Miracle-dz/UniFAR-FTUs huggingface dataset:
Bias in the estimation of non-linear transformations of the integrated variance of returns

Volatility models such as GARCH, although misspecified with respect to the data-generating process, may well generate volatility forecasts that are unconditionally unbiased. In other words, they generate variance forecasts that, on average, are equal to the integrated variance. However, many applications in finance require a measure of return volatility that is a non-linear function of the variance of returns, rather than of the variance itself. Even if a volatility model generates forecasts of the integrated variance that are unbiased, non-linear transformations of these forecasts will be biased estimators of the same non-linear transformations of the integrated variance because of Jensen's inequality. In this paper, we derive an analytical approximation for the unconditional bias of estimators of non-linear transformations of the integrated variance. This bias is a function of the volatility of the forecast variance and the volatility of the integrated variance, and depends on the concavity of the non-linear transformation. In order to estimate the volatility of the unobserved integrated variance, we employ recent results from the realized volatility literature. As an illustration, we estimate the unconditional bias for both in-sample and out-of-sample forecasts of three non-linear transformations of the integrated standard deviation of returns for three exchange rate return series, where a GARCH(1, 1) model is used to forecast the integrated variance. Our estimation results suggest that, in practice, the bias can be substantial. Copyright © 2006 John Wiley & Sons, Ltd.
High-speed Recognition Algorithm Based on BRISK and Saliency Detection for Aerial Images

A fast ground object recognition method for aerial images, taking airports, oil depots, harbors etc. as research objects, is proposed in this paper based on BRISK and the visual saliency detection. According to the characteristics of aerial images, such as high resolution and complex background interference, saliency detection is applied to select the candidate object region where the target may exist. Therefore, it can reduce the searching range effectively. And then, BRISK matching method is used to recognize the object efficiently. A variety of experiments under different interference factors are carried out base on the typical object database of aerial images in this paper. Experimental results show that the proposed algorithm can not only maintain the validity of BRISK features under the conditions of rotation, scale, illumination and viewpoint changes, but also shorten the matching time, satisfying real-time demand.
A Blind CFO Estimation Algorithm for OFDMA Based on ESPRIT Algorithm

This paper proposes a blind Carrier Frequency Offset (CFO) estimation algorithm based on Estimating Signal Parameters via Rotational Invariance Techniques (ESPRIT) algorithm for the interleaved orthogonal frequency division multiple access (OFDMA) uplinks. This method utilizes the special periodic structure of the received signal and the subspace rotational invariance techniques to estimate the CFO of all users. The main advantages of this method are that it obtains the CFOs of all users simultaneously within only one OFDMA block and has high accuracy due to the application of data reconstruction. Moreover, it saves frequency band effectively and degrades the computational complexity greatly. Because of estimation quickly it is suitable for the rapid change channel especially. Simulation results show that this algorithm has good performance even under low SNR condition and improves the variance performance a lot.
Altruistically Unbalanced Kidney Exchange

Although a pilot national live-donor kidney exchange program was recently launched in the US, the kidney shortage is increasing faster than ever. A new solution paradigm is able to incorporate compatible pairs in exchange. In this paper, we consider an exchange framework that has both compatible and incompatible pairs, and patients are indifferent over compatible pairs. Only two-way exchanges are permitted because of institutional constraints. We explore the structure of Pareto-efficient matchings in this framework. We show that under Pareto-efficient matchings, the same number of patients receive transplants, and it is possible to construct Pareto-efficient matchings that match the same incompatible pairs while matching the least number of compatible pairs. We extend the celebrated Gallai–Edmonds Decomposition in the combinatorial optimization literature to our new framework. We also conduct comparative static exercises on how this decomposition changes as new compatible pairs join the pool.
Mechanisms responsible for enhanced fatty acid utilization by perfused hearts from type 2 diabetic db/db mice

Abstract The aim of this study was to determine the biochemical mechanism(s) responsible for enhanced FA utilization (oxidation and esterification) by perfused hearts from type 2 diabetic db/db mice. The plasma membrane content of fatty acid transporters FAT/CD36 and FABPpm was elevated in db/db hearts. Mitochondrial mechanisms that could contribute to elevated rates of FA oxidation were also examined. Carnitine palmitoyl transferase-1 activity was unchanged in mitochondria from db/db hearts, and sensitivity to inhibition by malonyl-CoA was unchanged. Malonyl-CoA content was elevated and AMP kinase activity was decreased in db/db hearts, opposite to what would be expected in hearts exhibiting elevated rates of FA oxidation. Uncoupling protein-3 expression was unchanged in mitochondria from db/db hearts. Therefore, enhanced FA utilization in db/db hearts is most likely due to increased FA uptake caused by increased plasma membrane content of FA transporters; the mitochondrial mechanisms examined do not contribute to elevated FA oxidation observed in db/db hearts.
The U.S. trade deficit and the "new economy"

Amidst the overall strength and longevity of the U.S. economic expansion of the 1990s, a growing current account deficit is one indicator that often is viewed with concern. In this article, Michael Pakko discusses some basic economic principles about current accounts and how they relate to the U.S. experience during the 1990s. He suggests that recent deficits should not be thought of as a source of weakness in an otherwise vigorous economy, but rather, that they are reflective of the same forces underlying recent economic strength.
Image-Based and Sensor-Based Approaches to Arabic Sign Language Recognition

Sign language continues to be the preferred method of communication among the deaf and the hearing-impaired. Advances in information technology have prompted the development of systems that can facilitate automatic translation between sign language and spoken language. More recently, systems translating between Arabic sign and spoken language have become popular. This paper reviews systems and methods for the automatic recognition of Arabic sign language. Additionally, this paper highlights the main challenges characterizing Arabic sign language as well as potential future research directions.
Thrombin Perturbs Neurite Outgrowth and Induces Apoptotic Cell Death in Enriched Chick Spinal Motoneuron Cultures through Caspase Activation

Increasing evidence indicates several roles for thrombin-like serine proteases and their cognate inhibitors (serpins) in normal development and/or pathology of the nervous system. In addition to its prominent role in thrombosis and/or hemostasis, thrombin inhibits neurite outgrowth in neuroblastoma and primary neuronal cellsin vitro, prevents stellation of glial cells, and induces cell death in glial and neuronal cell cultures. Thrombin is known to act via a cell surface protease-activated receptor (PAR-1), and recent evidence suggests that rodent neurons express PAR-1. Previously, we have shown that the thrombin inhibitor, protease nexin-1, significantly prevents neuronal cell death both in vitro and in vivo. Here we have examined the effects of human α-thrombin and the presence and/or activation of PAR-1 on the survival and differentiation of highly enriched cultures of embryonic chick spinal motoneurons. We show that thrombin significantly decreased the mean neurite length, prevented neurite branching, and induced motoneuron death by an apoptosis-like mechanism in a dose-dependent manner. These effects were prevented by cotreatment with hirudin, a specific thrombin inhibitor. Treatment of the cultures with a synthetic thrombin receptor-activating peptide (SFLLRNP) mimicked the deleterious effects of thrombin on motoneurons. Furthermore, cotreatment of the cultures with inhibitors of caspase activities completely prevented the death of motoneurons induced by either thrombin or SFLLRNP. These findings indicate that (1) embryonic avian spinal motoneurons express functional PAR-1 and (2) activation of this receptor induces neuronal cell degeneration and death via stimulation of caspases. Together with previous reports, our results suggest that thrombin, its receptor(s), and endogenous thrombin inhibitors may be important regulators of neuronal cell fate during development, after injury, and in pathology of the nervous system.
Meanings of Smoking among Adolescents in Chiang Mai, Thailand

The Meanings of Smoking Index-2 (MSI-2) was administered to 2516 Thai adolescents in an urban, suburban, rural, and vocational high school. Factor analysis identified six meanings of smoking factor domains: coping, social image, stimulation, weight, independence, and difficulty refusing smoking. Logistic regression analyses determined that the strongest positive association with smoking behavior and ever smoking was the coping domain, and coping was also positively associated with susceptibility to smoking. The individual meaning item which most differentiated current smokers from nonsmokers was “keeps from being bored” and the dimension of stimulation (gives more energy, helps to concentrate, helps to study, gives something to do) was positively associated with current smoking. Findings suggest that meanings of smoking is important because it can provide guidance to health educators and other health professionals in tailoring smoking prevention and cessation interventions by identifying and targeting meanings that are salient within specific adolescent populations.
Correlation between postpartum depression and premenstrual dysphoric disorder: Single center study

Objective To describe the prevalence and correlates of the postpartum depression and premenstrual dysphoric disorder. Methods One hundred sixty six women were assessed around 10th to 14th days after delivery in Gangneung Asan Hospital, Korea, from September 2011 to March 2012. We checked their risk factors for postpartum depressive disorders using the Beck Depression Inventory and the Edinburgh Postnatal Depression Scale. Premenstrual dysphoric disorder was evaluated retrospectively and was defined as having more than 5 of the following 10 symptoms: breast tenderness, bloating, headache, peripheral edema (hand and foot), depressive symptoms, anger, irritability, anxiety, oversensitivity, and exaggerated mood swings. Results The prevalence rate of postpartum depression using the Edinburgh Postnatal Depression Scale ≥10 and Beck Depression Inventory ≥10 was 13.9% (23/166). We found statistical differences (P<0.01) between the postpartum depression group and the postpartum non-depression group in smoking history, past history of psychiatric problems, and level of marital satisfaction. The prevalence rate of premenstrual syndrome (PMS) was 9% (15/166) and among 23 women in the postpartum depression group, eight were determined to have premenstrual dysphoric disorder, yielding a prevalence rate of 34.8% (8/23). Among 143 women in the postpartum non-depression group, seven were determined to have PMS, yielding a prevalence rate of 4.9% (7/143). A correlation between postpartum depression and PMS was thus found (P<0.01). Conclusion PMS appears to be associated with postpartum depression. This means that a hormone-related etiology appears to be one risk factor for postpartum depression.
Latency aware real time cryptographic communication model for MANET

With the advancement in radio technologies like Bluetooth, IEEE 802.11 or Hiperlan, a new concept of networking has emerged. This is known as Mobile ad hoc networking (MANET) in which potential mobile users/clients arrive within the common perimeter of radio link and participate in setting up the network topology for communication. Nodes within MANET are mobile and they communicate with each other within radio range through direct wireless links or multi-hop routing. With the advent of such technologies, some vulnerabilities have also emerged which provides an opportunity for an adversary to invade such network and share/steal/deform information. The adversary may be internal as well as external i.e. node either participating in MANET or not. In this paper, we propose a latency aware cryptographic real-time communication model for MANET which not only mitigates many known external attacks claimed/detected so far but also it is suitable for real-time applications where latency is a critical issue.
Structural Basis for the Species-specific Activity of TFIIS*

Many proteins involved in eukaryotic transcription are similar in function and in sequence between organisms. Despite the sequence similarities, there are many factors that do not function across species. For example, transcript elongation factor TFIIS is highly conserved among eukaryotes, and yet the TFIIS protein from Saccharomyces cerevisiae cannot function with mammalian RNA polymerase II and vice versa. To determine the reason for this species specificity, chimeras were constructed linking three structurally independent regions of the TFIIS proteins from yeast and human cells. Two independently folding domains, II and III, have been examined previously using NMR (1-3). Yeast domain II alone is able to bind yeast RNA polymerase II with the same affinity as the full-length TFIIS protein, and this domain was expected to confer the species selectivity. Domain III has previously been shown to be readily exchanged between mammalian and yeast factors. However, the results presented here indicate that domain II is insufficient to confer species selectivity, and a primary determinant lies in a 30-amino acid highly conserved linker region connecting domain II with domain III. These 30 amino acids may physically orient domains II and III to support functional interactions between TFIIS and RNA polymerase II.
Highly-excited CO emission in APM 08279+5255 at z = 3.9

We report the detection of the CO 4–3, 6–5, 9–8, 10–9, and 11–10 lines in the Broad Absorption Line quasar APM 08279+5255 at $z=3.9$ using the IRAM 30 m telescope. We also present IRAM PdBI high spatial resolution observations of the CO 4–3 and 9–8 lines, and of the 1.4 mm dust radiation as well as an improved spectrum of the HCN(5–4) line. Unlike CO in other QSO host galaxies, the CO line SED of APM 08279+5255 rises up to the CO(10–9) transition. The line fluxes in the CO ladder and the dust continuum fluxes are best fit by a two component model, a “cold” component at ~$ 65$ K with a high density of n (H 2 ) = 1$\times$10 5 cm -3 , and a “warm”, ~$ 220$ K component with a density of 1$\times$10 4 cm -3 . We show that IR pumping via the 14 $\mu{\rm m}$ bending mode of HCN is the most likely channel for the HCN excitation. From our models we find, that the CO(1–0) emission is dominated by the dense gas component which implies that the CO conversion factor is higher than usually assumed for high- z galaxies with $\alpha \approx$ 5$ M_{\odot}$ (K km s -1 pc 2 ) -1 . Using brightness temperature arguments, the results from our high-resolution mapping, and lens models from the literature, we argue that the molecular lines and the dust continuum emission arise from a very compact ( r ≈ 100-300 pc), highly gravitationally magnified ($ m = 60{-}110$) region surrounding the central AGN. Part of the difference relative to other high- z QSOs may therefore be due to the configuration of the gravitational lens, which gives us a high-magnification zoom right into the central 200-pc radius of APM 08279+5255 where IR pumping plays a significant role for the excitation of the molecular lines.
TEM wave propagation in a coaxial cable with a step discontinuity on the outer wall

In this report, the propagation of TEM waves along a coaxial waveguide with a step discontinuity on its outer wall is investigated rigorously by applying direct Fourier transform and reducing the problem into the solution of a modified WienerHopf equation. The solution for the field terms are determined in terms of infinite number of unknown coefficients which satisfy an infinite set of linear algebraic equations. These equations are solved numerically and the effect of area ratio is presented graphically at the end of the analysis. Also, the same problem is analyzed by applying mode matching technique and the results of the two approaches are compared. It is observed numerically that the Wiener-Hopf technique provides a better convergence than the mode matching technique.
The spinorial geometry of supersymmetric backgrounds

We propose a new method to solve the Killing spinor equations of 11-dimensional supergravity based on a description of spinors in terms of forms and on the Spin(1, 10) gauge symmetry of the supercovariant derivative. We give the canonical form of Killing spinors for backgrounds preserving two supersymmetries, N = 2, provided that one of the spinors represents the orbit of Spin(1, 10) with stability subgroup SU(5). We directly solve the Killing spinor equations of N = 1 and some N = 2, N = 3 and N = 4 backgrounds. In the N = 2 case, we investigate backgrounds with SU(5) and SU(4) invariant Killing spinors and compute the associated spacetime forms. We find that N = 2 backgrounds with SU(5) invariant Killing spinors admit a timelike Killing vector and that the space transverse to the orbits of this vector field is a Hermitian manifold with an SU(5)-structure. Furthermore, N = 2 backgrounds with SU(4) invariant Killing spinors admit two Killing vectors, one timelike and one spacelike. The space transverse to the orbits of the former is an almost Hermitian manifold with an SU(4)-structure. The spacelike Killing vector field leaves the almost complex structure invariant. We explore the canonical form of Killing spinors for backgrounds preserving more than two supersymmetries, N > 2. We investigate a class of N = 3 and N = 4 backgrounds with SU(4) invariant spinors. We find that in both cases the space transverse to a timelike vector field is a Hermitian manifold equipped with an SU(4)-structure and admits two holomorphic Killing vector fields. We also present an application to M-theory Calabi–Yau compactifications with fluxes to one dimension.
Effects of Channel Models and Rake Receiving Process on UWB-IR System Performance

In ultra-wideband impulse radio (UWB-IR) systems, multipath-delayed received pulses may overlap if two consecutive multipaths arrive within less than the pulse duration. This condition makes it nontrivial for the Rake receiver to capture enough multipath energies for reliable communications. In this paper, we study in detail the effects of channel models and Rake receiving process on the performance of UWB-IR systems. Specifically, we consider Tc- and T-spaced channel models and different Rake receiver implementations to maximize the captured signal energy, where we discuss their validity for real system considerations. Also, we show that code shift keying (CSK) impulse modulation can achieve about 1 dB performance gain over conventional pulse position modulation (PPM) when there is pulse overlapping, as it randomizes pulse transmit locations as opposed to fixed pulse transmit locations used by PPM.
Randomized Block Coordinate Non-Monotone Gradient Method for a Class of Nonlinear Programming

In this paper we propose a randomized block coordinate non-monotone gradient (RBCNMG) method for minimizing the sum of a smooth (possibly nonconvex) function and a block-separable (possibly nonconvex nonsmooth) function. At each iteration, this method randomly picks a block according to any prescribed probability distribution and typically solves several associated proximal subproblems that usually have a closed-form solution, until a certain sufficient reduction on the objective function is achieved. We show that the sequence of expected objective values generated by this method converges to the expected value of the limit of the objective value sequence produced by a random single run. Moreover, the solution sequence generated by this method is arbitrarily close to an approximate stationary point with high probability. When the problem under consideration is convex, we further establish that the sequence of expected objective values generated by this method converges to the optimal value of the problem. In addition, the objective value sequence is arbitrarily close to the optimal value with high probability. We also conduct some preliminary experiments to test the performance of our RBCNMG method on the l1-regularized least-squares problem. The computational results demonstrate that our method substantially outperform the randomized block coordinate descent method proposed in [16].
Presence or Absence of mlr Genes and Nutrient Concentrations Co-Determine the Microcystin Biodegradation Efficiency of a Natural Bacterial Community

The microcystin biodegradation potential of a natural bacterial community coexisting with a toxic cyanobacterial bloom was investigated in a water reservoir from central Spain. The biodegradation capacity was confirmed in all samples during the bloom and an increase of mlrA gene copies was found with increasing microcystin concentrations. Among the 24 microcystin degrading strains isolated from the bacterial community, only 28% showed presence of mlrA gene, strongly supporting the existence and abundance of alternative microcystin degradation pathways in nature. In vitro degradation assays with both mlr+ and mlr− bacterial genotypes (with presence and absence of the complete mlr gene cluster, respectively) were performed with four isolated strains (Sphingopyxis sp. IM-1, IM-2 and IM-3; Paucibacter toxinivorans IM-4) and two bacterial degraders from the culture collection (Sphingosinicella microcystinivorans Y2; Paucibacter toxinivorans 2C20). Differences in microcystin degradation efficiencies between genotypes were found under different total organic carbon and total nitrogen concentrations. While mlr+ strains significantly improved microcystin degradation rates when exposed to other carbon and nitrogen sources, mlr− strains showed lower degradation efficiencies. This suggests that the presence of alternative carbon and nitrogen sources possibly competes with microcystins and impairs putative non-mlr microcystin degradation pathways. Considering the abundance of the mlr− bacterial population and the increasing frequency of eutrophic conditions in aquatic systems, further research on the diversity of this population and the characterization and conditions affecting non-mlr degradation pathways deserves special attention.