Miracle-dz/UniFAR-FTUs huggingface dataset:
The initial-value problem for the equation (_{})_{}=ₓₓ

It is shown that the initial-value problem of the equation (tug) ) = u, with the value of u prescribed for t = 0 has a unique solution satisfying a maximum principle. In addition, several numerical schemes for its solution are proposed. Introduction. Consider the initial-value problem Problem A. Find a function u(x, t) satisfying the conditions (l) U1 = (tut), (tClt t + ut), t > 0, co X K 0 anld reduces to the heat equation (4) ut = u, (=' 1(x)), for t = 0, whence Problem A is a Goursat type problem in which u, is to be found initially from (4). In this paper we study both the theoretical and numerical aspects of solving Problem A. In Section 1 we briefly sketch the proofs of existence, of uniqueness and of a strong maximum principle, based on well-known concepts; in, Section 2 we examine an explicit difference scheme with variable time steps for the numerical solution, while in Section 3 other numerical schemes are described. 1. Solution of the Problem. The characteristics of Eq. (1) are parabolas (5) t(X-C)2, c = const, two of which pass through every point of the upper half-plane. In order to prove the Received October 15, 1969, revised November 24, 1969. AMS Subject Classifications. Primary 6561, 6567, 6568; Secondary 3501, 3507, 3552, 3570, 3578.
On the Homotopy Groups of the Union of Spheres

Let 8( be a sphere of dimension r,+ l, rt^ 1, i = 1, ., h, and let T be the union of the spheres Sv ., Sk, with a single common point. Then T serves as a universal example for homotopy constructions (see [1]). The object of this paper is to compute the group irn{T), n > 1, as a direct sum of homotopy groups of spheres of appropriate dimensions^:. Each summand is embedded in TTn{T) by a certain multiple Whitehead product; the products which appear will be called basic products and will now be defined. Let TQ = SUi v SU2 v. v SUm, where 1 < % < u2 < . < um < k. Then the injection 7rn(T0)->Trn(T) embeds 7rn(T0) univalently as a direct summand unrn(T). We will identify elements of 7rn(To) with their images in 7rn(T), and an element in the image of 7rn(T0) will be said to involve the spheres SUi, . , 8Um. With these conventions, we define and order the basic products as follows. The basic products § of weight 1 are the elements tl3 . , t,k, where i < h < ••• < k> i being the positive generator of 7rr. +1 (#,•), i = 1, . , k. Now suppose the basic products of weight < w defined and ordered. Then a basic product of weight w > 1 is a Whitehead product [a, 6], where a is a basic product of weight u, b is a basic product of weight v, u-\-v = w, a<b, and if b is defined as the Whitehead product, [c, d], of the basic products c, d, then c ̂ a. The basic products of weight w are then ordered arbitrarily among themselves and are greater than any product of lesser weight. It will be seen that a basic product of weight w is a string of symbols iVi.iVw, suitably bracketed, where l^v^k, j=l, . , w. Suppose i,occurs wi times in this string. Then we will say that the basic product involves the sphere S{ wi times, and the height of the basic product is k defined as S r\,«;,. t=i
QUASILINEAR THEORY OF INSTABILITY OF A PLASMA WITH AN ANISOTROPIC ION VELOCITY DISTRIBUTION

Equations are obtained that define the change of the longitudinal and transverse ion thermal energies and also the energy of an electromagnetic field in an instability due to anisotropy of the distribution function. Conditions of applicability of the equations are obtained that reduce to the requirement of smallness of deviation of the initial plasma parameters from the critical values at which instability sets in. The equations are employed for determining the state that the plasma finally acquires as a result of development of the instability. (auth)
Measurement of shear-induced dispersion in a dilute emulsion

The time-dependent drop distribution of a dilute, polydisperse emulsion is measured in a simple shear flow. The suspending fluid is much more viscous than the dispersed phase (1:1000). Drops are found to drift away from either bounding wall and accumulate near the center of the gap, due to the anisotropy of droplet–plane interactions. An expression for this drift velocity has been derived for single drops by Chan and Leal [J. Fluid Mech. 92, 131 (1979)] and was in agreement with isolated drop migration observed in our work. Eventually the inward drift is balanced by a shear-induced gradient diffusivity, and a steady-state concentration distribution is reached. When the drops are sufficiently far from either wall a self-similar, parabolic concentration profile is predicted at all times. Droplet diffusivities were determined for capillary numbers Ca=γāμ/σ between 0.17 and 0.92, where γ is the shear rate, ā is the mean drop radius, μ is the viscosity of the suspending fluid, and σ the interfacial tension.
Fuzzing Configurations of Program Options

While many real-world programs are shipped with configurations to enable/disable functionalities, fuzzers have mostly been applied to test single configurations of these programs. In this work, we first conduct an empirical study to understand how program configurations affect fuzzing performance. We find that limiting a campaign to a single configuration can result in failing to cover a significant amount of code. We also observe that different program configurations contribute differing amounts of code coverage, challenging the idea that each one can be efficiently fuzzed individually. Motivated by these two observations, we propose ConfigFuzz , which can fuzz configurations along with normal inputs. ConfigFuzz transforms the target program to encode its program options within part of the fuzzable input, so existing fuzzers’ mutation operators can be reused to fuzz program configurations. We instantiate ConfigFuzz on six configurable, common fuzzing targets, and integrate their executions in FuzzBench. In our evaluation, ConfigFuzz outperforms two baseline fuzzers in four targets, while the results are mixed in the other targets due to program size and configuration space. We also analyze the options fuzzed by ConfigFuzz and how they affect the performance.
The impact of economic sanctions on health and health systems in low-income and middle-income countries: a systematic review and narrative synthesis

Introduction Economic sanctions restrict customary commercial and financial ties between states to induce change in political constitution or conduct of the targeted country. Although the stated goals of sanctions often include humanitarian objectives, prospective procedures for health risk assessment are not regularly incorporated in their implementation. Moreover, past experience suggests that the burden of economic isolation may fall on the civilian population. We present key findings from a WHO-sponsored evidence review on the impact of economic sanctions on health and health systems in low-income and middle-income countries, aiming at comprehensive coverage and explicit consideration of issues of causality and mechanisms. Methods Broad searches of PubMed and Google Scholar (1970–2021) were designed to retrieve published and grey English-language literature expected to cut across disciplines, terminology and research methods. Studies providing an impact estimate were rated by a structured assessment based on ROBINS-I risk of bias domains, synthesised via vote counting and contextualised into the broader literature through a thematic synthesis. Results Included studies (185) were mostly peer-reviewed, mostly single-country, largely coming from medicine and public health, and chiefly concerned with three important target countries—Iraq, Haiti and Iran. Among studies providing impact estimates (31), most raised multiple risk-of-bias concerns. Excluding those with data integrity issues, a significant proportion (21/27) reported consistently adverse effects of sanctions across examined outcomes, with no apparent association to assessed quality, focus on early episodes or publication period. The thematic synthesis highlights the complexity of sanctions, their multidimensionality and the possible mechanisms of impact. Conclusion Future research should draw on qualitative knowledge to collect domain-relevant data, combining it with better estimation techniques and study design. However, only the adoption of a risk assessment framework based on prospective data collection and monitoring can certify claims that civilians are adequately protected.
The blast wave of the Shuttle plume at ionospheric heights

The main engine burn (MEB) of the Space Shuttle deposits {approximately} 2 x 10{sup 12} joules of explosive energy and {approximately} 3 x 10{sup 5} kg of exhaust in almost horizontal flight at 105-110 km altitude during the period 300-550 s into the ascent. This extremely robust perturbation provides a potential active-excitation source for a variety of geophysical processes, including (1) the effects of aurora-like localized heating on the generation of gravity waves in the thermosphere, (2) the ducting mechanisms for long-period infrasound in the upper atmosphere, (3) dynamo effects associated with transient charge separation, (4) interactions with ambient midlatitude current systems at E-layer heights, and (5) effects in the Earth-ionosphere waveguide of transient electron-density perturbations in the D-region. The sine qua non of such an agenda is to gain a quantitative understanding of the near-field behavior of the MEB exhaust-plume`s quasi-cylindrical expansion, which generates a blast wave propagating away from the explosion. The authors report on observed electron-density signatures of this blast wave as manifested on lines-of-sight (LOSs) from a very-long-baseline interferometer (VLBI) illuminated by 137-MHz beacon signals from the MARECS-B satellite. They also compare the observations to a preliminary three-dimensional neutral-air acoustic model coupled to the ionospheric electronmore » density. 7 refs., 5 figs., 1 tab. « less
The Ionizing Star Clusters of Giant H II Regions in NGC 2403

We present the results of a study on the massive star population down to about MV ∼ -3.1, or 12–15 M⊙, of the most luminous giant H II regions in the nearby spiral galaxy NGC 2403, based on Hubble Space Telescope images and ground-based spectrograms. Particular emphasis is placed on the distribution of the Wolf-Rayet and red supergiant stars and the information they provide about the recent star-forming history of these large complexes. We find direct evidence for the presence of Wolf-Rayet (WR) stars in five of the six giant H II regions investigated; 25–40 WR stars are inferred for the sole NGC 2403-I giant H II region. Red supergiant (RSG) stars are mainly distributed over a more extended halo, while the young blue stars and most WR stars are in or close to a compact core. One appears to be seeing young cores of O and WR stars surrounded by older halos containing red supergiants. We propose a scenario in which RSG stars belonging to an early phase of star formation were followed by a more recent burst corresponding to a very blue mean sequence. Delayed trigger with preheating over several 100 pc by the first generation of massive stars allowed the build-up of the required confinement for the production of parsec-scale cluster cores with luminosity up to a few times 106 L⊙. Finally, we present some interesting objects found in the field of NGC 2403 outside the giant H II regions, such as field WR stars, globular clusters and background galaxies.
Widespread mermithid nematode parasitism of Cretaceous insects

Mermithid nematodes are obligate invertebrate parasites dating back to the Early Cretaceous. Their fossil record is sparse, especially before the Cenozoic, thus little is known about their early host associations. This study reports 16 new mermithids associated with their insect hosts from mid-Cretaceous Kachin amber, 12 of which include previously unknown hosts. These fossils indicate that mermithid parasitism of invertebrates was already widespread and played an important role in the mid-Cretaceous terrestrial ecosystem. Remarkably, three hosts (bristletails, barklice and perforissid planthoppers) were previously unknown to be parasitized by mermithids both past and present. Furthermore, our statistical analyses show that in contrast to their Cenozoic counterparts, Cretaceous nematodes including mermithids are more abundant in heterometabolous insect hosts. This result suggests that nematodes have not completely exploited the dominant Holometabola as their hosts until the Cenozoic. This study reveals what appears to be a vanished history of nematodes that parasitized Cretaceous insects.
Proteomic insight into human directed evolution of the domesticated chicken Gallus gallus

Chicken domestication began at least 3,500 years ago for purposes of divination, cockfighting, and food. Prior to industrial scale chicken production, domestication selected larger birds with increased egg production. In the mid-20th century companies began intensive selection with the broiler (meat) industry focusing on improved feed conversion, rapid growth, and breast muscle yield. Here we present proteomic analysis comparing the Ross 708 modern broiler line with the UIUC legacy line. Comparing the breast muscle proteome between modern broilers and legacy lines not selected for these growth traits identifies cellular processes that have responded to human directed evolution. Mass spectrometry was used to identify differences in protein levels in the breast muscle of 6-day old chicks from Modern and Legacy lines. The results highlighted elevated levels of stress proteins, ribosomal proteins, and proteins that participate in the innate immune pathway in the Modern chickens. Furthermore, the comparative analyses indicated differences in the levels of proteins involved in multiple biochemical pathways. In particular, the Modern line had elevated levels of proteins affecting the pentose phosphate pathway, TCA cycle, and fatty acid oxidation and reduced protein levels of the first phase of glycolysis. These analyses provide hypotheses linking the morphometric changes driven by human directed selection to biochemical pathways. The results also have implications for the onset of Wooden Breast disease that arose due to selection for rapid breast muscle growth and is a major problem in the poultry industry.
Paracrine enhancement of tumor cell proliferation provides indirect stroma-mediated chemoresistance via acceleration of tumor recovery between chemotherapy cycles

The ability of tumors to survive therapy reflects both cell-intrinsic and microenvironmental mechanisms. Across many cancers, including triple-negative breast cancer (TNBC), a high stroma/tumor ratio correlates with poor survival. In many contexts, this correlation can be explained by the direct reduction of therapy sensitivity by stroma-produced paracrine factors. We sought to explore whether this direct effect contributes to the link between stroma and poor responses to chemotherapies. Our in vitro studies with panels of TNBC cell line models and stromal isolates failed to detect a direct modulation of chemoresistance. At the same time, consistent with prior studies, we observed treatment-independent enhancement of tumor cell proliferation by fibroblast-produced secreted factors. Using spatial statistics analyses, we found that proximity to stroma is often associated with enhanced tumor cell proliferation in vivo. Based on these observations, we hypothesized an indirect link between stroma and chemoresistance, where stroma-augmented proliferation potentiates the recovery of residual tumors between chemotherapy cycles. To evaluate the feasibility of this hypothesis, we developed a spatial agent-based model of stroma impact on proliferation/death dynamics. The model was quantitatively parameterized using inferences from histological analyses and experimental studies. We found that the observed enhancement of tumor cell proliferation within stroma-proximal niches can enable tumors to avoid elimination over multiple chemotherapy cycles. Therefore, our study supports the existence of a novel, indirect mechanism of environment-mediated chemoresistance that might contribute to the negative correlation between stromal content and poor therapy outcomes.
The representational dynamics of the animal appearance bias in human visual cortex are indicative of fast feedforward processing

The human visual system has a seemingly unique tendency to interpret zoomorphic objects as animals, not as objects. This animal appearance bias is very strong in the ventral visual pathway as measured through functional magnetic resonance imaging (fMRI), but it is absent in feedforward deep convolutional neural networks. Here we investigate how this bias emerges over time by probing its representational dynamics through multivariate electroencephalography (EEG). The initially activated representations to lookalike zoomorphic objects are very similar to the representations activated by animal pictures and very different from the neural responses to regular objects. Neural responses that reflect the true identity of the zoomorphic objects as inanimate objects are weaker and appear later, as do effects of task context. The strong early emergence of an animal appearance bias strongly supports a feedforward explanation, indicating that lack of recurrence in deep neural networks is not an explanation for their failure to show this bias.
MGA deletion leads to Richter’s transformation via modulation of mitochondrial OXPHOS

Richter’s transformation (RT) is a progression of chronic lymphocytic leukemia (CLL) to aggressive lymphoma. MGA (Max gene associated), a functional MYC suppressor, is mutated at 3% in CLL and 36% in RT. However, genetic models and molecular mechanisms of MGA deletion driving CLL to RT remain elusive. We established a novel RT mouse model by knockout of Mga in the Sf3b1/Mdr CLL model via CRISPR-Cas9 to determine the role of Mga in RT. Murine RT cells exhibit mitochondrial aberrations with elevated oxidative phosphorylation (OXPHOS). We identified Nme1 (Nucleoside diphosphate kinase) as a Mga target through RNA sequencing and functional characterization, which drives RT by modulating OXPHOS. As NME1 is also a known MYC target without targetable compounds, we found that concurrent inhibition of MYC and ETC complex II significantly prolongs the survival of RT mice in vivo. Our results suggest that Mga-Nme1 axis drives murine CLL-to-RT transition via modulating OXPHOS, highlighting a novel therapeutic avenue for RT. Statement of Significance We established a murine RT model through knockout of Mga in an existing CLL model based on co-expression of Sf3b1-K700E and del(13q). We determined that the MGA/NME1 regulatory axis is essential to the CLL-to-RT transition via modulation of mitochondrial OXPHOS, highlighting this pathway as a novel target for RT treatment.
Genome-wide mapping of the Escherichia coli PhoB regulon reveals many transcriptionally inert, intragenic binding sites

Genome-scale analyses have revealed many transcription factor binding sites within, rather than upstream of genes, raising questions as to the function of these binding sites. Here, we use complementary approaches to map the regulon of the Escherichia coli transcription factor PhoB, a response regulator that controls transcription of genes involved in phosphate homeostasis. Strikingly, the majority of PhoB binding sites are located within genes, but these intragenic sites are not associated with detectable transcription regulation and are not evolutionarily conserved. Many intragenic PhoB sites are located in regions bound by H-NS, likely due to shared sequence preferences of PhoB and H-NS. However, these PhoB binding sites are not associated with transcription regulation even in the absence of H-NS. We propose that for many transcription factors, including PhoB, binding sites not associated with promoter sequences are transcriptionally inert, and hence are tolerated as genomic “noise”. IMPORTANCE Recent studies have revealed large numbers of transcription factor binding sites within the genes of bacteria. The function, if any, of the vast majority of these binding sites has not been investigated. Here, we map the binding of the transcription factor PhoB across the Escherichia coli genome, revealing that the majority of PhoB binding sites are within genes. We show that PhoB binding sites within genes are not associated with regulation of the overlapping genes. Indeed, our data suggest that bacteria tolerate the presence of large numbers of non-regulatory, intragenic binding sites for transcription factors, and that these binding sites are not under selective pressure.
Intraoral thermal processing in the gustatory cortex of awake mice

Oral temperature is a sensory cue relevant to food preference and nutrition. To understand how orally-sourced thermal inputs are represented in the gustatory cortex (GC) we recorded neural responses from the GC of male and female mice presented with deionized water at different innocuous temperatures (14 °C, 25 °C, 36 °C) and taste stimuli (room temperature). Our results demonstrate that GC neurons encode orally-sourced thermal information in the absence of classical taste qualities at the single neuron and population levels, as confirmed through additional experiments comparing GC neuron responses to water and artificial saliva. Analysis of thermal-evoked responses showed broadly tuned neurons that responded to temperature in a mostly monotonic manner. Spatial location may play a minor role regarding thermosensory activity; aside from the most ventral GC, neurons reliably responded to and encoded thermal information across the dorso-ventral and antero-postero cortical axes. Additional analysis revealed that more than half of GC neurons that encoded chemosensory taste stimuli also accurately discriminated thermal information, providing additional evidence of the GC’s involvement in processing thermosensory information important for ingestive behaviors. In terms of convergence, we found that GC neurons encoding information about both taste and temperature were broadly tuned and carried more information than taste-selective only neurons; both groups encoded similar information about the palatability of stimuli. Altogether, our data reveal new details of the cortical code for the mammalian intraoral thermosensory system in behaving mice and pave the way for future investigations on GC functions and operational principles with respect to thermogustation.
Reassessing the Functional Significance of BOLD Variability

BOLD variability (SDBOLD) has emerged as a unique measure of the adaptive properties of neural systems that facilitate fast, stable responding, based on claims that SDBOLD is independent of mean BOLD signal (meanBOLD) and a powerful predictor of behavioural performance. We challenge these two claims. First, the apparent independence of SDBOLD and meanBOLD may reflect the presence of deactivations; we hypothesize that while SDBOLD may not be related to raw meanBOLD it will be linearly related to absolute meanBOLD. Second, the observed relationship between SDBOLD and performance may be an artifact of using fixed-length trials longer than response times. Such designs provide opportunities to toggle between on- and off-task states, and fast responders likely engage in more frequent state-switching, thereby artificially elevating SDBOLD. We hypothesize that SDBOLD will be higher and more strongly related to performance when using such fixed-length trials relative to self-paced trials that terminate upon a response. We test these two hypotheses in an fMRI study using blocks of fixed-length or self-paced trials. Results confirmed both hypotheses: (1) SDBOLD was robustly related with absolute meanBOLD; and (2) toggling between on- and off-task states during fixed-length trials reliably contributed to SDBOLD. Together, these findings suggest that a reappraisal of the functional significance of SDBOLD as a unique marker of cognitive performance is warranted.