Miracle-dz/UniFAR-FTUs huggingface dataset:
A Theoretically Sound Upper Bound on the Triplet Loss for Improving the Efficiency of Deep Distance Metric Learning

We propose a method that substantially improves the efficiency of deep distance metric learning based on the optimization of the triplet loss function. One epoch of such training process based on a na¨ıve optimization of the triplet loss function has a run-time complexity O(N^3), where N is the number of training samples. Such optimization scales poorly, and the most common approach proposed to address this high complexity issue is based on sub-sampling the set of triplets needed for the training process. Another approach explored in the field relies on an ad-hoc linearization (in terms of N) of the triplet loss that introduces class centroids, which must be optimized using the whole training set for each mini-batch – this means that a na¨ıve implementation of this approach has run-time complexity O(N^2). This complexity issue is usually mitigated with poor, but computationally cheap, approximate centroid optimization methods. In this paper, we first propose a solid theory on the linearization of the triplet loss with the use of class centroids, where the main conclusion is that our new linear loss represents a tight upper-bound to the triplet loss. Furthermore, based on the theory above, we propose a training algorithm that no longer requires the centroid optimization step, which means that our approach is the first in the field with a guaranteed linear run-time complexity. We show that the training of deep distance metric learning methods using the proposed upper-bound is substantially faster than triplet-based methods, while producing competitive retrieval accuracy results on benchmark datasets (CUB-200-2011 and CAR196).
Simplified model of the back surface of a charge-coupled device

A simplified model of the back surface of the CCD is discussed. The model incorporates parameters which account for the important features of the back surface: a surface recombination velocity, an electric field which can assist in or oppose the collection of signal charge, and a field free region. Calculations using the model equations are presented to illustrate the effect of these parameters on the distribution of excess carriers and on the resulting quantum efficiency. The results indicate that only moderate fields are required to achieve high quantum efficiencies even at short wavelengths.
Thermal stability of sputtered Cu films with nanoscale growth twins

We have investigated the thermal stability of sputter-deposited Cu thin films with a high density of nanoscale growth twins by using high-vacuum annealing up to 800 °C for 1 h. Average twin lamella thickness gradually increased from approximately 4 nm for as-deposited films to slightly less than 20 nm after annealing at 800 °C. The average columnar grain size, on the other hand, rapidly increased from approximately 50 to 500 nm. In spite of an order of magnitude increase in grain size, the annealed films retained a high hardness of 2.2 GPa, reduced from 3.5 GPa in the as-deposited state. The high hardness of the annealed films is interpreted in terms of the thermally stable nanotwinned structures. This study shows that nanostructures with a layered arrangement of low-angle coherent twin boundaries may exhibit better thermal stability than monolithic nanocrystals with high-angle grain boundaries.
Preparation and photoabsorption characterization of BiFeO3 nanowires

Perovskite-type polycrystalline BiFeO3 (BFO) nanowires (∼50nm in diameter and ∼5μm in length) were synthesized using the anodized alumina template technique. An energy band gap of ∼2.5eV was determined from the UV-visible diffuse reflectance spectrum, and its photocatalytic ability to produce O2 was revealed under UV irradiation. Weak ferromagnetism at room temperature and superparamagnetism at low temperature were observed for the BFO nanowires, different from the antiferromagnetic order in bulk BFO, reflecting the significant size effects on the magnetic ordering of BFO.
Thick-wall effects on the rotational stabilization of resistive wall modes in tokamaks

This paper is devoted to studying the combined effect of mode rotation and energy dissipation in the resistive wall on plasma stability. The problem is analysed on the basis of the energy approach complementing the standard methods of the traditional MHD theory of plasma stability. The key element that makes our model different from this theory and commonly used thin-wall approaches to the stability analysis of resistive wall modes (RWMs) is the incorporation of the skin effect. In the ideal MHD theory of plasma stability, the skin depth is, formally, zero. In contrast, the conventional thin-wall theory of RWM stability assumes a skin depth much larger than the wall thickness. The presented model considers the intermediate case with a finite skin depth compared with the wall thickness. This covers the modes in between the typical RWMs and the ideal MHD modes when wall resistivity still affects the mode dynamics. It is shown that, in this region, the growth rate of the locked modes must be substantially larger than that calculated in the thin-wall models. On the other hand, the fast RWMs can be completely stabilized by mode rotation above some critical level. Qualitatively, this corresponds to the rotational stabilization observed in the DIII-D tokamak and allowing the plasma operation above the no-wall stability limit (Strait et al 2003 Nucl. Fusion 43 430). This is the main result of this study, which is completely analytical with all dependences explicitly shown. In particular, the dispersion relations for the fast RWMs and the critical frequency of mode rotation necessary for rotational stabilization are expressed through quantities that depend on the plasma parameters or can be experimentally found by magnetic measurements outside the plasma.
Propagation of noise above ground having an impedance discontinuity

Controlled measurements above ground with an impedance discontinuity are described. The measurements were made outdoors with a source above asphalt and a receiver above grass, and indoors above surfaces of known impedance in the absence of atmospheric turbulence. The results were obtained for several sources and receiver heights and for various percentages of hard–soft ground to propagation distances of 2.4 m indoors and 10 m outdoors. The measurements are also extended to include the case of a source above ground of finite impedance but which is still harder than the ground on the receiver side. The measurements are compared with recent theory which includes semiempirical solutions and solutions obtained numerically from Green’s theorem. Good agreement between the measured results and all the theories is obtained in most cases. However, in more extreme situations, including the ‘‘soft–softer’’ ground case, the semiempirical solutions are in difficulty. Earlier work [Nicolas et al., J. Acoust. Soc. Am. 73.
Interactions between topographically and thermally forced stationary waves: implications for ice-sheet evolution

ABSTRACT This study examines mutual interactions between stationary waves and ice sheets using a dry atmospheric primitive-equation model coupled to a three-dimensional thermomechanical ice-sheet model. The emphasis is on how non-linear interactions between thermal and topographical forcing of the stationary waves influence the ice-sheet evolution by changing the ablation. Simulations are conducted in which a small ice cap, on an idealised Northern Hemisphere continent, evolves to an equilibrium continental-scale ice sheet. In the absence of stationary waves, the equilibrium ice sheet arrives at symmetric shape with a zonal equatorward margin. In isolation, the topographically induced stationary waves have essentially no impact on the equilibrium features of the ice sheet. The reason is that the temperature anomalies are located far from the equatorward ice margin. When forcing due to thermal cooling is added to the topographical forcing, thermally induced perturbation winds amplify the topographically induced stationary-wave response, which that serves to increase both the equatorward extent and the volume of the ice sheet. Roughly, a 10% increase in the ice volume is reported here. Hence, the present study suggests that the topographically induced stationary-wave response can be substantially enhanced by the high albedo of ice sheets.
Orbital period changes in Centaurus X-3

Two new times of mid-X-ray eclipse for Cen X-3 are presented on the basis of pulse arrival time analyses of pointed observations with SAS 3. When combined with all other published eclipse times based on Doppler delay measurements, the results show that the 2.1d binary period is decreasing at an average rate of 1.8 x 10 to the -6th/yr. The decrease, however, is seen as having significant fluctuations about a smooth, linear decrease. The changes observed in the orbital period can be accounted for by mass loss from the system through the L2 point, although the rates required are implausibly high. It is also shown that the long-term overall orbital decay can readily be interpreted as the result of torques exerted by the tidally distorted companion star (Krzeminski's star) on the orbiting neutron star. It is noted that the inferred asynchronism between the orbital frequency and the rotation frequency of the companion star may be maintained by mass and angular momentum loss in a stellar wind or by a tidal instability related to the Darwin effect. However, this would not provide a natural explanation for any short-term deviations from a constant rate of orbital decay.
Mathematical Modeling of Skin Bioheat Transfer

Advances in laser, microwave, and similar technologies have led to recent developments of thermal treatments for disease and injury involving skin tissue. In spite of the widespread use of heating therapies in dermatology, they do not draw upon the detailed understanding of the biothermomechanics of behavior, for none exists to date, even though each behavioral facet is well established and understood. It is proposed that a detailed understanding of the coupled biological-mechanical response under thermal agitation will contribute to the design, characterization, and optimization of strategies for delivering better treatment. For a comprehensive understanding on the underlying mechanisms of thermomechanical behavior of skin tissue, recent progress on bioheat transfer, thermal damage, thermomechanics, and thermal pain should be systematically reviewed. This article focuses on the transfer of heat through skin tissue. Experimental study, theoretical analysis, and numerical modeling of skin thermal behavior are reviewed, with theoretical analysis carried out and closed-form solutions obtained for simple one-layer Fourier theory based model. Non-Fourier bioheat transfer models for skin tissue are discussed, and various skin cooling technologies summarized. Finally, the predictive capacity of various heat transfer models is demonstrated with selected case studies. DOI: 10.1115/1.3124646
Multidirectional edge-directed interpolation with region division for natural images

Yujin Yun, Jonghyun Bae, and Jaeseok KimYonsei University, Department of Electrical and ElectronicEngineering, 50 Yonsei-ro, Seodaemun-gu, Seoul,Republic of KoreaE-mail: yujin.yun@yonsei.ac. krAbstract. A multidirectional edge-directed interpolation algo-rithm that features a region division method is proposed. Inthe proposed method, an interpolation pixel is newly modeledas a weighted sum of 12 neighboring pixels representing 12different directions. Each weight is estimated by Wiener filtertheory using geometric duality. The proposed method fordividing the interpolation region reduces the heavy computa-tional complexity of the proposed model. Analyzing edgecontinuities, the model divides an image into three regions,and only strong edge regions are interpolated. Simulationresults show that several directional edges are restoredclearly in a subjective test, with fair performance in an objec-tive test.
Ferromagnetism in cobalt-iron alloy nanowire arrays on W(110)

We have prepared arrays of parallel Fe1−xCox alloy nanowires along the atomic step edges of a miscut W(110) surface. Their magnetic properties have been studied with the surface magneto-optical Kerr effect as a function of the relative concentration of the two materials. At low (<35%) cobalt concentrations, the wire arrays exhibit a ferromagnetic easy axis along the substrate [1 −1 0] direction, which is in the surface plane, but perpendicular to the wires. Unlike the bulk alloy, this system shows a decrease in its Curie temperature as cobalt is added to pure Fe. The Curie temperature drops sharply near x=0.35, indicating that cobalt frustrates magnetic ordering in the system.
Testing for unit roots: a simple alternative to Dickey—Fuller

This ariticle proposes a very simple test for a unit root in a time series which is based on the residual autocorrelation function from a regression of the observed series on a linear trend. The test statistic is proportional to the maximum lag length for which the residual autocorrelations at all lower lag lengths are stickly positive. Critical values for the test are calculated using Monte Carlo simultation assuming a random walk DGP. Its robustness properties to different I(1) DGPs are examined along with its power characteristics. These are found to compare very favourably to those of Dickey–Fuller-type tests.
Application of L-moments for IDF determination in an Austrian basin

The aim of this paper is to evaluate a precise intensity-duration-frequency (IDF) relation for a small catchment area which is situated at the north part of Graz in Austria. In order to determine the probability of occurrence of any rainfall event, the frequency distribution, which can fit past characteristics on the magnitude and the probability of occurrence of such rainfalls, should be known. In this paper, in order to find the best-fit probability distribution model, some parameter estimation techniques such as L-moments and maximum likelihood models were used and for goodness of fit test, three methods were used as chi-square, Kolmogorov-Smirnov and the root mean square error (RMSE). In this paper, a comparison between four commonly used rainfall frequency distributions were carried out such as generalised extreme value (GEV), Gumbel, log-Pearson type 3 (LP3) and three-parameter log-normal (LN3). Finally, using the best-fit probability distribution, the IDF for this catchment area using a simple graphical method was determined.
Pattern‐mixture models with proper time dependence

Recently, pattern-mixture modelling has become a popular tool for modelling incomplete longitudinal data. Such models are under-identified in the sense that, for any drop-out pattern, the data provide no direct information on the distribution of the unobserved outcomes, given the observed ones. One simple way of overcoming this problem, ordinary extrapolation of sufficiently simple pattern-specific models, often produces rather unlikely descriptions; several authors consider identifying restrictions instead. Molenberghs et al. (1998) have constructed identifying restrictions corresponding to missing at random. In this paper, the family of restrictions where drop-out does not depend on future, unobserved observations is identified. The ideas are illustrated using a clinical study of Alzheimer patients. Copyright Biometrika Trust 2003, Oxford University Press.
Is there a “Socratic Effect” in Nonexperimental Panel Studies?

It has often been observed in experimental studies that the reliability of items increases if the same questions are asked of the same respondents more than once. This phenomenon, called the “Socratic effect,” also occurs in nonexperimental, short-wave panel studies. In the first section of this article a number of hypotheses presumed to underlie the “Socratic effect” are presented. It is argued that a distinction must be made between consistency processes at the structural level (latent attitudes) and the observational level (respondent behavior). Given this distinction, the hypotheses are tested within a LISREL framework that takes this differentiation into account. The hypotheses are then evaluated using four items to measure respondents' attitudes toward guestworkers in West Germany. By and large the central hypotheses are confirmed. It is also shown that two different models can be fit to the observed data equally well, and therefore a nonstatistical criterion has to be invoked to decide which model to use as the basic model for describing the stability and reliability of the attitude.
Noncollinearly Phase Matched Second Harmonic Generation in LiIO3

A formulation of the theory on the noncollinearly phase matched second harmonic generation is given. The theory treats the effects of phase mismatching and of the interaction volume of two differently directed fundamental laser beams. When the crystal is rotated from the matching angle, the second harmonic power decreases more rapidly with the enlargement of the interaction volume. The experimental results suggest the validity of the theory. Comparison with the collinear case indicates that higher power can be obtained in the noncollinear case.
A new DEI algorithm capable of investigating sub-pixel structures

Diffraction enhanced imaging (DEI) is a phase-sensitive x-ray imaging technique based on the use of an analyser crystal placed between the sample and the detector. In the recent years, DEI has proven outstanding image quality both in material science and medical imaging, as well as the capability to provide quantitative information. However, in the case of objects featuring a fine refractive structure, which is not resolved by the spatial resolution of the detector, the fundamental requirements for the applicability of the DEI algorithm are not fulfilled. Herein a new algorithm is presented that takes into account this particular case. Formally similar to DEI, it allows obtaining quantitative information on the absorption and refraction properties of the object. Thus, structures in the sub-pixel length scale can be imaged and analysed quantitatively.
Affine calibration based on invariable extrinsic parameters for stereo light microscope

Abstract. The stereo light microscope (SLM) plays an important role in the measurement of three-dimensional geometry on the microscopic scale. We propose a fast and precise affine calibration algorithm based on the invariable extrinsic parameters for the SLM. This calibration algorithm with a free planar reference consists of three steps: first, derive the extrinsic parameters based on their invariable definition in the pinhole and affine models; second, calculate the intrinsic parameters through homography matrix; finally, refine all the model parameters by global optimization with the previous closed-form solutions as the initial values. The effectiveness of assuming a noncoaxial optical system as an affine camera is also verified to affinely model all types of SLMs. The calibration experiments show that the affine calibration is preferable for multicriteria including running time, relative positioning precision, and absolute positioning precision. With PlanApo S 1.5× and a total magnification of 3.024×, the proposed affine calibration algorithm achieves a distance error of 0.423 μm and a positioning error of 0.195 mm within 10.6 s.
Many-pass resonant laser amplifier

A very high gain amplifier has been developed by arranging for many amplifying passes to be made through one system. Input pulses of millijoule energy have been amplified to the damage limit of the materials (∼10 J/cm2) by this method. One such system can replace several when amplification of low-energy pulses is required.
Refinements in asymptotic expansions for sums of weakly dependent random vectors

Let S0 denote the nth normalized partial sum of a sequence of mean zero, weakly dependent random vectors. This paper gives asymptotic expansions for Ef(Sn) under weaker moment conditions than those of G6tze and Hipp (1983). It is also shown that an expansion for Ef(Sn) with an error term o(n-(S -2)/2) is valid without any Cramer-type condition, if f has partial derivatives of order (s 1) only, This settles a conjecture of G6tze and Hipp in their 1983 paper.
Hospitalization Risk During Chemotherapy for Advanced Cancer: Development and Validation of Risk Stratification Models Using Real-World Data.

PURPOSE Hospitalizations are a common occurrence during chemotherapy for advanced cancer. Validated risk stratification tools could facilitate proactive approaches for reducing hospitalizations by identifying at-risk patients. PATIENTS AND METHODS We assembled two retrospective cohorts of patients receiving chemotherapy for advanced nonhematologic cancer; cohorts were drawn from three integrated health plans of the Cancer Research Network. We used these cohorts to develop and validate logistic regression models estimating 30-day hospitalization risk after chemotherapy initiation. The development cohort included patients in two health plans from 2005 to 2013. The validation cohort included patients in a third health plan from 2007 to 2016. Candidate predictor variables were derived from clinical data in institutional data warehouses. Models were validated based on the C-statistic, positive predictive value, and negative predictive value. Positive predictive value and negative predictive value were calculated in reference to a prespecified risk threshold (hospitalization risk ≥ 18.0%). RESULTS There were 3,606 patients in the development cohort (median age, 63 years) and 634 evaluable patients in the validation cohort (median age, 64 years). Lung cancer was the most common diagnosis in both cohorts (26% and 31%, respectively). The selected risk stratification model included two variables: albumin and sodium. The model C-statistic in the validation cohort was 0.69 (95% CI, 0.62 to 0.75); 39% of patients were classified as high risk according to the prespecified threshold; 30-day hospitalization risk was 24.2% (95% CI, 19.9% to 32.0%) in the high-risk group and 8.7% (95% CI, 6.1% to 12.0%) in the low-risk group. CONCLUSION A model based on data elements routinely collected during cancer treatment can reliably identify patients at high risk for hospitalization after chemotherapy initiation. Additional research is necessary to determine whether this model can be deployed to prevent chemotherapy-related hospitalizations.
Disjoint hard models for classification

The paper describes a new approach for disjoint hard modelling of classes. This involves developing independent PC models for each group in the class, and calculating both the Q statistic (square prediction error) for each sample to the class model and a separate statistic about how well samples are classified within the projected PC space. The latter statistic can be applied to different types of classifiers, in this paper we choose to illustrate by Quadratic Discriminant Analysis (D statistic) and one class Support Vector Domain Description (SVDD) (f‐value). The two measures (Q and the classifier dependent statistic) are combined into a joint decision function which uniquely classifies each sample. The disjoint hard models are contrasted to conjoint models where PCA is performed on the entire dataset using both QDA and Support Vector Machines (SVMs) classifiers. The optimum number of PCs for each model is determined using the bootstrap, and model performance assessed on 100 test sets obtained using different iterative splits, using %PA (Predictive Ability) and %CR (Classification Rate). The method is illustrated using a dataset consisting of 293 samples from nine groups of polymers obtained using thermal profiling. The approach described, in this paper, has many of the advantages of one class disjoint models (e.g. SIMCA) and of conventional hard models, and is useful if it is known that all samples must belong to one of a series of known groups but each group has a very different structure. Copyright © 2010 John Wiley & Sons, Ltd.