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Utilization enhancement is a key concern to cluster owners. Google's cluster
manager named Borg manages its clusters at an overall utilization higher than
many others' clusters. Recently, Google has disclosed the details of its
powerful cluster manager Borg. Quite a few lessons are summarized from the Borg
experiences. Nevertheless, we find that more can be learned if the Borg design
is correlated with the trace analysis of a Google cluster managed by Borg.
There is one such trace released four years ago. In this paper, we analyze the
Google cluster trace and make 10 observations not found in previous analyses.
We also correlates the results of our analysis and previous analyses to the
Borg design, such that we find two measures that can possibly further improve
cluster utilization over Borg.
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http://arxiv.org/abs/1508.02111v2
|
We will state 10 problems, and solve some of them, for partitions in triangle-free graphs related to Erd\H{o}s' Sparse Half Conjecture. Among others we prove the following variant of it: For every sufficiently large even integer $n$ the following holds. Every triangle-free graph on $n$ vertices has a partition $V(G)=A\cup B$ with $|A|=|B|=n/2$ such that $e(G[A])+e(G[B])\leq n^2/16$. This result is sharp since the complete bipartite graph with class sizes $3n/4$ and $n/4$ achieves equality, when $n$ is a multiple of 4. Additionally, we discuss similar problems for $K_4$-free graphs.
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https://arxiv.org/abs/2203.15764v1
|
In this paper the results of a beam test characterization campaign of 3D trench silicon pixel sensors are presented. A time resolution in the order of 10 ps was measured both for non-irradiated and irradiated sensors up to a fluence of $2.5 \cdot 10^{16}\,1\,MeV\, n_{eq}\,cm^{-2}$. This feature and a detection efficiency close to $99\%$ make this sensors one of the best candidates for 4D tracking detectors in High-Energy-Physics experiments.
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https://arxiv.org/abs/2209.14632v2
|
Boggle logic puzzles are based on the popular word game Boggle, where you are
given list of words, and your goal is to recreate a Boggle board. In this paper
we give an overview of known results and then propose a number of problems
related to these puzzles.
|
http://arxiv.org/abs/1506.04173v1
|
Loss of key personnel has always been a risk for research software projects. Key members of the team may have to step away due to illness or burnout, to care for a family member, from a loss of financial support, or because their career is going in a new direction. Today, though, political and financial changes are putting large numbers of researchers out of work simultaneously, potentially leaving large amounts of research software abandoned. This article presents ten tips to help researchers ensure that the software they have built will continue to be usable after they have left their present job -- whether in the course of voluntary career moves or researcher mobility, but particularly in cases of involuntary departure due to political or institutional changes.
|
https://arxiv.org/abs/2505.06484v1
|
Foundation models--such as GPT, CLIP, and DINO--have achieved revolutionary progress in the past several years and are commonly believed to be a promising approach for general-purpose AI. In particular, self-supervised learning is adopted to pre-train a foundation model using a large amount of unlabeled data. A pre-trained foundation model is like an ``operating system'' of the AI ecosystem. Specifically, a foundation model can be used as a feature extractor for many downstream tasks with little or no labeled training data. Existing studies on foundation models mainly focused on pre-training a better foundation model to improve its performance on downstream tasks in non-adversarial settings, leaving its security and privacy in adversarial settings largely unexplored. A security or privacy issue of a pre-trained foundation model leads to a single point of failure for the AI ecosystem. In this book chapter, we discuss 10 basic security and privacy problems for the pre-trained foundation models, including six confidentiality problems, three integrity problems, and one availability problem. For each problem, we discuss potential opportunities and challenges. We hope our book chapter will inspire future research on the security and privacy of foundation models.
|
https://arxiv.org/abs/2110.15444v3
|
Sentiment analysis has become a very important tool for analysis of social
media data. There are several methods developed for this research field, many
of them working very differently from each other, covering distinct aspects of
the problem and disparate strategies. Despite the large number of existent
techniques, there is no single one which fits well in all cases or for all data
sources. Supervised approaches may be able to adapt to specific situations but
they require manually labeled training, which is very cumbersome and expensive
to acquire, mainly for a new application. In this context, in here, we propose
to combine several very popular and effective state-of-the-practice sentiment
analysis methods, by means of an unsupervised bootstrapped strategy for
polarity classification. One of our main goals is to reduce the large
variability (lack of stability) of the unsupervised methods across different
domains (datasets). Our solution was thoroughly tested considering thirteen
different datasets in several domains such as opinions, comments, and social
media. The experimental results demonstrate that our combined method (aka,
10SENT) improves the effectiveness of the classification task, but more
importantly, it solves a key problem in the field. It is consistently among the
best methods in many data types, meaning that it can produce the best (or close
to best) results in almost all considered contexts, without any additional
costs (e.g., manual labeling). Our self-learning approach is also very
independent of the base methods, which means that it is highly extensible to
incorporate any new additional method that can be envisioned in the future.
Finally, we also investigate a transfer learning approach for sentiment
analysis as a means to gather additional (unsupervised) information for the
proposed approach and we show the potential of this technique to improve our
results.
|
http://arxiv.org/abs/1711.07915v1
|
This volume contains contributions presented at LLRF2022: the 10th Low-Level RF Workshop held in Brugg-Windisch, Switzerland on October 10-13, 2022.
|
https://arxiv.org/abs/2208.13680v4
|
Can cloud computing infrastructures provide HPC-competitive performance for scientific applications broadly? Despite prolific related literature, this question remains open. Answers are crucial for designing future systems and democratizing high-performance computing. We present a multi-level approach to investigate the performance gap between HPC and cloud computing, isolating different variables that contribute to this gap. Our experiments are divided into (i) hardware and system microbenchmarks and (ii) user application proxies. The results show that today's high-end cloud computing can deliver HPC-competitive performance not only for computationally intensive applications but also for memory- and communication-intensive applications - at least at modest scales - thanks to the high-speed memory systems and interconnects and dedicated batch scheduling now available on some cloud platforms.
|
https://arxiv.org/abs/2011.00656v2
|
Ten years ago, the Mathematics Subject Classification MSC 2010 was released, and a corresponding machine-readable Linked Open Data collection was published using the Simple Knowledge Organization System (SKOS). Now, the new MSC 2020 is out. This paper recaps the last ten years of working on machine-readable MSC data and presents the new machine-readable MSC 2020. We describe the processing required to convert the version of record, as agreed by the editors of zbMATH and Mathematical Reviews, into the Linked Open Data form we call MSC2020-SKOS. The new form includes explicit marking of the changes from 2010 to 2020, some translations of English code descriptions into Chinese, Italian, and Russian, and extra material relating MSC to other mathematics classification efforts. We also outline future potential uses for MSC2020-SKOS in semantic indexing and sketch its embedding in a larger vision of scientific research data.
|
https://arxiv.org/abs/2107.13877v2
|
The Immersion GRating INfrared Spectrometer (IGRINS) is a compact, high-resolution (R~45,000) near-infrared spectrograph spanning 1.45 to 2.45 um in a single exposure. We introduce the Raw and Reduced IGRINS Spectral Archive (RRISA), which provides public data access for all non-proprietary IGRINS data taken at McDonald Observatory's Harlan J. Smith Telescope, the Lowell Discovery Telescope (formerly Discovery Channel Telescope), and Gemini South. RRISA provides access to raw files, reduced data products, and cross-matched IGRINS targets with the SIMBAD, 2MASS, Gaia DR3, APOGEE2 DR17, and PASTEL catalogs. We also introduce version 3 of the IGRINS data reduction pipeline, IGRINS PLP v3, which implements an improved cosmic ray correction, pattern noise removal, and a new flexure correction that reduces telluric residuals. RRISA and supporting information can be found at http://igrinscontact.github.io.
|
https://arxiv.org/abs/2503.05867v1
|
Fair Representation Learning (FRL) is a broad set of techniques, mostly based on neural networks, that seeks to learn new representations of data in which sensitive or undesired information has been removed. Methodologically, FRL was pioneered by Richard Zemel et al. about ten years ago. The basic concepts, objectives and evaluation strategies for FRL methodologies remain unchanged to this day. In this paper, we look back at the first ten years of FRL by i) revisiting its theoretical standing in light of recent work in deep learning theory that shows the hardness of removing information in neural network representations and ii) presenting the results of a massive experimentation (225.000 model fits and 110.000 AutoML fits) we conducted with the objective of improving on the common evaluation scenario for FRL. More specifically, we use automated machine learning (AutoML) to adversarially "mine" sensitive information from supposedly fair representations. Our theoretical and experimental analysis suggests that deterministic, unquantized FRL methodologies have serious issues in removing sensitive information, which is especially troubling as they might seem "fair" at first glance.
|
https://arxiv.org/abs/2407.03834v1
|
The flaring M4 dwarf GJ 1243 has become a benchmark for studying stellar
flare and starspot activity thanks to the exceptional photometric monitoring
archive from the Kepler mission. New light curves from the TESS mission for
this star allow precise stellar activity characterization over more than a
decade timescale. We have carried out the first flare and starspot analysis of
GJ 1243 from over 50 days of data from TESS Sectors 14 and 15. Using 133 flare
events detected in the 2-minute cadence TESS data, we compare the cumulative
flare frequency distributions, and find the flare activity for GJ 1243 is
unchanged between the Kepler and TESS epochs. Two distinct starspot groups are
found in the TESS data, with the primary spot having the same rotational period
and phase as seen in Kepler. The phase of the secondary spot feature is
consistent with the predicted location of the secondary starspot and
measurement of weak differential rotation, suggesting this secondary spot may
be long-lived and stable in both latitude and longitude. As expected for this
highly active star, the constant spot and flare activity reveal no sign of
solar-like activity cycles over 10 years. However, we highlight the unique
ability for Kepler and TESS to use flare rates to detect activity cycles.
|
http://arxiv.org/abs/2005.10281v1
|
As of 2020, the international workshop on Procedural Content Generation enters its second decade. The annual workshop, hosted by the international conference on the Foundations of Digital Games, has collected a corpus of 95 papers published in its first 10 years. This paper provides an overview of the workshop's activities and surveys the prevalent research topics emerging over the years.
|
https://arxiv.org/abs/2104.11037v1
|
A decade ago the archetypal Seyfert-1 galaxy NGC 5548 was discovered to have undergone major spectral changes. The soft X-ray flux had dropped by a factor of 30 while new broad and blueshifted UV absorption lines appeared. This was explained by the emergence of a new obscuring wind from the accretion disk. Here we report on the striking long-term variability of the obscuring disk wind in NGC 5548 including new observations taken in 2021-2022 with the Swift Observatory and the Hubble Space Telescope's (HST) Cosmic Origins Spectrograph (COS). The X-ray spectral hardening as a result of obscuration has declined over the years, reaching its lowest in 2022 at which point we find the broad C IV UV absorption line to be nearly vanished. The associated narrow low-ionization UV absorption lines, produced previously when shielded from the X-rays, are also remarkably diminished in 2022. We find a highly significant correlation between the variabilities of the X-ray hardening and the equivalent width of the broad C IV absorption line, demonstrating that X-ray obscuration is inherently linked to disk winds. We derive for the first time a relation between the X-ray and UV covering fractions of the obscuring wind using its long-term evolution. The diminished X-ray obscuration and UV absorption are likely caused by an increasingly intermittent supply of outflowing streams from the accretion disk. This results in growing gaps and interstices in the clumpy disk wind, thereby reducing its covering fractions.
|
https://arxiv.org/abs/2207.09464v1
|
Abridged - Stars with ZAMS masses between 140 and $260 M_\odot$ are thought to explode as pair-instability supernovae (PISNe). During their thermonuclear runaway, PISNe can produce up to several tens of solar masses of radioactive nickel, resulting in luminous transients similar to some superluminous supernovae (SLSNe). Yet, no unambiguous PISN has been discovered so far. SN2018ibb is a H-poor SLSN at $z=0.166$ that evolves extremely slowly compared to the hundreds of known SLSNe. Between mid 2018 and early 2022, we monitored its photometric and spectroscopic evolution from the UV to the NIR with 2-10m class telescopes. SN2018ibb radiated $>3\times10^{51} \rm erg$ during its evolution, and its bolometric light curve reached $>2\times10^{44} \rm erg\,s^{-1}$ at peak. The long-lasting rise of $>93$ rest-frame days implies a long diffusion time, which requires a very high total ejected mass. The PISN mechanism naturally provides both the energy source ($^{56}$Ni) and the long diffusion time. Theoretical models of PISNe make clear predictions for their photometric and spectroscopic properties. SN2018ibb complies with most tests on the light curves, nebular spectra and host galaxy, potentially all tests with the interpretation we propose. Both the light curve and the spectra require 25-44 $M_\odot$ of freshly nucleosynthesised $^{56}$Ni, pointing to the explosion of a metal-poor star with a He-core mass of 120-130 $M_\odot$ at the time of death. This interpretation is also supported by the tentative detection of [Co II]$\lambda$1.025$\mu$m, which has never been observed in any other PISN candidate or SLSN before. Powering by a central engine, such as a magnetar or a black hole, can be excluded with high confidence. This makes SN2018ibb by far the best candidate for being a PISN, to date.
|
https://arxiv.org/abs/2305.05796v2
|
Unlike, momentum-dependent Rashba spin-splitting, materials exhibiting intrinsic momentum-independent unidirectional spin polarization also known as persistent spin texture (PST) in the full Brillouin zone are scarce. In this work, a list of characteristic electronic properties for identifying an ideal PST material is provided based on earlier analytical models, and a new semiconductor, the MgTe(110) facet is proposed which satisfies all these conditions and exhibits PST in the full Brillouin zone. The atomic arrangement in this particular facet exhibits three basic symmetries found in nature: rotation, reflection, and translation. Using the method of invariance, an effective Hamiltonian is constructed which reproduces the results obtained using the density functional theory. Further, mono/few layers of MgTe (110) facets of the zinc-blende structure are proposed for a ferromagnet-free non-ballistic spin-field effect transistor (s-FET) that combines both the spin-Hall effect and inverse spin-Hall effect, thus harmonizing spintronics with conventional electronics. Although only quantum well structures have been experimentally studied for nonballistic s-FET under the stringent condition of equal Rashba and Dresselhaus strength, PST originating intrinsically in the proposed 2D structures makes them an ideal alternate.
|
https://arxiv.org/abs/2309.10868v3
|
High bandwidth, low voltage electro-optic modulators with high optical power handling capability are important for improving the performance of analog optical communications and RF photonic links. Here we designed and fabricated a thin-film lithium niobate (LN) Mach-Zehnder modulator (MZM) which can handle high optical power of 110 mW, while having 3-dB bandwidth greater than 110 GHz at 1550 nm. The design does not require etching of thin-film LN, and uses hybrid optical modes formed by bonding LN to planarized silicon photonic waveguide circuits. A high optical power handling capability in the MZM was achieved by carefully tapering the underlying Si waveguide to reduce the impact of optically-generated carriers, while retaining a high modulation efficiency. The MZM has a $V_\pi L$ product of 3.1 V.cm and an on-chip optical insertion loss of 1.8 dB.
|
https://arxiv.org/abs/2210.14785v1
|
Integrated thin film lithium niobate (TFLN) modulators are emerging as an appealing solution to high-speed data processing and transmission due to their high modulation speed and low driving voltage. The key step in fabricating integrated TFLN modulators is the high-quality etching of TFLN, which typically requires long-term optimization of fabrication recipe and specialized equipment. Here we present an integrated TFLN modulator by incorporating low-index rib loaded waveguides onto TFLN without direct etching of TFLN. Based on our systematic investigation into the theory and design methodology of the proposed design, we experimentally demonstrated a TFLN etching-free Mach-Zehnder modulator, featuring a flat electro-optic response up to 110 GHz and a voltage-length product of 2.53 V cm. By significantly simplifying the fabrication process, our design opens up new ways of mass production of high-speed integrated TFLN modulators at low cost.
|
https://arxiv.org/abs/2308.03073v4
|
A compact Kerr-lens mode-locked thin-disk oscillator delivering 110 MW output peak power, the highest among all oscillators, is reported. A pulse train with a repetition rate of 14 MHz carries 115 fs long, 14.4 uJ pulses resulting in 202 W of average power. This compact, simple, and stable oscillator is a suitable driver and an important milestone for further high harmonics generation and the development of extreme ultraviolet transportable frequency comb sources.
|
https://arxiv.org/abs/2204.03384v2
|
Spinterface engineering has shown quite important roles in organic
spintronics as it can improve spin injection or extraction. In this study,
11,11,12,12-tetracyanonaptho-2,6-quinodimethane (TNAP) is introduced as an
interfacial layer for a prototype interface of Fe/TNAP. We report an
element-specific investigation of the electronic and magnetic structures of
Fe/TNAP system by use of near edge X-Ray absorption fine structure (NEXAFS) and
X-ray magnetic circular dichroism (XMCD). Strong hybridization between TNAP and
Fe and induced magnetization of N atoms in TNAP molecule are observed. XMCD sum
rule analysis demonstrates that the adsorption of TNAP reduces the spin moment
of Fe by 12%. In addition, induced magnetization in N K-edge of TNAP has also
been found with other commonly used ferromagnets in organic spintronics, such
as La0.7Sr0.3MnO3 and permalloy, which makes TNAP a very promising molecule for
spinterface engineering in organic spintronics.
|
http://arxiv.org/abs/1805.07906v1
|
We report the (111) facet-engineered cubic phase SnO2 (C-SnO2) as a novel electron transport layer (ETL) for triple-cation mixed-halide Cs0.05(FA0.83MA0.17)0.95Pb(I0.83Br0.17)3 perovskite solar cells (PSCs). The C-SnO2 layer was prepared via a normal sol-gel process followed by the spin-coating technique. The (111) facet C-SnO2 layer provides a larger surface contact area with an adjacent perovskite layer, enhancing charge transfer dynamics at the interface. In addition, the well-matched overlapping band structures improve the charge extraction efficiency between the two layers. Using (111) facet C-SnO2 as ETLs, we obtain PSCs with a higher power conversion efficiency of 20.34% (0.09 cm2) than those employing tetragonal phase SnO2 ETL. The PSCs with C-SnO2 ETL retain over 81% of their initial efficiency even after 480 h. This work concludes with a brief discussion on recombination and charge transport mechanisms, providing ways to optimize C-SnO2 ETL to improve the PSCs' performance and stability.
|
https://arxiv.org/abs/2502.15327v1
|
We present an implementation of all-diamond scanning probes for scanning
nitrogen-vacancy (NV) magnetometry fabricated from (111)-oriented diamond
material. The realized scanning probe tips on average contain single NV spins,
a quarter of which have their spin quantization axis aligned parallel to the
tip direction. Such tips enable single-axis vector magnetic field imaging with
nanoscale resolution, where the measurement axis is oriented normal to the scan
plane. We discuss how these tips bring multiple practical advantages for NV
magnetometry, in particular regarding quantitative analysis of the resulting
data. We further demonstrate the beneficial optical properties of NVs oriented
along the tip direction, such as polarization-insensitive excitation, which
simplifies optical setups needed for NV magnetometry. Our results will be
impactful for scanning NV magnetometry in general and for applications in
spintronics and the investigation of thin film magnets in particular.
|
http://arxiv.org/abs/1910.10733v2
|
(001) Si spin qubits are being intensively studied because they have structures similar to that of CMOS devices currently being produced, and thus have the advantage of utilizing state-of-the-art miniaturization, integration, and variation-reduction-technologies. However, there are still issues, such as further improvement of relaxation and decoherence time, stabilization of valley-splitting control, and reduction of the variation caused by the roughness of the interface. In this study, new measures are proposed to address these three issues. Instead of confining an electron to the minimum energy point $X_0$ of the conduction band along the band structure $\Gamma-\Delta-X$ in (001) Si crystals, we propose confining an electron to the L point along $\Gamma-\Lambda-L$ in (111) Si crystals. At the $X_0$ point, the symmetry causes spin-orbit interaction to act on the electron, and the sixfold degeneracy is lifted into a fourfold and a twofold, and the valley-splitting of the twofold conflicts with the two-level system. In the symmetry of the $L$ point, substantial spin polarization disappears, facilitating the reduction of the spin-orbit interaction, and the fourfold degeneracy is lifted to threefold and single, and the single becomes ground state. The need to increase the magnitude of the valley-splitting is exempt, allowing the electron to be controlled away from the interface, which is expected to reduce the variation caused by the roughness of the interface. Data on the confinement of an electron to the $L$ point and the control of fourfold degeneracy are needed, and it is hoped that prototype silicon spin qubits constructed on (111) Si crystals will be developed and that the proposed device structure will help implement quantum computers based on Si devices.
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https://arxiv.org/abs/2501.13546v1
|
We study classical spin ice under uniaxial strain along the $[111]$ crystallographic axis. Remarkably, such strain preserves the extensive ice degeneracy and the corresponding classical Coulomb phase. The emergent monopole excitations remain thermodynamically deconfined exactly as in the isotropic case. However, their motion under local heat bath dynamics depends qualitatively on the sign of the strain. In the low-temperature limit for negative strain, the monopoles diffuse, while for positive strain, they localize. Introducing additional ring exchange dynamics into the ice background transforms the localized monopoles into sub-dimensional excitations whose motion is restricted to diffusion in the $(111)$-plane. The phenomena we identify are experimentally accessible in rare-earth pyrochlores under uniaxial pressure as well as in tripod kagome materials. The diffusive versus localized nature of the monopoles manifests in characteristic magnetic noise spectra, which we compute.
|
https://arxiv.org/abs/2406.18649v2
|
Large Language Models (LLMs) have garnered significant attention due to their remarkable ability to process information across various languages. Despite their capabilities, they exhibit inconsistencies in handling identical queries in different languages, presenting challenges for further advancement. This paper introduces a method to enhance the multilingual performance of LLMs by aggregating knowledge from diverse languages. This approach incorporates a low-resource knowledge detector specific to a language, a language selection process, and mechanisms for answer replacement and integration. Our experiments demonstrate notable performance improvements, particularly in reducing language performance disparity. An ablation study confirms that each component of our method significantly contributes to these enhancements. This research highlights the inherent potential of LLMs to harmonize multilingual capabilities and offers valuable insights for further exploration.
|
https://arxiv.org/abs/2406.14721v1
|
A lattice is $(1+1+2)$-generated if it has a four-element generating set such that exactly two of the four generators are comparable. We prove that the lattice Quo$(n)$ of all quasiorders (also known as preorders) of an $n$-element set is $(1+1+2)$-generated for $n=3$ (trivially), $n=6$ (when Quo(6) consists of $209\,527$ elements), n=11, and for every natural number $n\geq 13$. In 2017, the second author and J. Kulin proved that Quo$(n)$ is $(1+1+2)$-generated if either $n$ is odd and at least $13$ or $n$ is even and at least $56$. Compared to the 2017 result, this paper presents twenty-four new numbers $n$ such that Quo$(n)$ is $(1+1+2)$-generated. Except for Quo(6), an extension of Z\'adori's method is used.
|
https://arxiv.org/abs/2104.14653v1
|
Software programming requires both API reference (know-what) knowledge and programming task (know-how) knowledge. Lots of programming know-what and know-how knowledge is documented in text, for example, API reference documentation and programming tutorials. To improve knowledge accessibility and usage, several recent studies use Natural Language Processing (NLP) methods to construct API know-what knowledge graph (API-KG) and programming task know-how knowledge graph (Task-KG) from software documentation. Although being promising, current API-KG and Task-KG are independent of each other, and thus are void of inherent connections between the two types of knowledge. Our empirical study on Stack Overflow questions confirms that only 36% of the API usage problems can be answered by the know-how or the know-what knowledge alone, while the rest questions require a fusion of both. Inspired by this observation, we make the first attempt to fuse API-KG and Task-KG by API entity linking. This fusion creates nine categories of API semantic relations and two types of task semantic relations which are not present in the stand-alone API-KG or Task-KG. According to the definitions of these new API and task semantic relations, our approach dives deeper than the surface-level API linking of API-KG and Task-KG, and infers nine categories of API semantic relations from task descriptions and two types of task semantic relations with the assistance of API-KG, which enrich the declaration or syntactic relations in the current API-KG and Task-KG. Our fused and semantically-enriched API-Task KG supports coherent API/Task-centric knowledge search by text or code queries.
|
https://arxiv.org/abs/2207.05560v3
|
In 1910, Hendrik Antoon Lorentz delved into the enigmatic Laplace eigenvalue equation, also known as the Helmholtz equation, pondering to what extent the geometry in which one solves the equation can be recovered from knowledge of the eigenvalues. Lorentz, inspired by physical and musical analogies, conjectured a fundamental relationship between eigenvalues, domain volume, and dimensionality. While his conjecture initially seemed insurmountable, Hermann Weyl's groundbreaking proof in 1912 illuminated the deep connection between eigenvalues and geometric properties. Over the ensuing 112 years, mathematicians and physicists have continued to decipher the intricate interplay between eigenvalues and geometry. From Weyl's law to Milnor's example of isospectral non-isometric flat tori, and Kac's inspiring question about hearing the shape of a drum, the field has witnessed remarkable progress, uncovering spectral invariants and advancing our understanding of geometric properties discernible through eigenvalues. We present an overview of this field amenable to both physicists and mathematicians.
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https://arxiv.org/abs/2406.18369v2
|
We present an alternative analysis of the $^{113}$Cd $\beta$-decay electron energy spectrum in terms of spectral moments $\mu_n$, corresponding to the averaged values of $n^{\rm th}$ powers of the $\beta$ particle energy. The zeroth moment $\mu_0$ is related to the decay rate, while higher moments $\mu_n$ are related to the spectrum shape. The here advocated spectral-moment method (SMM) allows for a complementary understanding of previous results, obtained using the so-called spectrum-shape method (SSM) and its revised version, in terms of two free parameters: $r=g_{\rm A}/g_{\rm V}$ (the ratio of axial-vector to vector couplings) and $s$ (the small vector-like relativistic nuclear matrix element, $s$-NME). We present numerical results for three different nuclear models with the conserved vector current hypothesis (CVC) assumption of $g_{\rm V}=1$. We show that most of the spectral information can be captured by the first few moments which are simple quadratic forms (conic sections) in the $(r,\,s)$ plane: an ellipse for $n=0$ and hyperbolae for $n\geq 1$, all being nearly degenerate as a result of cancellations among nuclear matrix elements. The intersections of these curves, as obtained by equating theoretical and experimental values of $\mu_n$, identify the favored values of $(r,\,s)$ at a glance, without performing detailed fits. In particular, we find that values around $r\sim 1$ and $s\sim 1.6$ are consistently favored in each nuclear model, confirming the evidence for $g_{\rm A}$ quenching in $^{113}$Cd, and shedding light on the role of the $s$-NME. We briefly discuss future applications of the SMM to other forbidden $\beta$-decay spectra sensitive to $g_{\rm A}$.
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https://arxiv.org/abs/2302.07048v2
|
Accurate long-distance ranging is crucial for diverse applications, including satellite formation flying, very-long-baseline interferometry, gravitational-wave observatory, geographical research, etc. The integration of the time-of-flight mesurement with phase interference in dual-comb method enables high-precision ranging with a rapid update rate and an extended ambiguity range. Pioneering experiments have demonstrated unprecedented precision in ranging, achieving 5 nm @ 60 ms for 1.1 m and 200 nm @ 0.5 s for 25 m. However, long-distance ranging remains technically challenging due to high transmission loss and noise. In this letter, we propose a two-way dual-comb ranging (TWDCR) approach that enables successful ranging over a distance of 113 kilometers. We employ air dispersion analysis and synthetic repetition rate technique to extend the ambiguity range of the inherently noisy channel beyond 100 km. The achieved ranging precision is 11.5 $\mu$m @ 1.3 ms, 681 nm @ 1 s, and 82 nm @ 21 s, as confirmed through a comparative analysis of two independent systems. The advanced long-distance ranging technology is expected to have immediate implications for space research initiatives, such as the space telescope array and the satellite gravimetry.
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https://arxiv.org/abs/2412.05542v1
|
Optical clock networks play important roles in various fields, such as precise navigation, redefinition of "second" unit, and gravitational tests. To establish a global-scale optical clock network, it is essential to disseminate time and frequency with a stability of $10^{-19}$ over a long-distance free-space link. However, such attempts were limited to dozens of kilometers in mirror-folded configuration. Here, we take a crucial step toward future satellite-based time-frequency disseminations. By developing the key technologies, including high-power frequency combs, high-stability and high-efficiency optical transceiver systems, and efficient linear optical sampling, we demonstrate free-space time-frequency dissemination over two independent links with femtosecond time deviation, $3\times10^{-19}$ at 10,000 s residual instability and $1.6\times10^{-20}\pm 4.3\times10^{-19}$ offset. This level of the stability retains for an increased channel loss up to 89 dB. Our work can not only be directly used in ground-based application, but also firmly laid the groundwork for future satellite time-frequency dissemination.
|
https://arxiv.org/abs/2203.11272v1
|
We prove that up to two exceptions, every connected subcubic triangle-free graph has fractional chromatic number at most 11/4. This is tight unless further exceptional graphs are excluded, and improves the known bound on the fractional chromatic number of subcubic triangle-free planar graphs.
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https://arxiv.org/abs/2204.12683v3
|
Knowledge of the past behavior of Antarctic polynyas such as the Ross and
Weddell Seas contributes to the understanding of biological productivity, sea
ice production, katabatic and Southern Hemisphere Westerly (SHW) wind strength,
Antarctic bottom water (ABW) formation, and marine CO2 sequestration. Previous
studies link barium (Ba) marine sedimentation to polynya primary productivity
(Bonn et al., 1998; McManus et al., 2002; Pirrung et al., 2008), polynya area
to katabatic wind strength and proximal cyclones (Bromwich et al., 1998;
Drucker et al., 2011), and highlight the influence of Ross Ice Shelf calving
event effects on the Ross Sea Polynya (RSP) (Rhodes et al., 2009). Here we use
the RICE ice core, located just 120 km from the Ross Ice Shelf front to capture
1150 years of RSP behavior. We link atmospheric Ba fluctuations to Ba marine
sedimentation in the summer Ross Sea Polynya, creating the first deep ice core
based RSP proxy. RSP area is currently the smallest ever observed over our
1150-year record, and varied throughout the Little Ice Age with fluctuations in
Amundsen Sea Low (ASL) strength related with Ross Sea cyclones. Past RSP
reconstructions allow us to predict future responses of RSP area to future
climate change, which is of special interest considering the recent
disappearance of the Weddell Sea Polynya in response to anthropogenic forcing
(de Lavergne et al., 2014).
|
http://arxiv.org/abs/2006.01093v1
|
We present a scalable mixed-species Coulomb crystal clock based on the $^1S_0$ $\leftrightarrow$ $^3P_0$ transition in $^{115}$In$^+$. $^{172}$Yb$^+$ ions are co-trapped and used for sympathetic cooling. Reproducible interrogation conditions for mixed-species Coulomb crystals are ensured by a conditional preparation sequence with permutation control. We demonstrate clock operation with a 1In$^+$-3Yb$^+$ crystal, achieving a relative systematic uncertainty of $2.5\times10^{-18}$ and a relative frequency instability of $1.6\times10^{-15}/\sqrt{\tau/1\;\mathrm{s}}$. We report on absolute frequency measurements with an uncertainty of $1.3\times10^{-16}$ and optical frequency comparisons with clocks based on $^{171}$Yb$^+$ (E3) and $^{87}$Sr. With a fractional uncertainty of $4.4\times10^{-18}$, the former is - to our knowledge - the most accurate frequency ratio value reported to date. For the $^{115}$In$^+$/$^{87}$Sr ratio, we improve upon the best previous measurement by more than an order of magnitude. We also demonstrate operation with four $^{115}$In$^+$ clock ions, which reduces the instability to $9.2\times10^{-16}/\sqrt{\tau/1\;\mathrm{s}}$.
|
https://arxiv.org/abs/2402.16807v3
|
Using a novel geometrically-shaped four-dimensional modulation format, we
transmitted 11x200 Gbit/s DWDM at 4.8 bit/4D-sym over 7,925 km and 11,700 km
using EDFA-only and hybrid amplification, respectively. A reach increase of 16%
is achieved over PM-8QAM.
|
http://arxiv.org/abs/1904.12561v1
|
We give a diagrammatic characterization of the $(1,1)$ knots in the three-sphere and lens spaces which admit large Dehn surgeries to manifolds with Heegaard Floer homology of next-to-minimal rank. This is inspired by a corresponding result for $(1,1)$ knots which admit large Dehn surgeries to manifolds with Heegaard Floer homology of minimal rank due to Greene-Lewallen-Vafaee.
|
https://arxiv.org/abs/2304.11475v1
|
The resonance region of $^{11}$B covering excitation energies from 8.4 MeV to 13.6 MeV was investigated with the $(d,p)$ reaction performed on an enriched $^{10}$B target at the Florida State University Super-Enge Split-Pole Spectrograph of the John D. Fox Superconducting Linear Accelerator Laboratory. Complementary measurements were performed with a target enriched in $^{11}$B to identify possible $^{12}$B contaminants in the $(d,p)$ reaction. Four strongly populated $^{11}$B states were observed above the $\alpha$-decay threshold. Angular distributions were measured and compared to DWBA calculations to extract angular momentum transfers and $^{10}\mathrm{B}\left(3^+\right)+n$ spectroscopic factors. The recently observed and heavily discussed resonance at 11.4 MeV in $^{11}$B was not observed in this work. This result is consistent with the interpretation that it is predominantly a $^{10}\mathrm{Be}\left(0^+\right)+p$ resonance with a possible additional $^{7}\mathrm{Li}+\alpha$ contribution. The predicted $^{10}\mathrm{B}\left(3^+\right)+n$ resonance at 11.6 MeV, analogous to the 11.4-MeV proton resonance, was not observed either. Upper limits for the $^{10}\mathrm{B}\left(3^+\right)+n$ spectroscopic factors of the 11.4-MeV and 11.6-MeV states were determined. In addition, supporting configuration interaction shell model calculations with the effective WBP interaction are presented.
|
https://arxiv.org/abs/2411.09831v1
|
A graph $H$ is a clique graph if $H$ is a vertex-disjoin union of cliques. Abu-Khzam (2017) introduced the $(a,d)$-{Cluster Editing} problem, where for fixed natural numbers $a,d$, given a graph $G$ and vertex-weights $a^*:\ V(G)\rightarrow \{0,1,\dots, a\}$ and $d^*{}:\ V(G)\rightarrow \{0,1,\dots, d\}$, we are to decide whether $G$ can be turned into a cluster graph by deleting at most $d^*(v)$ edges incident to every $v\in V(G)$ and adding at most $a^*(v)$ edges incident to every $v\in V(G)$. Results by Komusiewicz and Uhlmann (2012) and Abu-Khzam (2017) provided a dichotomy of complexity (in P or NP-complete) of $(a,d)$-{Cluster Editing} for all pairs $a,d$ apart from $a=d=1.$ Abu-Khzam (2017) conjectured that $(1,1)$-{Cluster Editing} is in P. We resolve Abu-Khzam's conjecture in affirmative by (i) providing a serious of five polynomial-time reductions to $C_3$-free and $C_4$-free graphs of maximum degree at most 3, and (ii) designing a polynomial-time algorithm for solving $(1,1)$-{Cluster Editing} on $C_3$-free and $C_4$-free graphs of maximum degree at most 3.
|
https://arxiv.org/abs/2210.07722v2
|
The covariance matrix adaptation evolution strategy (CMA-ES) is an efficient continuous black-box optimization method. The CMA-ES possesses many attractive features, including invariance properties and a well-tuned default hyperparameter setting. Moreover, several components to specialize the CMA-ES have been proposed, such as noise handling and constraint handling. To utilize these advantages in mixed-integer optimization problems, the CMA-ES with margin has been proposed. The CMA-ES with margin prevents the premature convergence of discrete variables by the margin correction, in which the distribution parameters are modified to leave the generation probability for changing the discrete variable. The margin correction has been applied to ($\mu/\mu_\mathrm{w}$,$\lambda$)-CMA-ES, while this paper introduces the margin correction into (1+1)-CMA-ES, an elitist version of CMA-ES. The (1+1)-CMA-ES is often advantageous for unimodal functions and can be computationally less expensive. To tackle the performance deterioration on mixed-integer optimization, we use the discretized elitist solution as the mean of the sampling distribution and modify the margin correction not to move the elitist solution. The numerical simulation using benchmark functions on mixed-integer, integer, and binary domains shows that (1+1)-CMA-ES with margin outperforms the CMA-ES with margin and is better than or comparable with several specialized methods to a particular search domain.
|
https://arxiv.org/abs/2305.00849v1
|
We prove that any $11$-colorable knot is presented by an $11$-colored diagram
where exactly five colors of eleven are assigned to the arcs. The number five
is the minimum for all non-trivially $11$-colored diagrams of the knot. We also
prove a similar result for any $11$-colorable ribbon $2$-knot.
|
http://arxiv.org/abs/1505.02980v1
|
We analyze how pre-existing entanglement between two Unruh-DeWitt particle
detectors evolves when one of the detectors falls through a Rindler firewall in
(1+1)-dimensional Minkowski space. The firewall effect is minor and does not
wash out the detector-detector entanglement, in some regimes even preserving
the entanglement better than Minkowski vacuum. The absence of cataclysmic
events should continue to hold for young black hole firewalls. A firewall's
prospective ability to resolve the information paradox must hence hinge on its
detailed gravitational structure, presently poorly understood.
|
http://arxiv.org/abs/1502.07749v2
|
We use a variational method to calculate the spectrum and the parton distribution function of ground state hadrons of various gauge theories in 1+1 dimensions. The template functions in our method minimize a free energy functional defined as a combination of free valence partons' kinetic energy on the lightcone and the Renyi entanglement entropy of biparton subsystems. Our results show that hadrons in these theories minimize the proposed free energy. The success of this technique motivates applying it to confining gauge theories in higher dimensions.
|
https://arxiv.org/abs/2301.03611v1
|
$1+1$-dimensional Dirac oscillator with minimal uncertainty in position and
maximal in momentum is investigated. To obtain energy spectrum SUSY QM
technique is applied. It is shown that the Dirac oscillator has two branches of
spectrum, the first one gives the standard spectrum of the Dirac oscillator
when the parameter of deformation goes to zero and the second branch does not
have nondeformed limit. Maximal momentum brings an upper bound for the energy
and it gives rise to the conclusion that the energy spectrum contains a finite
number of eigenvalues. We also calculate partition function for the spectrum of
the first type. The partition function allows us to derive thermodynamic
functions of the oscillator which are obtained numerically.
|
http://arxiv.org/abs/1810.00056v1
|
We introduce a four-dimensional extension of the Poincar\'{e} algebra
$(\mathcal{N})$ in (1+1)-dimensional space-time and obtain a (1+1)-dimensional
gauge symmetric gravity model using the algebra $\mathcal{N}$. We show that the
obtained gravity model is dual (canonically transformed) to the
(1+1)-dimensional anti de Sitter ($AdS$) gravity. We also obtain some black
hole and Friedmann-Robertson-Walker (FRW) solutions by solving its classical
equations of motion. Then, we study
$\frac{\mathbf{A}_{\mathbf{4,8}}}{\mathbf{A}_{\mathbf{1}}\otimes
\mathbf{A}_{\mathbf{1}}}$ gauged Wess-Zumino-Witten (WZW) model and obtain some
exact black hole and cosmological solutions in string theory. We show that some
obtained black hole and cosmological metrics in string theory are same as the
metrics obtained in solutions of our gauge symmetric gravity model.
|
http://arxiv.org/abs/1704.04634v2
|
We study 1+1 dimensional relativistic non-resistive magnetohydrodynamics (MHD) with longitudinal boost invariance and shear stress tensor. Several analytical solutions that describe the fluid temperature evolution under the equation of state (EoS) $\varepsilon=3p$ are derived, relevant to relativistic heavy-ion collisions. Extending the Victor-Bjorken ideal MHD flow to include non-zero shear viscosity, two perturbative analytical solutions for the first-order (Navier-Stokes) approximation are obtained. For small, power-law evolving external magnetic fields, our solutions are stable and show that both magnetic field and shear viscosity cause fluid heating with an early temperature peak, align with the numerical results. In the second-order (Israel-Stewart) theory, our findings show that the combined presence of magnetic field and shear viscosity leads to a slow cooling rate of fluid temperature, with initial shear stress significantly affecting temperature evolution of QGP.
|
https://arxiv.org/abs/2411.11398v1
|
We study scalar field theory in one space and one time dimensions on a q-deformed space with static background. We write the Lagrangian and the equation of motion and solve it to the first order in $q-1$ where $q$ is the deformation parameter of the space.
|
https://arxiv.org/abs/2301.03106v1
|
We present an implicit numerical method to solve the time-dependent equations
of radiation hydrodynamics (RHD) in axial symmetry assuming hydrostatic
equilibrium perpendicular to the equatorial plane (1+1D) of a gaseous disk. The
equations are formulated in conservative form on an adaptive grid and the
corresponding fluxes are calculated by a spacial second order advection scheme.
Self-gravity of the disk is included by solving the Possion equation. We test
the resulting numerical method through comparison with a simplified analytical
solution as well as through the long term viscous evolution of protoplanetary
disk when due to viscosity matter is transported towards the central host star
and the disk depletes. The importance of the inner boundary conditions on the
structural behaviour of disks is demonstrated with several examples.
|
http://arxiv.org/abs/2006.12939v1
|
To investigate1,1-Diphenyl-2-picrylhydrazyl (DPPH) and superoxide radical (SOR) 17 scavenging activities of 2-oxo-1,2,3,4-tetrahydropyrimidines derivatives. Free radicals are 18 highly unstable and reactive molecules/atoms. In the body, free radicals form during 19 normal and abnormal metabolism in the body and cause serious damage to other 20 biomolecules through generating oxidative stress (OS). If free radicals induced OS does 21 not neutralized properly, host multiple pathologies including several types of cancers.
|
https://arxiv.org/abs/2310.10063v1
|
We consider symmetry protected topological (SPT) phases with finite non-invertible symmetry $\mathcal{C}$ in 1+1d. In particular, we investigate interfaces and parameterized families of them within the framework of matrix product states. After revealing how to extract the $\mathcal{C}$-SPT invariant, we identify the algebraic structure of symmetry operators acting on the interface of two $\mathcal{C}$-SPT phases. By studying the representation theory of this algebra, we show that there must be a degenerate interface mode between different $\mathcal{C}$-SPT phases. This result generalizes the bulk-boundary correspondence for ordinary SPT phases. We then propose the classification of one-parameter families of $\mathcal{C}$-SPT states based on the explicit construction of invariants of such families. Our invariant is identified with a non-abelian generalization of the Thouless charge pump, which is the pump of a local excitation within a $\mathcal{C}$-SPT phase. Finally, by generalizing the results for one-parameter families of SPT phases, we conjecture the classification of general parameterized families of general gapped phases with finite non-invertible symmetries in both 1+1d and higher dimensions.
|
https://arxiv.org/abs/2408.15960v1
|
We review the structure of maximal $D=11$ and $D=10$ supergravities. Upon dimensional reduction, these theories give rise to the unique maximal supergravities in all lower spacetime dimensions $D<10$. In $D$ dimensions, maximal supergravity exhibits the exceptional global symmetry group E$_{11-D}$, part of which is realized as hidden symmetries and only manifest after proper dualization of the fields. We also briefly review the reformulation of $D=11$ supergravity as an exceptional field theory which renders the appearance of hidden symmetries manifest.
|
https://arxiv.org/abs/2303.12682v2
|
We study the promising idea of using dipolar molecular systems as analog
quantum simulators for quantum link models, which are discrete versions of
lattice gauge theories. In a quantum link model the link variables have a
finite number of degrees of freedom and discrete values. We construct the
effective Hamiltonian of a system of dipolar molecules with electric
dipole-dipole interactions, where we use the tunable parameters of the system
to match it to the target Hamiltonian describing a U(1) quantum link model in
1+1 dimensions.
|
http://arxiv.org/abs/2001.10002v1
|
Recently it has been proven that simple GP systems can efficiently evolve a conjunction of $n$ variables if they are equipped with the minimal required components. In this paper, we make a considerable step forward by analysing the behaviour and performance of a GP system for evolving a Boolean conjunction or disjunction of $n$ variables using a complete function set that allows the expression of any Boolean function of up to $n$ variables. First we rigorously prove that a GP system using the complete truth table to evaluate the program quality, and equipped with both the AND and OR operators and positive literals, evolves the exact target function in $O(\ell n \log^2 n)$ iterations in expectation, where $\ell \geq n$ is a limit on the size of any accepted tree. Additionally, we show that when a polynomial sample of possible inputs is used to evaluate the solution quality, conjunctions or disjunctions with any polynomially small generalisation error can be evolved with probability $1 - O(\log^2(n)/n)$. The latter result also holds if GP uses AND, OR and positive and negated literals, thus has the power to express any Boolean function of $n$ distinct variables. To prove our results we introduce a super-multiplicative drift theorem that gives significantly stronger runtime bounds when the expected progress is only slightly super-linear in the distance from the optimum.
|
https://arxiv.org/abs/2303.07455v1
|
The human hand possesses distinctive features which can reveal gender
information. In addition, the hand is considered one of the primary biometric
traits used to identify a person. In this work, we propose a large dataset of
human hand images (dorsal and palmar sides) with detailed ground-truth
information for gender recognition and biometric identification. Using this
dataset, a convolutional neural network (CNN) can be trained effectively for
the gender recognition task. Based on this, we design a two-stream CNN to
tackle the gender recognition problem. This trained model is then used as a
feature extractor to feed a set of support vector machine classifiers for the
biometric identification task. We show that the dorsal side of hand images,
captured by a regular digital camera, convey effective distinctive features
similar to, if not better, those available in the palmar hand images. To
facilitate access to the proposed dataset and replication of our experiments,
the dataset, trained CNN models, and Matlab source code are available at
(https://goo.gl/rQJndd).
|
http://arxiv.org/abs/1711.04322v9
|
We characterize the (1, 1) knots in the three-sphere and lens spaces that
admit non-trivial L-space surgeries. As a corollary, 1-bridge braids in these
manifolds admit non- trivial L-space surgeries. We also recover a
characterization of the Berge manifold amongst 1-bridge braid exteriors.
|
http://arxiv.org/abs/1610.04810v2
|
Broadband dual-comb spectroscopy (DCS) based on portable mode-locked fiber
frequency combs is a powerful tool for in situ, calibration free, multi-species
spectroscopy. While the acquisition of a single spectrum with mode-locked DCS
typically takes microseconds to milliseconds, the applications of these
spectrometers have generally been limited to systems and processes with time
changes on the order of seconds or minutes due to the need to average many
spectra to reach a high signal-to-noise ratio (SNR). Here, we demonstrate
high-speed, continuous, fiber mode-locked laser DCS with down to 11 $\mu$s time
resolution. We achieve this by filtering the comb spectra using portable
Fabry-Perot cavities to generate filtered combs with 1 GHz tooth spacing. The 1
GHz spacing increases the DCS acquisition speed and SNR for a given optical
bandwidth while retaining a sufficient spacing to resolve absorption features
over a wide range of conditions. We measure spectra of methane inside a rapid
compression machine throughout the 16 ms compression cycle with 133 cm$^{-1}$
bandwidth (4000 comb teeth) and 1.4 ms time resolution by spectrally filtering
one of the combs. By filtering both combs, we measured a single-shot, 25
cm$^{-1}$ (750 comb teeth) spectrum of CO around 6330 cm$^{-1}$ in 11 $\mu$s.
The technique enables simultaneously high-speed and high-resolution DCS
measurements, and can be applied anywhere within the octave-spanning spectrum
of robust and portable fiber mode-locked frequency combs.
|
http://arxiv.org/abs/2005.13050v1
|
It is demonstrated that, in the framework of the orbit method, a simple and
damped harmonic oscillators are indistinguishable at the level of an abstract
Lie algebra. This opens a possibility for treating the dissipative systems
within the orbit method. In depth analysis of the coadjoint orbits of the
$(1+1)$ dimensional Newton-Hooke group are presented. Further, it is argued
that the physical interpretation is carried by a specific realisation of the
Lie algebra of smooth functions on a phase space rather than by an abstract Lie
algebra.
|
http://arxiv.org/abs/1703.09583v2
|
We present the discovery of 11 new transiting brown dwarfs and low-mass M-dwarfs from NASA's TESS mission: TOI-2844, TOI-3122, TOI-3577, TOI-3755, TOI-4462, TOI-4635, TOI-4737, TOI-4759, TOI-5240, TOI-5467, and TOI-5882. They consist of 5 brown dwarf companions and 6 very low mass stellar companions ranging in mass from $25 M_{\rm J}$ to $128 M_{\rm J}$. We used a combination of photometric time-series, spectroscopic, and high resolution imaging follow-up as a part of the TESS Follow-up Observing Program (TFOP) in order to characterize each system. With over 50 transiting brown dwarfs confirmed, we now have a large enough sample to directly test different formation and evolutionary scenarios. We provide a renewed perspective on the transiting brown dwarf desert and its role in differentiating between planetary and stellar formation mechanisms. Our analysis of the eccentricity distribution for the transiting brown dwarf sample does not support previous claims of a transition between planetary and stellar formation at $\sim42$ $M_{\rm J}$. We also contribute a first look into the metallicity distribution of transiting companions in the range $7 - 150$ $M_{\rm J}$, showing that this too does not support a $\sim42$ $M_{\rm J}$ transition. Finally, we also detect a significant lithium absorption feature in one of the brown dwarf hosts (TOI-5882) but determine that the host star is likely old based on rotation, kinematic, and photometric measurements. We therefore claim that TOI-5882 may be a candidate for planetary engulfment.
|
https://arxiv.org/abs/2501.09795v1
|
The recent detection of the third planet in Kepler-47 has shown that binary
stars can host several planets in circumbinary orbits. To understand the
evolution of such systems we have performed two-dimensional hydrodynamic
simulations of the circumbinary disc with two embedded planets for several
Kepler systems. In two cases, Kepler-47 and -413, the planets are captured in a
1:1 mean-motion resonance at the planet parking position near the inner edge of
the disc. The orbits are fully aligned, have mean eccentricities of about 0.25
to 0.30, and the planets are entangled in a horseshoe type of motion.
Subsequent n-body simulations without the disc show that the configurations are
stable. Our results point to the existence of a new class of stable resonant
orbits around binary stars. It remains to be seen if such orbits exist in
reality.
|
http://arxiv.org/abs/1908.10395v1
|
Model interpretability was a bullet point in Concrete Problems in AI Safety (2016). Since then, interpretability has come to comprise entire research directions in technical safety agendas (2020). It is safe to say that interpretability is now a very popular area of research. In fact, the topic is sufficiently mainstream that there are books on the topic and corporate services promising to provide it.
Interpretability for reinforcement learning, however, has received much less attention than for supervised learning. So what's the state of research on this topic? What does progress in interpretable RL look like, and are we making progress?
What is this post? This post summarizes 11 recent papers on explaining reinforcement learning agents (in ICLR and related conferences), then provides commentary on the research. The summaries - and not the commentary - are the main point of this post. Though people like paper summaries, this is the kind of interpretive labor that isn't traditionally awarded space in research venues. We primarily select papers appearing between 2018 and 2020, in order to bridge the gap between foundational papers published in 2010-2017 and the more recent and diverse directions of research in the field.
|
https://openreview.net/forum?id=esxSIHrH2n
|
Chapter 11 in High-Luminosity Large Hadron Collider (HL-LHC) : Preliminary
Design Report. The Large Hadron Collider (LHC) is one of the largest scientific
instruments ever built. Since opening up a new energy frontier for exploration
in 2010, it has gathered a global user community of about 7,000 scientists
working in fundamental particle physics and the physics of hadronic matter at
extreme temperature and density. To sustain and extend its discovery potential,
the LHC will need a major upgrade in the 2020s. This will increase its
luminosity (rate of collisions) by a factor of five beyond the original design
value and the integrated luminosity (total collisions created) by a factor ten.
The LHC is already a highly complex and exquisitely optimised machine so this
upgrade must be carefully conceived and will require about ten years to
implement. The new configuration, known as High Luminosity LHC (HL-LHC), will
rely on a number of key innovations that push accelerator technology beyond its
present limits. Among these are cutting-edge 11-12 tesla superconducting
magnets, compact superconducting cavities for beam rotation with ultra-precise
phase control, new technology and physical processes for beam collimation and
300 metre-long high-power superconducting links with negligible energy
dissipation. The present document describes the technologies and components
that will be used to realise the project and is intended to serve as the basis
for the detailed engineering design of HL-LHC.
|
http://arxiv.org/abs/1705.09497v1
|
Convolutional neural networks (CNNs), inspired by biological visual cortex systems, are a powerful category of artificial neural networks that can extract the hierarchical features of raw data to greatly reduce the network parametric complexity and enhance the predicting accuracy. They are of significant interest for machine learning tasks such as computer vision, speech recognition, playing board games and medical diagnosis. Optical neural networks offer the promise of dramatically accelerating computing speed to overcome the inherent bandwidth bottleneck of electronics. Here, we demonstrate a universal optical vector convolutional accelerator operating beyond 10 TeraFLOPS (floating point operations per second), generating convolutions of images of 250,000 pixels with 8 bit resolution for 10 kernels simultaneously, enough for facial image recognition. We then use the same hardware to sequentially form a deep optical CNN with ten output neurons, achieving successful recognition of full 10 digits with 900 pixel handwritten digit images with 88% accuracy. Our results are based on simultaneously interleaving temporal, wavelength and spatial dimensions enabled by an integrated microcomb source. This approach is scalable and trainable to much more complex networks for demanding applications such as unmanned vehicle and real-time video recognition.
|
https://arxiv.org/abs/2011.07393v1
|
This volume contains contributions presented at the 11th Low-Level RF Workshop which was held in Gyeongju, South Korea on October 22-27, 2023. This workshop continued the series of successful international workshops held in Newport News, USA (2001), Geneva, Switzerland (2005), Knoxville, USA (2007), Tsukuba, Japan (2009), Hamburg, Germany (2011), Tahoe City, USA (2013), Shanghai, China (2015), Barcelona, Spain (2017), Chicago, USA (2019), and Brugg-Windisch, Switzerland (2023).
|
https://arxiv.org/abs/2310.03199v4
|
We have developed a program called MUDoS (Maastricht University Domineering
Solver) that solves Domineering positions in a very efficient way. This enables
the solution of known positions so far (up to the 10 x 10 board) much quicker
(measured in number of investigated nodes).
More importantly, it enables the solution of the 11 x 11 Domineering board, a
board up till now far out of reach of previous Domineering solvers. The
solution needed the investigation of 259,689,994,008 nodes, using almost half a
year of computation time on a single simple desktop computer. The results show
that under optimal play the first player wins the 11 x 11 Domineering game,
irrespective if Vertical or Horizontal starts the game.
In addition, several other boards hitherto unsolved were solved. Using the
convention that Vertical starts, the 8 x 15, 11 x 9, 12 x 8, 12 x 15, 14 x 8,
and 17 x 6 boards are all won by Vertical, whereas the 6 x 17, 8 x 12, 9 x 11,
and 11 x 10 boards are all won by Horizontal.
|
http://arxiv.org/abs/1602.05404v1
|
Security engineering, from security requirements engineering to the implementation of cryptographic protocols, is often supported by domain-specific languages (DSLs). Unfortunately, a lack of knowledge about these DSLs, such as which security aspects are addressed and when, hinders their effective use and further research. This systematic literature review examines 120 security-oriented DSLs based on six research questions concerning security aspects and goals, language-specific characteristics, integration into the software development lifecycle (SDLC), and effectiveness of the DSLs. We observe a high degree of fragmentation, which leads to opportunities for integration. We also need to improve the usability and evaluation of security DSLs.
|
https://arxiv.org/abs/2408.06219v2
|
Fiber Kerr resonators are simple driven resonators with desirable wavelength and repetition rate flexibility for generating ultrashort pulses for applications including telecommunications, biomedicine, and materials processing. However, fiber Kerr resonators to date often generate longer pulses and require more complicated techniques for generating single pulses than would be desirable for applications. Here we address these limits by demonstrating robust single-pulse performance with 120-fs pulse durations in fiber Kerr resonators based on stretched-pulse solitons. Through matching numerical and experimental studies, stretched-pulse soliton performance is found to strongly depend on the total cavity length, and the optimum length is found to depend on the drive, Raman scattering, and the total pulse stretching. By designing the cavity for this optimum with the described setup, stable stretched-pulse solitons with 120-fs duration are experimentally observed. In addition, soliton trapping is demonstrated with a pulsed drive source despite large intracavity breathing and single-pulse performance is observed. Robust with high performance single-pulse generation is a critical step toward useful femtosecond pulse generation.
|
https://arxiv.org/abs/2112.03323v2
|
Photonics offers a transformative approach to artificial intelligence (AI) and neuromorphic computing by enabling low-latency, high-speed, and energy-efficient computations. However, conventional photonic tensor cores face significant challenges in constructing large-scale photonic neuromorphic networks. Here, we propose a fully integrated photonic tensor core, consisting of only two thin-film lithium niobate (TFLN) modulators, a III-V laser, and a charge-integration photoreceiver. Despite its simple architecture, it is capable of implementing an entire layer of a neural network with a computational speed of 120 GOPS, while also allowing flexible adjustment of the number of inputs (fan-in) and outputs (fan-out). Our tensor core supports rapid in-situ training with a weight update speed of 60 GHz. Furthermore, it successfully classifies (supervised learning) and clusters (unsupervised learning) 112 * 112-pixel images through in-situ training. To enable in-situ training for clustering AI tasks, we offer a solution for performing multiplications between two negative numbers.
|
https://arxiv.org/abs/2311.16896v3
|
We present a novel distributed Brillouin optical time domain reflectometer (BOTDR) using standard telecommunication fibers based on single-photon avalanche diodes (SPADs) in gated mode, hd-BOTDR, with a range of 120 km and 10 m spatial resolution. We experimentally demonstrate the ability to perform a distributed temperature measurement, by detecting a hot spot at 100 km. Instead of using a frequency scan like conventional BOTDR, we use a frequency discriminator based on the slope of a fiber Bragg grating (FBG) to convert the count rate of the SPAD into a frequency shift. A procedure to take into account the FBG drift during the acquisition and perform sensitive and reliable distributed measurements is described. We also present the possibility to differentiate strain and temperature.
|
https://arxiv.org/abs/2302.07065v1
|
Hybrid distributed Raman-EDFA amplifiers, with a continuous 91 nm gain
bandwidth, are used to enable a record single mode fibre transmission capacity
of 120.0 Tbit/s using 312x35 GBd DP-256QAM over 9x70 km spans.
|
http://arxiv.org/abs/1804.01845v1
|
$^{121,123}Sb$ nuclear quadrupole resonance (NQR) was applied to
$Fe(Sb_{1-x}Te_x)_2$ in the low doping regime (\emph{x = 0, 0.01} and
\emph{0.05}) as a microscopic zero field probe to study the evolution of
\emph{3d} magnetism and the emergence of metallic behavior. Whereas the NQR
spectra itself reflects the degree of local disorder via the width of the
individual NQR lines, the spin lattice relaxation rate (SLRR) $1/T_1(T)$ probes
the fluctuations at the $Sb$ - site. The fluctuations originate either from
conduction electrons or from magnetic moments. In contrast to the semi metal
$FeSb_2$ with a clear signature of the charge and spin gap formation in
$1/T_1(T)T ( \sim exp/ (\Delta k_BT) ) $, the 1\% $Te$ doped system exhibits
almost metallic conductivity and a almost filled gap. A weak divergence of the
SLRR coefficient $1/T_1(T)T \sim T^{-n} \sim T^{-0.2}$ points towards the
presence of electronic correlations towards low temperatures wheras the
\textit{5\%} $Te$ doped sample exhibits a much larger divergence in the SLRR
coefficient showing $1/T_1(T)T \sim T^{-0.72} $. According to the specific heat
divergence a power law with $n\ =\ 2\ m\ =\ 0.56$ is expected for the SLRR.
Furthermore $Te$-doped $FeSb_2$ as a disordered paramagnetic metal might be a
platform for the electronic Griffith phase scenario. NQR evidences a
substantial asymmetric broadening of the $^{121,123}Sb$ NQR spectrum for the
\emph{5\%} sample. This has purely electronic origin in agreement with the
electronic Griffith phase and stems probably from an enhanced $Sb$-$Te$ bond
polarization and electronic density shift towards the $Te$ atom inside
$Sb$-$Te$ dumbbell.
|
http://arxiv.org/abs/1710.09571v1
|
This paper presents the solution proposed by the 1213Li team for subtask 3 in SemEval-2021 Task 6: identifying the multiple persuasion techniques used in the multi-modal content of the meme. We explored various approaches in feature extraction and the detection of persuasion labels. Our final model employs pre-trained models including RoBERTa and ResNet-50 as a feature extractor for texts and images, respectively, and adopts a label embedding layer with multi-modal attention mechanism to measure the similarity of labels with the multi-modal information and fuse features for label prediction. Our proposed method outperforms the provided baseline method and achieves 3rd out of 16 participants with 0.54860/0.22830 for Micro/Macro F1 scores.
|
https://aclanthology.org/2021.semeval-1.142
|
Virtual Try-On (VTON) has become a crucial tool in ecommerce, enabling the realistic simulation of garments on individuals while preserving their original appearance and pose. Early VTON methods relied on single generative networks, but challenges remain in preserving fine-grained garment details due to limitations in feature extraction and fusion. To address these issues, recent approaches have adopted a dual-network paradigm, incorporating a complementary "ReferenceNet" to enhance garment feature extraction and fusion. While effective, this dual-network approach introduces significant computational overhead, limiting its scalability for high-resolution and long-duration image/video VTON applications. In this paper, we challenge the dual-network paradigm by proposing a novel single-network VTON method that overcomes the limitations of existing techniques. Our method, namely MNVTON, introduces a Modality-specific Normalization strategy that separately processes text, image and video inputs, enabling them to share the same attention layers in a VTON network. Extensive experimental results demonstrate the effectiveness of our approach, showing that it consistently achieves higher-quality, more detailed results for both image and video VTON tasks. Our results suggest that the single-network paradigm can rival the performance of dualnetwork approaches, offering a more efficient alternative for high-quality, scalable VTON applications.
|
https://arxiv.org/abs/2501.05369v1
|
High-resolution spectroscopy has revealed large concentrations of CNO and
sometimes other intermediate-mass elements in the shells ejected during nova
outbursts, suggesting that the solar composition material transferred from the
secondary mixes with the outermost layers of the underlying white dwarf during
the thermonuclear runaway. Multidimensional simulations have shown that
Kelvin-Helmholtz instabilities provide self-enrichment of the accreted envelope
with material from the outermost layers of the white dwarf, at levels that
agree with observations. However, the Eulerian and time-explicit nature of most
multidimensional codes used to date and the overwhelming computational load
have limited their applicability, and no multidimensional simulation has been
conducted for a full nova cycle. This paper explores a new methodology that
combines 1-D and 3-D simulations. The early stages of the explosion (i.e.,
mass-accretion and initiation of the runaway) have been computed with the 1-D
hydrodynamic code SHIVA. When convection extends throughout the entire
envelope, the structures for each model were mapped into 3-D Cartesian grids
and were subsequently followed with the multidimensional code FLASH. Two key
physical quantities were extracted from the 3-D simulations and subsequently
implemented into SHIVA, which was used to complete the simulation through the
late expansion and ejection stages: the time-dependent amount of mass
dredged-up from the outer white dwarf layers, and the time-dependent convective
velocity profile throughout the envelope. More massive envelopes than those
reported from previous models with pre-enrichment have been found. This results
in more violent outbursts, characterized by higher peak temperatures and
greater ejected masses, with metallicity enhancements in agreement with
observations.
|
http://arxiv.org/abs/1912.08443v1
|
Despite the advances in probabilistic model checking, the scalability of the verification methods remains limited. In particular, the state space often becomes extremely large when instantiating parameterized Markov decision processes (MDPs) even with moderate values. Synthesizing policies for such \emph{huge} MDPs is beyond the reach of available tools. We propose a learning-based approach to obtain a reasonable policy for such huge MDPs. The idea is to generalize optimal policies obtained by model-checking small instances to larger ones using decision-tree learning. Consequently, our method bypasses the need for explicit state-space exploration of large models, providing a practical solution to the state-space explosion problem. We demonstrate the efficacy of our approach by performing extensive experimentation on the relevant models from the quantitative verification benchmark set. The experimental results indicate that our policies perform well, even when the size of the model is orders of magnitude beyond the reach of state-of-the-art analysis tools.
|
https://arxiv.org/abs/2410.18293v2
|
Various fields of science face a reproducibility crisis. For quantum software engineering as an emerging field, it is therefore imminent to focus on proper reproducibility engineering from the start. Yet the provision of reproduction packages is almost universally lacking. Actionable advice on how to build such packages is rare, particularly unfortunate in a field with many contributions from researchers with backgrounds outside computer science. In this article, we argue how to rectify this deficiency by proposing a 1-2-3~approach to reproducibility engineering for quantum software experiments: Using a meta-generation mechanism, we generate DOI-safe, long-term functioning and dependency-free reproduction packages. They are designed to satisfy the requirements of professional and learned societies solely on the basis of project-specific research artefacts (source code, measurement and configuration data), and require little temporal investment by researchers. Our scheme ascertains long-term traceability even when the quantum processor itself is no longer accessible. By drastically lowering the technical bar, we foster the proliferation of reproduction packages in quantum software experiments and ease the inclusion of non-CS researchers entering the field.
|
https://arxiv.org/abs/2201.12031v1
|
We experimentally demonstrate a record net capacity per wavelength of 1.23~Tb/s over a single silicon-on-insulator (SOI) multimode waveguide for optical interconnects employing on-chip mode-division multiplexing and 11$\times$11 multiple-in-multiple-out (MIMO) digital signal processing.
|
https://arxiv.org/abs/2010.10348v2
|
Record-high data rate of 125 Gb/s and SE over 2 bits/s/Hz in burst-mode
single-polarization NFDM transmissions were achieved over 976 km of SSMF with
EDFA-only amplification by transmitting and processing 222 32 QAM-modulated
nonlinear subcarriers simultaneously
|
http://arxiv.org/abs/1710.00776v1
|
In the MSSM, the tension between the observed Higgs boson mass and the
experimental result of the muon $g-2$ measurement requires a large mass
splitting between stops and smuons/charginos/neutralinos. We consider a
5-dimensional (5D) framework of the MSSM with the Randall-Sundrum warped
background metric, and show that such a mass hierarchy is naturally achieved in
terms of geometry. In our setup, the supersymmetry is broken at the ultraviolet
(UV) brane, while all the MSSM multiplets reside in the 5D bulk. An appropriate
choice of the bulk mass parameters for the MSSM matter multiplets can naturally
realize the sparticle mass hierarchy desired to resolve the tension. Gravitino
is localized at the UV brane and hence becomes very heavy, while the gauginos
spreading over the bulk acquire their masses suppressed by the 5th dimensional
volume. As a result, the LSP neutralino is a candidate for the dark matter as
usual in the MSSM. In addition to reproducing the SM-like Higgs boson mass of
around 125 GeV and the measured value of the muon $g-2$, we consider a variety
of phenomenological constraints, and present the benchmark particle mass
spectra which can be explored at the LHC Run-2 in the near future.
|
http://arxiv.org/abs/1606.05329v3
|
Recently, the CMS and ATLAS Collaborations have reported direct searches for
the 125 GeV Higgs decay with lepton flavor violation, $h\rightarrow \mu \tau$.
In this work, we analyze the signal of the lepton flavour violating (LFV) Higgs
decay $h\rightarrow \mu \tau$ in the $\mu$ from $\nu$ Supersymmetric Standard
Model ($\mu\nu$SSM) with slepton flavor mixing. Simultaneously, we consider the
constraints from the LFV decay $\tau \rightarrow \mu \gamma$, the muon
anomalous magnetic dipole moment and the lightest Higgs mass around 125 GeV.
|
http://arxiv.org/abs/1511.08979v2
|
The tungsten ditelluride WTe2 was suggested to belong to the Weyl semimetal
family. We studied 125Te spin-lattice relaxation and NMR spectra in a WTe2
single crystal within a large range from 28 K up to room temperature.
Measurements were carried out on a Bruker Avance 500 NMR pulse spectrometer for
two orientations of the crystalline c axis, parallel and perpendicular to
magnetic field. Relaxation proved to be single-exponential. The relaxation time
varied depending on the sample position in magnetic field and frequency offset.
The relaxation rate increased about linearly with temperature below 70 K
however the dependence became nearly quadratic at higher temperatures. The
relaxation rate within the total temperature range was fitted using a
theoretical model developed in [41] for Weyl semimetals and assuming the
decrease of the chemical potential with increasing temperature. The results
obtained for 125Te spin-lattice relaxation evidence in favor of the topological
nontriviality of the WTe2 semimetal. The 125Te NMR spectra agreed with the
occurrence of nonequivalent tellurium sites and varied insignificantly with
temperature.
|
http://arxiv.org/abs/2007.12510v2
|
We present the discovery and statistical analysis of $12\;660$ spotted
variable stars toward and inside the Galactic bulge from over two-decade-long
Optical Gravitational Lensing Experiment (OGLE) data. We devise a new method of
dereddening of individual stars toward the Galactic bulge where strong and
highly nonuniform extinction is present. In effect, $11\;812$ stars were
classified as giants and $848$ as dwarfs. Well defined correlations between the
luminosity, variability amplitude and rotation period were found for the
giants. Rapidly rotating dwarfs with periods $P \leq 2$ d show I-band
amplitudes lower than 0.2 mag which is substantially less than the amplitudes
of up to 0.8 mag observed in giants and slowly rotating dwarfs. We also notice
that amplitudes of stars brighter than $I_0 \approx 16$ mag do not exceed
0.3-0.4 mag. We divide the stars into three groups characterized by correlation
between light and color variations. The positive correlation is characteristic
for stars that are cooler when fainter, which results from the variable
coverage of the stellar surface with spots similar to the sunspots. The
variability of stars that are cooler when brighter (negative correlation) can
be characterized by chemical spots with overabundance of heavy elements inside
and variable line-blanketing effect, which is observed in chemically peculiar
stars. The null correlation may results from very high level of the magnetic
activity with rapidly variable magnetic fields. This division is readily
visible on the color-magnitude diagram (CMD), which suggests that it may depend
on the radius of the stars. We detect 79 flaring objects and discuss briefly
their properties. Among others, we find that relative brightening during flares
is correlated with brightness amplitude.
|
http://arxiv.org/abs/1903.05651v2
|
Squeezed states are an interesting class of quantum states that have numerous applications. This work presents the design, characterisation, and operation of a bow-tie optical parametric amplifier (OPA) for squeezed vacuum generation. We report the high duty cycle operation and long-term stability of the system that makes it suitable for post-selection based continuous-variable quantum information protocols, cluster-state quantum computing, quantum metrology, and potentially gravitational wave detectors. Over a 50 hour continuous operation, the measured squeezing levels were greater than 10 dB with a duty cycle of 96.6%. Alternatively, in a different mode of operation, the squeezer can also operate 10 dB below the quantum noise limit over a 12 hour period with no relocks, with an average squeezing of 11.9 dB. We also measured a maximum squeezing level of 12.6 dB at 1550 nm. This represents one of the best reported squeezing results at 1550 nm to date for a bow-tie cavity. We discuss the design aspects of the experiment that contribute to the overall stability, reliability, and longevity of the OPA, along with the automated locking schemes and different modes of operation.
|
https://arxiv.org/abs/2211.06632v1
|
The Jupiter Trojan asteroid 128383 (2004 JW52) was recently reported to have optical colors that are incongruous with its dynamical class. New and archival observations show that this is not the case. This is a reminder that we must always rule out the possibility that the Point Spread Function (PSF) of a minor planet is blended with that of a background sidereal source in survey images before its colors in the associated survey catalog can be considered reliable.
|
https://arxiv.org/abs/2201.01785v1
|
We present two prototypes of a gigabit transceiver ASIC, GBCR1 and GBCR2,
both designed in a 65-nm CMOS technology for the ATLAS Inner Tracker Pixel
Detector readout upgrade.
The first prototype, GBCR1, has four upstream receiver channels and one
downstream transmitter channel with pre-emphasis. Each upstream channel
receives the data at 5.12 Gbps through a 5 meter AWG34 Twinax cable from an
ASIC driver located on the pixel module and restores the signal from the high
frequency loss due to the low mass cable. The signal is retimed by a recovered
clock before it is sent to the optical transmitter VTRx+. The downstream driver
is designed to transmit the 2.56 Gbps signal from lpGBT to the electronics on
the pixel module over the same cable. The peak-peak jitter (throughout the
paper jitter is always peak-peak unless specified) of the restored signal is
35.4 ps at the output of GBCR1, and 138 ps for the downstream channel at the
cable ends. GBCR1 consumes 318 mW and is tested.
The second prototype, GBCR2, has seven upstream channels and two downstream
channels. Each upstream channel works at 1.28 Gbps to recover the data directly
from the RD53B ASIC through a 1 meter custom FLEX cable followed by a 6 meter
AWG34 Twinax cable. The equalized signal of each upstream channel is retimed by
an input 1.28 GHz phase programmable clock. Compared with the signal at the
FLEX input, the additional jitter of the equalized signal is about 80 ps when
the retiming logic is o . When the retiming logic is on, the jitter is 50 ps at
GBCR2 output, assuming the 1.28 GHz retiming clock is from lpGBT. The
downstream is designed to transmit the 160 Mbps signal from lpGBT through the
same cable connection to RD53B and the jitter is about 157 ps at the cable
ends. GBCR2 consumes about 150 mW when the retiming logic is on. This design
was submitted in November 2019.
|
http://arxiv.org/abs/2008.09738v1
|
Quantum technology is playing an increasingly important role due to the
intrinsic parallel processing capabilities endorsed by quantum superposition,
exceeding upper limits of classical performances in diverse fields. Integrated
photonic chip offers an elegant way to construct large-scale quantum systems in
a physically scalable fashion, however, nonuniformity of quantum sources
prevents all the elements from being connected coherently for exponentially
increasing Hilbert space. Here, we experimentally demonstrate 128 identical
quantum sources integrated on a single silica chip. By actively controlling the
light-matter interaction in femtosecond laser direct writing, we are able to
unify the properties of waveguides comprehensively and therefore the
spontaneous four-wave mixing process for quantum sources. We verify the
indistinguishability of the on-chip sources by a series of heralded two-source
Hong-Ou-Mandel interference, with all the dip visibilities above 90%. In
addition, the brightness of the sources is found easily reaching MHz and being
applicable to both discrete-variable and continuous-variable platform, showing
either clear anti-bunching feature or large squeezing parameter under different
pumping regimes. The demonstrated scalability and uniformity of quantum
sources, together with integrated photonic network and detection, will enable
large-scale all-on-chip quantum processors for real-life applications.
|
http://arxiv.org/abs/2005.12918v1
|
The composition of the early Solar System can be inferred from meteorites. Many elements heavier than iron were formed by the rapid neutron-capture process (r process), but the astrophysical sources where this occurred remain poorly understood. We demonstrate that the near-identical half-lives ($\simeq$ 15.6 Myr) of the radioactive r-process nuclei 129I and 247Cm preserve their ratio, irrespective of the time between production and incorporation into the Solar System. We constrain the last r-process source by comparing the measured meteoritic 129I / 247Cm = 438 $\pm$ 184 to nucleosynthesis calculations based on neutron star merger and magneto-rotational supernova simulations. Moderately neutron-rich conditions, often found in merger disk ejecta simulations, are most consistent with the meteoritic value. Uncertain nuclear physics data limit our confidence in this conclusion.
|
https://arxiv.org/abs/2006.04833v2
|
In this paper, we obtain the necessary and sufficient condition that two knot
projections are related by a finite sequence of the first and second flat
Reidemeister moves (Theorem 1). We also consider an equivalence relation that
is called weak (1, 3) homotopy. This equivalence relation occurs by the first
flat Reidemeister move and one of the third flat Reidemeister moves. We
introduce a map sending weak (1, 3) homotopy classes to knot isotopy classes
(Sec. 3). Using the map, we determine which knot projections are trivialized
under weak (1, 3) homotopy (Corollary 3).
|
http://arxiv.org/abs/2004.06312v1
|
We study fair distribution of a collection of m indivisible goods among a group of n agents, using the widely recognized fairness principles of Maximin Share (MMS) and Any Price Share (APS). These principles have undergone thorough investigation within the context of additive valuations. We explore these notions for valuations that extend beyond additivity. First, we study approximate MMS under the separable (piecewise-linear) concave (SPLC) valuations, an important class generalizing additive, where the best known factor was 1/3-MMS. We show that 1/2-MMS allocation exists and can be computed in polynomial time, significantly improving the state-of-the-art. We note that SPLC valuations introduce an elevated level of intricacy in contrast to additive. For instance, the MMS value of an agent can be as high as her value for the entire set of items. Further, the equilibrium computation problem, which is polynomial-time for additive valuations, becomes intractable for SPLC. We use a relax-and-round paradigm that goes through competitive equilibrium and LP relaxation. Our result extends to give (symmetric) 1/2-APS, a stronger guarantee than MMS. APS is a stronger notion that generalizes MMS by allowing agents with arbitrary entitlements. We study the approximation of APS under submodular valuation functions. We design and analyze a simple greedy algorithm using concave extensions of submodular functions. We prove that the algorithm gives a 1/3-APS allocation which matches the current best-known factor. Concave extensions are hard to compute in polynomial time and are, therefore, generally not used in approximation algorithms. Our approach shows a way to utilize it within analysis (while bypassing its computation), and might be of independent interest.
|
https://arxiv.org/abs/2312.08504v1
|
Some applications require electronic systems to operate at extremely high temperature. Extending the operating temperature range of automotive-grade CMOS processes -- through the use of dedicated design techniques -- can provide an important cost-effective advantage. We present a second-order discrete-time delta-sigma analog-to-digital converter operating at a temperature of up to 250 $^\circ$C, well beyond the 175 $^\circ$C qualification temperature of the automotive-grade CMOS process used for its fabrication (XFAB XT018). The analog-to-digital converter incorporates design techniques that are effective in mitigating the adverse effects of the high temperature, such as increased leakage currents and electromigration. We use configurations of dummy transistors for leakage compensation, clock-boosting methods to limit pass-gate cross-talk, and we optimized the circuit architecture to ensure stability and accuracy at high temperature. Comprehensive measurements demonstrate that the analog-to-digital converter achieves a signal-to-noise ratio exceeding 93 dB at 250 $^\circ$C, with an effective number of bits of 12, and a power consumption of only 44~mW. The die area of the converter is only 0.065~mm$^2$ and the area overhead of the high-temperature mitigation circuits is only 13.7%. The Schreier Figure of Merit is 140~dB at the maximum temperature of 250 $^\circ$C, proving the potential of the circuit for reliable operation in challenging applications such as gas and oil extraction and aeronautics.
|
https://arxiv.org/abs/2501.00482v1
|
The total cross sections of the neutron radiative capture on 12B at
astrophysical energies to the ground state of 13B have been calculated in the
energy range of 10E-8 to 10 MeV within the framework of a modified potential
cluster model with the classification of orbital states according to Young
diagrams. Reaction rates in the temperature range of 0.01 to 10 T9 and their
analytical parameterization were obtained. The calculated rates of
12B(n,gamma)13B excess the previous results by approximately to one order.
Cross sections and reaction rates of 12C(n,gamma)13C are calculated and
compared to the n10B, n11B, n12B, and p12C reaction rates. It is proposed that
obtained rates of the 12B(n,gamma)13B reaction should be taken into account in
novel scenarios of stable isotope 13C synthesis without of 12C hydrogen
burning.
|
http://arxiv.org/abs/2004.13525v1
|
We study three point functions of half BPS operators in $\mathcal{N}=4$ super Yang-Mills theory focusing on correltors of two of the operators with dimension of order $\Delta\sim N^2$ and a light single trace operator. These describe vacuum expectation values of type IIB supergravity modes in LLM backgrounds that do not necessarily preserve the same symmetries as the background solution. We propose a class of complex matrix models that fully capture the combinatorics of the problem, and describe their solution in the large $N$ limit. In simple regimes when the dual description is in terms of widely separated condensates of giant gravitons we find that the models are solvable in the large $N$ and can be approximated by unitary Jacobi ensembles; we describe how these distributions are reproduced in the dual bubbling geometry picture for large droplets. In the case of two eigenvalue droplets the model is exactly solvable at finite $N$. As a result we compute all half-BPS structure constants of heavy-heavy-light type, and reproduce the formulas found via holographic renormalization in the large $N$ limit. We also comment on structure constants of three heavy operators.
|
https://arxiv.org/abs/2305.06390v1
|
Strings in $\mathcal{N}=2$ supersymmetric ${\rm U}(1)^N$ gauge theories with
$N$ hypermultiplets are studied in the generic setting of an arbitrary
Fayet-Iliopoulos triplet of parameters for each gauge group and an invertible
charge matrix. Although the string tension is generically of a square-root
form, it turns out that all existing BPS (Bogomol'nyi-Prasad-Sommerfield)
solutions have a tension which is linear in the magnetic fluxes, which in turn
are linearly related to the winding numbers. The main result is a series of
theorems establishing three different kinds of solutions of the so-called
constraint equations, which can be pictured as orthogonal directions to the
magnetic flux in ${\rm SU}(2)_R$ space. We further prove for all cases, that a
seemingly vanishing Bogomol'nyi bound cannot have solutions. Finally, we write
down the most general vortex equations in both master form and Taubes-like
form.
|
http://arxiv.org/abs/2008.13440v1
|
We study the 1/2 BPS circular Wilson loop in four-dimensional SU(N), $N = 2$ SYM theories with massless hypermultiplets and non-vanishing $\beta$-function. Using super-symmetric localization on $S_4$ , we map the path-integral associated with this observable onto an interacting matrix model. Despite the breaking of conformal symmetry at the quantum level, we show that, within a specific regime, the matrix model predictions remain consistent with the perturbative results in flat space up to order $g^6$ . At this order, our analysis reveals that the reorganization of Feynman diagrams based on the matrix model interaction potential, widely tested in (super)conformal models, also applies to these non-conformal set-ups and is realized by interference mechanisms.
|
https://arxiv.org/abs/2410.14847v1
|
Carbon fusion is important to understand the late stages in the evolution of a massive star. Astronomically interesting energy ranges for the 12C+12C reactions have been, however, poorly constrained by experiments. Theoretical studies on stellar evolution have relied on reaction rates that are extrapolated from those measured in higher energies. In this work, we update the carbon fusion reaction rates by fitting the astrophysical S-factor data obtained from direct measurements based on the Fowler, Caughlan, & Zimmerman (1975) formula. We examine the evolution of a 20 M_sun star with the updated 12C+12C reaction rates performing simulations with the MESA (Modules for Experiments for Stellar Astrophysics) code. Between 0.5 and 1 GK, the updated reaction rates are 0.35 to 0.5 times less than the rates suggested by Caughlan and Fowler (1988). The updated rates result in the increase of core temperature by about 7% and of the neutrino cooling by about a factor of three. Moreover, the carbon-burning lifetime is reduced by a factor of 2.7. The updated carbon fusion reaction rates lead to some changes in the details of the stellar evolution model, their impact seems relatively minor compared to other uncertain physical factors like convection, overshooting, rotation, and mass-loss history. The astrophysical S-factor measurements in lower energies have large errors below the Coulomb barrier. More precise measurements in lower energies for the carbon burning would be useful to improve our study and to understand the evolution of a massive star.
|
https://arxiv.org/abs/2406.13458v1
|
In our previous paper, we tested the chiral (Kyushu) folding model for $^{12}$C+$^{12}$C scattering, since the profile function in the Glauber mode is constructed for the system. We found that the folding model is reliable for reaction cross sections $\sigma_{\rm R}$ in $30 \lsim E_{\rm lab} \lsim 100 $~MeV and $250 \lsim E_{\rm lab} \lsim 400 $~MeV. Accurate data are available for $^{12}$C scattering on $^{9}$Be, $^{12}$C, $^{27}$Al targets in $30 \lsim E_{\rm lab} \lsim 400 $~MeV. We determine matter radius $r_{m}({\rm exp})$ of $^{12}$C from the accurate $\sigma_{\rm R}({\rm exp})$, using the Kyushu $g$-matrix folding model. Our result is $r_{\rm m}^{12}({\rm exp}) =2.352 \pm 0.013$~fm for $^{12}$C. The model is applied for the accurate data on $^{12}$C+$^{27}$Al scattering, and yields $r_{\rm m}({\rm exp}) =2.936 \pm 0.012$~fm for $^{27}$Al. Our conclusion is that $r_{\rm m}({\rm exp}) =2.352 \pm 0.013$~fm agrees with $r_{\rm m}({\rm exp}) =2.35 \pm 0.02$~fm determined from interaction cross sections by Tanihata {\it et. al.}.
|
https://arxiv.org/abs/2306.15178v1
|
Carbon isotope ratios, along with carbon and nitrogen abundances, are derived
in a sample of 11 red-giant members of one of the most metal-rich clusters in
the Milky Way, NGC 6791. The selected red-giants have a mean metallicity and
standard deviation of [Fe/H]=+0.39+-0.06 (Cunha et al. 2015). We used high
resolution H-band spectra obtained by the SDSS-IV Apache Point Observatory
Galactic Evolution Experiment (APOGEE). The advantage of using high-resolution
spectra in the H-band is that lines of CO are well represented and their line
profiles are sensitive to the variation of 12C/13C. Values of the 12C/13C ratio
were obtained from a spectrum synthesis analysis. The derived 12C/13C ratios
varied between 6.3 and 10.6 in NGC 6791, in agreement with the final isotopic
ratios from thermohaline-induced mixing models. The ratios derived here are
combined with those obtained for more metal poor red-giants from the literature
to examine the correlation between 12C/13C, mass, metallicity and evolutionary
status.
|
http://arxiv.org/abs/1711.08183v2
|
Despite a rich observational background, few spectroscopic studies have dealt with the measurement of the carbon isotopic ratio in giant stars. However, it is a key element in understanding the mixing mechanisms that occur in the interiors of giant stars. We present the CNO and $^{12}$C/$^{13}$C abundances derived for 71 giant field stars. Then, using this new catalogue and complementary data from the Kepler and Gaia satellites, we study the efficiency of mixing occurring in the giant branch as a function of the stellar properties. We have determined the abundances of CNO and more specifically 12C/13C using the FIES Spectrograph on the Nordic Optical Telescope, for 71 giant field stars. In addition, asteroseismology is available for all stars, providing their mass, age as well as the evolutionary states. Finally, astrometry from Gaia data is also available for the majority of the sample. We compare these new determinations with stellar evolution models taking into account the effects of transport processes. To exploit the complete potential of our extensive catalogue and considering both the Galactic evolution and the impact of stellar evolution, we built mock catalogues using the Besancon Galaxy model in which stellar evolution models taking into account the effects of thermohaline instability are included. We confirm that 12C/13C at the surface of core He-burning stars is lower than that of first ascent RGB stars. 12C/13C measured at the surface of the core He-burning stars increases with [Fe/H] and mass while it decreases with age. These trends are all very well explained by the thermohaline mixing that occurs in red giants. We have shown that our models can explain the behaviour of 12C/13C versus N/O, although the observations seem to show a lower N/O than the models. We also note that more constraints on the thick disc core He-burning stars are needed to understand this difference.
|
https://arxiv.org/abs/2312.08197v1
|
The isotope abundances provide powerful diagnostics of the chemical enrichment in our Galaxy. The star HD 140283 is one of the best-studied very metal-poor dwarf stars. It is very old, and the chemical abundance in this star is a good witness of the chemical composition of the matter in the early Galaxy. The aim of this work is to measure the precise abundances of carbon, nitrogen, oxygen, and mainly the 12C/13C isotopic ratio in this very old metal-poor star in order to have a good reference for the computations of the chemical evolution of the Galaxy. We used very high spectral resolution data, with extremely high signal-to-noise ratios obtained with the spectrographs ESPaDOnS at the CFHT, ESPRESSO at the VLT, and HARPS at the ESO 3.6m telescope. For the first time, we were able to measure the 12C/13C ratio in a very old metal-poor dwarf that was born at the very beginning of the Galaxy: 27 < 12C/13C < 45. We also obtained a precise determination of the abundance of the CNO elements in this star. These abundances suggest that the effect of super-asymptotic giant branch stars or fast-rotating massive stars was significant in the early Galaxy.
|
https://arxiv.org/abs/2108.04072v1
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Background: A recent inelastic alpha-scattering experiment [Phys. Rev. Lett. 129, 102701 (2022)] found $0^+$ resonances in $^{24}$Mg on and above the $^{12}$C+$^{12}$C break-up threshold. It has been conjectured that the states have a $^{12}$C+$^{12}$C cluster structure, and play a similar role in accelerating $^{12}$C+$^{12}$C fusion to the manner in which the Hoyle state accelerates production of $^{12}$C in massive stars. Purpose: We wish to build up a quantitative theoretical basis for the considerations of the Hoyle-state paradigm, by calculating the distribution of the $0^+$ states in the shell, as well as in the relevant cluster models. Methods: We determine the spectrum of excited $0^+$ states in $^{24}$Mg nucleus using multiconfigurational dynamical symmetry calculations leading to a unified description of the quartet (or shell), $^{12}$C+$^{12}$C and $^{20}$Ne+$^{4}$He cluster configurations. Results: The density of $0^+$ states in the quartet spectrum is comparable to that found in experiment; however, the density of cluster states is considerably less. Conclusions: The recently observed alpha-scattering resonances do not seem to be simple $^{12}$C+$^{12}$C cluster states, but are more plausibly interpreted as fragmented cluster states due to coupling to quartet excitations, as background states.
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https://arxiv.org/abs/2312.08318v1
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High-momentum configurations of nucleon pairs at short-distance are probed using measurements of the $^{12}$C$(e,e'p)$ and $^{12}$C$(e,e'pN)$ reactions (where $N$ is either $n$ or $p$), at high-$Q^2$ and $x_B>1.1$. The data span a missing-momentum range of 300--1000 MeV/c and are predominantly sensitive to the transition region of the strong nuclear interaction from a Tensor to Scalar interaction. The data are well reproduced by theoretical calculations using the Generalized Contact Formalism with both chiral and phenomenological nucleon-nucleon ($NN$) interaction models. This agreement suggests that the measured high missing-momentum protons up to $1000$ MeV/c predominantly belong to short-ranged correlated (SRC) pairs. The measured $^{12}$C$(e,e'pN)$ / $^{12}$C$(e,e'p)$ and $^{12}$C$(e,e'pp)$ / $^{12}$C$(e,e'pn)$ cross-section ratios are consistent with a decrease in the fraction of proton-neutron SRC pairs and increase in the fraction of proton-proton SRC pairs with increasing missing momentum. This confirms the transition from an isospin-dependent tensor $NN$ interaction at $\sim 400$ MeV/c to an isospin-independent scalar interaction at high-momentum around $\sim 800$ MeV/c as predicted by theoretical calculation.
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https://arxiv.org/abs/2004.07304v2
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