ទីមុំជា azimuthal រវាងគ្រាប់ដែលគ្មានការប៉ះទង្គិច និងគ្រាប់ដែលមានលក្ខណៈរាវ។
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The space of invariant affine connections on every $3$-Sasakian homogeneous manifold of dimension at least $7$ is described. In particular, the remarkable subspaces of invariant affine metric connections, and the subclass with skew-torsion, are also determined. To this aim, an explicit construction of all $3$-Sasakian homogeneous manifolds is exhibited. The unique $3$-Sasakian homogeneous manifolds which admit nontrivial Einstein with skew-torsion invariant affine connections are those of dimension $7$, that is, $\mathbb{S}^7=\mathrm{Sp} (2)/ \mathrm{Sp(1)}$, $\mathbb{R} P^7=\mathrm{Sp}(2)/ \mathrm{Sp(1)}\times \mathbb{Z}_{2}$ and the Aloff-Wallach space $\mathfrak{W}^{7}_{1,1}= \mathrm{SU}(3)/ \mathrm{U}(1)$. For $\mathbb{S}^7$ and $\mathbb{R} P^7$, the set of such connections is in one to one correspondence with two copies of the conformal linear transformation group of the Euclidean space, while it is strictly bigger for $\mathfrak{W}^{7}_{1,1}$. In addition, the set of invariant connections with totally skew-symmetric torsion whose Ricci tensor is multiple of the metric, with different factors, on the canonical vertical and horizontal distributions, is fully described on every $3$-Sasakian homogeneous manifold. An affine connection satisfying these conditions is distinguished, characterized by parallelizing all the characteristic vector fields associated to the $3$-Sasakian structure. This connection is Einstein with skew-torsion for the $7$-dimensional examples. Several results have also been adapted to the nonnecessarily homogeneous setting. In this case, the above mentioned sets of affine connections are, in general, only proper subsets satisfying the properties.
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O espaço das conexões afins invariantes em toda variedade homogênea 3-Sasakiana de dimensão pelo menos 7 é descrito. Em particular, determinam-se também os subespaços notáveis das conexões afins métricas invariantes, bem como a subclasse com torção antissimétrica. Para tanto, apresenta-se uma construção explícita de todas as variedades homogêneas 3-Sasakianas. As únicas variedades homogêneas 3-Sasakianas que admitem conexões afins invariantes não triviais do tipo Einstein com torção antissimétrica são aquelas de dimensão 7, isto é, $\mathbb{S}^7=\mathrm{Sp}(2)/\mathrm{Sp(1)}$, $\mathbb{R} P^7=\mathrm{Sp}(2)/\mathrm{Sp(1)}\times \mathbb{Z}_{2}$ e o espaço de Aloff-Wallach $\mathfrak{W}^{7}_{1,1}= \mathrm{SU}(3)/ \mathrm{U}(1)$. Para $\mathbb{S}^7$ e $\mathbb{R} P^7$, o conjunto dessas conexões está em correspondência biunívoca com duas cópias do grupo de transformações lineares conformes do espaço euclidiano, enquanto que para $\mathfrak{W}^{7}_{1,1}$ é estritamente maior. Além disso, descreve-se completamente o conjunto das conexões invariantes com torção totalmente antissimétrica cujo tensor de Ricci é múltiplo da métrica, com fatores distintos, nas distribuições vertical e horizontal canônicas, em toda variedade homogênea 3-Sasakiana. Uma conexão afim que satisfaz essas condições destaca-se, caracterizada por paralelizar todos os campos vetoriais característicos associados à estrutura 3-Sasakiana. Essa conexão é do tipo Einstein com torção antissimétrica nos exemplos de dimensão 7. Diversos resultados também foram adaptados ao contexto não necessariamente homogêneo. Nesse caso, os conjuntos acima mencionados de conexões afins são, em geral, apenas subconjuntos próprios que satisfazem as propriedades.
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We study classical and quantum hidden symmetries of a particle with electric charge $e$ in the background of a Dirac monopole of magnetic charge $g$ subjected to an additional central potential $V(r)=U(r) +(eg)^2/2mr^{2}$ with $U(r)=\tfrac{1}{2}m\omega^2r^2$, similar to that in the one-dimensional conformal mechanics model of de Alfaro, Fubini and Furlan (AFF). By means of a non-unitary conformal bridge transformation, we establish a relation of the quantum states and of all symmetries of the system with those of the system without harmonic trap, $U(r)=0$. Introducing spin degrees of freedom via a very special spin-orbit coupling, we construct the $\mathfrak{osp}(2,2)$ superconformal extension of the system with unbroken $\mathcal{N}=2$ Poincar\'e supersymmetry and show that two different superconformal extensions of the one-dimensional AFF model with unbroken and spontaneously broken supersymmetry have a common origin. We also show a universal relationship between the dynamics of a Euclidean particle in an arbitrary central potential $U(r)$ and the dynamics of a charged particle in a monopole background subjected to the potential $V(r)$.
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Sinusuri namin ang mga klasikal at kwantum na nakatagong simetria ng isang partikulo na may elektrikong singa $e$ sa likod ng isang Dirac monopole na may magnetikong singa na $g$ na napapailalim sa karagdagang sentral na potensyal na $V(r)=U(r) +(eg)^2/2mr^{2}$ kung saan $U(r)=\tfrac{1}{2}m\omega^2r^2$, na katulad ng potensyal sa isang-dimensyonal na modelo ng pangsinga na mekaniks ni de Alfaro, Fubini at Furlan (AFF). Sa pamamagitan ng isang hindi unitary na pangsinga na pagbabagong-boses, itinatag namin ang ugnayan ng mga kwantum na estado at ng lahat ng simetria ng sistema sa sistema naman na walang harmonic trap, $U(r)=0$. Sa pamamagitan ng pagpapakilala ng mga antas ng pag-ikot (spin degrees of freedom) gamit ang isang napakalalong espesyal na spin-orbit coupling, binuo namin ang $\mathfrak{osp}(2,2)$ superpangsinga na pagpapalawig ng sistema na may buong $\mathcal{N}=2$ Poincar\'e supersymmetry at ipinakita na ang dalawang magkaibang superpangsinga na pagpapalawig ng isang-dimensyonal na modelo ni AFF na may buong at boluntaryong nabasag na supersymmetry ay may iisang pinagmulan. Ipakikita rin namin ang isang pangkalahatang ugnayan sa pagitan ng dinamika ng isang Euclidean na partikulo sa isang arbitraryong sentral na potensyal na $U(r)$ at ang dinamika ng isang singadong partikulo sa isang monopole na likuran na napapailalim sa potensyal na $V(r)$.
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tl
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We investigate dust entrainment by photoevaporative winds in protoplanetary discs using dusty smoothed particle hydrodrodynamics (SPH). We use unequal-mass particles to resolve more than five orders of magnitude in disc/outflow density and a one-fluid formulation to efficiently simulate an equivalent magnitude range in drag stopping time. We find that only micron sized dust grains and smaller can be entrained in EUV driven winds. The maximum grain size is set by dust settling in the disc rather than aerodynamic drag in the wind. More generally, there is a linear relationship between the base flow density and the maximum entrainable grain size in the wind. A pileup of micron sized dust grains can occur in the upper atmosphere at critical radii in the disc as grains decouple from the low-density wind. Entrainment is a strong function of location in the disc, resulting in a size sorting of grains in the outflow---the largest grain being carried out between $10$--$20\,$AU. The peak dust density for each grain size occurs at the inner edge of its own entrainment region.
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Nous étudions l'entraînement de poussière par des vents photoévaporatifs dans les disques protoplanétaires à l'aide de la méthode hydrodynamique particulaires lissée (SPH) avec poussière. Nous utilisons des particules de masses inégales afin de résoudre plus de cinq ordres de grandeur en densité entre le disque et l'éjection, ainsi qu'une formulation monofluide pour simuler efficacement une plage équivalente en temps de freinage dû au drag. Nous constatons que seuls les grains de poussière d'une taille inférieure ou égale au micron peuvent être entraînés par des vents induits par le rayonnement EUV. La taille maximale des grains est déterminée par leur tassement dans le disque plutôt que par la traînée aérodynamique dans le vent. Plus généralement, une relation linéaire existe entre la densité du flux de base et la taille maximale des grains pouvant être entraînés dans le vent. Un accumulement de grains de poussière de taille micronique peut se produire dans la haute atmosphère, aux rayons critiques du disque, lorsque les grains se découplent du vent de faible densité. L'entraînement dépend fortement de la position dans le disque, entraînant un tri par taille des grains dans l'éjection : les plus gros grains étant expulsés entre $10$ et $20\,$UA. La densité maximale de poussière pour chaque taille de grain se situe au bord interne de sa propre zone d'entraînement.
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fr
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We investigate dust entrainment by photoevaporative winds in protoplanetary discs using dusty smoothed particle hydrodrodynamics (SPH). We use unequal-mass particles to resolve more than five orders of magnitude in disc/outflow density and a one-fluid formulation to efficiently simulate an equivalent magnitude range in drag stopping time. We find that only micron sized dust grains and smaller can be entrained in EUV driven winds. The maximum grain size is set by dust settling in the disc rather than aerodynamic drag in the wind. More generally, there is a linear relationship between the base flow density and the maximum entrainable grain size in the wind. A pileup of micron sized dust grains can occur in the upper atmosphere at critical radii in the disc as grains decouple from the low-density wind. Entrainment is a strong function of location in the disc, resulting in a size sorting of grains in the outflow---the largest grain being carried out between $10$--$20\,$AU. The peak dust density for each grain size occurs at the inner edge of its own entrainment region.
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Studiamo il trascinamento della polvere da parte di venti fotoevaporativi nei dischi protoplanetari utilizzando la dinamica dei fluidi a particelle lisce (SPH) polverosa. Utilizziamo particelle di massa disuguale per risolvere più di cinque ordini di grandezza nella densità del disco/efflusso e una formulazione monofluido per simulare in modo efficiente un intervallo equivalente nel tempo di arresto dovuto alla resistenza aerodinamica. Scopriamo che soltanto le particelle di polvere di dimensioni micrometriche o inferiori possono essere trascinate dai venti generati da radiazione EUV. La dimensione massima delle particelle è determinata dal sedimentarsi della polvere nel disco piuttosto che dalla resistenza aerodinamica nel vento. Più in generale, esiste una relazione lineare tra la densità del flusso alla base e la dimensione massima delle particelle trascinabili nel vento. Può verificarsi un accumulo di particelle di dimensioni micrometriche nell'atmosfera superiore alle distanze radiali critiche nel disco, quando le particelle si disaccoppiano dal vento a bassa densità. Il trascinamento dipende fortemente dalla posizione nel disco, determinando una separazione per dimensione delle particelle nell'efflusso: le particelle più grandi vengono espulse tra $10$ e $20\,$UA. La densità massima di polvere per ciascuna dimensione delle particelle si verifica al bordo interno della propria regione di trascinamento.
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it
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To constrain a contribution of deep carbonated mantle, to fractionation of Hf relative to rare earth elements (REE) in volcanic series, we examine available high-quality data on major, trace element and Nd-Hf isotope compositions of primitive lavas and glasses erupted during preshield, postshield and mostly rejuvenated stage of the Hawaiian hot spot (Pacific Ocean). Strong variations of Hf/Sm, Zr/Sm, Ti/Eu, K/Th, Nb/Th, La/K and Ba/K in the lavas are not features of the melt equilibration with residual amphibole or phlogopite, and cannot be due to variable degrees of batch or dynamic melting of uncarbonated lherzolite source. Enrichment in REE, Th and Ba relative to K, Hf, Zr, Ti and Nb together and low Si, high Na, K and Ca contents in the Hawaiian lavas are compositional features of carbonated mantle lithospheric to asthenospheric peridotite source affected by carbonatite metasomatism. In contrast, major and trace element signatures of most primitive preshield- and postshield-stage magmas require pyroxenite source. The available data infer that Salt Lake Crater garnet pyroxenite xenoliths hosted by the Koolau volcano lavas on Oahu, Hawaii, were derived from deep eclogite source likely generating the carbonatite melts within the Hawaiian plume. Highly radiogenic Hf and decoupled Nd-Hf isotope systematics recorded in the Salt Lake Crater mantle xenolith series on Oahu may be explained by strong Hf fractionation relative to REE owing to ancient event of carbonatite metasomatism, which is likely related to partial melting of the deeply subducted carbonated eclogite within the Hawaiian plume.
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ដើម្បីកំណត់ការចូលរួមរបស់ផ្នែកដីថ្មដែលមានកាបូនាតជ្រៅ និងការបំបែកអ៊ីសូតូប Hf ធៀបនឹងធាតុដីកម្រ (REE) ក្នុងស៊េរីភ្នំភ្លើង យើងបានសិក្សាទិន្នន័យដែលមានគុណភាពខ្ពស់អំពីធាតុធំៗ ធាតុតូចៗ និងសមាសភាពអ៊ីសូតូប Nd-Hf របស់ថ្មរាវ និងកញ្ចក់ដែលបានផ្ទះពីដំណាក់កាលមុនពេលរុញឡើង ក្រោយពេលរុញឡើង និងជាច្រើនតែដំណាក់កាលបន្តបន្ទាប់នៃកន្លែងក្តៅហាវ៉ៃ (មហាសមុទ្រប៉ាស៊ីហ្វិក)។ ការប្រែប្រួលខ្លាំងនៃសមាមាត្រ Hf/Sm, Zr/Sm, Ti/Eu, K/Th, Nb/Th, La/K និង Ba/K ក្នុងថ្មរាវមិនមែនជាលក្ខណៈរបស់ដំណើររលាយសម្របសម្រួលជាមួយអំបិលអាមផ៊ីបូល ឬផ្លូហ្គូព៉ៃត និងក៏មិនអាចបណ្តាលមកពីកម្រិតរលាយមិនស្មើគ្នា ឬការរលាយដោយមានចលនារបស់ប្រភពថ្មលឺហ្សូលីតដែលគ្មានកាបូនាតនោះដែរ។ ការបំពេញបន្ថែមនៃធាតុដីកម្រ (REE), Th និង Ba ធៀបនឹង K, Hf, Zr, Ti និង Nb រួមគ្នា និងការមានសារធាតុ Si ទាប និង Na, K និង Ca ខ្ពស់ក្នុងថ្មរាវហាវ៉ៃ គឺជាលក្ខណៈសម្បត្តិគីមីរបស់ប្រភពថ្មប៉េរ៉ូដូតីតដែលមានកាបូនាត ពីថ្នាំងផ្នែកដីទៅអាសថេណូស្វែរ ដែលបានទទួលរងឥទ្ធិពលពីការប្រែប្រួលដោយកាបូនាត។ ផ្ទុយពីនេះ សញ្ញាគីមីធាតុធំៗ និងធាតុតូចៗរបស់ម៉ាញ៉ាដំបូងបំផុតក្នុងដំណាក់កាលមុនរុញឡើង និងក្រោយរុញឡើង ទាមទារឲ្យមានប្រភពថ្មពីរុយសែនីត។ ទិន្នន័យដែលមានស្រាប់បង្ហាញថា គំរូថ្មចេញពីប្រភពហ្គាន់នែត-ពីរុយសែនីតនៃអាងភ្នំភ្លើងស៊ើលលែកខ្សាច់ ដែលស្ថិតនៅក្នុងថ្មរាវភ្នំគូឡៅ នៅអ៊ូអាហ្វូ ហាវ៉ៃ បានមកពីប្រភពអ៊ិកឡូហ្ស៊ីតជ្រៅ ដែលប្រហែលជាបង្កើតជារាវកាបូនាតនៅក្នុងដំបូកហាវ៉ៃ។ សញ្ញាអ៊ីសូតូប Hf ដែលមានការវិវត្តខ្លាំង និងប្រព័ន្ធអ៊ីសូតូប Nd-Hf ដែលមិនភ្ជាប់គ្នា ដែលត្រូវបានកត់ត្រាក្នុងស៊េរីគំរូថ្មផ្នែកដីនៃអាងភ្នំភ្លើងស៊ើលលែកខ្សាច់ នៅអ៊ូអាហ្វូ អាចពន្យល់បានដោយការបំបែកអ៊ីសូតូប Hf ខ្លាំងធៀបនឹងធាតុដីកម្រ ដោយសារព្រឹត្តិការណ៍បុរាណនៃការប្រែប្រួលដោយកាបូនាត ដែលប្រហែលជាទាក់ទងនឹងការរលាយផ្នែកដោយថ្មអ៊ិកឡូហ្ស៊ីតដែលមានកាបូនាតជ្រៅនៅក្នុងដំបូកហាវ៉ៃ។
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km
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Choosing a decision threshold is one of the challenging job in any classification tasks. How much the model is accurate, if the deciding boundary is not picked up carefully, its entire performance would go in vain. On the other hand, for imbalance classification where one of the classes is dominant over another, relying on the conventional method of choosing threshold would result in poor performance. Even if the threshold or decision boundary is properly chosen based on machine learning strategies like SVM and decision tree, it will fail at some point for dynamically varying databases and in case of identity-features that are more or less similar, like in face recognition and person re-identification models. Hence, with the need for adaptability of the decision threshold selection for imbalanced classification and incremental database size, an online optimization-based statistical feature learning adaptive technique is developed and tested on the LFW datasets and self-prepared athletes datasets. This method of adopting adaptive threshold resulted in 12-45% improvement in the model accuracy compared to the fixed threshold {0.3,0.5,0.7} that are usually taken via the hit-and-trial method in any classification and identification tasks. Source code for the complete algorithm is available at: https://github.com/Varat7v2/adaptive-threshold
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Việc lựa chọn ngưỡng quyết định là một trong những công việc thách thức trong mọi tác vụ phân loại. Dù mô hình có độ chính xác cao đến đâu, nếu ranh giới quyết định không được chọn cẩn thận thì toàn bộ hiệu suất của nó sẽ trở nên vô ích. Mặt khác, đối với bài toán phân loại mất cân bằng, trong đó một lớp chiếm ưu thế hơn lớp còn lại, việc dựa vào phương pháp truyền thống để chọn ngưỡng sẽ dẫn đến hiệu suất kém. Ngay cả khi ngưỡng hay ranh giới quyết định được chọn đúng cách dựa trên các chiến lược học máy như SVM và cây quyết định, phương pháp này vẫn thất bại ở một số điểm đối với các cơ sở dữ liệu thay đổi động và trong trường hợp các đặc trưng nhận dạng giống nhau nhiều hay ít, như trong các mô hình nhận dạng khuôn mặt và nhận dạng lại người. Do đó, nhằm đáp ứng nhu cầu về khả năng thích ứng trong việc lựa chọn ngưỡng quyết định đối với phân loại mất cân bằng và kích thước cơ sở dữ liệu tăng dần, một kỹ thuật học đặc trưng thống kê thích ứng dựa trên tối ưu hóa trực tuyến đã được phát triển và kiểm nghiệm trên các bộ dữ liệu LFW và các bộ dữ liệu vận động viên do chúng tôi tự chuẩn bị. Phương pháp áp dụng ngưỡng thích ứng này đã mang lại sự cải thiện từ 12-45% về độ chính xác của mô hình so với ngưỡng cố định {0,3; 0,5; 0,7} thường được chọn theo phương pháp thử và sai trong mọi tác vụ phân loại và nhận dạng. Mã nguồn cho toàn bộ thuật toán có sẵn tại: https://github.com/Varat7v2/adaptive-threshold
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vi
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In this paper a Gaussian impurity moving through an equilibrium Bose-Einstein condensate at T = 0 is studied. The problem can be described by a Gross-Pitaevskii equation, which is solved perturbatively. The analysis is done for systems of 2 and 3 spatial dimensions and generalises the work by [G.E. Astrakharchik and L.P. Pitaevskii, Phys. Rev. A 70, 013608 (2004)]. The Bogoliubov equation solutions for the condensate perturbed by a finite impurity are calculated in the co-moving frame, which are formally equivalent up to a dimension dependent form factor for general dimensions. From those solutions the total energy of the perturbed system is determined as a function of the width and the amplitude of the moving Gaussian impurity and its velocity. Finally we derive the drag force the Gaussian impurity approximately experiences as it moves through the superfluid, which proofs the existence of a superfluid phase for finite extensions of the impurities below the speed of sound and that the force increases monotonically with velocity until it decreases again.
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এই গবেষণাপত্রে T = 0 তাপমাত্রায় একটি সাম্যাবস্থার বোস-আইনস্টাইন ঘনীভবনের মধ্য দিয়ে চলমান একটি গাউসীয় অশুদ্ধি নিয়ে আলোচনা করা হয়েছে। এই সমস্যাটিকে একটি গ্রস-পিতাভস্কি সমীকরণ দ্বারা বর্ণনা করা যায়, যা বাধাদান পদ্ধতিতে সমাধান করা হয়। এই বিশ্লেষণটি 2 এবং 3 মাত্রার ব্যবস্থার জন্য করা হয়েছে এবং [G.E. আস্ত্রাখারচিক এবং L.P. পিতাভস্কি, ফিজ. রেভ. A 70, 013608 (2004)]-এর কাজকে সাধারণীকরণ করে। সসীম অশুদ্ধি দ্বারা বিকৃত ঘনীভবনের জন্য বোগোলিউবোভ সমীকরণের সমাধানগুলি চলমান ফ্রেমে গণনা করা হয়, যা আনুপাতিকভাবে সাধারণ মাত্রার জন্য মাত্রার উপর নির্ভরশীল একটি ফর্ম ফ্যাক্টর পর্যন্ত সমতুল্য। এই সমাধানগুলি থেকে বিকৃত ব্যবস্থার মোট শক্তিকে গতিশীল গাউসীয় অশুদ্ধির প্রস্থ, বিস্তার এবং তার বেগের ফাংশন হিসাবে নির্ধারণ করা হয়। অবশেষে, গাউসীয় অশুদ্ধির উপর ঘর্ষণ বলের আসন্ন মান নির্ণয় করা হয় যা অতিপ্রবাহীর মধ্য দিয়ে চলার সময় অশুদ্ধির উপর ক্রিয়া করে, যা শব্দের গতির নিচে অশুদ্ধির সসীম বিস্তারের জন্য অতিপ্রবাহী অবস্থার অস্তিত্বকে প্রমাণ করে এবং এটিও প্রমাণ করে যে বলটি বেগের সাথে একঘেয়েভাবে বৃদ্ধি পায় এবং পরে আবার হ্রাস পায়।
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bn
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Computational procedures to foresee the 3D structure of aptamers are in continuous progress. They constitute a crucial input to research, mainly when the crystallographic counterpart of the structures in silico produced is not present. At now, many codes are able to perform structure and binding prediction, although their ability in scoring the results remains rather weak. In this paper, we propose a novel procedure to complement the ranking outcomes of free docking code, by applying it to a set of anti-angiopoietin aptamers, whose performances are known. We rank the in silico produced configurations, adopting a maximum likelihood estimate, based on their topological and electrical properties. From the analysis, two principal kinds of conformers are identified, whose ability to mimick the binding features of the natural receptor is discussed. The procedure is easily generalizable to many biological biomolecules, useful for increasing chances of success in designing high-specificity biosensors (aptasensors).
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Les procédures informatiques permettant de prédire la structure 3D des aptamères progressent continuellement. Elles constituent un apport essentiel à la recherche, principalement lorsque la contrepartie cristallographique des structures produites in silico n'est pas disponible. À l'heure actuelle, de nombreux logiciels sont capables d'effectuer des prédictions de structure et de liaison, bien que leur capacité à évaluer la qualité des résultats reste plutôt limitée. Dans cet article, nous proposons une nouvelle procédure visant à compléter les résultats de classement d'un logiciel de docking libre, en l'appliquant à un ensemble d'aptamères anti-angiopoïétine dont les performances sont connues. Nous classons les configurations produites in silico en adoptant une estimation par maximum de vraisemblance, fondée sur leurs propriétés topologiques et électriques. L'analyse permet d'identifier deux types principaux de conformères, et la capacité de ceux-ci à imiter les caractéristiques de liaison du récepteur naturel est discutée. La procédure est facilement généralisable à de nombreuses biomolécules biologiques, et utile pour augmenter les chances de succès dans la conception de biocapteurs à haute spécificité (aptasenseurs).
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fr
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The prompt optical emission of GRB 990123 was uncorrelated to the gamma-ray light-curve and exhibited temporal properties similar to those of the steeply-decaying, early X-ray emission observed by Swift at the end of many bursts. These facts suggest that the optical counterpart of GRB 990123 was the large-angle emission released during (the second pulse of) the burst. If the optical and gamma-ray emissions of GRB 990123 have, indeed, the same origin then their properties require that (i) the optical counterpart was synchrotron emission and the gamma-rays arose from inverse-Compton scatterings ("synchrotron self-Compton model"), (ii) the peak-energy of the optical-synchrotron component was at ~20 eV, and (iii) the burst emission was produced by a relativistic outflow moving at Lorentz factor > 450 and at a radius > 10^{15} cm, which is comparable to the outflow deceleration radius. Because the spectrum of GRB 990123 was optically thin above 2 keV, the magnetic field behind the shock must have decayed on a length-scale of <1% of the thickness of the shocked gas, which corresponds to 10^6-10^7 plasma skin-depths. Consistency of the optical counterpart decay rate and its spectral slope (or that of the burst, if they represent different spectral components) with the expectations for the large-angle burst emission represents the most direct test of the unifying picture proposed here for GRB 990123.
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L'emissione ottica precoce del GRB 990123 non era correlata alla curva di luce in raggi gamma ed esibiva proprietà temporali simili a quelle dell'emissione X iniziale in rapido decadimento osservata da Swift alla fine di molti burst. Questi fatti suggeriscono che la controparte ottica del GRB 990123 fosse l'emissione a grande angolo rilasciata durante (il secondo impulso del) burst. Se le emissioni ottica e gamma del GRB 990123 hanno effettivamente la stessa origine, allora le loro proprietà richiedono che (i) la controparte ottica fosse emissione sincrotrone e i raggi gamma derivassero da scattering Compton inverso ("modello Compton inverso auto-sincrotrone"), (ii) l'energia di picco della componente sincrotrone ottica fosse a ~20 eV, e (iii) l'emissione del burst fosse prodotta da un flusso relativistico in espansione con fattore di Lorentz maggiore di 450 e a un raggio maggiore di 10^{15} cm, valore paragonabile al raggio di decelerazione del flusso. Poiché lo spettro del GRB 990123 era otticamente sottile al di sopra di 2 keV, il campo magnetico a valle dell'urto deve essersi attenuato su una scala spaziale inferiore all'1% dello spessore del gas urtato, corrispondente a 10^6-10^7 lunghezze di pelle del plasma. La coerenza tra il tasso di decadimento della controparte ottica e la sua pendenza spettrale (o quella del burst, se esse rappresentano componenti spettrali diverse) con le previsioni relative all'emissione del burst a grande angolo rappresenta il test più diretto dell'immagine unificata qui proposta per il GRB 990123.
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it
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We use a representative sample of 65 galaxy clusters observed with the Einstein IPC to constrain the range of cluster X-ray morphologies. We develop and apply quantitative and reproducible measures to constrain the intrinsic distributions of emission weighted centroid variation, axial ratio, orientation, and the radial fall--off. We then use the range of cluster X--ray morphologies to constrain three generic cosmological models (Omega=1, Omega_0=0.2, and Omega_0=0.2 & lambda_0=0.8). For each of these models, we evolve eight sets of Gaussian random initial conditions consistent with an effective power spectrum $P(k)\propto k^{-1}$ on cluster scales. Using this sample of 24 numerical cluster simulations, we compare the X--ray morphologies of the observed and simulated clusters. The comparisons indicate that: (i) cluster centroid variations, axial ratios, and radial fall-offs are sensitive to the underlying cosmological model, and (ii) galaxy clusters with the observed range of X--ray morphologies are very unlikely in low Omega_0 cosmologies. The analysis favors the Omega=1 model, though some discrepancies remain. We discuss the effects of changing the initial conditions and including additional physics in the simulations.
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ہم آئن سٹائن آئی پی سی کے ساتھ مشاہدہ کیے گئے 65 کہکشانی کلچرز کے ایک نمائندہ نمونے کو کلچرز کی ایکس رے ہیئت کی حد کو محدود کرنے کے لیے استعمال کرتے ہیں۔ ہم اخراج وزنی سنٹرآئیڈ تبدیلی، محوری تناسب، سمت اور شعاعی کمی کے ذاتی تقسیم کو محدود کرنے کے لیے مقداری اور دہرائے جانے والے پیمانوں کو تیار کرتے ہیں اور ان کا اطلاق کرتے ہیں۔ پھر ہم کلچرز کی ایکس رے ہیئت کی حد کو تین عمومی کاسمولوجیکل ماڈلز (Omega=1، Omega_0=0.2، اور Omega_0=0.2 و lambda_0=0.8) کو محدود کرنے کے لیے استعمال کرتے ہیں۔ ان ماڈلز میں سے ہر ایک کے لیے، ہم کلچر اسکیلز پر موثر پاور اسپیکٹرم $P(k)\propto k^{-1}$ کے مطابق گاؤسی تصادفی ابتدائی حالات کے آٹھ سیٹس کو ترقی دیتے ہیں۔ اس 24 عددی کلچر مآخذ کے نمونے کا استعمال کرتے ہوئے، ہم مشاہدہ شدہ اور ماخوذ کلچرز کی ایکس رے ہیئت کا موازنہ کرتے ہیں۔ یہ موازنہ یہ اشارہ کرتا ہے کہ: (i) کلچر کے سنٹرآئیڈ تغیرات، محوری تناسب، اور شعاعی کمی بنیادی کاسمولوجیکل ماڈل پر منحصر ہوتے ہیں، اور (ii) کم Omega_0 کاسمولوجیز میں مشاہدہ کردہ ایکس رے ہیئت کی حد کے ساتھ کہکشانی کلچرز بہت غیر ممکن ہیں۔ تجزیہ Omega=1 ماڈل کی حمایت کرتا ہے، اگرچہ کچھ اختلافات باقی ہیں۔ ہم مآخذ میں ابتدائی حالات میں تبدیلی اور اضافی طبیعیات کو شامل کرنے کے اثرات پر بحث کرتے ہیں۔
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ur
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To make microtask programming more efficient and reduce the potential for conflicts between contributors, I developed a new behavior-driven approach to microtasking programming. In our approach, each microtask asks developers to identify a behavior behavior from a high-level description of a function, implement a unit test for it, implement the behavior, and debug it. It enables developers to work on functions in isolation through high-level function descriptions and stubs. In addition, I developed the first approach for building microservices through microtasks. Building microservices through microtasks is a good match because our approach requires a client to first specify the functionality the crowd will create through an API. This API can then take the form of a microservice description. A traditional project may ask a crowd to implement a new microservice by simply describing the desired behavior in a API and recruiting a crowd. We implemented our approach in a web-based IDE, \textit{Crowd Microservices}. It includes an editor for clients to describe the system requirements through endpoint descriptions as well as a web-based programming environment where crowd workers can identify, test, implement, and debug behaviors. The system automatically creates, manages, assigns microtasks. After the crowd finishes, the system automatically deploys the microservice to a hosting site.
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မိုက်ခရိုတာ့စ်က်ပရိုဂရမ်မင်းကို ပိုမိုထိရောက်စေရန်နှင့် ပံ့ပိုးသူများကြား ပဋိပက္ခဖြစ်နိုင်ခြေကို လျှော့ချရန်အတွက် မိုက်ခရိုတာ့စ်က်ပရိုဂရမ်မင်း၏ အပြုအမူအပေါ်အခြေခံသော နည်းလမ်းအသစ်တစ်ခုကို ကျွန်ုပ်ဖွံ့ဖြိုးတီထွင်ခဲ့သည်။ ကျွန်ုပ်တို့၏ နည်းလမ်းတွင် မိုက်ခရိုတာ့စ်တစ်ခုစီသည် ဖန်တီးမှု၏ အဆင့်မြင့်ဖော်ပြချက်မှ အပြုအမူတစ်ခုကို ရှာဖွေရန်၊ ၎င်းအတွက် ယူနစ်တက်စ်တစ်ခုကို အကောင်အထည်ဖော်ရန်၊ အပြုအမူကို အကောင်အထည်ဖော်ရန်နှင့် ပြဿနာဖြေရှင်းရန် ပရိုဂရမ်ရေးသားသူများအား တောင်းဆိုသည်။ ထိုနည်းလမ်းသည် အဆင့်မြင့်ဖန်တီးမှုဖော်ပြချက်များနှင့် စတပ်များကို အသုံးပြု၍ ဖန်တီးမှုများကို သီးခြားလုပ်ဆောင်နိုင်စေသည်။ ထို့အပြင် မိုက်ခရိုတာ့စ်များဖြင့် မိုက်ခရိုဆာဗစ်များကို တည်ဆောက်ရန် ပထမဆုံးနည်းလမ်းကို ကျွန်ုပ်ဖွံ့ဖြိုးတီထွင်ခဲ့သည်။ မိုက်ခရိုတာ့စ်များဖြင့် မိုက်ခရိုဆာဗစ်များကို တည်ဆောက်ခြင်းသည် ကိုက်ညီမှုကောင်းပါသည်။ အကြောင်းမှာ ကျွန်ုပ်တို့၏ နည်းလမ်းသည် ဖောက်သည်များအား ဦးစွာ API တစ်ခုဖြင့် လူအများက ဖန်တီးပေးမည့် လုပ်ဆောင်ချက်ကို ဖော်ပြရန် လိုအပ်သောကြောင့်ဖြစ်သည်။ ထို API သည် နောက်ပိုင်းတွင် မိုက်ခရိုဆာဗစ်ဖော်ပြချက်၏ ပုံစံကို ရယူနိုင်သည်။ ရိုးရာပရောဂျက်တစ်ခုသည် လူအများအား API တွင် လိုချင်သော အပြုအမူကို ရိုးရိုးဖော်ပြပြီး လူအများကို စုစည်းခိုင်းခြင်းဖြင့် မိုက်ခရိုဆာဗစ်အသစ်တစ်ခုကို အကောင်အထည်ဖော်ရန် တောင်းဆိုနိုင်သည်။ ကျွန်ုပ်တို့သည် ကျွန်ုပ်တို့၏ နည်းလမ်းကို ဝဘ်အခြေပြု IDE၊ \textit{Crowd Microservices} တွင် အကောင်အထည်ဖော်ခဲ့သည်။ ၎င်းတွင် ဖန်တီးမှုလိုအပ်ချက်များကို အပ်စ်ပိုင်းဖော်ပြချက်များမှတစ်ဆင့် ဖော်ပြရန် ဖောက်သည်များအတွက် တည်းဖြတ်စက်တစ်ခုပါဝင်ပြီး လူအများသည် အပြုအမူများကို ရှာဖွေခြင်း၊ စမ်းသပ်ခြင်း၊ အကောင်အထည်ဖော်ခြင်းနှင့် ပြဿနာဖြေရှင်းခြင်းများကို ပြုလုပ်နိုင်သော ဝဘ်အခြေပြု ပရိုဂရမ်ရေးသားမှုပတ်ဝန်းကျင်လည်း ပါဝင်သည်။ စနစ်သည် မိုက်ခရိုတာ့စ်များကို အလိုအလျောက်ဖန်တီးပြီး စီမံခန့်ခွဲကာ ခွဲဝေပေးသည်။ လူအများ လုပ်ငန်းပြီးဆုံးပြီးနောက် စနစ်သည် မိုက်ခရိုဆာဗစ်ကို အလိုအလျောက် မိတ္တူတင်ပို့ပေးသည်။
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my
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Very-long baseline interferometric observations have resolved structure on scales of only a few Schwarzschild radii around the supermassive black holes at the centers of our Galaxy and M87. In the near future, such observations are expected to image the shadows of these black holes together with a bright and narrow ring surrounding their shadows. For a Kerr black hole, the shape of this photon ring is nearly circular unless the black hole spins very rapidly. Whether or not, however, astrophysical black holes are truly described by the Kerr metric as encapsulated in the no-hair theorem still remains an untested assumption. For black holes that differ from Kerr black holes, photon rings have been shown numerically to be asymmetric for small to intermediate spins. In this paper, I calculate semi-analytic expressions of the shapes of photon rings around black holes described by a new Kerr-like metric which is valid for all spins. I show that photon rings in this spacetime are affected by two types of deviations from the Kerr metric which can cause the ring shape to be highly asymmetric. I argue that the ring asymmetry is a direct measure of a potential violation of the no-hair theorem and that both types of deviations can be detected independently if the mass and distance of the black hole are known. In addition, I obtain approximate expressions of the diameters, displacements, and asymmetries of photon rings around Kerr and Kerr-like black holes.
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Çok uzun baz çizgili interferometrik gözlemler, Samanyolu Galaksimizin ve M87'nin merkezlerindeki süper kütleli kara deliklerin etrafında yalnızca birkaç Schwarzschild yarıçapı ölçeğinde yapıları çözümlemiştir. Yakın gelecekte, bu gözlemlerin kara deliklerin gölgelerini ve bu gölgelerin etrafını saran parlak ve dar bir halkayı birlikte görüntülemesi beklenmektedir. Kerr kara deliği için, bu foton halkasının şekli, kara delik çok hızlı dönmüyorsa neredeyse daireseldir. Bununla birlikte, astrofiziksel kara deliklerin, saç teoremiyle özetlenen Kerr metriğiyle gerçekten tanımlanıp tanımlanmadığı hâlâ denenmemiş bir varsayımdır. Kerr kara deliklerinden farklı olan kara delikler için, foton halkalarının küçükten orta düzey dönmelere kadar sayısal olarak asimetrik olduğu gösterilmiştir. Bu makalede, tüm dönmeler için geçerli yeni bir Kerr-benzeri metrikle tanımlanan kara delikler etrafındaki foton halkalarının şekilleri için yarı-analitik ifadeler hesapladım. Bu uzayzamanda foton halkalarının Kerr metriğinden iki tür sapmadan etkilendiğini ve bu sapmaların halka şeklini oldukça asimetrik yapabileceğini gösterdim. Halka asimetrisinin saç teoreminin olası bir ihlalinin doğrudan bir ölçüsü olduğunu ve eğer kara deliğin kütlesi ve uzaklığı biliniyorsa bu iki tür sapmanın bağımsız olarak tespit edilebileceğini savunuyorum. Ayrıca, Kerr ve Kerr-benzeri kara delikler etrafındaki foton halkalarının çapları, yer değiştirmeleri ve asimetriklikleri için yaklaşık ifadeler elde ettim.
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tr
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Determining the principal energy pathways for allosteric communication in biomolecules, that occur as a result of thermal motion, remains challenging due to the intrinsic complexity of the systems involved. Graph theory provides an approach for making sense of such complexity, where allosteric proteins can be represented as networks of amino acids. In this work, we establish the eigenvector centrality metric in terms of the mutual information, as a mean of elucidating the allosteric mechanism that regulates the enzymatic activity of proteins. Moreover, we propose a strategy to characterize the range of the physical interactions that underlie the allosteric process. In particular, the well known enzyme, imidazol glycerol phosphate synthase (IGPS), is utilized to test the proposed methodology. The eigenvector centrality measurement successfully describes the allosteric pathways of IGPS, and allows to pinpoint key amino acids in terms of their relevance in the momentum transfer process. The resulting insight can be utilized for refining the control of IGPS activity, widening the scope for its engineering. Furthermore, we propose a new centrality metric quantifying the relevance of the surroundings of each residue. In addition, the proposed technique is validated against experimental solution NMR measurements yielding fully consistent results. Overall, the methodologies proposed in the present work constitute a powerful and cost effective strategy to gain insight on the allosteric mechanism of proteins.
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Určení hlavních energetických drah alosterické komunikace v biomolekulách, ke kterým dochází v důsledku tepelného pohybu, zůstává náročné kvůli vnitřní složitosti zkoumaných systémů. Teorie grafů nabízí přístup k pochopení této složitosti, při němž lze alosterické proteiny reprezentovat jako sítě aminokyselin. V této práci stanovujeme metriku centrálnosti vlastního vektoru ve vztahu k vzájemné informaci jako prostředek objasnění alosterického mechanismu, který reguluje enzymatickou aktivitu proteinů. Navíc navrhujeme strategii pro charakterizaci rozsahu fyzikálních interakcí, které leží v základu alosterického procesu. Konkrétně je použit dobře známý enzym imidazolglycerol fosfát syntáza (IGPS) k ověření navrhované metodiky. Měření centrálnosti vlastního vektoru úspěšně popisuje alosterické dráhy IGPS a umožňuje identifikovat klíčové aminokyseliny z hlediska jejich významu pro proces přenosu hybnosti. Získané poznatky lze využít k přesnější regulaci aktivity IGPS a rozšířit tak možnosti jejího inženýrského využití. Dále navrhujeme novou metriku centrálnosti kvantifikující význam okolí každého zbytku. Kromě toho je navržená technika ověřena pomocí experimentálních měření NMR v roztoku, která vykazují plně konzistentní výsledky. Celkově metody navržené v této práci představují silnou a nákladově efektivní strategii pro pochopení alosterického mechanismu proteinů.
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cs
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Recent research in the field of computer vision strongly focuses on deep learning architectures to tackle image processing problems. Deep neural networks are often considered in complex image processing scenarios since traditional computer vision approaches are expensive to develop or reach their limits due to complex relations. However, a common criticism is the need for large annotated datasets to determine robust parameters. Annotating images by human experts is time-consuming, burdensome, and expensive. Thus, support is needed to simplify annotation, increase user efficiency, and annotation quality. In this paper, we propose a generic workflow to assist the annotation process and discuss methods on an abstract level. Thereby, we review the possibilities of focusing on promising samples, image pre-processing, pre-labeling, label inspection, or post-processing of annotations. In addition, we present an implementation of the proposal by means of a developed flexible and extendable software prototype nested in hybrid touchscreen/laptop device.
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ການຄົ້ນຄວ້າຫຼ້າສຸດໃນຂົງເຂດວິໄສທັດຂອງຄອມພິວເຕີ້ ໄດ້ໃຫ້ຄວາມສຳຄັນຢ່າງຍິ່ງຕໍ່ກັບໂຄງສ້າງການຮຽນຮູ້ເລິກເພື່ອແກ້ໄຂບັນຫາການດຳເນີນການພາບ. ການເຄືອຂ່າຍປານຍະຫຼາຍຊັ້ນມັກຈະຖືກພິຈາລະນາໃນສະຖານະການການດຳເນີນການພາບທີ່ສັບສົນ, ເນື່ອງຈາກວິທີການດັ້ງເດີມຂອງວິໄສທັດຄອມພິວເຕີ້ມີຄ່າໃຊ້ຈ່າຍສູງໃນການພັດທະນາ ຫຼື ເຂົ້າເຖິງຂອດຂອງມັນຍ້ອນຄວາມສຳພັນທີ່ສັບສົນ. ແຕ່ຢ່າງໃດກໍຕາມ, ການວິພາກວິຈານທີ່ພົບເຫັນບໍ່ຫຼາຍປານໃດກໍຄື ຄວາມຈຳເປັນຕ້ອງມີຊຸດຂໍ້ມູນທີ່ຖືກກຳກົດໝາຍໃນຂະນະທີ່ໃຫຍ່ເພື່ອກຳນົດພາລາມິເຕີ້ທີ່ມີຄວາມໝັ້ນຄົງ. ການກຳກົດໝາຍພາບໂດຍຜູ້ຊ່ຽວຊານມະນຸດນັ້ນໃຊ້ເວລາດົນ, ໜັກໜ່ວງ ແລະ ມີຄ່າໃຊ້ຈ່າຍສູງ. ສະນັ້ນ, ຈຶ່ງຕ້ອງການການຊ່ວຍເຫຼືອເພື່ອງ່າຍດາຍໃນການກຳກົດໝາຍ, ເພີ່ມປະສິດທິພາບຂອງຜູ້ໃຊ້ ແລະ ຄຸນນະພາບຂອງການກຳກົດໝາຍ. ໃນບົດຄວາມນີ້, ພວກເຮົາຂໍສະເໜີຂະບວນການທົ່ວໄປເພື່ອຊ່ວຍໃນຂະບວນການກຳກົດໝາຍ ແລະ ອະພິປາຍວິທີການໃນລະດັບດູດຊຶມ. ໂດຍຜ່ານນັ້ນ, ພວກເຮົາໄດ້ທົບທວນຄືນເຖິງຄວາມເປັນໄປໄດ້ໃນການມຸ່ງເນັ້ນໃສ່ຕົວຢ່າງທີ່ມີຄວາມຫວັງ, ການດຳເນີນການກ່ອນພາບ, ການກຳກົດໝາຍກ່ອນ, ການກວດກາເລື່ອງກຳກົດໝາຍ, ຫຼື ການດຳເນີນການຫຼັງຈາກກຳກົດໝາຍ. ນອກຈາກນັ້ນ, ພວກເຮົາຍັງນຳສະເໜີການຈັດຕັ້ງປະຕິບັດຂໍ້ສະເໜີດັ່ງກ່າວໂດຍຜ່ານໂປຣແທັກໄຊທີ່ຖືກພັດທະນາຂຶ້ນເຊິ່ງມີຄວາມຍືດຍຸ່ນ ແລະ ສາມາດຂະຫຍາຍໄດ້, ທີ່ຖືກຝັງຢູ່ໃນອຸປະກອນລະບົບສຳຜັດ/ລະບົບແລັບທັອບທີ່ປະສົມປະສານກັນ.
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lo
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Choosing a decision threshold is one of the challenging job in any classification tasks. How much the model is accurate, if the deciding boundary is not picked up carefully, its entire performance would go in vain. On the other hand, for imbalance classification where one of the classes is dominant over another, relying on the conventional method of choosing threshold would result in poor performance. Even if the threshold or decision boundary is properly chosen based on machine learning strategies like SVM and decision tree, it will fail at some point for dynamically varying databases and in case of identity-features that are more or less similar, like in face recognition and person re-identification models. Hence, with the need for adaptability of the decision threshold selection for imbalanced classification and incremental database size, an online optimization-based statistical feature learning adaptive technique is developed and tested on the LFW datasets and self-prepared athletes datasets. This method of adopting adaptive threshold resulted in 12-45% improvement in the model accuracy compared to the fixed threshold {0.3,0.5,0.7} that are usually taken via the hit-and-trial method in any classification and identification tasks. Source code for the complete algorithm is available at: https://github.com/Varat7v2/adaptive-threshold
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결정 임계값을 선택하는 것은 모든 분류 작업에서 어려운 과제 중 하나이다. 모델이 얼마나 정확하더라도 결정 경계를 신중하게 설정하지 않으면 전체 성능이 무의미해질 수 있다. 반면, 한 클래스가 다른 클래스보다 우세한 불균형 분류의 경우 기존의 임계값 선택 방법에 의존하면 성능이 저하된다. SVM이나 결정 트리와 같은 기계 학습 전략에 기반하여 임계값 또는 결정 경계를 적절히 선택하더라도, 데이터베이스가 동적으로 변화하거나 얼굴 인식 및 개인 재식별 모델과 같이 서로 유사한 정체성 특징을 다룰 때에는 어느 시점에서 실패하게 된다. 따라서 불균형 분류와 점진적으로 증가하는 데이터베이스 크기에 대응하기 위한 결정 임계값 선택의 적응성이 요구됨에 따라, 온라인 최적화 기반의 통계적 특징 학습 적응 기법을 개발하여 LFW 데이터셋과 자체 제작한 운동선수 데이터셋에서 테스트하였다. 고정된 임계값 {0.3, 0.5, 0.7}을 히트앤트라이 방식으로 사용하는 기존 방법과 비교했을 때, 적응형 임계값을 채택한 이 방법은 모델 정확도에서 12-45%의 향상을 달성하였다. 전체 알고리즘의 소스 코드는 다음에서 확인할 수 있다: https://github.com/Varat7v2/adaptive-threshold
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ko
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The celebrated quantum no-cloning theorem states that an arbitrary quantum state cannot be cloned perfectly. This raises questions about cloning of classical states, which have also attracted attention. Here, we present a physical approach to the classical cloning process showing how cloning can be realised using Hamiltonians. After writing down a canonical transformation that clones classical states, we show how this can be implemented by Hamiltonian evolution. We then propose an experiment using the tools of nonlinear optics to realise the ideas presented here. Finally, to understand the cloning process in a more realistic context, we introduce statistical mechanical noise to the system and study how this affects the cloning process. While most of our work deals with linear systems and harmonic oscillators, we give some examples of cloning maps on manifolds and show that any system whose configuration space is a group manifold admits a cloning canonical transformation.
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Le célèbre théorème quantique de non-clonage établit qu'un état quantique arbitraire ne peut pas être cloné parfaitement. Cela soulève des questions concernant le clonage d'états classiques, qui a également retenu l'attention. Ici, nous présentons une approche physique du processus de clonage classique, montrant comment le clonage peut être réalisé à l'aide d'hamiltoniens. Après avoir écrit une transformation canonique qui clone des états classiques, nous montrons comment celle-ci peut être mise en œuvre par une évolution hamiltonienne. Nous proposons ensuite une expérience utilisant les outils de l'optique non linéaire afin de concrétiser les idées présentées ici. Enfin, pour comprendre le processus de clonage dans un contexte plus réaliste, nous introduisons un bruit mécanique statistique dans le système et étudions comment cela affecte le processus de clonage. Bien que la majeure partie de notre travail concerne des systèmes linéaires et des oscillateurs harmoniques, nous donnons quelques exemples de transformations de clonage sur des variétés et montrons que tout système dont l'espace de configuration est une variété de groupe admet une transformation canonique de clonage.
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fr
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The last decade witnessed a rise in the importance of supervised learning applications involving {\em big data} and {\em big models}. Big data refers to situations where the amounts of training data available and needed causes difficulties in the training phase of the pipeline. Big model refers to situations where large dimensional and over-parameterized models are needed for the application at hand. Both of these phenomena lead to a dramatic increase in research activity aimed at taming the issues via the design of new sophisticated optimization algorithms. In this paper we turn attention to the {\em big constraints} scenario and argue that elaborate machine learning systems of the future will necessarily need to account for a large number of real-world constraints, which will need to be incorporated in the training process. This line of work is largely unexplored, and provides ample opportunities for future work and applications. To handle the {\em big constraints} regime, we propose a {\em stochastic penalty} formulation which {\em reduces the problem to the well understood big data regime}. Our formulation has many interesting properties which relate it to the original problem in various ways, with mathematical guarantees. We give a number of results specialized to nonconvex loss functions, smooth convex functions, strongly convex functions and convex constraints. We show through experiments that our approach can beat competing approaches by several orders of magnitude when a medium accuracy solution is required.
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گزشتہ دہائی میں بڑے ڈیٹا (big data) اور بڑے ماڈلز (big models) سے متعلق نگرانی شدہ سیکھنے کی درخواستوں کی اہمیت میں اضافہ دیکھا گیا ہے۔ بڑا ڈیٹا ان حالات کو ظاہر کرتا ہے جہاں دستیاب اور ضروری تربیتی ڈیٹا کی مقدار پائپ لائن کے تربیتی مرحلے میں مشکلات پیدا کرتی ہے۔ بڑا ماڈل ان حالات کو ظاہر کرتا ہے جہاں مطلوبہ درخواست کے لیے بڑے پیمانے پر پیچیدہ اور زائد پیرامیٹر والے ماڈلز کی ضرورت ہوتی ہے۔ ان دونوں پہلوؤں نے نئے جدید بہینگی الگورتھم تیار کرنے کے ذریعے مسائل پر قابو پانے کے لیے تحقیقی سرگرمیوں میں نمایاں اضافہ کیا ہے۔ اس مقالے میں ہم توجہ "بڑی قیود" (big constraints) کی صورتحال کی طرف مبذول کراتے ہیں اور دلیل دیتے ہیں کہ مستقبل کے پیچیدہ مشین لرننگ نظاموں کو حقیقی دنیا کی بڑی تعداد میں قیود کا احاطہ کرنا ضروری ہوگا، جنہیں تربیت کے عمل میں شامل کرنا ہوگا۔ یہ تحقیق کا شعبہ ابھی تک کافی حد تک ناقابلِ تحقیق ہے، اور مستقبل کی تحقیق و درخواستوں کے لیے وافر مواقع فراہم کرتا ہے۔ "بڑی قیود" کے حالتِ زمانہ کو سنبھالنے کے لیے، ہم ایک "اجادی سزا" (stochastic penalty) فارمولہ پیش کرتے ہیں جو "مسئلے کو اچھی طرح سمجھے گئے بڑے ڈیٹا کے حالتِ زمانہ میں کم کردیتا ہے"۔ ہمارا فارمولہ کئی دلچسپ خصوصیات رکھتا ہے جو مختلف طریقوں سے اصل مسئلے سے متعلق ہیں، اور ریاضیاتی ضمانتیں فراہم کرتے ہیں۔ ہم غیر محدب نقصان فنکشنز، ہموار محدب فنکشنز، مضبوط محدب فنکشنز اور محدب قیود کے لیے کئی نتائج پیش کرتے ہیں۔ تجربات کے ذریعے ہم دکھاتے ہیں کہ جب درمیانی درجے کی درستگی کا حل درکار ہو تو ہمارا طریقہ مسابقتی طریقوں کو متعدد درجے تک پیچھے چھوڑ دیتا ہے۔
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ur
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The space of invariant affine connections on every $3$-Sasakian homogeneous manifold of dimension at least $7$ is described. In particular, the remarkable subspaces of invariant affine metric connections, and the subclass with skew-torsion, are also determined. To this aim, an explicit construction of all $3$-Sasakian homogeneous manifolds is exhibited. The unique $3$-Sasakian homogeneous manifolds which admit nontrivial Einstein with skew-torsion invariant affine connections are those of dimension $7$, that is, $\mathbb{S}^7=\mathrm{Sp} (2)/ \mathrm{Sp(1)}$, $\mathbb{R} P^7=\mathrm{Sp}(2)/ \mathrm{Sp(1)}\times \mathbb{Z}_{2}$ and the Aloff-Wallach space $\mathfrak{W}^{7}_{1,1}= \mathrm{SU}(3)/ \mathrm{U}(1)$. For $\mathbb{S}^7$ and $\mathbb{R} P^7$, the set of such connections is in one to one correspondence with two copies of the conformal linear transformation group of the Euclidean space, while it is strictly bigger for $\mathfrak{W}^{7}_{1,1}$. In addition, the set of invariant connections with totally skew-symmetric torsion whose Ricci tensor is multiple of the metric, with different factors, on the canonical vertical and horizontal distributions, is fully described on every $3$-Sasakian homogeneous manifold. An affine connection satisfying these conditions is distinguished, characterized by parallelizing all the characteristic vector fields associated to the $3$-Sasakian structure. This connection is Einstein with skew-torsion for the $7$-dimensional examples. Several results have also been adapted to the nonnecessarily homogeneous setting. In this case, the above mentioned sets of affine connections are, in general, only proper subsets satisfying the properties.
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L'espace des connexions affines invariantes sur toute variété homogène 3-sasakienne de dimension au moins égale à 7 est décrit. En particulier, les sous-espaces remarquables des connexions affines invariantes compatibles avec une métrique, ainsi que la sous-classe à torsion antisymétrique, sont également déterminés. À cette fin, une construction explicite de toutes les variétés homogènes 3-sasakiennes est présentée. Les uniques variétés homogènes 3-sasakiennes admettant des connexions affines invariantes non triviales d'Einstein à torsion antisymétrique sont celles de dimension 7, à savoir $\mathbb{S}^7=\mathrm{Sp}(2)/\mathrm{Sp(1)}$, $\mathbb{R} P^7=\mathrm{Sp}(2)/\mathrm{Sp(1)}\times \mathbb{Z}_{2}$ et l'espace d'Aloff-Wallach $\mathfrak{W}^{7}_{1,1}= \mathrm{SU}(3)/ \mathrm{U}(1)$. Pour $\mathbb{S}^7$ et $\mathbb{R} P^7$, l'ensemble de telles connexions est en correspondance biunivoque avec deux copies du groupe des transformations linéaires conformes de l'espace euclidien, tandis qu'il est strictement plus grand pour $\mathfrak{W}^{7}_{1,1}$. En outre, l'ensemble des connexions invariantes à torsion totalement antisymétrique dont le tenseur de Ricci est multiple de la métrique, avec des facteurs différents, sur les distributions verticale et horizontale canoniques, est entièrement décrit sur chaque variété homogène 3-sasakienne. Une connexion affine satisfaisant ces conditions se distingue, caractérisée par le fait de paralléliser tous les champs de vecteurs caractéristiques associés à la structure 3-sasakienne. Cette connexion est d'Einstein à torsion antisymétrique pour les exemples de dimension 7. Plusieurs résultats ont également été adaptés au cadre non nécessairement homogène. Dans ce cas, les ensembles mentionnés ci-dessus de connexions affines sont, en général, seulement des sous-ensembles propres satisfaisant les propriétés.
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fr
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One way to recognise an object is to study how the echo has been shaped during the interaction with the target. Wideband sonar allows the study of the energy distribution for a large range of frequencies. The frequency distribution contains information about an object, including its inner structure. This information is a key for automatic recognition. The scattering by a target can be quantitatively described by its Form Function. The Form Function can be calculated based on the data of the initial pulse, reflected pulse and parameters of a medium where the pulse is propagating. In this work spherical objects are classified based on their filler material - water or air. We limit the study to spherical 2 layered targets immersed in water. The Form Function is used as a descriptor and fed into a Neural Network classifier, Multilayer Perceptron (MLP). The performance of the classifier is compared with Support Vector Machine (SVM) and the Form Function descriptor is examined in contrast to the Time and Frequency Representation of the echo.
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Un modo per riconoscere un oggetto consiste nello studiare come l'eco è stata modificata durante l'interazione con il bersaglio. Il sonar a banda larga permette di analizzare la distribuzione dell'energia su un ampio intervallo di frequenze. La distribuzione in frequenza contiene informazioni sull'oggetto, inclusa la sua struttura interna. Queste informazioni sono fondamentali per il riconoscimento automatico. La diffusione provocata da un bersaglio può essere descritta quantitativamente mediante la sua Funzione di Forma. La Funzione di Forma può essere calcolata a partire dai dati dell'impulso iniziale, dell'impulso riflesso e dei parametri del mezzo in cui l'impulso si propaga. In questo lavoro, oggetti sferici vengono classificati in base al materiale di riempimento: acqua o aria. Lo studio è limitato a bersagli sferici a due strati immersi in acqua. La Funzione di Forma viene utilizzata come descrittore ed inserita in un classificatore a rete neurale, il Perceptron Multistrato (MLP). Le prestazioni del classificatore vengono confrontate con quelle della Macchina a Vettori di Supporto (SVM) e il descrittore Funzione di Forma viene esaminato in confronto alla Rappresentazione nel Tempo e nella Frequenza dell'eco.
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it
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Computational procedures to foresee the 3D structure of aptamers are in continuous progress. They constitute a crucial input to research, mainly when the crystallographic counterpart of the structures in silico produced is not present. At now, many codes are able to perform structure and binding prediction, although their ability in scoring the results remains rather weak. In this paper, we propose a novel procedure to complement the ranking outcomes of free docking code, by applying it to a set of anti-angiopoietin aptamers, whose performances are known. We rank the in silico produced configurations, adopting a maximum likelihood estimate, based on their topological and electrical properties. From the analysis, two principal kinds of conformers are identified, whose ability to mimick the binding features of the natural receptor is discussed. The procedure is easily generalizable to many biological biomolecules, useful for increasing chances of success in designing high-specificity biosensors (aptasensors).
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Prosedur komputasi untuk memprediksi struktur 3D dari aptamer terus mengalami kemajuan. Prosedur ini merupakan masukan penting bagi penelitian, terutama ketika struktur kristalografi dari struktur yang dihasilkan secara in silico tidak tersedia. Saat ini, banyak perangkat lunak yang mampu melakukan prediksi struktur dan pengikatan, meskipun kemampuannya dalam menilai hasil tetap relatif lemah. Dalam makalah ini, kami mengusulkan prosedur baru untuk melengkapi hasil peringkat dari perangkat lunak docking bebas, dengan menerapkannya pada satu set aptamer anti-angiopoietin, yang kinerjanya telah diketahui. Kami melakukan peringkat terhadap konfigurasi yang dihasilkan secara in silico, menggunakan estimasi kemungkinan maksimum berdasarkan sifat topologis dan listriknya. Dari analisis tersebut, dua jenis konformer utama diidentifikasi, dan kemampuannya meniru karakteristik pengikatan reseptor alami dibahas. Prosedur ini mudah digeneralisasi ke berbagai biomolekul biologis, serta berguna untuk meningkatkan peluang keberhasilan dalam merancang biosensor berspesifisitas tinggi (aptasensor).
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id
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Efficient exploration remains a challenging problem in reinforcement learning, especially for those tasks where rewards from environments are sparse. A commonly used approach for exploring such environments is to introduce some "intrinsic" reward. In this work, we focus on model uncertainty estimation as an intrinsic reward for efficient exploration. In particular, we introduce an implicit generative modeling approach to estimate a Bayesian uncertainty of the agent's belief of the environment dynamics. Each random draw from our generative model is a neural network that instantiates the dynamic function, hence multiple draws would approximate the posterior, and the variance in the future prediction based on this posterior is used as an intrinsic reward for exploration. We design a training algorithm for our generative model based on the amortized Stein Variational Gradient Descent. In experiments, we compare our implementation with state-of-the-art intrinsic reward-based exploration approaches, including two recent approaches based on an ensemble of dynamic models. In challenging exploration tasks, our implicit generative model consistently outperforms competing approaches regarding data efficiency in exploration.
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Die effiziente Erkundung bleibt ein schwieriges Problem im Verstärkungslernen, insbesondere bei Aufgaben, bei denen die Belohnungen aus der Umgebung spärlich sind. Ein häufig verwendeter Ansatz zur Erkundung solcher Umgebungen besteht darin, eine zusätzliche „intrinsische“ Belohnung einzuführen. In dieser Arbeit konzentrieren wir uns auf die Abschätzung der Modellunsicherheit als intrinsische Belohnung für eine effiziente Erkundung. Insbesondere führen wir einen impliziten Ansatz zur generativen Modellierung ein, um die bayessche Unsicherheit der Überzeugung des Agenten bezüglich der Umgebungsdynamik zu schätzen. Jede zufällige Stichprobe aus unserem generativen Modell ist ein neuronales Netzwerk, das die Dynamikfunktion realisiert; daher approximieren mehrere Stichproben die Posterior-Verteilung, und die Varianz der zukünftigen Vorhersage basierend auf dieser Posterior-Verteilung wird als intrinsische Belohnung für die Erkundung verwendet. Wir entwerfen einen Trainingsalgorithmus für unser generatives Modell basierend auf dem amortisierten Stein-Variational-Gradient-Descent. In Experimenten vergleichen wir unsere Implementierung mit aktuellen, auf intrinsischer Belohnung basierenden Erkundungsansätzen, einschließlich zweier kürzlich vorgestellter Methoden, die auf einem Ensemble von Dynamikmodellen beruhen. Bei anspruchsvollen Erkundungsaufgaben übertrifft unser implizites generatives Modell die konkurrierenden Ansätze hinsichtlich der Dateneffizienz bei der Erkundung durchgängig.
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de
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This paper discusses one of the most significant challenges of next-generation big data (BD) federation platforms, namely, Hadoop access control. Privacy and security on a federation scale remain significant concerns among practitioners. Hadoop's current primitive access control presents security concerns and limitations, such as the complexity of deployment and the consumption of resources. However, this major concern has not been a subject of intensive study in the literature. This paper critically reviews and investigates these security limitations and provides a framework called BD federation access broker to address 8 main security limitations. This paper proposes the federated access control reference model (FACRM) to formalize the design of secure BD solutions within the Apache Hadoop stack. Furthermore, this paper discusses the implementation of the access broker and its usefulness for security breach detection and digital forensics investigations. The efficiency of the proposed access broker has not sustainably affected the performance overhead. The experimental results show only 1\% of each 100 MB read/write operation in a WebHDFS. Overall, the findings of the paper pave the way for a wide range of revolutionary and state-of-the-art enhancements and future trends within Hadoop stack security and privacy.
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ဤစာတမ်းသည် နောက်မျိုးဆက်ကြီးမားသော ဒေတာ (BD) ဖက်ဒရေးရှင်း ပလက်ဖောင်းများ၏ အရေးပါဆုံး စိန်ခေါ်မှုများထဲမှ တစ်ခုဖြစ်သည့် Hadoop ဝင်ရောက်ခွင့် ထိန်းချုပ်မှုကို ဆွေးနွေးထားသည်။ ဖက်ဒရေးရှင်းအဆင့်တွင် လုံခြုံရေးနှင့် ပုဂ္ဂလိကရေးတို့သည် လက်တွေ့လုပ်ကိုင်သူများအကြား အဓိကစိုးရိမ်မှုများအဖြစ် ရှိနေဆဲဖြစ်သည်။ Hadoop ၏ လက်ရှိရိုးရှင်းသော ဝင်ရောက်ခွင့်ထိန်းချုပ်မှုသည် အသုံးပြုမှုရှုပ်ထွေးမှုနှင့် ရင်းမြစ်များ သုံးစွဲမှုကဲ့သို့သော လုံခြုံရေးဆိုင်ရာ စိုးရိမ်မှုများနှင့် ကန့်သတ်ချက်များကို ဖြစ်ပေါ်စေသည်။ သို့သော် ဤအဓိကစိုးရိမ်မှုသည် စာပေများတွင် အကြံပြုလေ့လာမှုခံရသော အကြောင်းအရာ မဟုတ်ပါ။ ဤစာတမ်းသည် ဤလုံခြုံရေးကန့်သတ်ချက်များကို အကဲဖြတ်သုံးသပ်လေ့လာပြီး အဓိက လုံခြုံရေးကန့်သတ်ချက် ၈ ခုကို ဖြေရှင်းရန် BD ဖက်ဒရေးရှင်း ဝင်ရောက်ခွင့် အိုင်းဂျင့် (access broker) ဟုခေါ်သော အခြေခံကျသည့် စနစ်တစ်ခုကို ပေးဆောင်ထားသည်။ ဤစာတမ်းသည် Apache Hadoop စတက်ခ်အတွင်း လုံခြုံသော BD ဖြေရှင်းချက်များ၏ ဒီဇိုင်းကို စံချိန်စံညွှန်းဖြစ်အောင်ပြုလုပ်ရန် ဖက်ဒရေးရှင်း ဝင်ရောက်ခွင့်ထိန်းချုပ်မှု ကိုးကားမှု မော်ဒယ် (FACRM) ကို အဆိုပြုထားသည်။ ထို့အပြင် ဤစာတမ်းသည် ဝင်ရောက်ခွင့်အိုင်းဂျင့်၏ အကောင်အထည်ဖော်မှုနှင့် လုံခြုံရေး ချို့ယွင်းမှုများကို ရှာဖွေတွေ့ရှိခြင်းနှင့် ဒစ်ဂျစ်တယ် ဖောရင်စစ်ဆေးစစ်မှုများတွင် ၎င်း၏အသုံးဝင်မှုကို ဆွေးနွေးထားသည်။ အဆိုပြုထားသော ဝင်ရောက်ခွင့်အိုင်းဂျင့်၏ ထိရောက်မှုသည် စွမ်းဆောင်ရည်ဆိုင်ရာ အပိုအားသုံးမှုကို တည်ငြိမ်စွာ သက်ရောက်မှု မရှိခဲ့ပါ။ စမ်းသပ်မှုရလဒ်များအရ WebHDFS တွင် 100 MB ဖတ်ရှုခြင်း/ရေးသားခြင်း လုပ်ဆောင်ချက်တစ်ခုချင်းစီတွင် ၁% သာ ရှိသည်။ စုစုပေါင်းအားဖြင့် ဤစာတမ်း၏ ရလဒ်များသည် Hadoop စတက်ခ်အတွင်း လုံခြုံရေးနှင့် ပုဂ္ဂလိကရေးဆိုင်ရာ တီထွင်မှုအဆင့်မြင့် တိုးတက်မှုများနှင့် အနာဂတ်အခြေအနေများအတွက် လမ်းကြောင်းဖွင့်ပေးထားသည်။
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my
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The structure of Gamma Ray Burst (GRB) jets impacts on their prompt and afterglow emission properties. The jet of GRBs could be uniform, with constant energy per unit solid angle within the jet aperture, or it could instead be structured, namely with energy and velocity that depend on the angular distance from the axis of the jet. We try to get some insight about the still unknown structure of GRBs by studying their luminosity function. We show that low (1e46-1e48 erg/s) and high (i.e. with L > 1e50 erg/s) luminosity GRBs can be described by a unique luminosity function, which is also consistent with current lower limits in the intermediate luminosity range (1e48-1e50} erg/s). We derive analytical expressions for the luminosity function of GRBs in uniform and structured jet models and compare them with the data. Uniform jets can reproduce the entire luminosity function with reasonable values of the free parameters. A structured jet can also fit adequately the current data, provided that the energy within the jet is relatively strongly structured, i.e. E propto theta^{-k} with k > 4. The classical E propto theta^{-2} structured jet model is excluded by the current data.
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伽马射线暴（GRB）喷流的结构影响其瞬时辐射和余辉辐射的特性。GRB的喷流可能是均匀的，即在喷流张角内单位立体角的能量保持恒定；也可能是具有结构的，即能量和速度依赖于距喷流轴线的角距离。我们试图通过研究GRB的光度函数来获得关于其尚不明确的结构的一些认识。我们发现，低光度（1e46–1e48 erg/s）和高光度（即L > 1e50 erg/s）的GRB可以用一个统一的光度函数来描述，该函数也与中间光度范围（1e48–1e50 erg/s）现有的下限值一致。我们推导了均匀喷流和结构化喷流模型下GRB光度函数的解析表达式，并将其与观测数据进行比较。在合理的自由参数取值下，均匀喷流模型能够重现整个光度函数。结构化喷流模型也能较好地拟合当前数据，但前提是喷流内部能量具有较强的结构，即E ∝ θ^{-k}，其中k > 4。经典的E ∝ θ^{-2}结构化喷流模型被当前数据排除。
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zh
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Context. Stellar magnetic fields are one of the candidates often invoked to explain the missing transport of angular momentum observed in the models of stellar interiors. However, the properties of an internal magnetic field and the consequences of its presence on stellar evolution are largely unknown. Aims. We study the effect of an axisymmetric internal magnetic field on the frequency of gravity modes in rapidly rotating stars to check whether gravity modes can be used to detect and probe such a field. Methods. Rotation is taken into account using the traditional approximation of rotation and the effect of the magnetic field is computed using a perturbative approach. As a proof of concept, we compute frequency shifts due to a mixed (i.e. with both poloidal and toroidal components) fossil magnetic field for a representative model of a known magnetic, rapidly rotating, slowly pulsating B-type star, namely HD 43317. Results. We find that frequency shifts induced by the magnetic field scale with the square of its amplitude. A magnetic field with a near-core strength of order 150 kG (which is consistent with the observed surface field strength of order 1 kG) leads to signatures that are detectable in period spacings for high-radial-order gravity modes. Conclusions. The predicted frequency shifts can be used to constrain internal magnetic fields and offers the potential for a significant step forward in our interpretation of the observed structure of gravity-mode period spacing patterns in rapidly rotating stars.
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บริบท สนามแม่เหล็กของดาวฤกษ์เป็นหนึ่งในปัจจัยที่มักถูกกล่าวถึงเพื่ออธิบายการขาดหายไปของการถ่ายโอนโมเมนตัมเชิงมุม ซึ่งสังเกตได้ในแบบจำลองภายในดาวฤกษ์ อย่างไรก็ตาม คุณสมบัติของสนามแม่เหล็กภายในและผลที่ตามมาต่อวิวัฒนาการของดาวฤกษ์ยังไม่เป็นที่ทราบอย่างชัดเจน
วัตถุประสงค์ เราศึกษาผลกระทบของสนามแม่เหล็กภายในที่มีสมมาตรตามแนวแกนต่อความถี่ของโหมดแรงโน้มถ่วงในดาวฤกษ์ที่หมุนเร็ว เพื่อตรวจสอบว่าโหมดแรงโน้มถ่วงสามารถใช้ในการตรวจจับและสำรวจสนามดังกล่าวได้หรือไม่
วิธีการ การพิจารณาการหมุนทำโดยใช้การประมาณแบบดั้งเดิมของการหมุน (traditional approximation of rotation) และผลกระทบของสนามแม่เหล็กคำนวณโดยใช้วิธีการรบกวน (perturbative approach) เพื่อเป็นการพิสูจน์แนวคิด เราคำนวณการเปลี่ยนแปลงความถี่ที่เกิดจากสนามแม่เหล็กฟอสซิลแบบผสม (คือมีทั้งองค์ประกอบโพลอยดัลและโทรอยดัล) สำหรับแบบจำลองตัวแทนของดาวฤกษ์ประเภทบีที่มีการสั่นพ้องช้า หมุนเร็ว และมีสนามแม่เหล็กซึ่งรู้จักกันดี ได้แก่ HD 43317
ผลลัพธ์ เราพบว่าการเปลี่ยนแปลงความถี่ที่เกิดจากสนามแม่เหล็กมีสเกลตามกำลังสองของความแรงของสนาม สนามแม่เหล็กที่มีความแรงใกล้แกนกลางประมาณ 150 กิโลแกสส์ (ซึ่งสอดคล้องกับความแรงของสนามที่ผิวดาวที่สังเกตได้ประมาณ 1 กิโลแกสส์) ทำให้เกิดลักษณะเฉพาะที่สามารถตรวจพบได้จากการเว้นระยะของคาบในโหมดแรงโน้มถ่วงที่มีลำดับรัศมีสูง
ข้อสรุป การเปลี่ยนแปลงความถี่ที่คาดการณ์ไว้สามารถใช้จำกัดขอบเขตของสนามแม่เหล็กภายในได้ และเปิดโอกาสให้มีความก้าวหน้าอย่างมีนัยสำคัญต่อการตีความโครงสร้างรูปแบบการเว้นระยะของคาบของโหมดแรงโน้มถ่วงในดาวฤกษ์ที่หมุนเร็ว
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th
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The $B$-meson decay constant can be measured on the lattice using a $1/m_b$ expansion. To relate the physical quantity to Monte Carlo data one has to know the renormalization coefficient, $Z$, between the lattice operators and their continuum counterparts. We come back to this computation to resolve discrepancies found in previous calculations. We define and discuss in detail the renormalization procedure that allows the (perturbative) computation of $Z$. Comparing the one-loop calculations in the effective Lagrangian approach with the direct two-loop calculation of the two-point $B$-meson correlator in the limit of large $b$-quark mass, we prove that the two schemes give consistent results to order $\alpha_s$. We show that there is, however, a renormalization prescription ambiguity that can have sizeable numerical consequences. This ambiguity can be resolved in the framework of an $O(a)$ improved calculation, and we describe the correct prescription in that case. Finally we give the numerical values of $Z$ that correspond to the different types of lattice approximations discussed in the paper.
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Přesnost rozpadu $B$-mesonu lze na mřížce změřit pomocí rozvoje v $1/m_b$. Pro spojení fyzikální veličiny s daty získanými Monte Carlo metodou je třeba znát renormalizační koeficient $Z$ mezi mřížkovými operátory a jejich spojitými ekvivalenty. Vracíme se k tomuto výpočtu, abychom vyřešili nesrovnalosti nalezené v předchozích výpočtech. Definujeme a podrobně rozebíráme renormalizační postup, který umožňuje (perturbační) výpočet $Z$. Porovnáním výpočtů do jedné smyčky v rámci efektivního lagrangiánu s přímým výpočtem do dvou smyček dvoubodové $B$-mesonové korelační funkce v limitě velké hmotnosti $b$-kvarku dokazujeme, že obě schémata dávají konzistentní výsledky do řádu $\alpha_s$. Ukazujeme však, že existuje nejednoznačnost renormalizačního předpisu, která může mít významné numerické důsledky. Tato nejednoznačnost může být vyřešena v rámci výpočtu zlepšeného do řádu $O(a)$, a popisujeme správný předpis pro tento případ. Nakonec uvádíme numerické hodnoty $Z$, které odpovídají různým typům mřížkových aproximací diskutovaných v článku.
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cs
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Data for human-human spoken dialogues for research and development are currently very limited in quantity, variety, and sources; such data are even scarcer in healthcare. In this work, we investigate fast prototyping of a dialogue comprehension system by leveraging on minimal nurse-to-patient conversations. We propose a framework inspired by nurse-initiated clinical symptom monitoring conversations to construct a simulated human-human dialogue dataset, embodying linguistic characteristics of spoken interactions like thinking aloud, self-contradiction, and topic drift. We then adopt an established bidirectional attention pointer network on this simulated dataset, achieving more than 80% F1 score on a held-out test set from real-world nurse-to-patient conversations. The ability to automatically comprehend conversations in the healthcare domain by exploiting only limited data has implications for improving clinical workflows through red flag symptom detection and triaging capabilities. We demonstrate the feasibility for efficient and effective extraction, retrieval and comprehension of symptom checking information discussed in multi-turn human-human spoken conversations.
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Atualmente, os dados de diálogos falados entre humanos para pesquisa e desenvolvimento são muito limitados em quantidade, variedade e fontes; tais dados são ainda mais escassos na área da saúde. Neste trabalho, investigamos a prototipagem rápida de um sistema de compreensão de diálogos aproveitando conversas mínimas entre enfermeiros e pacientes. Propomos um framework inspirado em conversas clínicas de monitoramento de sintomas iniciadas por enfermeiros para construir um conjunto de dados simulado de diálogos entre humanos, incorporando características linguísticas de interações faladas, como pensar em voz alta, contradição própria e desvio de tema. Em seguida, adotamos uma rede ponteira com atenção bidirecional estabelecida neste conjunto de dados simulado, alcançando mais de 80% de pontuação F1 em um conjunto de testes reservado proveniente de conversas reais entre enfermeiros e pacientes. A capacidade de compreender automaticamente conversas no domínio da saúde explorando apenas dados limitados tem implicações para a melhoria dos fluxos de trabalho clínicos por meio da detecção de sintomas de alerta e capacidades de triagem. Demonstramos a viabilidade da extração, recuperação e compreensão eficientes e eficazes de informações sobre verificação de sintomas discutidas em conversas faladas entre humanos com múltiplas rodadas.
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pt
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We investigate dust entrainment by photoevaporative winds in protoplanetary discs using dusty smoothed particle hydrodrodynamics (SPH). We use unequal-mass particles to resolve more than five orders of magnitude in disc/outflow density and a one-fluid formulation to efficiently simulate an equivalent magnitude range in drag stopping time. We find that only micron sized dust grains and smaller can be entrained in EUV driven winds. The maximum grain size is set by dust settling in the disc rather than aerodynamic drag in the wind. More generally, there is a linear relationship between the base flow density and the maximum entrainable grain size in the wind. A pileup of micron sized dust grains can occur in the upper atmosphere at critical radii in the disc as grains decouple from the low-density wind. Entrainment is a strong function of location in the disc, resulting in a size sorting of grains in the outflow---the largest grain being carried out between $10$--$20\,$AU. The peak dust density for each grain size occurs at the inner edge of its own entrainment region.
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Kami menyiasat kemasukan debu oleh angin foto-penyusutan dalam cakera protoplanet menggunakan dinamik hidro hamparan zarah berdebu (SPH). Kami menggunakan zarah berjisim tidak sama bagi menyelesaikan lebih daripada lima magnitud dalam ketumpatan cakera/aliran keluar dan menggunakan formulasi satu-bendalir untuk mensimulasi julat magnitud setara dalam masa perhentian seretan secara cekap. Kami mendapati bahawa hanya butiran debu bersaiz mikron dan lebih kecil sahaja yang boleh dikemasukkan ke dalam angin yang dipacu oleh EUV. Saiz maksimum butiran ditentukan oleh pemendapan debu dalam cakera dan bukannya seretan aerodinamik dalam angin. Secara umumnya, terdapat hubungan linear antara ketumpatan aliran asas dan saiz maksimum butiran yang boleh dikemasukkan dalam angin. Penimbunan butiran debu bersaiz mikron boleh berlaku di lapisan atmosfera atas pada jejari genting dalam cakera apabila butiran terlerai daripada angin yang berketumpatan rendah. Kemasukan adalah fungsi yang kuat terhadap lokasi dalam cakera, menghasilkan pengisihan saiz butiran dalam aliran keluar—dengan butiran terbesar dibawa keluar antara $10$--$20\,$AU. Ketumpatan debu puncak bagi setiap saiz butiran berlaku pada tepi dalam kawasan kemasukannya sendiri.
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ms
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The celebrated quantum no-cloning theorem states that an arbitrary quantum state cannot be cloned perfectly. This raises questions about cloning of classical states, which have also attracted attention. Here, we present a physical approach to the classical cloning process showing how cloning can be realised using Hamiltonians. After writing down a canonical transformation that clones classical states, we show how this can be implemented by Hamiltonian evolution. We then propose an experiment using the tools of nonlinear optics to realise the ideas presented here. Finally, to understand the cloning process in a more realistic context, we introduce statistical mechanical noise to the system and study how this affects the cloning process. While most of our work deals with linear systems and harmonic oscillators, we give some examples of cloning maps on manifolds and show that any system whose configuration space is a group manifold admits a cloning canonical transformation.
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تنص نظرية عدم النسخ الكمية الشهيرة على أن الحالة الكمية التعسفية لا يمكن نسخها بشكل مثالي. ويثير هذا تساؤلات حول نسخ الحالات الكلاسيكية، والتي لاقت هي الأخرى اهتمامًا. هنا، نقدم نهجًا فيزيائيًا لعملية النسخ الكلاسيكية يوضح كيف يمكن تحقيق النسخ باستخدام الهاملتونيات. وبعد كتابة تحويل كانوني يقوم بنسخ الحالات الكلاسيكية، نُظهر كيف يمكن تنفيذه عبر تطور هاملتوني. ثم نقترح تجربة باستخدام أدوات البصريات غير الخطية لتجسيد الأفكار المقدمة هنا. وأخيرًا، لفهم عملية النسخ في سياق أكثر واقعية، نُدخل ضجيجًا ميكانيكيًا إحصائيًا إلى النظام وندرس كيف يؤثر هذا على عملية النسخ. في حين أن معظم عملنا يتعامل مع الأنظمة الخطية والمتذبذبات التوافقية، نورد بعض الأمثلة على تحويلات النسخ على التنوّرات، ونُظهر أن أي نظام تكون فيه فضاءات التكوين عبارة عن تنوّرة زمرية يقبل تحويلًا كانونيًا للنسخ.
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ar
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We use Wang-Landau and replica exchange techniques to study the effect of an increasing stiffness on the formation of secondary structures in protein-like systems. Two possible models are considered. In both models, a polymer chain is formed by tethered beads where non-consecutive backbone beads attract each other via a square-well potential representing the tendency of the chain to fold. In addition, smaller hard spheres are attached to each non-terminal backbone bead along the direction normal to the chain to mimic the steric hindrance of side chains in real proteins. The two models, however, differ in the way bending rigidity is enforced. In the first model, partial overlap between consecutive beads is allowed. This reduces the possible bending angle between consecutive bonds thus producing an effective entropic stiffness that competes with a short-range attraction, and leads to a formation of secondary structures characteristic of proteins. We discuss the low-temperature phase diagram as a function of increasing interpenetration, and find a transition from a planar, beta-like structure, to helical shape. In the second model, an energetic stiffness is explicitly introduced by imposing an infinitely large energy penalty for bending above a critical angle between consecutive bonds, and no penalty below it. The low-temperature phase of this model does not show any sign of protein-like secondary structures. At intermediate temperatures, however, where the chain is still in the coil conformation but stiffness is significant, we find the two models to predict a quite similar dependence of the persistence length as a function of the stiffness. This behaviour is rationalized in terms of a simple geometrical mapping between the two models. Finally, we discuss the effect of shrinking side chains to zero, and find the above mapping to still hold true.
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Мы используем метод Ванга–Ландау и метод обмена репликами для изучения влияния возрастающей жесткости на формирование вторичных структур в системах, подобных белкам. Рассматриваются две возможные модели. В обеих моделях полимерная цепь образована соединёнными бусинами, где неконсекутинные бусины основной цепи притягиваются друг к другу посредством потенциала квадратной ямы, что отражает склонность цепи к сворачиванию. Кроме того, к каждой неконцевой бусине основной цепи в направлении, нормальном к цепи, прикреплены более мелкие твёрдые сферы, имитирующие стерические препятствия боковых цепей в реальных белках. Однако две модели различаются способом задания изгибной жёсткости. В первой модели допускается частичное перекрытие между последовательными бусинами. Это ограничивает возможный угол изгиба между последовательными связями, создавая эффективную энтропийную жёсткость, которая конкурирует с короткодействующим притяжением и приводит к формированию вторичных структур, характерных для белков. Мы обсуждаем фазовую диаграмму при низких температурах в зависимости от возрастающего взаимопроникновения и обнаруживаем переход от плоской, напоминающей бета-структуру, формы к спиральной. Во второй модели энергетическая жёсткость вводится явно путём наложения бесконечно большой энергетической пенальти за изгиб, превышающий критический угол между последовательными связями, и отсутствия пенальти при меньших углах. Низкотемпературная фаза этой модели не демонстрирует признаков белковых вторичных структур. Однако при промежуточных температурах, когда цепь всё ещё находится в конформации клубка, но жёсткость значительна, мы обнаруживаем, что обе модели предсказывают весьма схожую зависимость длины персистентности от жёсткости. Такое поведение объясняется простым геометрическим отображением между двумя моделями. Наконец, мы обсуждаем эффект уменьшения боковых цепей до нулевого размера и обнаруживаем, что указанное отображение остаётся справедливым.
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ru
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Efficient exploration remains a challenging problem in reinforcement learning, especially for those tasks where rewards from environments are sparse. A commonly used approach for exploring such environments is to introduce some "intrinsic" reward. In this work, we focus on model uncertainty estimation as an intrinsic reward for efficient exploration. In particular, we introduce an implicit generative modeling approach to estimate a Bayesian uncertainty of the agent's belief of the environment dynamics. Each random draw from our generative model is a neural network that instantiates the dynamic function, hence multiple draws would approximate the posterior, and the variance in the future prediction based on this posterior is used as an intrinsic reward for exploration. We design a training algorithm for our generative model based on the amortized Stein Variational Gradient Descent. In experiments, we compare our implementation with state-of-the-art intrinsic reward-based exploration approaches, including two recent approaches based on an ensemble of dynamic models. In challenging exploration tasks, our implicit generative model consistently outperforms competing approaches regarding data efficiency in exploration.
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Eksplorasi yang efisien tetap menjadi masalah yang menantang dalam pembelajaran penguatan, terutama untuk tugas-tugas di mana imbalan dari lingkungan bersifat langka. Pendekatan yang umum digunakan untuk mengeksplorasi lingkungan semacam ini adalah dengan memperkenalkan imbalan "intrinsik". Dalam karya ini, kami berfokus pada estimasi ketidakpastian model sebagai imbalan intrinsik untuk eksplorasi yang efisien. Secara khusus, kami memperkenalkan pendekatan pemodelan generatif implisit untuk memperkirakan ketidakpastian Bayesian terhadap keyakinan agen mengenai dinamika lingkungan. Setiap pengambilan sampel acak dari model generatif kami merupakan jaringan saraf yang mewujudkan fungsi dinamis, sehingga beberapa kali pengambilan sampel akan mendekati distribusi posterior, dan varians dalam prediksi masa depan berdasarkan posterior ini digunakan sebagai imbalan intrinsik untuk eksplorasi. Kami merancang algoritma pelatihan untuk model generatif kami berdasarkan Amortized Stein Variational Gradient Descent. Dalam eksperimen, kami membandingkan implementasi kami dengan pendekatan eksplorasi berbasis imbalan intrinsik terkini, termasuk dua pendekatan terbaru yang berbasis ensemble model dinamis. Dalam tugas-tugas eksplorasi yang menantang, model generatif implisit kami secara konsisten melampaui pendekatan-pendekatan saingannya dalam hal efisiensi data pada eksplorasi.
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id
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The space of invariant affine connections on every $3$-Sasakian homogeneous manifold of dimension at least $7$ is described. In particular, the remarkable subspaces of invariant affine metric connections, and the subclass with skew-torsion, are also determined. To this aim, an explicit construction of all $3$-Sasakian homogeneous manifolds is exhibited. The unique $3$-Sasakian homogeneous manifolds which admit nontrivial Einstein with skew-torsion invariant affine connections are those of dimension $7$, that is, $\mathbb{S}^7=\mathrm{Sp} (2)/ \mathrm{Sp(1)}$, $\mathbb{R} P^7=\mathrm{Sp}(2)/ \mathrm{Sp(1)}\times \mathbb{Z}_{2}$ and the Aloff-Wallach space $\mathfrak{W}^{7}_{1,1}= \mathrm{SU}(3)/ \mathrm{U}(1)$. For $\mathbb{S}^7$ and $\mathbb{R} P^7$, the set of such connections is in one to one correspondence with two copies of the conformal linear transformation group of the Euclidean space, while it is strictly bigger for $\mathfrak{W}^{7}_{1,1}$. In addition, the set of invariant connections with totally skew-symmetric torsion whose Ricci tensor is multiple of the metric, with different factors, on the canonical vertical and horizontal distributions, is fully described on every $3$-Sasakian homogeneous manifold. An affine connection satisfying these conditions is distinguished, characterized by parallelizing all the characteristic vector fields associated to the $3$-Sasakian structure. This connection is Einstein with skew-torsion for the $7$-dimensional examples. Several results have also been adapted to the nonnecessarily homogeneous setting. In this case, the above mentioned sets of affine connections are, in general, only proper subsets satisfying the properties.
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차원이 7 이상인 모든 3-서서키안 동차다양체 위의 불변 아핀 접속들의 공간이 기술된다. 특히, 불변 아핀 계량 접속들의 주목할 만한 부분공간과 비틀림이 반대칭인 부분류도 결정된다. 이를 위해, 모든 3-서서키안 동차다양체들의 명시적 구성이 제시된다. 비자명한 비틀림이 있는 아인슈타인 불변 아핀 접속을 허용하는 유일한 3-서서키안 동차다양체는 차원이 7인 경우들이다. 즉, $\mathbb{S}^7=\mathrm{Sp}(2)/\mathrm{Sp(1)}$, $\mathbb{R} P^7=\mathrm{Sp}(2)/\mathrm{Sp(1)}\times \mathbb{Z}_{2}$ 및 알로프-월라흐 공간 $\mathfrak{W}^{7}_{1,1}= \mathrm{SU}(3)/ \mathrm{U}(1)$이다. $\mathbb{S}^7$과 $\mathbb{R} P^7$의 경우, 이러한 접속들의 집합은 유클리드 공간의 등각 선형 변환군의 두 개의 사본과 일대일 대응을 이루는 반면, $\mathfrak{W}^{7}_{1,1}$의 경우는 엄격히 더 크다. 또한, 표준적인 수직 및 수평 분포 위에서 리치 텐서가 서로 다른 상수배로 계량과 일치하는, 전적으로 반대칭인 비틀림을 갖는 불변 접속들의 집합이 모든 3-서서키안 동차다양체 위에서 완전히 기술된다. 이러한 조건들을 만족하는 하나의 접속이 두드러지는데, 이는 3-서서키안 구조에 관련된 모든 특성 벡터장들을 평행하게 만드는 것으로 특징지어진다. 이 접속은 7차원 예제들에 대해 비틀림이 있는 아인슈타인 접속이다. 또한 몇 가지 결과들은 반드시 동차적이지 않은 경우로도 확장되었다. 이 경우, 위에서 언급한 아핀 접속들의 집합들은 일반적으로 해당 성질을 만족하는 진부분집합에 불과하다.
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ko
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In this paper, we study the structure and combustion of magnegases$^{TM}$ (Patented and International Patents Pending), new clean fuels developed by one of us (R.M.S.) [1], which are produced as byproducts of recycling nonradioactive liquid feedstock such as antifreeze waste, engine oil waste, town sewage, crude oil, etc., and generally vary with the liquid used for their production. A new technology, called PlasmaArcFlow\tm, flows the waste through a submerged electric arc between conventional electrodes. The arc decomposes the liquid molecules into their atomic constituents, and forms a plasma in the immediate vicinity of the electrodes at about 10,000$^o$ F. The technology then moves the plasma away from the electrodes, and controls its recombination into environmentally acceptable fuels. The new fuels possess a ew chemical structure first identified by one of us (R.M.S.), which is characterized by clusters of ordinary molecules and atoms under a new bond of electromagnetic nature. These clusters constitute a new chemical species different than the conventional molecules, since they are stable at ordinary conditions while exhibiting no infrared signature (other than those of conventional molecular constituents), thus confirming that the bond is not of valence type. For this reason the new chemical species is called ''Santilli's electromagnecules'' or ''magnecules''.
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នៅក្នុងឯកសារនេះ យើងសិក្សាអំពីរចនាសម្ព័ន្ធ និងការឆេះរបស់ម៉ាញ៉េហ្គាស$^{TM}$ (បានចុះប៉ាតង់ និងប៉ាតង់អន្តរជាតិកំពុងរង់ចាំ) ដែលជាឥន្ធនៈស្អាតថ្មីដែលត្រូវបានអភិវឌ្ឍដោយម្នាក់ក្នុងចំណោមយើង (R.M.S.) [1] ដែលត្រូវបានផលិតជាផលិតផលបន្ទាប់ពីការប្រើប្រាស់ឡើងវិញនូវវត្ថុធាតុដើមរាវដែលគ្មានរ៉ាឌីយ៉ូសកម្មដូចជាសំណល់អង់ទីហ្វ្រីស សំណល់ប្រេងម៉ាស៊ីន ទឹកស្អុយក្រុង ប្រេងកាត ជាដើម ហើយជាទូទៅប្រែប្រួលទៅតាមប្រភេទរាវដែលប្រើសម្រាប់ផលិតវា។ បច្ចេកវិទ្យាថ្មីមួយ ដែលហៅថា PlasmaArcFlow\tm ធ្វើឱ្យសំណល់ហូរឆ្លងកាត់ច្រកភ្លើងអគ្គិសនីដែលស្ថិតនៅក្រោមទឹករវាងអេឡិចត្រូតធម្មតា។ ច្រកភ្លើងនោះបំបែកម៉ូលេគុលរាវទៅជាធាតុអាតូមរបស់វា ហើយបង្កើតភ្លើងភាសីនៅក្បែរអេឡិចត្រូតនៅសីតុណ្ហភាពប្រហែល 10,000$^o$ F។ បន្ទាប់មកបច្ចេកវិទ្យានេះធ្វើឱ្យភ្លើងភាសីនោះចេញពីអេឡិចត្រូត ហើយគ្រប់គ្រងការបង្រួមឡើងវិញរបស់វាទៅជាឥន្ធនៈដែលអាចទទួលយកបានសម្រាប់បរិស្ថាន។ ឥន្ធនៈថ្មីទាំងនេះមានរចនាសម្ព័ន្ធគីមីថ្មីមួយ ដែលត្រូវបានកំណត់អត្តសញ្ញាណជាលើកដំបូងដោយម្នាក់ក្នុងចំណោមយើង (R.M.S.) ដែលត្រូវបានគេសម្គាល់ដោយក្រុមម៉ូលេគុល និងអាតូមធម្មតានៅក្រោមការភ្ជាប់ថ្មីមួយដែលមានលក្ខណៈអេឡិចត្រូម៉ាញ៉េទិក។ ក្រុមទាំងនេះបង្កើតជាប្រភេទគីមីថ្មីមួយ ខុសពីម៉ូលេគុលធម្មតា ដោយសារតែវាស្ថិតនៅក្នុងស្ថានភាពធម្មតា ហើយបង្ហាញពីសញ្ញាអ៊ីនហ្វ្រារែដគ្មាន (លើកលែងតែសញ្ញារបស់ធាតុម៉ូលេគុលធម្មតា) ដែលធ្វើឱ្យបញ្ជាក់ថាការភ្ជាប់នោះមិនមែនជាប្រភេទវ៉ាឡង់នោះទេ។ ដោយសារហេតុផលនេះ ប្រភេទគីមីថ្មីត្រូវបានហៅថា ''ម៉ូលេគុលអេឡិចត្រូម៉ាញ៉េទិករបស់សង់ទីលី'' ឬ ''ម៉ាញ៉េគុល''។
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Efficient exploration remains a challenging problem in reinforcement learning, especially for those tasks where rewards from environments are sparse. A commonly used approach for exploring such environments is to introduce some "intrinsic" reward. In this work, we focus on model uncertainty estimation as an intrinsic reward for efficient exploration. In particular, we introduce an implicit generative modeling approach to estimate a Bayesian uncertainty of the agent's belief of the environment dynamics. Each random draw from our generative model is a neural network that instantiates the dynamic function, hence multiple draws would approximate the posterior, and the variance in the future prediction based on this posterior is used as an intrinsic reward for exploration. We design a training algorithm for our generative model based on the amortized Stein Variational Gradient Descent. In experiments, we compare our implementation with state-of-the-art intrinsic reward-based exploration approaches, including two recent approaches based on an ensemble of dynamic models. In challenging exploration tasks, our implicit generative model consistently outperforms competing approaches regarding data efficiency in exploration.
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يبقى الاستكشاف الفعّال مشكلة صعبة في التعلم المعزز، لا سيما بالنسبة للمهام التي تكون فيها المكافآت من البيئات نادرة. إن إحدى الطرق الشائعة لاستكشاف مثل هذه البيئات هي إدخال مكافأة "داخلية" معينة. في هذا العمل، نركز على تقدير عدم اليقين في النموذج باعتباره مكافأة داخلية من أجل استكشاف فعّال. وتحديدًا، نقدّم نهجًا نموذجيًا توليديًا ضمنيًا لتقدير عدم اليقين البايزي في اعتقادات العامل بشأن ديناميكيات البيئة. كل سحب عشوائي من النموذج التوليدي لدينا يُنتج شبكة عصبية تمثّل دالة الديناميكية، وبالتالي فإن السحوبات المتعددة تُقدّر التوزيع اللاحق، ويُستخدم التباين في التنبؤات المستقبلية المبنية على هذا التوزيع اللاحق كمكافأة داخلية للاستكشاف. نُصمم خوارزمية تدريب للنموذج التوليدي لدينا تعتمد على نزول التدرج التبايني المُموّل (amortized Stein Variational Gradient Descent). في التجارب، قمنا بمقارنة تنفيذنا مع أحدث الطرق المعتمدة على المكافآت الداخلية، بما في ذلك نهجان حديثان يعتمدان على مجموعة من نماذج الديناميكية. في مهام الاستكشاف الصعبة، تفوق النموذج التوليدي الضمني الخاص بنا باستمرار على الطرق المنافسة من حيث الكفاءة في استخدام البيانات أثناء الاستكشاف.
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We investigate dust entrainment by photoevaporative winds in protoplanetary discs using dusty smoothed particle hydrodrodynamics (SPH). We use unequal-mass particles to resolve more than five orders of magnitude in disc/outflow density and a one-fluid formulation to efficiently simulate an equivalent magnitude range in drag stopping time. We find that only micron sized dust grains and smaller can be entrained in EUV driven winds. The maximum grain size is set by dust settling in the disc rather than aerodynamic drag in the wind. More generally, there is a linear relationship between the base flow density and the maximum entrainable grain size in the wind. A pileup of micron sized dust grains can occur in the upper atmosphere at critical radii in the disc as grains decouple from the low-density wind. Entrainment is a strong function of location in the disc, resulting in a size sorting of grains in the outflow---the largest grain being carried out between $10$--$20\,$AU. The peak dust density for each grain size occurs at the inner edge of its own entrainment region.
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Investigamos o arraste de poeira por ventos fotoevaporativos em discos protoplanetários utilizando hidrodinâmica de partículas suavizadas com poeira (SPH). Utilizamos partículas de massas desiguais para resolver mais de cinco ordens de grandeza na densidade do disco/fluxo de saída e uma formulação de um único fluido para simular eficientemente uma faixa equivalente na escala de tempo de arrasto. Descobrimos que apenas grãos de poeira de tamanho micrométrico ou menores podem ser arrastados por ventos impulsionados por radiação EUV. O tamanho máximo dos grãos é determinado pelo assentamento da poeira no disco, e não pelo arrasto aerodinâmico no vento. De forma mais geral, existe uma relação linear entre a densidade do fluxo na base e o tamanho máximo dos grãos passíveis de arraste no vento. Pode ocorrer um acúmulo de grãos de poeira de tamanho micrométrico na atmosfera superior em raios críticos do disco, quando os grãos se desacoplam do vento de baixa densidade. O arraste é fortemente dependente da localização no disco, resultando em uma separação por tamanho dos grãos no fluxo de saída—os maiores grãos sendo transportados entre $10$--$20\,$UA. A densidade máxima de poeira para cada tamanho de grão ocorre na borda interna da sua própria região de arraste.
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Computational procedures to foresee the 3D structure of aptamers are in continuous progress. They constitute a crucial input to research, mainly when the crystallographic counterpart of the structures in silico produced is not present. At now, many codes are able to perform structure and binding prediction, although their ability in scoring the results remains rather weak. In this paper, we propose a novel procedure to complement the ranking outcomes of free docking code, by applying it to a set of anti-angiopoietin aptamers, whose performances are known. We rank the in silico produced configurations, adopting a maximum likelihood estimate, based on their topological and electrical properties. From the analysis, two principal kinds of conformers are identified, whose ability to mimick the binding features of the natural receptor is discussed. The procedure is easily generalizable to many biological biomolecules, useful for increasing chances of success in designing high-specificity biosensors (aptasensors).
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Aptamerlerin 3D yapısını öngörmek amacıyla hesaplamalı prosedürler sürekli gelişmektedir. Bu prosedürler, özellikle in silico üretilen yapıların kristalografi verileri mevcut olmadığında araştırmalar için kritik bir girdi oluşturur. Şu anda birçok kod, yapı ve bağlanma tahmini yapabilmektedir, ancak sonuçları puanlama yetenekleri hâlâ oldukça sınırlıdır. Bu makalede, performansları bilinen bir dizi anti-anjiyopoietin aptamerine uygulayarak, serbest dokinq kodlarının sıralama sonuçlarını tamamlayan yeni bir prosedür öneriyoruz. Yapıların topolojik ve elektriksel özelliklerine dayalı bir maksimum olabilirlik tahmini kullanarak in silico üretilen konfigürasyonları sıralıyoruz. Analiz sonucunda, doğal reseptörün bağlanma özelliklerini taklit etme yetenekleri tartışılan iki ana konformer türü belirlenmiştir. Bu prosedür, yüksek özgüllükte biyosensörlerin (aptasensörlerin) tasarımında başarı şansını artırmak için faydalı olacak şekilde birçok biyolojik biomolekül için kolayca genellenebilir.
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Estimating a covariance matrix is an important task in applications where the number of variables is larger than the number of observations. Shrinkage approaches for estimating a high-dimensional covariance matrix are often employed to circumvent the limitations of the sample covariance matrix. A new family of nonparametric Stein-type shrinkage covariance estimators is proposed whose members are written as a convex linear combination of the sample covariance matrix and of a predefined invertible target matrix. Under the Frobenius norm criterion, the optimal shrinkage intensity that defines the best convex linear combination depends on the unobserved covariance matrix and it must be estimated from the data. A simple but effective estimation process that produces nonparametric and consistent estimators of the optimal shrinkage intensity for three popular target matrices is introduced. In simulations, the proposed Stein-type shrinkage covariance matrix estimator based on a scaled identity matrix appeared to be up to 80% more efficient than existing ones in extreme high-dimensional settings. A colon cancer dataset was analyzed to demonstrate the utility of the proposed estimators. A rule of thumb for adhoc selection among the three commonly used target matrices is recommended.
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Bir değişken sayısının gözlem sayısından daha fazla olduğu uygulamalarda kovaryans matrisinin tahmini önemli bir görevdir. Örnek kovaryans matrisinin sınırlamalarını aşmak için yüksek boyutlu bir kovaryans matrisini tahmin etmede sıkça büzülme (shrinkage) yöntemleri kullanılır. Örnek kovaryans matrisi ile önceden tanımlanmış tersinir bir hedef matrisin dışbükey doğrusal kombinasyonu olarak ifade edilen yeni bir parametrik olmayan Stein tipi büzülmeli kovaryans kestiricisi ailesi önerilmiştir. Frobenius norm kriterine göre, en iyi dışbükey doğrusal kombinasyonu belirleyen optimal büzülme şiddeti gözlemlenemeyen kovaryans matrisine bağlıdır ve bu nedenle verilerden tahmin edilmelidir. Üç popüler hedef matris için optimal büzülme şiddetinin parametrik olmayan ve tutarlı tahmincilerini üreten basit ancak etkili bir tahmin süreci sunulmuştur. Benzetimlerde, ölçeklenmiş birim matrise dayalı önerilen Stein tipi büzülmeli kovaryans matrisi kestiricisi, aşırı yüksek boyutlu durumlarda mevcut kestiricilere göre %80'e varan oranda daha verimli olmuştur. Önerilen kestiricilerin yararlılığını göstermek için bir kolon kanseri veri seti analiz edilmiştir. Üç yaygın kullanılan hedef matris arasında keyfi seçim için genel bir kural önerilmiştir.
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The Berkeley spectrograph aboard the ORFEUS telescope made its second flight on the 14-day ORFEUS-SPAS II mission of the Space Shuttle Columbia in November/December 1996. Approximately half of the available observing time was dedicated to the Berkeley spectrograph, which was used by both Principal and Guest Investigators. The spectrograph's full bandpass is 390-1218 A; here we discuss its in-flight performance at far-ultraviolet (FUV) wavelengths, where most of the observations were performed. The instrument's effective area peaks at 8.9 +/- 0.5 cm^2 near 1020 A, and the mean spectral resolution is 95 km/s FWHM for point sources. Over most of the spectral range, the typical night-time background event rate in each spectral resolution element was about 0.003/s. Simultaneous background observations of an adjacent blank field were provided through a secondary, off-axis aperture. The Berkeley spectrograph's unique combination of sensitivity and resolution provided valuable observations of approximately 105 distinct astronomical targets, ranging in distance from the earth's own moon to some of the brightest AGN.
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1996 жылғы қараша-желтоқсан айларындағы 14 күнге созылған ORFEUS-SPAS II миссиясы кезінде ORFEUS телескопына орнатылған Беркли спектрографы өзінің екінші ұшысын жасады. Байқауға болатын уақыттың шамамен жартысы Беркли спектрографына бөлінді, оны Бас және Шақырылған зерттеушілер де пайдаланды. Спектрографтың толық жұмыс істеу диапазоны 390-1218 А; бұл жерде біз байқаулардың көпшілігі жүргізілген алыс ультракүлгін (FUV) толқын ұзындықтарындағы ұшудағы оның жұмыс істеуін қарастырамыз. Құрылғының тиімді ауданы 1020 А маңында 8,9 +/- 0,5 см^2 шамасында шоғырланады, ал нүктелік бұлақтар үшін орташа спектрлік ажыратымдылық 95 км/с FWHM құрайды. Спектрлік диапазонның көбісінде әрбір спектрлік ажыратымдылық элементі үшін тәуліктің түнгі уақытындағы фондық оқиғалар жиілігі шамамен 0,003/с құрады. Сыртқы осьтен ауытқыған екінші тесік арқылы көршілес бос аймақтың фондық байқаулары бір уақытта жүргізілді. Сезімталдық пен ажыратымдылықтың Беркли спектрографына тән үйлесімі Жердің өзінің айынан бастап ең жарық AGN-дерге дейінгі аралықта орналасқан шамамен 105 әртүрлі астрономиялық мақсаттар бойынша бағалы байқаулар жасауға мүмкіндік берді.
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We examine classical and quantum aspects of the planar non-compact spin system coupled with Chern-Simons gauge field in the presence of background charge. We first define our classical spin system as non- relativistic non-linear sigma model in which the order parameter spin takes value in the non-compact manifold ${\cal M}=SU(1,1)/U(1)$. Although the naive model does not allow any finite energy self dual solitons, it is shown that the gauged system admits static Bogomol'nyi solitons with finite energy whose rotationally symmetric soliton solutions are analyzed in detail. We also discuss the large spin limit in which the self-dual equation reduces to the well-known gauged non- linear Schr\"odinger model or Abelian Higgs model, depending on the choice of the background charge term. Then, we perform quantization of the model. We find that the spin algebra satisfies anomalous commutation relations, and the system is a field theoretic realization of the anyons.
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យើងសិក្សាផ្នែក បុរាណ និង ប៉ោងក់របស់ប្រព័ន្ធស្ពិនល្ខ័នដែលគ្មានកំហាប់ ដែលភ្ជាប់ជាមួយនឹងវាល ហ្គែល Chern-Simons នៅក្នុងបរិបទនៃបន្ទុកផ្ទៃខាងក្រោយ។ ជាដំបូង យើងកំណត់ប្រព័ន្ធស្ពិនបុរាណរបស់យើងថាជាម៉ូដែលស៊ីគម៉ា មិនលីនេអ៊ែរ មិនទាក់ទងនឹងទ្រព្យសម្បត្តិ ដែលស្ពិនប៉ារ៉ាម៉ែត្រលំដាប់ យកតម្លៃនៅក្នុងចំនុចមិនកំហាប់ ${\cal M}=SU(1,1)/U(1)$។ ទោះបីជាម៉ូដែលដើមមិនអនុញ្ញាតឱ្យមានសូលីតុងស្វ័យភាពដែលមានថាមពលកំណត់ក៏ដោយ ប៉ុន្តែបានបង្ហាញថា ប្រព័ន្ធដែលមានហ្គែលអនុញ្ញាតឱ្យមានសូលីតុង Bogomol'nyi ស្ថិតស្ថេរដែលមានថាមពលកំណត់ ដែលដំណោះស្រាយសូលីតុងដែលមានស៊ីម៉ែត្រវិលជុំវិញត្រូវបានវិភាគយ៉ាងលម្អិត។ យើងក៏ពិភាក្សាផងដែរអំពីដែនកំណត់ស្ពិនធំ ដែលសមីការស្វ័យភាពបន្ថយទៅជាម៉ូដែល Schr\"odinger មិនលីនេអ៊ែរដែលមានហ្គែល ឬម៉ូដែល Higgs អាបេលី ដែលអាស្រ័យលើការជ្រើសរើសពាក្យបន្ទុកផ្ទៃខាងក្រោយ។ បន្ទាប់មក យើងធ្វើការបំបែកប្រព័ន្ធទៅជាប៉ោងក់។ យើងរកឃើញថា ពិជគណិតស្ពិនផ្ទៀងផ្ទាត់ទំនាក់ទំនងប្តូរកន្លែងមានកំហុស ហើយប្រព័ន្ធនេះគឺជាការសម្រេចបាននូវទ្រឹស្តីវាលសម្រាប់ anyons។
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km
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We extend the study of a model of competitive cluster growth in an active medium to a basis of networks; this is done by adding nonlocal connections with probability $p$ to sites on a regular lattice, thus enabling one to interpolate between regularity and full randomness. The model on networks demonstrates high sensitivity to small changes in initial configurations, which we characterize using damage spreading. The main focus of this paper is, however, the devising of survival strategies through selective networking, to alter the the fate of an arbitrarily chosen cluster: whether this be to revive a dying cluster to life, or to make a weak survivor into a stronger one. Although such goals are typically achieved by networking with relatively small clusters, our results suggest that it ought to be possible also to network with peers and larger clusters. The main indication of this comes from the probability distributions of mass differences between survivors and their immediate neighbours, which show an astonishing universality; they suggest strategies for winning against the odds.
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เราขยายการศึกษาแบบจำลองการเติบโตของกลุ่มก้อนที่แข่งขันกันในสื่อที่มีกิจกรรม ไปสู่พื้นฐานของเครือข่าย โดยการเพิ่มการเชื่อมโยงแบบไม่ท้องถิ่นด้วยความน่าจะเป็น $p$ เข้ากับตำแหน่งต่าง ๆ บนตาข่ายปกติ ซึ่งทำให้สามารถแทรกค่าระหว่างความเป็นระเบียบและสุ่มอย่างสมบูรณ์ได้ แบบจำลองบนเครือข่ายแสดงความไวต่อการเปลี่ยนแปลงเล็กน้อยในสภาพเริ่มต้นอย่างมาก ซึ่งเราอธิบายโดยใช้การแพร่กระจายของความเสียหาย อย่างไรก็ตาม จุดเน้นหลักของบทความนี้คือการวางกลยุทธ์เพื่อความอยู่รอดผ่านการสร้างเครือข่ายแบบคัดเลือก เพื่อเปลี่ยนชะตากรรมของกลุ่มก้อนที่เลือกขึ้นมาอย่างสุ่ม ไม่ว่าจะเป็นการฟื้นคืนชีพกลุ่มก้อนที่กำลังจะตาย หรือการเปลี่ยนผู้อยู่รอดที่อ่อนแอให้แข็งแกร่งขึ้น แม้ว่าเป้าหมายดังกล่าวมักจะบรรลุได้โดยการสร้างเครือข่ายกับกลุ่มก้อนขนาดเล็ก ผลลัพธ์ของเราชี้ให้เห็นว่าควรเป็นไปได้ที่จะสร้างเครือข่ายกับกลุ่มก้อนขนาดใกล้เคียงกันหรือกลุ่มก้อนที่ใหญ่กว่าได้ด้วย ข้อบ่งชี้หลักประการหนึ่งเกิดจากการแจกแจงความน่าจะเป็นของความต่างของมวลระหว่างกลุ่มก้อนที่อยู่รอดกับเพื่อนบ้านโดยตรง ซึ่งแสดงถึงความเป็นสากลที่น่าประหลาดใจ และชี้แนะกลยุทธ์ในการเอาชนะความน่าจะเป็นที่ไม่เอื้ออำนวย
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th
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The prompt optical emission of GRB 990123 was uncorrelated to the gamma-ray light-curve and exhibited temporal properties similar to those of the steeply-decaying, early X-ray emission observed by Swift at the end of many bursts. These facts suggest that the optical counterpart of GRB 990123 was the large-angle emission released during (the second pulse of) the burst. If the optical and gamma-ray emissions of GRB 990123 have, indeed, the same origin then their properties require that (i) the optical counterpart was synchrotron emission and the gamma-rays arose from inverse-Compton scatterings ("synchrotron self-Compton model"), (ii) the peak-energy of the optical-synchrotron component was at ~20 eV, and (iii) the burst emission was produced by a relativistic outflow moving at Lorentz factor > 450 and at a radius > 10^{15} cm, which is comparable to the outflow deceleration radius. Because the spectrum of GRB 990123 was optically thin above 2 keV, the magnetic field behind the shock must have decayed on a length-scale of <1% of the thickness of the shocked gas, which corresponds to 10^6-10^7 plasma skin-depths. Consistency of the optical counterpart decay rate and its spectral slope (or that of the burst, if they represent different spectral components) with the expectations for the large-angle burst emission represents the most direct test of the unifying picture proposed here for GRB 990123.
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Pancaran optik awal GRB 990123 tidak berkaitan dengan lengkung-cahaya sinar-gamma dan menunjukkan sifat masa yang serupa dengan pancaran sinar-X awal yang berkurang dengan mendadak yang diperhatikan oleh Swift pada akhir banyak letupan. Fakta-fakta ini mencadangkan bahawa rupa sepadan optik GRB 990123 adalah pancaran sudut-besar yang dibebaskan semasa (denyutan kedua) letupan tersebut. Jika pancaran optik dan sinar-gamma GRB 990123 memang mempunyai asal yang sama, maka sifat-sifat mereka memerlukan bahawa (i) rupa sepadan optik adalah pancaran sinchrotron dan sinar-gamma timbul daripada serakan Compton songsang ("model sinchrotron sendiri-Compton"), (ii) tenaga puncak komponen sinchrotron optik berada di ~20 eV, dan (iii) pancaran letupan dihasilkan oleh aliran keluar kerelatifan yang bergerak pada faktor Lorentz > 450 dan pada jejari > 10^{15} cm, yang sebanding dengan jejari perlahanan aliran keluar. Memandangkan spektrum GRB 990123 adalah nipis secara optik di atas 2 keV, medan magnet di belakang kejutan mesti telah mereput pada skala panjang <1% daripada ketebalan gas terkejut, yang sepadan dengan 10^6-10^7 kedalaman kulit plasma. Kekonsistenan kadar penyusutan rupa sepadan optik dan kecerunan spektrumnya (atau spektrum letupan, jika mereka mewakili komponen spektrum yang berbeza) dengan jangkaan bagi pancaran letupan sudut-besar merupakan ujian paling langsung terhadap gambaran penyatuan yang dicadangkan di sini untuk GRB 990123.
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ms
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We present the discovery of 130.87 day periodic near-infrared flux variability for the Class II T Tauri star WL 4 (= 2MASS J16271848-2429059, ISO-Oph 128). Our data are from the 2MASS Calibration Point Source Working Database, and constitute 1580 observations in J, H and Ks of a field in Rho Ophiuchus used to calibrate the 2MASS All-Sky Survey. We identify a light curve for WL 4 with eclipse amplitudes of ~0.4 mag lasting more than one-quarter the period, and color variations in J-H and H-Ks of ~0.1 mag. The long period cannot be explained by stellar rotation. We propose that WL 4 is a triple YSO system, with an inner binary orbital period of 130.87 days. We posulate that we are observing each component of the inner binary alternately being eclipsed by a circum-binary disk with respect to our line of sight. This system will be useful in investigating terrestrial zone YSO disk properties and dynamics at ~1 Myr.
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Біз II класының Т Тельцулы жұлдызы WL 4 (= 2MASS J16271848-2429059, ISO-Oph 128) үшін 130,87 тәулік периодты жақын инфрақызыл сәуле шығару өзгерімін аштық. Біздің деректер 2MASS Калибрлеу Нүктелік Көзі Жұмыс Баспасынан алынған және 2MASS Барлық Аспан Шолуын калибрлеу үшін қолданылатын Рхо Офиухус аймағының J, H және Ks диапазоны бойынша 1580 бақылаудан тұрады. Біз WL 4 үшін периодтың төрттен бірінен астам уақыт бойы созылатын және жарықтығы шамамен 0,4 шам шамасын құрайтын жарық қисығын, сондай-ақ J-H және H-Ks түстеріндегі шамамен 0,1 шам шамасындағы өзгерістерді анықтадық. Ұзақ период жұлдыздың айналуымен түсіндірілмейді. Біз WL 4 жүйесінің ішкі екі компоненті бар және олардың бір-бірінен айналу периоды 130,87 тәулік болатын үш еселі ЖЖО жүйесі болуы мүмкін деп ұсынамыз. Біз осы екі компоненттің әрқайсысы көзбен көру сызығымызға қатысты екі жұлдызды дискінің айналасында біртіндеп бір-бірінің жарығын басып тұрғанын байқап отырмыз деп болжаймыз. Бұл жүйе шамамен 1 млн жылдық жергілікті аймақтағы ЖЖО дискілерінің қасиеттері мен динамикасын зерттеу үшін пайдалы болады.
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kk
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We consider as given a discrete time financial market with a risky asset and options written on that asset and determine both the sub- and super-hedging prices of an American option in the model independent framework of ArXiv:1305.6008. We obtain the duality of results for the sub- and super-hedging prices. For the sub-hedging prices we discuss whether the sup and inf in the dual representation can be exchanged (a counter example shows that this is not true in general). For the super-hedging prices we discuss several alternative definitions and argue why our choice is more reasonable. Then assuming that the path space is compact, we construct a discretization of the path space and demonstrate the convergence of the hedging prices at the optimal rate. The latter result would be useful for numerical computation of the hedging prices. Our results generalize those of ArXiv:1304.3574 to the case when static positions in (finitely many) European options can be used in the hedging portfolio.
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আমরা একটি ঝুঁকিপূর্ণ সম্পদ এবং ঐ সম্পদের উপর লেখা অপশনগুলির উপর ভিত্তি করে একটি বিচ্ছিন্ন সময়ের আর্থিক বাজারকে প্রদত্ত হিসাবে বিবেচনা করি এবং ArXiv:1305.6008-এর মডেল-স্বাধীন কাঠামোতে একটি আমেরিকান অপশনের সাব-এবং সুপার-হেজিং মূল্যগুলি নির্ধারণ করি। আমরা সাব- এবং সুপার-হেজিং মূল্যগুলির জন্য দ্বৈততা ফলাফল পাই। সাব-হেজিং মূল্যের ক্ষেত্রে আমরা আলোচনা করি যে দ্বৈত উপস্থাপনায় sup এবং inf-এর স্থান পরিবর্তন করা যায় কিনা (একটি প্রতি-উদাহরণ দেখায় যে সাধারণভাবে এটি সত্য নয়)। সুপার-হেজিং মূল্যগুলির ক্ষেত্রে আমরা বেশ কয়েকটি বিকল্প সংজ্ঞার আলোচনা করি এবং ব্যাখ্যা করি যে কেন আমাদের পছন্দটি আরও যুক্তিসঙ্গত। তারপর ধরে নেওয়া হয় যে পথ-স্থানটি সংকুচিত, আমরা পথ-স্থানের একটি বিচ্ছিন্নকরণ গঠন করি এবং ন্যূনতম হারে হেজিং মূল্যগুলির অভিসরণ প্রদর্শন করি। পরবর্তী ফলাফলটি হেজিং মূল্যগুলির সাংখ্যিক গণনার ক্ষেত্রে উপযোগী হবে। আমাদের ফলাফলগুলি ArXiv:1304.3574-এর ফলাফলগুলিকে সেই ক্ষেত্রে সাধারণীকরণ করে যেখানে হেজিং পোর্টফোলিওতে (সসীম সংখ্যক) ইউরোপীয় অপশনগুলিতে স্ট্যাটিক অবস্থানগুলি ব্যবহার করা যেতে পারে।
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bn
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The stochastic nature of photovoltaic (PV) power has led both academia and industry to a large amount of research work aiming at the development of accurate PV power forecasting models. However, most of those models are based on machine learning algorithms and are considered as black boxes which do not provide any insight or explanation about their predictions. Therefore, their direct implementation in environments, where transparency is required, and the trust associated with their predictions may be questioned. To this end, we propose a two stage probabilistic forecasting framework able to generate highly accurate, reliable, and sharp forecasts yet offering full transparency on both the point forecasts and the prediction intervals (PIs). In the first stage, we exploit natural gradient boosting (NGBoost) for yielding probabilistic forecasts while in the second stage, we calculate the Shapley additive explanation (SHAP) values in order to fully understand why a prediction was made. To highlight the performance and the applicability of the proposed framework, real data from two PV parks located in Southern Germany are employed. Initially, the natural gradient boosting is thoroughly compared with two state-of-the-art algorithms, namely Gaussian process and lower upper bound estimation, in a wide range of forecasting metrics. Secondly, a detailed analysis of the model's complex nonlinear relationships and interaction effects between the various features is presented. The latter allows us to interpret the model, identify some learned physical properties, explain individual predictions, reduce the computational requirements for the training without jeopardizing the model accuracy, detect possible bugs, and gain trust in the model. Finally, we conclude that the model was able to develop nonlinear relationships following human logic and intuition based on learned physical properties.
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ফটোভোলটাইক (PV) বিদ্যুতের স্টোকাস্টিক প্রকৃতির কারণে একাডেমিয়া এবং শিল্প উভয় ক্ষেত্রেই সঠিক ফটোভোলটাইক বিদ্যুৎ ভবিষ্যদ্বাণী মডেল উন্নয়নের উদ্দেশ্যে অসংখ্য গবেষণার কাজ হয়েছে। তবে এমন বেশিরভাগ মডেল মেশিন লার্নিং অ্যালগরিদমের উপর ভিত্তি করে তৈরি হয়েছে এবং এগুলিকে ব্ল্যাক বক্স হিসাবে বিবেচনা করা হয় যা তাদের ভবিষ্যদ্বাণী সম্পর্কে কোনো অন্তর্দৃষ্টি বা ব্যাখ্যা প্রদান করে না। ফলস্বরূপ, যেসব পরিবেশে স্বচ্ছতা প্রয়োজন, সেগুলিতে এগুলির সরাসরি প্রয়োগ এবং এদের ভবিষ্যদ্বাণীর সঙ্গে যুক্ত বিশ্বাসযোগ্যতা নিয়ে প্রশ্ন উঠতে পারে। এ উদ্দেশ্যে, আমরা একটি দ্বিপর্যায়ী সম্ভাব্যতাভিত্তিক ভবিষ্যদ্বাণী কাঠামো প্রস্তাব করি যা অত্যন্ত নির্ভুল, নির্ভরযোগ্য এবং সূক্ষ্ম ভবিষ্যদ্বাণী উৎপন্ন করতে সক্ষম হবে কিন্তু পয়েন্ট ভবিষ্যদ্বাণী এবং ভবিষ্যদ্বাণী ব্যবধি (PIs)-এর ক্ষেত্রে সম্পূর্ণ স্বচ্ছতা প্রদান করবে। প্রথম পর্যায়ে, আমরা সম্ভাব্যতাভিত্তিক ভবিষ্যদ্বাণী প্রদানের জন্য ন্যাচারাল গ্র্যাডিয়েন্ট বুস্টিং (NGBoost) ব্যবহার করি, আর দ্বিতীয় পর্যায়ে আমরা কেন একটি নির্দিষ্ট ভবিষ্যদ্বাণী করা হয়েছে তা সম্পূর্ণভাবে বোঝার জন্য শ্যাপলি যোগজ ব্যাখ্যা (SHAP) মানগুলি গণনা করি। প্রস্তাবিত কাঠামোর কার্যকারিতা এবং প্রয়োগযোগ্যতা তুলে ধরার জন্য দক্ষিণ জার্মানিতে অবস্থিত দুটি ফটোভোলটাইক পার্কের প্রকৃত তথ্য ব্যবহার করা হয়। প্রথমত, ন্যাচারাল গ্র্যাডিয়েন্ট বুস্টিংকে গাউসিয়ান প্রক্রিয়া এবং নিম্ন ও ঊর্ধ্ব সীমা অনুমান নামক দুটি অগ্রণী অ্যালগরিদমের সাথে ভবিষ্যদ্বাণীর বিভিন্ন মেট্রিকের এক বিস্তৃত পরিসরে তুলনামূলক বিশ্লেষণ করা হয়। দ্বিতীয়ত, বিভিন্ন বৈশিষ্ট্যগুলির মধ্যে মডেলের জটিল অরৈখিক সম্পর্ক এবং পারস্পরিক প্রভাবের একটি বিস্তারিত বিশ্লেষণ উপস্থাপন করা হয়। এর ফলে আমরা মডেলটি ব্যাখ্যা করতে পারি, কিছু শেখা পদার্থবিজ্ঞানের ধর্মগুলি চিহ্নিত করতে পারি, পৃথক পৃথক ভবিষ্যদ্বাণী ব্যাখ্যা করতে পারি, মডেলের নির্ভুলতা ক্ষতিগ্রস্ত না করে প্রশিক্ষণের জন্য প্রয়োজনীয় গণনার চাহিদা কমাতে পারি, সম্ভাব্য বাগগুলি শনাক্ত করতে পারি এবং মডেলের প্রতি বিশ্বাস অর্জন করতে পারি। অবশেষে, আমরা এই উপসংহারে আসি যে মডেলটি শেখা পদার্থবিজ্ঞানের ধর্মের উপর ভিত্তি করে মানুষের যুক্তি এবং সহজানুভূতি অনুসারে অরৈখিক সম্পর্ক গঠন করতে সক্ষম হয়েছে।
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bn
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In multi-band systems, electrons from different orbitals coexist at the Fermi surface. An attractive interaction among these quasi-particles gives rise to inter-band or hybrid pairs which eventually condense in a superconducting state. These quasi-particles have a natural mismatch of their Fermi wave-vectors, $\delta k_F$, which depends on the strength of the hybridization between their orbitals. The existence of this natural scale suggests the possibility of inhomogeneous superconducting ground states in these systems, even in the absence of an applied magnetic field. Furthermore, since hybridization $V$ depends on pressure, this provides an external parameter to control the wave-vectors mismatch at the Fermi surface. In this work, we study the phase diagram of a two-dimensional, two-band metal with inter-band pairing. We show that as the mismatch between the Fermi wave-vectors of the two hybrid bands is reduced, the system presents a normal-to-inhomogeneous superconductor quantum phase transition at a critical value of the hybridization $V_c=\Delta_0$. The superconducting ground state for $V<V_c$ is characterized by a wave-vector with magnitude $|\mathbf{q}_c|=q_c=2 \Delta_0/\bar{v}_f$. Here $\Delta_0$ is the superconducting gap in the homogeneous state and $\bar{v}_f$ the average Fermi velocity. We discuss the nature of the quantum critical point (QCP) at $V_c$ and obtain the associated quantum critical exponents.
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ในระบบหลายแถบ อิเล็กตรอนจากวงโคจรต่างๆ จะอยู่ร่วมกันที่ผิวของเฟอร์มี การมีปฏิสัมพันธ์ดึงดูดระหว่างอนุภาคกึ่งอิสระเหล่านี้ทำให้เกิดคู่ที่มีการผสมข้ามแถบ หรือคู่แบบไฮบริด ซึ่งในที่สุดจะควบแน่นกลายเป็นสถานะซูเปอร์คอนดักเตอร์ อนุภาคกึ่งอิสระเหล่านี้มีเวกเตอร์คลื่นของเฟอร์มีที่ไม่สอดคล้องกันตามธรรมชาติ $\delta k_F$ ซึ่งขึ้นอยู่กับความเข้มข้นของการไฮบริดไรเซชันระหว่างวงโคจรของพวกมัน การมีอยู่ของสเกลธรรมชาตินี้ชี้ให้เห็นถึงความเป็นไปได้ของสถานะพื้นซูเปอร์คอนดักเตอร์ที่ไม่สม่ำเสมอในระบบเหล่านี้ แม้จะไม่มีสนามแม่เหล็กภายนอก ยิ่งไปกว่านั้น เนื่องจากการไฮบริดไรเซชัน $V$ ขึ้นกับแรงดัน จึงทำให้แรงดันเป็นพารามิเตอร์ภายนอกที่สามารถควบคุมความไม่สอดคล้องกันของเวกเตอร์คลื่นที่ผิวเฟอร์มีได้ ในงานนี้ เราศึกษาแผนภาพเฟสของโลหะสองมิติที่มีสองแถบและมีการจับคู่ข้ามแถบ เราแสดงให้เห็นว่าเมื่อความไม่สอดคล้องกันของเวกเตอร์คลื่นเฟอร์มีของแถบไฮบริดทั้งสองลดลง ระบบจะเกิดการเปลี่ยนเฟสควอนตัมจากสถานะปกติไปเป็นซูเปอร์คอนดักเตอร์ที่ไม่สม่ำเสมอ ที่ค่าวิกฤตของการไฮบริดไรเซชัน $V_c=\Delta_0$ สถานะพื้นซูเปอร์คอนดักเตอร์สำหรับ $V<V_c$ มีลักษณะโดยเวกเตอร์คลื่นที่มีขนาด $|\mathbf{q}_c|=q_c=2 \Delta_0/\bar{v}_f$ โดยที่ $\Delta_0$ คือช่องว่างซูเปอร์คอนดักเตอร์ในสถานะที่สม่ำเสมอ และ $\bar{v}_f$ คือความเร็วเฟอร์มีเฉลี่ย เราอภิปรายลักษณะของจุดวิกฤตควอนตัม (QCP) ที่ $V_c$ และหาเลขชี้กำลังวิกฤตควอนตัมที่เกี่ยวข้องได้
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th
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Binary black holes on quasicircular orbits with spins aligned with their orbital angular momentum have been testbeds for analytic and numerical relativity for decades, not least because symmetry ensures that such configurations are equilibrium solutions to the spin-precession equations. In this work, we show that these solutions can be unstable when the spin of the higher-mass black hole is aligned with the orbital angular momentum and the spin of the lower-mass black hole is anti-aligned. Spins in these configurations are unstable to precession to large misalignment when the binary separation $r$ is between the values $r_{\rm ud\pm}= (\sqrt{\chi_1} \pm \sqrt{q \chi_2})^4 (1-q)^{-2} M$, where $M$ is the total mass, $q \equiv m_2/m_1$ is the mass ratio, and $\chi_1$ ($\chi_2$) is the dimensionless spin of the more (less) massive black hole. This instability exists for a wide range of spin magnitudes and mass ratios and can occur in the strong-field regime near merger. We describe the origin and nature of the instability using recently developed analytical techniques to characterize fully generic spin precession. This instability provides a channel to circumvent astrophysical spin alignment at large binary separations, allowing significant spin precession prior to merger affecting both gravitational-wave and electromagnetic signatures of stellar-mass and supermassive binary black holes.
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Двоичные чёрные дыры на квазикруговых орбитах со спинами, направленными вдоль их орбитального момента импульса, на протяжении десятилетий служили испытательной площадкой для аналитической и численной теории относительности, не в последнюю очередь потому, что симметрия гарантирует, что такие конфигурации являются равновесными решениями уравнений прецессии спинов. В настоящей работе мы показываем, что эти решения могут быть неустойчивыми в случае, когда спин более массивной чёрной дыры направлен по орбитальному моменту импульса, а спин менее массивной чёрной дыры — против него. Спины в таких конфигурациях неустойчивы к прецессии, приводящей к большим углам несоосности, когда расстояние между компонентами двойной системы $r$ находится между значениями $r_{\rm ud\pm}= (\sqrt{\chi_1} \pm \sqrt{q \chi_2})^4 (1-q)^{-2} M$, где $M$ — полная масса, $q \equiv m_2/m_1$ — отношение масс, а $\chi_1$ ($\chi_2$) — безразмерный спин более (менее) массивной чёрной дыры. Эта неустойчивость существует в широком диапазоне величин спинов и соотношений масс и может возникать в сильнопольном режиме вблизи слияния. Мы описываем происхождение и характер этой неустойчивости с использованием недавно разработанных аналитических методов, позволяющих полностью охарактеризовать произвольную прецессию спинов. Данная неустойчивость представляет канал, позволяющий обойти астрофизическое выравнивание спинов на больших расстояниях в двойной системе, обеспечивая значительную прецессию спинов до слияния, что влияет как на гравитационно-волновые, так и на электромагнитные сигналы от двойных чёрных дыр звёздных и сверхмассивных масс.
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ru
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It was shown recently that the anomalous scaling of simultaneous correlation functions in turbulence is intimately related to the breaking of temporal scale invariance, which is equivalent to the appearance of infinitely many times scales in the time dependence of time-correlation functions. In this paper we derive a continued fraction representation of turbulent time correlation functions which is exact and in which the multiplicity of time scales is explicit. We demonstrate that this form yields precisely the same scaling laws for time derivatives and time integrals as the "multi-fractal" representation that was used before. Truncating the continued fraction representation yields the "best" estimates of time correlation functions if the given information is limited to the scaling exponents of the simultaneous correlation functions up to a certain, finite order. It is worth noting that the derivation of a continued fraction representation obtained here for an operator which is not Hermitian or anti-Hermitian may be of independent interest.
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Недавно было показано, что аномальное масштабирование одновременных корреляционных функций в турбулентности тесно связано с нарушением временной масштабной инвариантности, что эквивалентно появлению бесконечного числа временных масштабов в временной зависимости временных корреляционных функций. В данной работе мы выводим представление временных корреляционных функций турбулентности в виде непрерывной дроби, которое является точным и в котором множественность временных масштабов явно выражена. Мы показываем, что данная форма приводит к тем же самым законам масштабирования для временных производных и временных интегралов, что и ранее использовавшееся «мультифрактальное» представление. Усечение представления в виде непрерывной дроби даёт «наилучшие» оценки временных корреляционных функций, если имеющаяся информация ограничена показателями масштабирования одновременных корреляционных функций до определённого, конечного порядка. Следует отметить, что вывод представления в виде непрерывной дроби, полученный здесь для оператора, не являющегося эрмитовым или антиэрмитовым, может представлять самостоятельный интерес.
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ru
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We employ the Schwinger boson mean-field approach to study the effects of arbitrary frustrated bonds and plaquettes (formed from four frustrated bonds) in two-dimensional ferro- and antiferromagnets on the spin-wave spectrum and the correlation length at finite temperatures. We distinguish between strongly frustrated bonds (plaquettes), when the frustrated coupling $J^\prime$ exceeds the spin canting threshold $J_c$, and weakly frustrated bonds (plaquettes), with $J^\prime <J_c, (J_c-J^\prime)/J_c\sim 1$. It is shown that in antiferromagnets the amplitude of spin-wave scattering on strongly frustrated bonds or plaquettes grows with the decrease of the temperature. A small amount of such defects reduces significantly the spin-wave stiffness and the correlation length at low temperatures. As a result, the quasi-2D N\'eel temperature is sharply suppressed. Quantum fluctuations are also considered and their effect on the spin-wave spectrum is shown to be of the order of $(2S)^{-2}\ln^{-1}2S$ in the large spin limit. For weakly frustrated (nonfrustrated) defect bonds (plaquettes) the spin-wave stiffness renormalization is of the order of the dopant concentration and does not depend on the temperature. The results account for the observed properties of doped quasi-2D $La_2CuO_{4+x}$.
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Nous utilisons l'approche du champ moyen à bosons de Schwinger pour étudier les effets de liaisons frustrées arbitraires et de plaquettes (formées de quatre liaisons frustrées) dans des ferro- et antiferromagnétiques bidimensionnels sur le spectre des ondes de spin et la longueur de corrélation à température finie. Nous distinguons entre les liaisons (plaquettes) fortement frustrées, lorsque le couplage frustré $J^\prime$ dépasse le seuil de basculement du spin $J_c$, et les liaisons (plaquettes) faiblement frustrées, pour lesquelles $J^\prime < J_c$, avec $(J_c - J^\prime)/J_c \sim 1$. Nous montrons que, dans les antiferromagnétiques, l'amplitude de la diffusion des ondes de spin sur des liaisons ou plaquettes fortement frustrées augmente lorsque la température diminue. Une faible concentration de tels défauts réduit significativement la rigidité des ondes de spin et la longueur de corrélation à basse température. En conséquence, la température de Néel quasi-2D est fortement abaissée. Les fluctuations quantiques sont également prises en compte, et leur effet sur le spectre des ondes de spin est montré être d'ordre $(2S)^{-2}\ln^{-1}2S$ dans la limite du spin élevé. Pour les liaisons (plaquettes) défaut faiblement frustrées (non frustrées), la renormalisation de la rigidité des ondes de spin est de l'ordre de la concentration des dopants et ne dépend pas de la température. Ces résultats rendent compte des propriétés observées dans les composés quasi-2D dopés $La_2CuO_{4+x}$.
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fr
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Estimating a covariance matrix is an important task in applications where the number of variables is larger than the number of observations. Shrinkage approaches for estimating a high-dimensional covariance matrix are often employed to circumvent the limitations of the sample covariance matrix. A new family of nonparametric Stein-type shrinkage covariance estimators is proposed whose members are written as a convex linear combination of the sample covariance matrix and of a predefined invertible target matrix. Under the Frobenius norm criterion, the optimal shrinkage intensity that defines the best convex linear combination depends on the unobserved covariance matrix and it must be estimated from the data. A simple but effective estimation process that produces nonparametric and consistent estimators of the optimal shrinkage intensity for three popular target matrices is introduced. In simulations, the proposed Stein-type shrinkage covariance matrix estimator based on a scaled identity matrix appeared to be up to 80% more efficient than existing ones in extreme high-dimensional settings. A colon cancer dataset was analyzed to demonstrate the utility of the proposed estimators. A rule of thumb for adhoc selection among the three commonly used target matrices is recommended.
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يُعد تقدير مصفوفة التباين المشترك مهمة مهمة في التطبيقات التي يكون فيها عدد المتغيرات أكبر من عدد الملاحظات. وغالبًا ما تُستخدم طرق التقلص لتقدير مصفوفة التباين المشترك عالية الأبعاد لتفادي محدوديات مصفوفة التباين المشترك العينة. ويُقترح فئة جديدة من مقدرات التباين المشترك التقديرية من نوع شتاين غير المعلمية، التي تكون عناصرها عبارة عن تركيبة خطية محدبة من مصفوفة التباين المشترك العينة ومصفوفة مستهدفة محددة مسبقًا وقابلة للانعكاس. وفقًا لمعيار المعيار التبادلي، فإن شدة التقلص المثلى التي تُعرِّف أفضل تركيبة خطية محدبة تعتمد على مصفوفة التباين المشترك غير الملحوظة، ويجب تقديرها من البيانات. ويُقدَّم عملية تقدير بسيطة لكنها فعالة تُنتج مقدرات غير معلمية ومتسقة لشدة التقلص المثلى بالنسبة لثلاث مصفوفات مستهدفة شائعة. وفي المحاكاة، بدا أن مقدر مصفوفة التباين المشترك بتقنية التقلص من نوع شتاين المقترح، والقائم على مصفوفة هوية مقياسية، أكثر كفاءة بنسبة تصل إلى 80٪ مقارنة بالمقدرات الحالية في البيئات العالية الأبعاد للغاية. وتم تحليل مجموعة بيانات سرطان القولون لتوضيح فائدة المقدرات المقترحة. ويُوصى بقاعدة تقريبية للاختيار العشوائي بين المصفوفات المستهدفة الثلاث الشائعة الاستخدام.
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ar
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Combining multi-site data can strengthen and uncover trends, but is a task that is marred by the influence of site-specific covariates that can bias the data and therefore any downstream analyses. Post-hoc multi-site correction methods exist but have strong assumptions that often do not hold in real-world scenarios. Algorithms should be designed in a way that can account for site-specific effects, such as those that arise from sequence parameter choices, and in instances where generalisation fails, should be able to identify such a failure by means of explicit uncertainty modelling. This body of work showcases such an algorithm, that can become robust to the physics of acquisition in the context of segmentation tasks, while simultaneously modelling uncertainty. We demonstrate that our method not only generalises to complete holdout datasets, preserving segmentation quality, but does so while also accounting for site-specific sequence choices, which also allows it to perform as a harmonisation tool.
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کئی مقامات کے ڈیٹا کو ملانے سے رجحانات کو مضبوط کیا جا سکتا ہے اور نئے رجحانات کو ظاہر کیا جا سکتا ہے، لیکن اس کام پر مقامات کے مخصوص متغیرات کے اثرات کی وجہ سے رکاوٹیں حائل ہوتی ہیں جو ڈیٹا میں تعصب پیدا کر سکتے ہیں اور اس طرح تمام بعد کے تجزیات کو متاثر کر سکتے ہیں۔ متعدد مقامات کی اصلاح کے طریقہ کار موجود ہیں لیکن ان کی مضبوط فرضیات اکثر حقیقی دنیا کی صورتحال میں درست نہیں ہوتیں۔ الگورتھم کو اس انداز میں ڈیزائن کیا جانا چاہیے کہ وہ تسلسل کے پیرامیٹر کے انتخاب جیسے مقامات کے مخصوص اثرات کو بھی مدنظر رکھ سکے، اور اس صورت میں جب جنرلائزیشن ناکام ہو جائے، وہ صریح عدم یقینی کی ماڈلنگ کے ذریعے اس ناکامی کی نشاندہی کرنے کے قابل ہو۔ اس کام کا مجموعہ ایسے الگورتھم کو دکھاتا ہے جو تقسیم کے کاموں کے تناظر میں حصول کی طبیعیات کے لحاظ سے مضبوط ہو سکتا ہے، جبکہ اسی وقت عدم یقینی کی ماڈلنگ بھی کرتا ہے۔ ہم یہ ظاہر کرتے ہیں کہ ہمارا طریقہ نہ صرف مکمل ہولڈ آؤٹ ڈیٹا سیٹس پر جنرلائز کرتا ہے اور تقسیم کی معیار کو برقرار رکھتا ہے، بلکہ یہ مقامات کے مخصوص تسلسل کے انتخابات کا احاطہ کرتے ہوئے یہ کام بھی کرتا ہے، جس کی وجہ سے یہ ہم آہنگی کے آلے کے طور پر بھی کام کر سکتا ہے۔
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ur
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Anomaly detection presents a unique challenge in machine learning, due to the scarcity of labeled anomaly data. Recent work attempts to mitigate such problems by augmenting training of deep anomaly detection models with additional labeled anomaly samples. However, the labeled data often does not align with the target distribution and introduces harmful bias to the trained model. In this paper, we aim to understand the effect of a biased anomaly set on anomaly detection. Concretely, we view anomaly detection as a supervised learning task where the objective is to optimize the recall at a given false positive rate. We formally study the relative scoring bias of an anomaly detector, defined as the difference in performance with respect to a baseline anomaly detector. We establish the first finite sample rates for estimating the relative scoring bias for deep anomaly detection, and empirically validate our theoretical results on both synthetic and real-world datasets. We also provide an extensive empirical study on how a biased training anomaly set affects the anomaly score function and therefore the detection performance on different anomaly classes. Our study demonstrates scenarios in which the biased anomaly set can be useful or problematic, and provides a solid benchmark for future research.
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异常检测在机器学习中面临独特挑战，主要原因在于标注的异常数据稀缺。近期研究尝试通过引入额外的标注异常样本，以增强深度异常检测模型的训练，从而缓解此类问题。然而，这些标注数据通常与目标分布不一致，会为训练出的模型引入有害偏差。本文旨在理解有偏异常数据集对异常检测的影响。具体而言，我们将异常检测视为一项监督学习任务，其目标是在给定假阳性率下优化召回率。我们形式化地研究了异常检测器的相对评分偏差，该偏差定义为相对于基准异常检测器在性能上的差异。我们首次建立了用于估计深度异常检测相对评分偏差的有限样本收敛速率，并在合成数据集和真实世界数据集上对理论结果进行了实证验证。此外，我们还进行了广泛的实证研究，分析有偏的训练异常集如何影响异常评分函数，进而影响对不同异常类别检测性能的影响。本研究展示了有偏异常集在某些情况下可能有益或有害的情形，为未来研究提供了坚实的基准。
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zh
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We conduct a series of measurements on the thermodynamic properties of an optically-trapped strongly interacting Fermi gas, including the energy $E$, entropy $S$, and sound velocity $c$. Our model-independent measurements of $E$ and $S$ enable a precision study of the finite temperature thermodynamics. The $E(S)$ data are directly compared to several recent predictions. The temperature in both the superfluid and normal fluid regime is obtained from the fundamental thermodynamic relation $T=\partial E/\partial S$ by parameterizing the $E(S)$ data. Our $E(S)$ data are also used to experimentally calibrate the endpoint temperatures obtained for adiabatic sweeps of the magnetic field between the ideal and strongly interacting regimes. This enables the first experimental calibration of the temperature scale used in experiments on fermionic pair condensation. Our calibration shows that the ideal gas temperature measured for the onset of pair condensation corresponds closely to the critical temperature estimated in the strongly interacting regime from the fits to our $E(S)$ data. The results are in very good agreement with recent predictions. Finally, using universal thermodynamic relations, we estimate the chemical potential and heat capacity of the trapped gas from the $E(S)$ data.
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ພວກເຮົາດຳເນີນການວັດແທກຊຸດໜຶ່ງຕໍ່ຄຸນສົມບັດທາງດ້ານອຸນຫະພູມຂອງກາຊ Fermi ທີ່ມີການປ່ຽນແປງກັນຢ່າງເຂັ້ມຂຸ້ນ ແລະ ຖືກຈັບໄວ້ດ້ວຍແສງ, ລວມທັງພະລັງງານ $E$, ອັນຕະລາຍ $S$, ແລະ ຄວາມໄວຂອງສຽງ $c$. ການວັດແທກ $E$ ແລະ $S$ ທີ່ບໍ່ຂຶ້ນກັບຮູບແບບຂອງພວກເຮົາ ເຮັດໃຫ້ສາມາດສຶກສາດ້ານອຸນຫະພູມທີ່ມີຄວາມແນ່ນອນໃນອຸນຫະພູມຈຳກັດ. ຂໍ້ມູນ $E(S)$ ແມ່ນຖືກນຳມາປຽບທຽບໂດຍກົງກັບຄາດຄະເນຫຼາຍຢ່າງໃນຊ່ວງເວລາຜ່ານມາ. ອຸນຫະພູມໃນທັງສອງຂອບເຂດຂອງສົ້ນລຽບລຽນ ແລະ ຂອງສົ້ນທຳມະດາ ແມ່ນໄດ້ມາຈາກຄວາມສຳພັນພື້ນຖານດ້ານອຸນຫະພູມ $T=\partial E/\partial S$ ໂດຍການອະທິບາຍຂໍ້ມູນ $E(S)$. ຂໍ້ມູນ $E(S)$ ຂອງພວກເຮົາຍັງຖືກນຳໃຊ້ເພື່ອປັບຄ່າຄວາມຖືກຕ້ອງຂອງອຸນຫະພູມໃນຈຸດສິ້ນສຸດທີ່ໄດ້ມາຈາກການເຄື່ອນຂອງເຄື່ອງຈັກເຄື່ອງມາກເນຕິກຈາກຂອບເຂດອິດສະຫຼະໄປສູ່ຂອບເຂດທີ່ມີການປ່ຽນແປງກັນຢ່າງເຂັ້ມຂຸ້ນ. ສິ່ງນີ້ເຮັດໃຫ້ເກີດການປັບຄ່າຄວາມຖືກຕ້ອງດ້ານອຸນຫະພູມຄັ້ງທຳອິດໃນການທົດລອງກ່ຽວກັບການກົດຕົວຂອງຄູ່ fermion. ການປັບຄ່າຂອງພວກເຮົາສະແດງໃຫ້ເຫັນວ່າ ອຸນຫະພູມຂອງກາຊອິດສະຫຼະທີ່ຖືກວັດແທກໃນຂະນະທີ່ເລີ່ມເກີດການກົດຕົວຂອງຄູ່ ສອດຄ່ອງຢ່າງໃກ້ຊິດກັບອຸນຫະພູມສຳຄັນທີ່ຄາດຄະເນໄວ້ໃນຂອບເຂດທີ່ມີການປ່ຽນແປງກັນຢ່າງເຂັ້ມຂຸ້ນ ຈາກການຈັບຄູ່ຂໍ້ມູນ $E(S)$ ຂອງພວກເຮົາ. ຜົນໄດ້ຮັບສອດຄ່ອງຢ່າງດີກັບຄາດຄະເນຫຼ້າສຸດ. ສຸດທ້າຍ, ໂດຍການນຳໃຊ້ຄວາມສຳພັນທາງດ້ານອຸນຫະພູມທີ່ເປັນສາກົນ, ພວກເຮົາປະເມີນຄວາມເປັນໄປໄດ້ຂອງເຄມີ ແລະ ຄວາມສາມາດຮັບຄວາມຮ້ອນຂອງກາຊທີ່ຖືກຈັບໄວ້ຈາກຂໍ້ມູນ $E(S)$.
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lo
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The space of invariant affine connections on every $3$-Sasakian homogeneous manifold of dimension at least $7$ is described. In particular, the remarkable subspaces of invariant affine metric connections, and the subclass with skew-torsion, are also determined. To this aim, an explicit construction of all $3$-Sasakian homogeneous manifolds is exhibited. The unique $3$-Sasakian homogeneous manifolds which admit nontrivial Einstein with skew-torsion invariant affine connections are those of dimension $7$, that is, $\mathbb{S}^7=\mathrm{Sp} (2)/ \mathrm{Sp(1)}$, $\mathbb{R} P^7=\mathrm{Sp}(2)/ \mathrm{Sp(1)}\times \mathbb{Z}_{2}$ and the Aloff-Wallach space $\mathfrak{W}^{7}_{1,1}= \mathrm{SU}(3)/ \mathrm{U}(1)$. For $\mathbb{S}^7$ and $\mathbb{R} P^7$, the set of such connections is in one to one correspondence with two copies of the conformal linear transformation group of the Euclidean space, while it is strictly bigger for $\mathfrak{W}^{7}_{1,1}$. In addition, the set of invariant connections with totally skew-symmetric torsion whose Ricci tensor is multiple of the metric, with different factors, on the canonical vertical and horizontal distributions, is fully described on every $3$-Sasakian homogeneous manifold. An affine connection satisfying these conditions is distinguished, characterized by parallelizing all the characteristic vector fields associated to the $3$-Sasakian structure. This connection is Einstein with skew-torsion for the $7$-dimensional examples. Several results have also been adapted to the nonnecessarily homogeneous setting. In this case, the above mentioned sets of affine connections are, in general, only proper subsets satisfying the properties.
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次元が7以上であるすべての3-サスカイン等質多様体上の不変アフィン接続の空間が記述されている。特に、不変アフィン計量接続の注目すべき部分空間、および歪ねじれを持つ部分クラスも決定されている。この目的のために、すべての3-サスカイン等質多様体の明示的な構成が示されている。非自明な歪ねじれ付きアインシュタイン不変アフィン接続を許容する唯一の3-サスカイン等質多様体は、次元7のものに限られ、すなわち、$\mathbb{S}^7=\mathrm{Sp}(2)/\mathrm{Sp(1)}$、$\mathbb{R} P^7=\mathrm{Sp}(2)/\mathrm{Sp(1)}\times \mathbb{Z}_{2}$、およびアロフ-ウォラッハ空間$\mathfrak{W}^{7}_{1,1}= \mathrm{SU}(3)/ \mathrm{U}(1)$である。$\mathbb{S}^7$および$\mathbb{R} P^7$については、このような接続の集合は、ユークリッド空間の共形線型変換群の2つのコピーと一対一に対応するが、$\mathfrak{W}^{7}_{1,1}$については、その集合は真に大きくなる。さらに、標準的な垂直および水平分布上でリッチテンソルが（異なる係数を持つ）計量のスカラー倍となるような完全に歪対称なねじれを持つ不変接続の集合が、すべての3-サスカイン等質多様体上で完全に記述されている。このような条件を満たす接続として一つの特別な接続が特筆され、これは3-サスカイン構造に付随するすべての特性ベクトル場を平行化するという特徴を持つ。この接続は7次元の例に対しては歪ねじれ付きアインシュタインである。いくつかの結果は、必ずしも等質でない設定にまで拡張されている。この場合、上記のアフィン接続の集合は、一般には、該当する性質を満たす真の部分集合にすぎない。
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ja
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We propose an automatic parameter selection strategy for the problem of image super-resolution for images corrupted by blur and additive white Gaussian noise with unknown standard deviation. The proposed approach exploits the structure of both the down-sampling and the blur operators in the frequency domain and computes the optimal regularisation parameter as the one optimising a suitable residual whiteness measure. Computationally, the proposed strategy relies on the fast solution of generalised Tikhonov $\ell_2$-$\ell_2$ problems as proposed in a work from Zhao et al. These problems naturally appear as substeps of the Alternating Direction Method of Multipliers (ADMM) optimisation approach used to solve super-resolution problems with non-quadratic and often non-smooth, sparsity-promoting regularisers both in convex and in non-convex regimes. After detailing the theoretical properties defined in the frequency domain which allow to express the whiteness functional in a compact way, we report an exhaustive list of numerical experiments proving the effectiveness of the proposed approach for different type of problems, in comparison with well-known parameter selection strategy such as, e.g., the discrepancy principle.
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เราเสนอกลยุทธ์การเลือกพารามิเตอร์โดยอัตโนมัติสำหรับปัญหาการเพิ่มความละเอียดของภาพ (image super-resolution) สำหรับภาพที่มีการเบลอและมีสัญญาณรบกวนแบบ Gaussian เพิ่มเข้ามา โดยไม่ทราบค่าส่วนเบี่ยงเบนมาตรฐาน วิธีการที่เสนออาศัยโครงสร้างของตัวดำเนินการลดขนาดภาพ (down-sampling) และตัวดำเนินการเบลอ (blur operators) ในโดเมนความถี่ และคำนวณค่าพารามิเตอร์ของการปรับให้มีความเรียบ (regularisation parameter) ที่เหมาะสมที่สุด โดยเลือกค่าที่ทำให้ตัวชี้วัดความเป็นสุญญากาศของส่วนตกค้าง (residual whiteness measure) มีค่าเหมาะสมที่สุด ในเชิงการคำนวณ กลยุทธ์ที่เสนออาศัยการแก้ปัญหาทั่วไปของปัญหา Tikhonov แบบทั่วไป (generalised Tikhonov $\ell_2$-$\ell_2$) อย่างรวดเร็ว ตามที่เสนอไว้ในงานของ Zhao และคณะ ปัญหาดังกล่าวเกิดขึ้นตามธรรมชาติเป็นขั้นตอนย่อยหนึ่งในวิธีการปรับทิศทางแบบสลับ (Alternating Direction Method of Multipliers: ADMM) ซึ่งใช้แก้ปัญหาการเพิ่มความละเอียดของภาพที่มีตัวปรับให้มีความเรียบที่ไม่ใช่เชิงกำลังสอง (non-quadratic) และมักไม่เรียบ (non-smooth) ที่ส่งเสริมความเบาบาง (sparsity-promoting regularisers) ทั้งในกรณีที่เป็นเชิงนูน (convex) และไม่เป็นเชิงนูน (non-convex) หลังจากอธิบายรายละเอียดคุณสมบัติทางทฤษฎีที่นิยามในโดเมนความถี่ ซึ่งทำให้สามารถแสดงฟังก์ชันวัดความเป็นสุญญากาศได้อย่างกระชับ เราได้รายงานผลการทดลองทางตัวเลขอย่างละเอียดครอบคลุม เพื่อพิสูจน์ประสิทธิภาพของวิธีการที่เสนอในปัญหาหลายประเภท โดยเปรียบเทียบกับกลยุทธ์การเลือกพารามิเตอร์ที่เป็นที่รู้จักดี เช่น หลักการความคลาดเคลื่อน (discrepancy principle)
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th
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We perform numerical simulations of a two-dimensional bidisperse granular packing subjected to both a static confining pressure and a sinusoidal dynamic forcing applied by a wall on one edge of the packing. We measure the response experienced by a wall on the opposite edge of the packing and obtain the resonant frequency of the packing as the static or dynamic pressures are varied. Under increasing static pressure, the resonant frequency increases, indicating a velocity increase of elastic waves propagating through the packing. In contrast, when the dynamic amplitude is increased for fixed static pressure, the resonant frequency decreases, indicating a decrease in the wave velocity. This occurs both for compressional and for shear dynamic forcing, and is in agreement with experimental results. We find that the average contact number $Z_c$ at the resonant frequency decreases with increasing dynamic amplitude, indicating that the elastic softening of the packing is associated with a reduced number of grain-grain contacts through which the elastic waves can travel. We image the excitations created in the packing and show that there are localized disturbances or soft spots that become more prevalent with increasing dynamic amplitude. Our results are in agreement with experiments on glass bead packings and earth materials such as sandstone and granite, and may be relevant to the decrease in elastic wave velocities that has been observed to occur near fault zones after strong earthquakes, in surficial sediments during strong ground motion, and in structures during earthquake excitation.
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Kami menjalankan simulasi berangka bagi susunan butiran dua dimensi berdisperse dwi yang dikenakan tekanan statik mengurung dan daya dinamik berbentuk sinus yang dikenakan oleh dinding pada satu tepi susunan tersebut. Kami mengukur sambutan yang dialami oleh dinding pada tepi susunan yang bertentangan dan memperoleh frekuensi resonan susunan tersebut apabila tekanan statik atau dinamik diubah. Dengan peningkatan tekanan statik, frekuensi resonan meningkat, menunjukkan peningkatan halaju gelombang elastik yang merambat melalui susunan tersebut. Sebaliknya, apabila amplitud dinamik ditingkatkan pada tekanan statik tetap, frekuensi resonan menurun, menunjukkan penurunan halaju gelombang. Ini berlaku bagi daya dinamik mampatan dan ricih, dan sejajar dengan keputusan eksperimen. Kami mendapati bahawa nombor sentuhan purata $Z_c$ pada frekuensi resonan berkurang dengan peningkatan amplitud dinamik, menunjukkan bahawa pelunakan elastik susunan tersebut dikaitkan dengan pengurangan bilangan sentuhan butiran-butiran yang menjadi laluan gelombang elastik. Kami menghasilkan imej gangguan yang terbentuk dalam susunan tersebut dan menunjukkan kewujudan gangguan setempat atau tompok lembut yang menjadi semakin kerap dengan peningkatan amplitud dinamik. Keputusan kami sejajar dengan eksperimen ke atas susunan manik kaca dan bahan bumi seperti batu pasir dan granit, serta berkemungkinan berkaitan dengan penurunan halaju gelombang elastik yang diperhatikan berlaku berhampiran zon sesar selepas gempa bumi kuat, dalam enapan permukaan semasa gerakan tanah kuat, dan dalam struktur semasa gegaran gempa bumi.
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ms
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We perform numerical simulations of a two-dimensional bidisperse granular packing subjected to both a static confining pressure and a sinusoidal dynamic forcing applied by a wall on one edge of the packing. We measure the response experienced by a wall on the opposite edge of the packing and obtain the resonant frequency of the packing as the static or dynamic pressures are varied. Under increasing static pressure, the resonant frequency increases, indicating a velocity increase of elastic waves propagating through the packing. In contrast, when the dynamic amplitude is increased for fixed static pressure, the resonant frequency decreases, indicating a decrease in the wave velocity. This occurs both for compressional and for shear dynamic forcing, and is in agreement with experimental results. We find that the average contact number $Z_c$ at the resonant frequency decreases with increasing dynamic amplitude, indicating that the elastic softening of the packing is associated with a reduced number of grain-grain contacts through which the elastic waves can travel. We image the excitations created in the packing and show that there are localized disturbances or soft spots that become more prevalent with increasing dynamic amplitude. Our results are in agreement with experiments on glass bead packings and earth materials such as sandstone and granite, and may be relevant to the decrease in elastic wave velocities that has been observed to occur near fault zones after strong earthquakes, in surficial sediments during strong ground motion, and in structures during earthquake excitation.
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نُجري محاكاة عددية لتعبئة حبيبية ثنائية الأبعاد ومختلطة الحجم، تخضع لكل من ضغط تقييدي ثابت وتحريض ديناميكي جيبي يتم تطبيقه بواسطة جدار عند أحد حافتي التعبئة. نقيس الاستجابة التي يختبرها جدار موجود عند الحافة المقابلة للتعبئة، ونحصل على التردد الرنيني للتعبئة مع تغير الضغط الثابت أو الديناميكي. مع زيادة الضغط الثابت، يزداد التردد الرنيني، مما يدل على زيادة سرعة الموجات المرنة الممتدة عبر التعبئة. على النقيض من ذلك، عندما يزداد السعة الديناميكية مع بقاء الضغط الثابت ثابتاً، ينخفض التردد الرنيني، مما يشير إلى انخفاض في سرعة الموجة. ويحدث هذا كلاً في حالة التحريض الديناميكي الانضغاطي والقصي، وهو متفق مع النتائج التجريبية. نجد أن عدد التماس المتوسط $Z_c$ عند التردد الرنيني يقل مع زيادة السعة الديناميكية، مما يدل على أن التليين المرن للتعبئة يرتبط بعدد أقل من تماسات الحبيبات التي يمكن أن تنتقل خلالها الموجات المرنة. نُصوّر الإثارات الناتجة داخل التعبئة ونُظهر وجود اضطرابات موضعية أو مناطق رخوة تصبح أكثر انتشاراً مع زيادة السعة الديناميكية. نتائجنا تتفق مع التجارب التي أُجريت على تعبئات كريات زجاجية وعلى مواد أرضية مثل الحجر الرملي والجرانيت، وقد تكون ذات صلة بالانخفاض الملاحظ في سرعات الموجات المرنة بالقرب من مناطق الصدوع بعد الزلازل القوية، وفي الرواسب السطحية أثناء الحركة الأرضية الشديدة، وفي المنشآت أثناء الإثارة الزلزالية.
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ar
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We perform numerical simulations of a two-dimensional bidisperse granular packing subjected to both a static confining pressure and a sinusoidal dynamic forcing applied by a wall on one edge of the packing. We measure the response experienced by a wall on the opposite edge of the packing and obtain the resonant frequency of the packing as the static or dynamic pressures are varied. Under increasing static pressure, the resonant frequency increases, indicating a velocity increase of elastic waves propagating through the packing. In contrast, when the dynamic amplitude is increased for fixed static pressure, the resonant frequency decreases, indicating a decrease in the wave velocity. This occurs both for compressional and for shear dynamic forcing, and is in agreement with experimental results. We find that the average contact number $Z_c$ at the resonant frequency decreases with increasing dynamic amplitude, indicating that the elastic softening of the packing is associated with a reduced number of grain-grain contacts through which the elastic waves can travel. We image the excitations created in the packing and show that there are localized disturbances or soft spots that become more prevalent with increasing dynamic amplitude. Our results are in agreement with experiments on glass bead packings and earth materials such as sandstone and granite, and may be relevant to the decrease in elastic wave velocities that has been observed to occur near fault zones after strong earthquakes, in surficial sediments during strong ground motion, and in structures during earthquake excitation.
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Realizamos simulaciones numéricas de un empaquetamiento granular bidisperso bidimensional sometido tanto a una presión de confinamiento estática como a una fuerza dinámica sinusoidal aplicada por una pared en uno de los bordes del empaquetamiento. Medimos la respuesta experimentada por una pared en el borde opuesto del empaquetamiento y obtenemos la frecuencia de resonancia del empaquetamiento mientras se varía la presión estática o dinámica. Al aumentar la presión estática, la frecuencia de resonancia aumenta, lo que indica un incremento en la velocidad de las ondas elásticas que se propagan a través del empaquetamiento. En contraste, cuando la amplitud dinámica se incrementa para una presión estática fija, la frecuencia de resonancia disminuye, indicando una reducción en la velocidad de las ondas. Esto ocurre tanto para fuerzas dinámicas de compresión como de corte, y concuerda con resultados experimentales. Encontramos que el número medio de contactos \(Z_c\) en la frecuencia de resonancia disminuye al aumentar la amplitud dinámica, lo que indica que el ablandamiento elástico del empaquetamiento está asociado con una reducción en el número de contactos entre granos a través de los cuales pueden propagarse las ondas elásticas. Visualizamos las excitaciones generadas en el empaquetamiento y mostramos que existen perturbaciones localizadas o puntos débiles que se vuelven más prevalentes al aumentar la amplitud dinámica. Nuestros resultados concuerdan con experimentos realizados en empaquetamientos de perlas de vidrio y materiales terrestres como arenisca y granito, y podrían ser relevantes para explicar la disminución en las velocidades de las ondas elásticas que se ha observado cerca de zonas de falla después de terremotos fuertes, en sedimentos superficiales durante movimientos sísmicos intensos, y en estructuras durante la excitación sísmica.
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es
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We study the supersymmetric particle spectra and LHC collider observables for the large-volume string models with a fundamental scale of 10^{11} GeV that arise in moduli-fixed string compactifications with branes and fluxes. The presence of magnetic fluxes on the brane world volume, required for chirality, perturb the soft terms away from those previously computed in the dilute-flux limit. We use the difference in high-scale gauge couplings to estimate the magnitude of this perturbation and study the potential effects of the magnetic fluxes by generating many random spectra with the soft terms perturbed around the dilute flux limit. Even with a 40% variation in the high-scale soft terms the low-energy spectra take a clear and predictive form. The resulting spectra are broadly similar to those arising on the SPS1a slope, but more degenerate. In their minimal version the models predict the ratios of gaugino masses to be M_1 : M_2 : M_3=(1.5 - 2) : 2 : 6, different to both mSUGRA and mirage mediation. Among the scalars, the squarks tend to be lighter and the sleptons heavier than for comparable mSUGRA models. We generate 10 fb^{-1} of sample LHC data for the random spectra in order to study the range of collider phenomenology that can occur. We perform a detailed mass reconstruction on one example large-volume string model spectrum. 100 fb^{-1} of integrated luminosity is sufficient to discriminate the model from mSUGRA and aspects of the sparticle spectrum can be accurately reconstructed.
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我们研究了在带有膜和通量的模场固定弦紧化中产生的、基本能标为10^{11} GeV的大体积弦模型的超对称粒子谱以及LHC对撞机可观测量。膜世界体上为产生手征性所必需的磁通量，会使软项偏离此前在稀疏通量极限下计算的结果。我们利用高能标下规范耦合的差异来估计这种扰动的大小，并通过在稀疏通量极限附近随机扰动软项生成大量粒子谱，以研究磁通量可能造成的影响。即使高能标软项变化达40%，低能谱仍呈现出清晰且可预测的形式。所得谱在总体上与SPS1a斜率上出现的谱相似，但具有更高的简并性。在最简版本中，这些模型预测的胶子微子质量比为M_1 : M_2 : M_3 = (1.5 - 2) : 2 : 6，与mSUGRA和幻影中介机制均不同。在标量粒子中，相比于类似的mSUGRA模型，squark通常更轻，而slepton则更重。我们为这些随机谱生成了10 fb^{-1}的LHC模拟数据，以研究可能出现的对撞现象范围。我们对一个典型的大体积弦模型谱进行了详细的质量重建。100 fb^{-1}的积分亮度足以将该模型与mSUGRA区分开，并可对超对称粒子谱的若干特征进行精确重建。
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zh
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