Miracle-dz/UniFAR-FTUs huggingface dataset:
A local search approximation algorithm for k-means clustering

In k-means clustering we are given a set of n data points in d-dimensional space Rd and an integer k, and the problem is to determine a set of k points in ÓC;d, called centers, to minimize the mean squared distance from each data point to its nearest center. No exact polynomial-time algorithms are known for this problem. Although asymptotically efficient approximation algorithms exist, these algorithms are not practical due to the extremely high constant factors involved. There are many heuristics that are used in practice, but we know of no bounds on their performance.We consider the question of whether there exists a simple and practical approximation algorithm for k-means clustering. We present a local improvement heuristic based on swapping centers in and out. We prove that this yields a (9+ε)-approximation algorithm. We show that the approximation factor is almost tight, by giving an example for which the algorithm achieves an approximation factor of (9-ε). To establish the practical value of the heuristic, we present an empirical study that shows that, when combined with Lloyd's algorithm, this heuristic performs quite well in practice.
Enhanced gene expression through temperature profile‐induced variations in molecular architecture of thermoresponsive polymer vectors

Successful non‐viral gene targeting requires vectors to meet two conflicting needs—strong binding to protect the genetic material during transit and weak binding at the target site to enable release. Responsive polymers could fulfil such requirements through the switching of states, e.g. the chain‐extended coil to chain‐collapsed globule phase transition that occurs at a lower critical solution temperature (LCST), in order to transport nucleic acid in one polymer state and release it in another.
Black-Box Attacks against RNN based Malware Detection Algorithms

Recent researches have shown that machine learning based malware detection algorithms are very vulnerable under the attacks of adversarial examples. These works mainly focused on the detection algorithms which use features with fixed dimension, while some researchers have begun to use recurrent neural networks (RNN) to detect malware based on sequential API features. This paper proposes a novel algorithm to generate sequential adversarial examples, which are used to attack a RNN based malware detection system. It is usually hard for malicious attackers to know the exact structures and weights of the victim RNN. A substitute RNN is trained to approximate the victim RNN. Then we propose a generative RNN to output sequential adversarial examples from the original sequential malware inputs. Experimental results showed that RNN based malware detection algorithms fail to detect most of the generated malicious adversarial examples, which means the proposed model is able to effectively bypass the detection algorithms.
Validation of FLT uptake as a measure of thymidine kinase-1 activity in A549 carcinoma cells.

UNLABELLED The thymidine analog (18)F-3'-deoxy-3' -fluorothymidine (FLT) is being used clinically for PET imaging of tumor proliferation. Appropriate use of this tracer requires validating the mechanisms by which it accumulates in dividing cells. We tested the accuracy with which FLT uptake predicted the activity of cytosolic thymidine kinase-1 (TK(1)), an enzyme that is upregulated before and during DNA synthesis. METHODS Cultured A549 human lung carcinoma cells were manipulated to a range of proliferation rates from actively dividing to growth arrested. Uptake of radiolabeled FLT was compared with cell cycle activity, which was expressed as the percentage of cells in S phase, and with activity of cytosolic TK(1). We also compared uptake of FLT and deoxyglucose. We genetically manipulated A549 cells by transfecting them with human papillomavirus type 16 E6 (designated A549-E6) to abrogate function of the tumor suppressor gene, p53. Although radiation typically inhibits progression of mammalian cells through the cell cycle, abrogation of p53 function eliminates this inhibition. We then compared FLT uptake with the percentage of cells in S phase and TK(1) activity in irradiated A549-E6 cells and in irradiated control cells having normal p53 function and the expected radiation-induced growth delay. RESULTS A549 cells with only 3%-5% cells in S phase took up little FLT and had low levels of TK(1) activity. When cells were stimulated to grow by being placed into fresh medium, we observed a strong correlation between increased FLT uptake and increased TK(1) activity. As expected, FLT uptake varied much more as a function of growth than did uptake of deoxyglucose. Nonproliferating A549 cells did not enter the cell cycle if they were irradiated before being placed into fresh medium, and they did not accumulate FLT or show elevated TK(1) activity. In contrast, radiation did not inhibit the cell cycle progression of A549-E6 cells. When subcultured, they began to grow and showed increased uptake of FLT commensurate with greater TK(1) activity. CONCLUSION In cultured A549 cells FLT uptake is positively correlated with cell growth and TK(1) activity. Inhibition of cell cycle progression prevents FLT uptake and increased TK(1) activity. These results suggest that FLT images reflect TK(1) activity and the percentage of cells in S phase.
Multi-Head Finite Automata: Characterizations, Concepts and Open Problems

Multi-head finite automata were introduced in (Rabin, 1964) and (Rosenberg, 1966). Since that time, a vast literature on computational and descriptional complexity issues on multi-head finite automata documenting the importance of these devices has been developed. Although multi-head finite automata are a simple concept, their computational behavior can be already very complex and leads to undecidable or even non-semi-decidable problems on these devices such as, for example, emptiness, finiteness, universality, equivalence, etc. These strong negative results trigger the study of subclasses and alternative characterizations of multi-head finite automata for a better understanding of the nature of non-recursive trade-offs and, thus, the borderline between decidable and undecidable problems. In the present paper, we tour a fragment of this literature.
Multiple origins of viral capsid proteins from cellular ancestors

Significance The entire history of life is the story of virus–host coevolution. Therefore the origins and evolution of viruses are an essential component of this process. A signature feature of the virus state is the capsid, the proteinaceous shell that encases the viral genome. Although homologous capsid proteins are encoded by highly diverse viruses, there are at least 20 unrelated varieties of these proteins. We show here that many, if not all, capsid proteins evolved from ancestral proteins of cellular organisms on multiple, independent occasions. These findings reveal a stronger connection between the virosphere and cellular life forms than previously suspected. Viruses are the most abundant biological entities on earth and show remarkable diversity of genome sequences, replication and expression strategies, and virion structures. Evolutionary genomics of viruses revealed many unexpected connections but the general scenario(s) for the evolution of the virosphere remains a matter of intense debate among proponents of the cellular regression, escaped genes, and primordial virus world hypotheses. A comprehensive sequence and structure analysis of major virion proteins indicates that they evolved on about 20 independent occasions, and in some of these cases likely ancestors are identifiable among the proteins of cellular organisms. Virus genomes typically consist of distinct structural and replication modules that recombine frequently and can have different evolutionary trajectories. The present analysis suggests that, although the replication modules of at least some classes of viruses might descend from primordial selfish genetic elements, bona fide viruses evolved on multiple, independent occasions throughout the course of evolution by the recruitment of diverse host proteins that became major virion components.
Local Action and Abstract Separation Logic

Separation logic is an extension of Hoare's logic which supports a local way of reasoning about programs that mutate memory. We present a study of the semantic structures lying behind the logic. The core idea is of a local action, a state transformer that mutates the state in a local way. We formulate local actions for a class of models called separation algebras, abstracting from the RAM and other specific concrete models used in work on separation logic. Local actions provide a semantics for a generalized form of (sequential) separation logic. We also show that our conditions on local actions allow a general soundness proof for a separation logic for concurrency, interpreted over arbitrary separation algebras.
Improving Lpc Spectral Envelope Extraction Of Voiced Speech By True-Envelope Estimation

n this work we address the problem of all pole spectral envelope estimation for speech signals. The currently widely used all pole spectral envelope model suffers from well-known systematic errors and more severely from model order mismatch. We will propose a procedure to first establish a band limited interpolation of the observed spectrum using a recently rediscovered true envelope estimator and then using the band limited envelope to derive an all pole envelope model named TE-LPC . The band-limited envelope that is used to derive the all pole envelope model reduces the problem of the unknown all pole model order. For the experimental investigation we propose a new perceptually motivated residual spectral peak flatness measure. The experimental results demonstrate that the proposed method significantly increases the spectral flatness for the perceptually especially important low order harmonics of voiced utterances
The Impact of Partial Orders among Strict and Probabilistic Quorums on the Data Consistency vs. Operation Availabilities Trade-Off

Operation availabilities of pessimistic quorum-based replication strategies are strictly upper-bounded. Probabilistically relaxing their strict consistency notion permits to overcome this bound by introducing probabilistic data replication strategies. These strategies allow the exploitation of the data consistency vs. operation availabilities trade-off. In our approach, we add a certain number of only probabilistically intersecting quorums to the originally strictly intersecting partially ordered quorum system in order to "closely conserve" their original characteristic behavior. As one expects, the number and nature of probabilistic quorums added have a strong impact on the particular trade-off. But furthermore, it turns out that the order in which probabilistic and strict quorums must be probed is also very important. We relate two general strategies of ordering the probabilistic and strict quorums of those probabilistic quorum systems and evaluate their impact on the data consistency vs. operation availabilities trade-off. The evaluation uses Markov chain-based steady state analysis applied to representative instances of probabilistic quorum systems with the adequate partial orderings.
Differential Recovery of Candida Species from Subgingival Sites in Human Immunodeficiency Virus-Positive and Healthy Children from Rio de Janeiro, Brazil

ABSTRACT The prevalence of subgingival Candida species was studied in 52 human immunodeficiency virus (HIV)-positive and 42 HIV-negative children. Candida was cultured from 22 (42.3%) and 3 (7.1%) HIV-infected and control children, respectively. C. albicans was the most common Candida species isolated from HIV-infected children, followed by C. dubliniensis, C. glabrata, and C. tropicalis. In the HIV-positive group, the prevalence of Candida isolation was significantly higher in children who presented with low CD4+-T-lymphocyte counts, elevated viral loads, and gingivitis.
Closed-form correlative coding (CFC2) blind identification of MIMO channels: isometry fitting to second order statistics

We present a blind closed-form consistent channel estimator for multiple-input multiple-output (MIMO) systems that uses only second order statistics. We spectrally modulate the output of each source by correlative coding it with a distinct filter. The correlative filters are designed to meet the following desirable characteristics: no additional power or bandwidth is required; no synchronization between the sources is needed; the original data rate is maintained. We first prove an identifiability theorem: under a simple spectral condition on the transmitted random processes, the MIMO channel is uniquely determined, up to a phase offset per user, from the second order statistics of the received data. We then develop the closed-form algorithm that attains this identifiability bound. We show that minimum-phase finite impulse response filters with arbitrary memory satisfy our sufficient spectral identifiability condition. This results in a computationally attractive scheme for retrieving the data information sequences after the MIMO channel has been identified. We assess the performance of the proposed algorithms by computer simulations. In particular, the results show that our technique outperforms the previously introduced transmitter-induced conjugate cyclostationarity approach when there are carrier frequency misadjustments.
The Effect of Soil Reinforcement on the Stress and Strain Field Around Underground Square-Shaped Areas and its Internal Lining Efforts in Urban Areas

The passage of underground structures from the bottom of the structures on the ground causes a change in the stresses and strains created in the structure as well as the soil environment surrounding the tunnel due to the existence of an interaction between these two sides. In this way, the existence of the surface structure leads to a change in the strain and stress conditions around the tunnel, and in contrast, the tunnel also leads to a change in the stress and settlement around the structures. Therefore, such a reciprocal behavior is very important. In this research, with the help of Abaqus finite element software, two main possible conditions are considered: the creation of an underground structure in the presence of the superstructure, as well as the reverse state of the concept of constructing a building in the state in which the underground structure already exists. One of the subjects studied in this research is the physical modelling effect of the structure, rather than the effect of its wide load on the ground. Other parameters considered in this research are the number of story, the depth of the tunnel, the width of the tunnel, the thickness of the lining, the effect of changes in the soil parameters in the depth and the horizontal distance of the tunnel center from the building center. The results of this research are validated based on the results obtained by other researchers. According to the results obtained in this research, by the increase of the distance between the tunnel center and structure center and depending on the stiffness of the tunnel lining, significant asymmetric stresses are created in the superstructure. The construction of the structure before and after the tunnel construction can affect the unsymmetrical settlement of the structure The stress and strain created in the lining of the tunnel and the surrounding area are also different due to the amount of mobilized force in the reinforcements.
Strong Successive Refinability and Rate-Distortion-Complexity Tradeoff

We investigate the second order asymptotics (source dispersion) of the successive refinement problem. Similar to the classical definition of a successively refinable source, we say that a source is strongly successively refinable if successive refinement coding can achieve the second order optimum rate (including the dispersion terms) at both decoders. We establish a sufficient condition for strong successive refinability. We show that any discrete source under Hamming distortion and the Gaussian source under quadratic distortion are strongly successively refinable. We also demonstrate how successive refinement ideas can be used in point-to-point lossy compression problems in order to reduce complexity. We give two examples, the binary-Hamming and Gaussian-quadratic cases, in which a layered code construction results in a low complexity scheme that attains optimal performance. For example, when the number of layers grows with the block length n, we show how to design an O(nlog(n)) algorithm that asymptotically achieves the rate-distortion bound.
Pure Motor Stroke From Presumed Lacunar Infarct: Long-Term Prognosis for Survival and Risk of Recurrent Stroke

Background and Purpose— A low risk of recurrent stroke and death after lacunar infarction has previously been reported, but follow-up has been limited to ≤5 years. Methods— One hundred eighty patients with pure motor stroke, collected between 1983 and 1986 from a hospital-based stroke registry, were followed up until at least 10 years after the index stroke. Two patients were lost to follow-up. Survival status was determined from the official population registry and compared with survival rates of the Swedish population, matched for age and sex. Cox proportional hazards regression analyses were used to identify independent prognostic predictors. Results— During follow-up 106 (60%) of the 178 patients died, most commonly as a result of coronary heart disease. During the first 5 years after the stroke, survival rates were similar to those of the general population. Beyond this time the risk of death was increased among patients with pure motor stroke, with an excess of 10 to 15 percent units compared with the general population. Independent determinants for death were age (P <0.01), male sex (P <0.01), and nonuse of acetylsalicylic acid (P =0.02). Recurrent stroke occurred in 42 (23.5%) of the patients, corresponding to an annual risk of 2.4%. Hypertension (P =0.025) and diabetes (P =0.024) were independent risk factors for recurrent stroke. Conclusions— For the first few years after lacunar infarct, the risk of death was similar to that of the general population, but later a clear excess of death was observed. The long-term prognosis in lacunar infarction appears less favorable than previously reported.
Dynamics of Consumer Adoption of Financial Innovation: The Case of ATM Cards

We develop a structural consumer life-cycle model to investigate consumers' adoption and usage decisions of ATM cards. If consumers are forward-looking with a known discount factor, our framework can control for the heterogeneous life span faced by consumers of different ages, and hence measure adoption costs more accurately. Moreover, our framework can recover the monetary value of total adoption costs. To estimate our model, we use an Italian panel data set, which contains information on consumers' adoption decisions for ATM cards, and their cash withdrawal patterns before and after adoption. Our results suggest that one could significantly overestimate adoption costs for the elderly when ignoring their shorter life span. Our policy experiments show that a sign-up bonus targeted to the elderly could be much more effective if implemented as a limited-time offer rather than a permanent offer. Interestingly, if the sign-up bonus is permanent, younger consumers may strategically postpone adoption. This paper was accepted by Pradeep Chintagunta, marketing.
Silicon self‐diffusion in wadsleyite: Implications for rheology of the mantle transition zone and subducting plates

Si self‐diffusion rates in Mg2SiO4 polycrystalline wadsleyite were measured at 18 GPa and 1430–1630°C using an isotopic tracer (29Si) and secondary ion mass spectrometry. The volume diffusion coefficient (Dv) and grain‐boundary diffusion coefficient (Dgb) were determined to be Dv = 3.44 × 10−11 [m2/s] exp (−299 [kJ/mol]/RT) and δDgb = 1.14 × 10−17 [m3/s] exp (−248 [kJ/mol]/RT), respectively. Si diffusion rates in wadsleyite are about 5 orders of magnitude slower than Mg‐Fe interdiffusion rates at 1400°C. Assuming that Si is the slowest diffusing species in wadsleyite, the geophysical model of the viscosity in the mantle transition zone can be explained by diffusion creep in wadsleyite for a grain size of about 0.5–5 mm. Some portions in cold subducting slabs, where the grain size reduces to less than 1 μm after the olivine‐spinel transformation, become weaker than the surrounding mantle.
On the Theory of Structural Subtyping

We show that the first-order theory of structural subtyping of non-recursive types is decidable. Let be a language consisting of function symbols (representing type constructors) and C a decidable structure in the relational language L containing a binary relation . C represents primitive types; represents a subtype ordering. We introduce the notion of -term-power of C, which generalizes the structure arising in structural subtyping. The domain of the -term-power of C is the set of -terms over the set of elements of C. We show that the decidability of the first-order theory of C implies the decidability of the first-order theory of the term-power of C. This result implies the decidability of the first-order theory of structural subtyping of non-recursive types. Our decision procedure is based on quantifier elimination and makes use of quantifier elimination for term algebras and Feferman-Vaught construction for products of decidable structures. We also explore connections between the theory of structural subtyping of recursive types and monadic second-order theory of tree-like structures. In particular, we give an embedding of the monadic second-order theory of infinite binary tree into the first-order theory of structural subtyping of recursive types.
Earth's Correlation Wavefield: Late Coda Correlation

Cross correlation of seismograms provides new information on the Earth both through the exploitation of ambient noise and specific components of earthquake records. Here we cross‐correlate recordings of large earthquakes on a planetary scale and identify a range of hitherto unobserved seismic phases in Earth's correlation wavefield. We show that both arrivals with the timing expected for the regular seismic wavefield and previously unexplained phases are produced by interference between seismic paths having the same ray parameter but with only a subset of propagation legs in common. This insight explains the origin and generation mechanism of the features of Earth's correlation wavefield and opens up new ways of addressing issues in global seismology. Strong similarity between observed and synthesized correlation wavefields indicates that the Earth's radial structure is remarkably well constrained in the intermediate period range.