cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
The Peril of Popular Deep Learning Uncertainty Estimation Methods
Creators: name: Liu, Yehao
name: Pagliardini, Matteo
name: Chavdarova, Tatjana
name: Stich, Sebastian U.
Publisher: name: CISPA
Year: 2023

description: Uncertainty estimation (UE) techniques -- such as the Gaussian process (GP), Bayesian neural networks (BNN), Monte Carlo dropout (MCDropout) -- aim to improve the interpretability of machine learning models by assigning an estimated uncertainty value to each of their prediction outputs. However, since too high uncertainty estimates can have fatal consequences in practice, this paper analyzes the above techniques.
Firstly, we show that GP methods always yield high uncertainty estimates on out of distribution (OOD) data. Secondly, we show on a 2D toy example that both BNNs and MCDropout do not give high uncertainty estimates on OOD samples. Finally, we show empirically that this pitfall of BNNs and MCDropout holds on real world datasets as well. Our insights (i) raise awareness for the more cautious use of currently popular UE methods in Deep Learning, (ii) encourage the development of UE methods that approximate GP-based methods -- instead of BNNs and MCDropout, and (iii) our empirical setups can be used for verifying the OOD performances of any other UE method. The source code is available at https://github.com/epfml/uncertainity-estimation.
Perturbation Theory for Metastable States of the Dirac Equation with Quadratic Vector Interaction
Creators: name: Giachetti, R.
name: Grecchi, V.
Publisher: name: arXiv
Year: 2009
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: The spectral problem of the Dirac equation in an external quadratic vector potential is considered using the methods of the perturbation theory. The problem is singular and the perturbation series is asymptotic, so that the methods for dealing with divergent series must be used. Among these, the Distributional Borel Sum appears to be the most well suited tool to give answers and to describe the spectral properties of the system. A detailed investigation is made in one and in three space dimensions with a central potential. We present numerical results for the Dirac equation in one space dimension: these are obtained by determining the perturbation expansion and using the Padé approximants for calculating the distributional Borel transform. A complete agreement is found with previous non-perturbative results obtained by the numerical solution of the singular boundary value problem and the determination of the density of the states from the continuous spectrum.
description: 10 pages, 1 figure
Masked Training of Neural Networks with Partial Gradients
Creators: name: Mohtashami, Amirkeivan
name: Jaggi, Martin
name: Stich, Sebastian
Publisher: name: CISPA
Year: 2023

description: State-of-the-art training algorithms for deep learning models are based on stochastic gradient descent (SGD). Recently, many variations have been explored: perturbing parameters for better accuracy (such as in Extragradient), limiting SGD updates to a subset of parameters for increased efficiency (such as meProp) or a combination of both (such as Dropout). However, the convergence of these methods is often not studied in theory. We propose a unified theoretical framework to study such SGD variants -- encompassing the aforementioned algorithms and additionally a broad variety of methods used for communication efficient training or model compression. Our insights can be used as a guide to improve the efficiency of such methods and facilitate generalization to new applications. As an example, we tackle the task of jointly training networks, a version of which (limited to sub-networks) is used to create Slimmable Networks. By training a low-rank Transformer jointly with a standard one we obtain superior performance than when it is trained separately.
COORDINATION BETWEEN TCP/IP PROTOCOL ON VAX AND APOLLO DOMAIN
Creators: name: M. L. FERRER
name: F. SGAMMA
name: J. WANG
Publisher: name: INFN Open Access Repository
Year: 1991

description: TCP/IP protocol has defined two types of routing methods: static and dynamic. In this note we give detailes how these routing methods could be coordinated between VAX and APOLLO Domain.
Medial knee pain after trauma
Creators: name: Janne D'Othee, Bertrand
Publisher: name: EURORAD
Year: 2015
Subjects: subject: Musculoskeletal joint
subject: CT
subject: MR
subject: Diagnostic procedure
subject: Trauma

description: Clinical History Image Findings Discussion Find Diagnosis Differential Diagnosis
description: female, 76 years
description: Clinical History: Fifteen days after being struck by a bus, a 76 year old woman was referred to our department for CT scan (Figure 1) due to persisting, exquisite pain along the medial compartment of her right knee. Based on her imaging findings, she then underwent a... Final Diagnosis: Reverse Segond fracture.
Uncommon cause of lower back pain during childhood.
Creators: name: Eiroa, Daniel
Publisher: name: EURORAD
Year: 2015
Subjects: subject: Bones
subject: Musculoskeletal bone
subject: Musculoskeletal system
subject: CT
subject: Conventional radiography
subject: MR
subject: Plain radiographic studies
subject: Diagnostic procedure
subject: Neoplasia

description: Clinical History Image Findings Discussion Find Diagnosis Differential Diagnosis
description: female, 13 years
description: Clinical History: A 13 year-old female patient with no history of previous trauma, who refers lower back pain that has been present for two years. The orthopaedic surgeon requests an X-ray. Final Diagnosis: Osteoid Osteoma
Masked Training of Neural Networks with Partial Gradients
Creators: name: Mohtashami, Amirkeivan
name: Jaggi, Martin
name: Stich, Sebastian U.
Publisher: name: CISPA
Year: 2023

description: State-of-the-art training algorithms for deep learning models are based on stochastic gradient descent (SGD). Recently, many variations have been explored: perturbing parameters for better accuracy (such as in Extragradient), limiting SGD updates to a subset of parameters for increased efficiency (such as meProp) or a combination of both (such as Dropout). However, the convergence of these methods is often not studied in theory. We propose a unified theoretical framework to study such SGD variants -- encompassing the aforementioned algorithms and additionally a broad variety of methods used for communication efficient training or model compression. Our insights can be used as a guide to improve the efficiency of such methods and facilitate generalization to new applications. As an example, we tackle the task of jointly training networks, a version of which (limited to sub-networks) is used to create Slimmable Networks. By training a low-rank Transformer jointly with a standard one we obtain superior performance than when it is trained separately.
Additional file 9 of The pattern of alternative splicing and DNA methylation alteration and their interaction in linseed (Linum usitatissimum L.) response to repeated drought stresses
Creators: name: Wang, Ling
name: Wang, Lei
name: Tan, Meilian
name: Wang, Linhai
name: Zhao, Wei
name: You, Jun
name: Wang, Lijun
name: Yan, Xingchu
name: Wang, Wei
Publisher: name: figshare
Year: 2023
Subjects: subject: Genetics
subject: FOS: Biological sciences

description: Additional file 9: Figure S3. REVIGO analysis of overlapping DSGs and DEGs.
Low-power Radio Galaxies in the Distant Universe: A search for FRI at 1
Creators: name: Chiaberge, Marco
name: Tremblay, Grant
name: Capetti, Alessandro
name: Macchetto, F. Duccio
name: Tozzi, Paolo
name: Sparks, William B.
Publisher: name: arXiv
Year: 2009
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: FOS: Physical sciences

description: We present a search for FRI radio galaxies between 1 < z < 2 in the COSMOS field. In absence of spectroscopic redshift measurements, the selection method is based on multiple steps which make use of both radio and optical constraints. The basic assumptions are that 1) the break in radio power between low-power FRIs and the more powerful FRIIs does not change with redshift, and 2) that the photometric properties of the host galaxies of low power radio galaxies in the distant universe are similar to those of FRIIs in the same redshift bin, as is the case for nearby radio galaxies. We describe the results of our search, which yields 37 low-power radio galaxy candidates that are possibly FRIs. We show that a large fraction of these low-luminosity radio galaxies display a compact radio morphology, that does not correspond to the FRI morphological classification. Furthermore, our objects are apparently associated with galaxies that show clear signs of interactions, at odds with the typical behavior observed in low-z FRI hosts. The compact radio morphology might imply that we are observing intrinsically small and possibly young objects, that will eventually evolve into the giant FRIs we observe in the local universe. One of the objects appears as point-like in HST images. This might belong to a population of FRI-QSOs, which however would represent a tiny minority of the overall population of high-z FRIs. As for the local FRIs, a large fraction of our objects are likely to be associated with groups or clusters, making them "beacons" for high redshift clusters of galaxies. Our search for candidate high-z FRIs we present in this paper constitutes a pilot study for objects to be observed with future high-resolution and high-sensitivity instruments (shortened)
description: 44 pages, 11 figures, version accepted for publication in ApJ
Evolution of a large online social network
Creators: name: Hu, Haibo
name: Wang, Xiaofan
Publisher: name: arXiv
Year: 2009
Subjects: subject: Physics and Society (physics.soc-ph)
subject: Data Analysis, Statistics and Probability (physics.data-an)
subject: Popular Physics (physics.pop-ph)
subject: FOS: Physical sciences

description: Although recently there are extensive research on the collaborative networks and online communities, there is very limited knowledge about the actual evolution of the online social networks (OSN). In the Letter, we study the structural evolution of a large online virtual community. We find that the scale growth of the OSN shows non-trivial S shape which may provide a proper exemplification for Bass diffusion model. We reveal that the evolutions of many network properties, such as density, clustering, heterogeneity and modularity, show non-monotone feature, and shrink phenomenon occurs for the path length and diameter of the network. Furthermore, the OSN underwent a transition from degree assortativity characteristic of collaborative networks to degree disassortativity characteristic of many OSNs. Our study has revealed the evolutionary pattern of interpersonal interactions in a specific population and provided a valuable platform for theoretical modeling and further analysis.
description: 14 pages, 9 figures, 1 table
ProxSkip: Yes! Local Gradient Steps Provably Lead to Communication Acceleration! Finally!
Creators: name: Mishchenko, Konstantin
name: Malinovsky, Grigory
name: Richtarik, Peter
name: Stich, Sebastian
Publisher: name: CISPA
Year: 2023

description: We introduce ProxSkip—a surprisingly simple and provably efficient method for minimizing the sum of a smooth (f) and an expensive nonsmooth proximable (ψ) function. The canonical approach to solving such problems is via the proximal gradient descent (ProxGD) algorithm, which is based on the evaluation of the gradient of f and the prox operator of ψ in each iteration. In this work we are specifically interested in the regime in which the evaluation of prox is costly relative to the evaluation of the gradient, which is the case in many applications. ProxSkip allows for the expensive prox operator to be skipped in most iterations: while its iteration complexity is O(κlog 1/ε), where κ is the condition number of f, the number of prox evaluations is O(κ−−√log 1/ε) only. Our main motivation comes from federated learning, where evaluation of the gradient operator corresponds to taking a local GD step independently on all devices, and evaluation of prox corresponds to (expensive) communication in the form of gradient averaging. In this context, ProxSkip offers an effective acceleration of communication complexity. Unlike other local gradient-type methods, such as FedAvg, SCAFFOLD, S-Local-GD and FedLin, whose theoretical communication complexity is worse than, or at best matching, that of vanilla GD in the heterogeneous data regime, we obtain a provable and large improvement without any heterogeneity-bounding assumptions.
Evolution of Dark Energy Perturbations in Scalar-Tensor Cosmologies
Creators: name: Sanchez, J. C. Bueno
name: Perivolaropoulos, L.
Publisher: name: arXiv
Year: 2010
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We solve analytically and numerically the generalized Einstein equations in scalar-tensor cosmologies to obtain the evolution of dark energy and matter linear perturbations. We compare our results with the corresponding results for minimally coupled quintessence perturbations. Our results for natural (O(1)) values of parameters in the Lagrangian which lead to a background expansion similar to LCDM are summarized as follows: 1. Scalar-Tensor dark energy density perturbations are amplified by a factor of about 10^6 compared to minimally coupled quintessence perturbations on scales less than about 100 h^{-1} Mpc. On these scales dark energy perturbations constitute a fraction of about 10% compared to matter density perturbations. 2. Scalar-Tensor dark energy density perturbations are anti-correlated with matter linear perturbations on sub-Hubble scales. Thus clusters of galaxies are predicted to overlap with voids of dark energy. 3. This anti-correlation of matter with negative pressure perturbations induces a mild amplification of matter perturbations by about 10% on sub-Hubble scales. 4. The evolution of scalar field perturbations on sub-Hubble scales, is scale independent and therefore it corresponds to a vanishing effective speed of sound (c_{sΦ}=0). It also involves large oscillations at early times induced by the amplified effective mass of the field. This amplification is due to the non-minimal coupling of the field to the Ricci curvature scalar and (thus) to matter. No such oscillations are present in minimally coupled quintessence perturbations which are suppressed on sub-Hubble scales (c_{sΦ}=1). Implications of our results include modified predictions for cluster halo profiles observed properties. These profiles are known to be in some tension with the predictions of LCDM.
description: 15 pages (revtex), 11 figures. References added, corrected caption of Fig. 11. The mathematica files used for the production of the figures and the numerical analysis include detailed pedagogical comments and may be downloaded from http://leandros.physics.uoi.gr/deperts/deperts.htm
The identification and distribution of two species of Peromyscus in southeastern Ontario
Creators: name: Lanko, Joyce Laurian
Publisher: name: University of British Columbia
Year: 2011

description: One hundred and sixty-nine mice of Peromyscus leucopus noveboracensis and Peromyscus maniculatus gracilis were examined for characters to best separate them. Each species was obtained from an area in Ontario where it was known to be the only one present. An additional 12 mice of both species were obtained from an area of sympatry. The best characters found to separate them were, in order of importance: ear length, interparietal length, tail length, skull length, and rostral length. Although ear length and interparietal length separated most of the individuals, there were still individuals that could not be separated. The two species were found to be completely separable, using either one of two indices: Ear length X tall length X interparietal length skull length or, Ear length X tail length X interparietal length rostral length. With skull length, P. 1. noveboracensis has an index value of 2.57-4.09 and P. m. gracilis has an index value of 4.26-7.90. With rostral length, P. 1. noveboracensis has an index value of 7.39-12.50 and P. m. gracilis has an index value of 12.83-22.77. Six crossbreeding experiments were attempted between P. 1. noveboracensis and four subspecies of P. maniculatus. The animals were kept together for periods ranging from 71 days to over a year. No offspring resulted. Three pairs of P. leucopus and four pairs of P. maniculatus were kept for the same periods of time in the same room, as a control. One pair of leucopus produced two litters, another pair produced one, and the third pair, none. Two pairs of maniculatus produced one litter each and the two pairs, none. P. m. gracilis was not as excitable or nervous as P. 1. noveboracensis and was therefore easier to handle. Although the ranges of P. 1. noveboracensis and P. m. gracilis differ, the mice meet in a zone of overlap where they occur sympatrically. Correlations were made between the ranges of the mice and vegetation, food preference, temperature tolerance, water requirement, morphology, color of pelage, and behavior. P. m. gracilis was found to occur in coniferous and P. 1. noveboracensis in deciduous vegetation. No correlation was found between the ranges of the mice and food preference, temperature tolerance, water requirement, morphology, and color of pelage. Correlation between the ranges of the mice and their behavior was doubtful. Preliminary tests were made of the ability of one species to discriminate between its odor and that of the other species. Results showed that a mouse entered more often and stayed longer in a chamber containing the odor of its own species. A chamber containing odor of either species was preferred to the control chamber without odor.
Search for double beta decay of Zinc and Tungsten with the help of low-background ZnWO4 crystal scintillators
Creators: name: Belli, P.
name: Bernabei, R.
name: Cappella, F.
name: Cerulli, R.
name: Danevich, F. A.
name: Grinyov, B. V.
name: Incicchitti, A.
name: Kobychev, V. V.
name: Mokina, V. M.
name: Nagorny, S. S.
name: Nagornaya, L. L.
name: Nisi, S.
name: Nozzoli, F.
name: Poda, D. V.
name: Prosperi, D.
name: Tretyak, V. I.
name: Yurchenko, S. S.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Nuclear Experiment (nucl-ex)
subject: FOS: Physical sciences

description: Double beta processes in 64-Zn, 70-Zn, 180-W, and 186-W have been searched for with the help of large volume (0.1-0.7 kg) low background ZnWO4 crystal scintillators at the Gran Sasso National Laboratories of the INFN. Total time of measurements exceeds 10 thousands hours. New improved half-life limits on double electron capture and electron capture with positron emission in 64-Zn have been set, in particular (all the limits are at 90% C.L.): T1/2(0nu2EC)> 1.1e20 yr, T1/2(2nuECbeta+)>7.0e20 yr, and T1/2(0nuECbeta+)>4.3e20 yr. The different modes of double beta processes in 70-Zn, 180-W, and 186-W have been restricted at the level of 1e17-1e20 yr.
description: 20 p., submitted to Phys. Rev. C
Fermion Masses from the Planck Mass
Creators: name: G. Preparata
name: She-Sheng-Xue
Publisher: name: INFN Open Access Repository
Year: 1992

description: The "no-go" theorem of Nielsen and Ninomiya, forbidding a sensible formulation of the usual electroweak action on a lattice, has been revised proceeding from the hypothesis that space-time, as a result of the dynamics of quantum gravity, is a four-dimensional random lattice with constant a_p, the Planck length. We find that a sensible electroweak theory at long wave-lengths is recovered by adding a chiral-gauge-invariant quadrilinear fermionic term. Dynamical symmetry breaking of Nambu-Jona-Lasinio (NJL) type is shown to be crucial for making contact with known phenomenology. The relation of this approach to similar recent proposal is briefly discussed.
Additional file 4 of CD248 promotes migration and metastasis of osteosarcoma through ITGB1-mediated FAK-paxillin pathway activation
Creators: name: Lu, Shiqi
name: Lu, Tong
name: Zhang, Jiayu
name: Gan, Lunbiao
name: Wu, Xinjie
name: Han, Donghui
name: Zhang, Keying
name: Xu, Chao
name: Liu, Shaojie
name: Qin, Weijun
name: Yang, Fa
name: Wen, Weihong
Publisher: name: figshare
Year: 2023
Subjects: Physical Sciences not elsewhere classified
Medicine
Cell Biology
Molecular Biology
Biological Sciences not elsewhere classified
Developmental Biology
Cancer

description: Supplementary Material 4
Time-dependent barrier passage of Two-dimensional non-Ohmic damping system
Creators: name: Wang, Chun-Yang
Publisher: name: arXiv
Year: 2009
Subjects: subject: Statistical Mechanics (cond-mat.stat-mech)
subject: FOS: Physical sciences

description: The time-dependent barrier passage of an anomalous damping system is studied via the generalized Langevin equation (GLE) with non-Ohmic memory damping friction tensor and corresponding thermal colored noise tensor describing a particle passing over the saddle point of a two-dimensional quadratic potential energy surface. The time-dependent passing probability and transmission coefficient are analytically obtained by using of the reactive flux method. The long memory aspect of friction is revealed to originate a non-monotonic $δ$(power exponent of the friction) dependence of the passing probability, the optimal incident angle of the particle and the steady anomalous transmission coefficient. In the long time limit a bigger steady transmission coefficient is obtained which means less barrier recrossing than the one-dimensional case.
description: 6 pages, 5 figures, 24 reference
ProxSkip: Yes! Local Gradient Steps Provably Lead to Communication Acceleration! Finally!
Creators: name: Mishchenko, Konstantin
name: Malinovsky, Grigory
name: Stich, Sebastian U.
name: Richtarik, Peter
Publisher: name: CISPA
Year: 2023

description: We introduce ProxSkip—a surprisingly simple and provably efficient method for minimizing the sum of a smooth (f) and an expensive nonsmooth proximable (ψ) function. The canonical approach to solving such problems is via the proximal gradient descent (ProxGD) algorithm, which is based on the evaluation of the gradient of f and the prox operator of ψ in each iteration. In this work we are specifically interested in the regime in which the evaluation of prox is costly relative to the evaluation of the gradient, which is the case in many applications. ProxSkip allows for the expensive prox operator to be skipped in most iterations: while its iteration complexity is O(κlog 1/ε), where κ is the condition number of f, the number of prox evaluations is O(κ−−√log 1/ε) only. Our main motivation comes from federated learning, where evaluation of the gradient operator corresponds to taking a local GD step independently on all devices, and evaluation of prox corresponds to (expensive) communication in the form of gradient averaging. In this context, ProxSkip offers an effective acceleration of communication complexity. Unlike other local gradient-type methods, such as FedAvg, SCAFFOLD, S-Local-GD and FedLin, whose theoretical communication complexity is worse than, or at best matching, that of vanilla GD in the heterogeneous data regime, we obtain a provable and large improvement without any heterogeneity-bounding assumptions.
Microcanonical Fermionic Average Method for Monte Carlo Simulations of Lattice Gauge Theories with Dynamical Fermions
Creators: name: V. Azcoiti
name: V. Laliena
name: X. Q. Luo
name: C. E. Piedrafita
name: G. Di Carlo
name: A. Galante
name: A. F. Grillo
name: L. A. Fernandez
name: A. Vladikas
Publisher: name: INFN Open Access Repository
Year: 1994

description: We present a comprehensive exposition of a method for performing numerical simulations of lattice gauge theories with dinamical fermions. Its main aspects have been presented elsewhere. This work is a systematic study of the feasibility of the method, which amounts to separating the evaluation of the fermionic determinant from the generation of gauge configurations through a microcanonical process. The main advantage consists in the fact that the parts of the simulation which are most computer intensive must not be repeated when varying the parameters of the theory. Moreover, we achieve good control over critical slowing down, since the configurations over which the determinant is measured are always very well decorrelated; in addition, the actual implementation of the method allows us to perform simulations at exactly zero fermion mass. We relate the numerical feasibility of this approach to an expansion in the number of flavors; the criteria for its convergence are analyzed both theoretically and in connection with physical problems. On more speculative grounds, we argue that the origin of the applicability of the method stems from the nonlocality of the theoryunder consideration. PACS number(s): 11.15.Ha, 02.70.Lq, 12.20.Ds
Sharper Convergence Guarantees for Asynchronous SGD for Distributed and Federated Learning
Creators: name: Koloskova, Anastasia
name: Jaggi, Martin
name: Stich, Sebastian
Publisher: name: CISPA
Year: 2023

description: We study the asynchronous stochastic gradient descent algorithm for distributed training over n workers which have varying computation and communication frequency over time. In this algorithm, workers compute stochastic gradients in parallel at their own pace and return those to the server without any synchronization. Existing convergence rates of this algorithm for non-convex smooth objectives depend on the maximum gradient delay τ_{max} and show that an ϵ-stationary point is reached after O(σ^2ϵ^{−2}+τ_{max}ϵ^{−1}) iterations, where σ denotes the variance of stochastic gradients.
In this work (i) we obtain a tighter convergence rate of O(σ^2ϵ^{−2}+ √ τ_{max}τ_{avg}ϵ^{−1}) without any change in the algorithm where τ_{avg} is the average delay, which can be significantly smaller than τ_{max}. We also provide (ii) a simple delay-adaptive learning rate scheme, under which asynchronous SGD achieves a convergence rate of O(σ^2ϵ^{−2}+τ_{avg}ϵ^{−1}), and does not require any extra hyperparameter tuning nor extra communications. Our result allows to show for the first time that asynchronous SGD is always faster than mini-batch SGD. In addition, (iii) we consider the case of heterogeneous functions motivated by federated learning applications and improve the convergence rate by proving a weaker dependence on the maximum delay compared to prior works. In particular, we show that the heterogeneity term in convergence rate is only affected by the average delay within each worker.
On the Developing of Net Ce Magnetic Moment Upon H2 Absorption in Ce2Fe14B: An XCMD Investigation
Creators: name: J. Chaboy
name: A. Marcelli
name: J. Garcia
name: H. Maruyama
name: L. M. Garcia
name: K. Kobajashi
name: L. Bozukov
Publisher: name: INFN Open Access Repository
Year: 1995

description: We present a combined X-ray Absorption Spectroscopy (XAS) and X-ray Circular Magnetic Dichroism (XCMD) investigation performed at the Ce L-edges in the case of Ce2Fe14B and its hydride derivantives. Both XAS and XCMD data do not show any modification of the mixed-valence electronic state of cerium upon hydriding. In fact, our results rule out the hypothesis of the presence of a pure Ce3+ configuration in the hydride derivative and the resulting induction of a localized 4f magnetic moment on the Ce sites upon hydriding.
Thermal-magnetic noise measurement of spin-torque effects on ferromagnetic resonance in MgO-based magnetic tunnel junctions
Creators: name: Guan, Yongfeng
name: Sun, Jonathan Z.
name: Jiang, Xin
name: Moriya, Rai
name: Gao, Li
name: Parkin, Stuart S. P.
Publisher: name: arXiv
Year: 2009
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: Thermal-magnetic noise at ferromagnetic resonance (T-FMR) can be used to measure magnetic perpendicular anisotropy of nanoscale magnetic tunnel junctions (MTJs). For this purpose, T-FMR measurements were conducted with an external magnetic field up to 14 kOe applied perpendicular to the film surface of MgO-based MTJs under a dc bias. The observed frequency-field relationship suggests that a 20 A CoFeB free layer has an effective demagnetization field much smaller than the intrinsic bulk value of CoFeB, with 4PiMeff = (6.1 +/- 0.3) kOe. This value is consistent with the saturation field obtained from magnetometry measurements on extended films of the same CoFeB thickness. In-plane T-FMR on the other hand shows less consistent results for the effective demagnetization field, presumably due to excitations of more complex modes. These experiments suggest that the perpendicular T-FMR is preferred for quantitative magnetic characterization of nanoscale MTJs.
description: 10 pages, 3 figures, accepted by APL
KONSEPT TUSHUNCHASI TA'RIFI, MAZMUNI VA STRUKTUR XUSUSIYATLARI
Creators: name: Alijonova, Oqila
Publisher: name: Zenodo
Year: 2023

description: Ushbu maqolada kontseptsiya tushunchasi muhokama qilinadi. Tushunchalar madaniy, lingvistik, psixologik, falsafiy va boshqa jihatlarda ko'rib chiqilib, ko'plab sharhlar, tasniflar va tadqiqot usullari taklif etiladi.
Sharper Convergence Guarantees for Asynchronous SGD for Distributed and Federated Learning
Creators: name: Koloskova, Anastasia
name: Stich, Sebastian U.
name: Jaggi, Martin
Publisher: name: CISPA
Year: 2023

description: We study the asynchronous stochastic gradient descent algorithm for distributed training over n workers which have varying computation and communication frequency over time. In this algorithm, workers compute stochastic gradients in parallel at their own pace and return those to the server without any synchronization. Existing convergence rates of this algorithm for non-convex smooth objectives depend on the maximum gradient delay τ_{max} and show that an ϵ-stationary point is reached after O(σ^2ϵ^{−2}+τ_{max}ϵ^{−1}) iterations, where σ denotes the variance of stochastic gradients.
In this work (i) we obtain a tighter convergence rate of O(σ^2ϵ^{−2}+ √ τ_{max}τ_{avg}ϵ^{−1}) without any change in the algorithm where τ_{avg} is the average delay, which can be significantly smaller than τ_{max}. We also provide (ii) a simple delay-adaptive learning rate scheme, under which asynchronous SGD achieves a convergence rate of O(σ^2ϵ^{−2}+τ_{avg}ϵ^{−1}), and does not require any extra hyperparameter tuning nor extra communications. Our result allows to show for the first time that asynchronous SGD is always faster than mini-batch SGD. In addition, (iii) we consider the case of heterogeneous functions motivated by federated learning applications and improve the convergence rate by proving a weaker dependence on the maximum delay compared to prior works. In particular, we show that the heterogeneity term in convergence rate is only affected by the average delay within each worker.
Evidence of Magnetically Driven Structural Phase Transition in Parent Compounds RFeAsO (R = La, Sm, Gd, Tb): study of low-temperature X-ray diffraction
Creators: name: Luo, Yongkang
name: Tao, Qian
name: Li, Yuke
name: Lin, Xiao
name: Li, Linjun
name: Cao, Guanghan
name: Xu, Zhu-an
name: Kaneko, Hiroshi
name: Savinkov, Andrey V.
name: Xue, Yun
name: Suzuki, Haruhiko
name: Fang, Chen
name: Hu, Jiangping
Publisher: name: arXiv
Year: 2009
Subjects: subject: Superconductivity (cond-mat.supr-con)
subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: We report measurements of structural phase transition of four parent compounds $R$FeAsO ($R$ = La, Sm, Gd, and Tb) by means of low-temperature X-ray diffraction (XRD). Magnetic transition temperatures associated with Fe ions ($T_{N1}$) are also determined from the temperature dependence of resistivity. As $R$ is changed from La, through Sm and Gd, to Tb, both the c-axis and a-axis lattice constants decrease significantly. Meanwhile both the structural phase transition temperature ($T_S$) and $T_{N1}$ decrease monotonously. It is also found that the temperature gap between $T_S$ and $T_{N1}$ becomes smaller when the distance between FeAs layer becomes shorter. This result is consistent with magnetically driven structural phase transition and suggests that the dimensionality have an important effect on the AFM ordering.
description: 6 pages, 5 figures
Decentralized Local Stochastic Extra-Gradient for Variational Inequalities
Creators: name: Beznosikov, Aleksandr
name: Dvurechensky, Pavel
name: Koloskova, Anastasia
name: Samokhin, Valentin
name: Gasnikov, Alexander
name: Stich, Sebastian
Publisher: name: CISPA
Year: 2023

description: We consider distributed stochastic variational inequalities (VIs) on unbounded domains with the problem data that is heterogeneous (non-IID) and distributed across many devices. We make a very general assumption on the computational network that, in particular, covers the settings of fully decentralized calculations with time-varying networks and centralized topologies commonly used in Federated Learning. Moreover, multiple local updates on the workers can be made for reducing the communication frequency between workers. We extend the stochastic extragradient method to this very general setting and theoretically analyze its convergence rate in the strongly monotone, monotone, and non-monotone settings when a Minty solution exists. The provided rates explicitly exhibit the dependence on network characteristics (e.g., mixing time), iteration counter, data heterogeneity, variance, number of devices, and other standard parameters. As a special case, our method and analysis apply to distributed stochastic saddle-point problems (SPP), e.g., to training Deep Generative Adversarial Networks (GANs) for which decentralized training has been reported to be extremely challenging. In experiments for decentralized training of GANs we demonstrate the effectiveness of our proposed approach.
Two new secondary metabolites from a mangrove-derived fungus Cladosporium sp. JJM22
Creators: name: Wu, Jia-Ting
name: Zheng, Cai-Juan
name: Zhang, Bin
name: Zhou, Xue-Ming
name: Zhou, Qi
name: Chen, Guang-Ying
name: Zeng, Zhuo-Er
name: Xie, Jin-Long
name: Han, Chang-Ri
name: Lyu, Ji-Xing
Publisher: name: Taylor & Francis
Year: 2018
Subjects: subject: Biochemistry
subject: Physical Sciences not elsewhere classified
subject: Medicine
subject: Microbiology
subject: FOS: Biological sciences
subject: Pharmacology
subject: Environmental Sciences not elsewhere classified
subject: Chemical Sciences not elsewhere classified
subject: Ecology
subject: Biological Sciences not elsewhere classified
subject: Plant Biology

description: Two new compounds (1 and 2), together with six known compounds (3–8), were obtained from the Cladosporium sp. JJM22, an endophytic fungus isolated from the stem bark of the mangrove plant Ceriops tagal collected in South China Sea. Their structures were elucidated on the basis of detailed spectroscopic analysis. The absolute configurations of 1 and 2 were confirmed by the comparison of optical rotation and the CD data with those of known compounds. The inhibitory activities of the isolated compounds against six terrestrial pathogenic bacteria and human cervical carcinoma Hela cell line were evaluated. Compound 3 exhibited a broad spectrum of antibacterial activities.
Heterogeneous Bond Percolation on Multitype Networks with an Application to Epidemic Dynamics
Creators: name: Allard, Antoine
name: Noël, Pierre-André
name: Dubé, Louis J.
name: Pourbohloul, Babak
Publisher: name: arXiv
Year: 2008
Subjects: subject: Populations and Evolution (q-bio.PE)
subject: Statistical Mechanics (cond-mat.stat-mech)
subject: FOS: Biological sciences
subject: FOS: Physical sciences

description: Considerable attention has been paid, in recent years, to the use of networks in modeling complex real-world systems. Among the many dynamical processes involving networks, propagation processes -- in which final state can be obtained by studying the underlying network percolation properties -- have raised formidable interest. In this paper, we present a bond percolation model of multitype networks with an arbitrary joint degree distribution that allows heterogeneity in the edge occupation probability. As previously demonstrated, the multitype approach allows many non-trivial mixing patterns such as assortativity and clustering between nodes. We derive a number of useful statistical properties of multitype networks as well as a general phase transition criterion. We also demonstrate that a number of previous models based on probability generating functions are special cases of the proposed formalism. We further show that the multitype approach, by naturally allowing heterogeneity in the bond occupation probability, overcomes some of the correlation issues encountered by previous models. We illustrate this point in the context of contact network epidemiology.
description: 10 pages, 5 figures. Minor modifications were made in figures 3, 4 and 5 and in the text. Explanations and references were added
Upward muon signals at neutrino detectors as a probe of dark matter properties
Creators: name: Hisano, Junji
name: Nakayama, Kazunori
name: Yang, Masaki J. S.
Publisher: name: arXiv
Year: 2009
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: We study upward muon flux at neutrino detectors such as Super-Kamiokande resulting from high-energy neutrinos produced by the dark matter annihilation/decay at the Galactic center. In particular, we distinguish showering and non-showering muons as their energy loss processes inside the detector, and show that this information is useful for discriminating dark matter models.
description: 7 pages, 6 figures; minor correction, to appear in PLB
Decentralized Local Stochastic Extra-Gradient for Variational Inequalities
Creators: name: Beznosikov, Aleksandr
name: Dvurechensky, Pavel
name: Koloskova, Anastasia
name: Samokhin, Valentin
name: Stich, Sebastian U.
name: Gasnikov, Alexander
Publisher: name: CISPA
Year: 2023

description: We consider distributed stochastic variational inequalities (VIs) on unbounded domains with the problem data that is heterogeneous (non-IID) and distributed across many devices. We make a very general assumption on the computational network that, in particular, covers the settings of fully decentralized calculations with time-varying networks and centralized topologies commonly used in Federated Learning. Moreover, multiple local updates on the workers can be made for reducing the communication frequency between workers. We extend the stochastic extragradient method to this very general setting and theoretically analyze its convergence rate in the strongly monotone, monotone, and non-monotone settings when a Minty solution exists. The provided rates explicitly exhibit the dependence on network characteristics (e.g., mixing time), iteration counter, data heterogeneity, variance, number of devices, and other standard parameters. As a special case, our method and analysis apply to distributed stochastic saddle-point problems (SPP), e.g., to training Deep Generative Adversarial Networks (GANs) for which decentralized training has been reported to be extremely challenging. In experiments for decentralized training of GANs we demonstrate the effectiveness of our proposed approach.
Problems of thinning and small log handling in second growth western hemlock stands with special reference to the research forest on East Thurlow Island
Creators: name: Adamovich, Lazlo Leslie
Publisher: name: University of British Columbia
Year: 2011

description: Diminishing virgin timber on the Coast of British Columbia leads to consideration as to how management of the second-growth forests will supply the timber industry with a sufficient quantity of good quality raw material in the future. One of the possibilities would be intensive forest management supported by thinnings. The stands of western hemlock (Tsuga heterophylla (Rafn.) Sarg.), which comprise the largest area on the Coast, may be suited to this treatment because of their advantageous silvicultural characteristics. Little information exists on proper methods of thinning these hemlock stands. In addition, experience in logging methods and means of economically handling small logs are lacking. Among the few experiments which have been established to study thinning of hemlock, one is located on East Thurlow Island where nearly pure stands of hemlock occur. The Research Forest on the Island was scheduled to become an experimental and demonstration area for the study of thinning techniques. Studies under way on that area have shown that the methods used, had limited economic success. Commercial thinning operations turned out to be unprofitable partly because there was no adequate road system available for logging. Thinning problems in general, as well as the particular aspect of thinning western hemlock and the methods of handling small logs are discussed in this thesis to illustrate the basic problems involved in a development plan for the Research Forest. Finally, this thesis presents a general road development plan for the Research Forest area and proposes a preliminary management and logging plan. Through cost analysis it is shown that the basic access road system can be constructed economically during a preparatory period by clearcutting scattered overmature stands. Subsequent thinning experiments can be based on that road network. The approach to these problems is general rather than specific because there are few detailed data available from past experiments.
Solar-Terrestrial Simulation in the STEREO Era: The January 24-25, 2007 Eruptions
Creators: name: Lugaz, N.
name: Vourlidas, A.
name: Roussev, I. I.
name: Morgan, H.
Publisher: name: arXiv
Year: 2009
Subjects: subject: Space Physics (physics.space-ph)
subject: FOS: Physical sciences

description: The SECCHI instruments aboard the recently launched STEREO spacecraft enable for the first time the continuous tracking of coronal mass ejections (CMEs) from the Sun to 1 AU. We analyze line-of-sight observations of the January 24-25, 2007 CMEs and fill the 20-hour gap in SECCHI coverage in January 25 by performing a numerical simulation using a three-dimensional magneto-hydrodynamic (MHD) code, the Space Weather Modeling Framework (SWMF). We show how the observations reflect the interaction of the two successive CMEs with each other and with the structured solar wind. We make detailed comparison between the observations and synthetic images from our model, including time-elongation maps for several position angles. Having numerical simulations to disentangle observational from physical effects, we are able to study the three-dimensional nature of the ejections and their evolution in the inner heliosphere. This study reflects the start of a new era where, on one hand, models of CME propagation and interaction can be fully tested by using heliospheric observations and, on the other hand, observations can be better interpreted by using global numerical models.
description: 18 pages, 6 figures, accepted to the topical issue of Solar Physics on STEREO results at solar minimum
Revisiting Gradient Clipping: Stochastic bias and tight convergence guarantees
Creators: name: Koloskova, Anastasia
name: Hendrikx, Hadrien
name: Stich, Sebastian
Publisher: name: CISPA
Year: 2023

description: Gradient clipping is a popular modification to standard (stochastic) gradient descent, at every iteration limiting the gradient norm to a certain value
. It is widely used for example for stabilizing the training of deep learning models (Goodfellow et al., 2016), or for enforcing differential privacy (Abadi et al., 2016). Despite popularity and simplicity of the clipping mechanism, its convergence guarantees often require specific values of
 and strong noise assumptions. In this paper, we give convergence guarantees that show precise dependence on arbitrary clipping thresholds
 and show that our guarantees are tight with both deterministic and stochastic gradients. In particular, we show that (i) for deterministic gradient descent, the clipping threshold only affects the higher-order terms of convergence, (ii) in the stochastic setting convergence to the true optimum cannot be guaranteed under the standard noise assumption, even under arbitrary small step-sizes. We give matching upper and lower bounds for convergence of the gradient norm when running clipped SGD, and illustrate these results with experiments.
Additional file 1 of Genetically engineered CXCR4-modified exosomes for delivery of miR-126 mimics to macrophages alleviate periodontitis
Creators: name: Luo, Haotian
name: Chen, Danying
name: Li, Ruoyu
name: Li, Runze
name: Teng, Yungshan
name: Cao, Yang
name: Zou, Xuenong
name: Wang, Weicai
name: Zhou, Chen
Publisher: name: figshare
Year: 2023
Subjects: subject: Microbiology
subject: FOS: Biological sciences
subject: Pharmacology
subject: Environmental Sciences not elsewhere classified
subject: Immunology
subject: FOS: Clinical medicine
subject: Biological Sciences not elsewhere classified
subject: Science Policy
subject: Infectious Diseases
subject: FOS: Health sciences

description: Supplementary Material 1
PlasmaPy as an Educational Resource
Creators: name: Schaffner, David
Publisher: name: Zenodo
Year: 2021

description: As a software ecosystem, the PlasmaPy Project aims to incorporate a multitude of educational resources for the plasma community in addition to developing an open source Python package for plasma physics research. Potential educational resources include: 1) extensive documentation for diagnostic analysis tools that go beyond code function and aim to clearly explain how such diagnostics operate, 2) a suite of Jupyter notebooks that introduce plasma concepts using functionality from PlasmaPy, and 3) development of PlasmaPy-based code and tools for incorporation into undergraduate laboratory curricula. Many of these educational elements will be designed with an eye toward expanding the pipeline of students into plasma physics careers, with resources aimed at introducing students to both plasma concepts and software best practices at graduate, undergraduate and even high school levels. In this poster, we will discuss current capabilities and future plans for using PlasmaPy as an educational resource.
description: This work was primarily supported by NSF grant 1931393.