1,909 research outputs found

    Answering Mermin's Challenge with Conservation per No Preferred Reference Frame

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    In 1981, Mermin published a now famous paper titled, "Bringing home the atomic world: Quantum mysteries for anybody" that Feynman called, "One of the most beautiful papers in physics that I know." Therein, he presented the "Mermin device" that illustrates the conundrum of quantum entanglement per the Bell spin states for the "general reader." He then challenged the "physicist reader" to explain the way the device works "in terms meaningful to a general reader struggling with the dilemma raised by the device." Herein, we show how "conservation per no preferred reference frame (NPRF)" answers that challenge. In short, the explicit conservation that obtains for Alice and Bob's Stern-Gerlach spin measurement outcomes in the same reference frame holds only on average in different reference frames, not on a trial-by-trial basis. This conservation is SO(3) invariant in the relevant symmetry plane in real space per the SU(2) invariance of its corresponding Bell spin state in Hilbert space. Since NPRF is also responsible for the postulates of special relativity, and therefore its counterintuitive aspects of time dilation and length contraction, we see that the symmetry group relating non-relativistic quantum mechanics and special relativity via their "mysteries" is the restricted Lorentz group.Comment: 18 pages, 9 figures. This version as revised and resubmitted to Scientific Report

    A Primer on the Law of Deceptive Practices

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    Quantifying sleep architecture dynamics and individual differences using big data and Bayesian networks

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    The pattern of sleep stages across a night (sleep architecture) is influenced by biological, behavioral, and clinical variables. However, traditional measures of sleep architecture such as stage proportions, fail to capture sleep dynamics. Here we quantify the impact of individual differences on the dynamics of sleep architecture and determine which factors or set of factors best predict the next sleep stage from current stage information. We investigated the influence of age, sex, body mass index, time of day, and sleep time on static (e.g. minutes in stage, sleep efficiency) and dynamic measures of sleep architecture (e.g. transition probabilities and stage duration distributions) using a large dataset of 3202 nights from a non-clinical population. Multi-level regressions show that sex effects duration of all Non-Rapid Eye Movement (NREM) stages, and age has a curvilinear relationship for Wake After Sleep Onset (WASO) and slow wave sleep (SWS) minutes. Bayesian network modeling reveals sleep architecture depends on time of day, total sleep time, age and sex, but not BMI. Older adults, and particularly males, have shorter bouts (more fragmentation) of Stage 2, SWS, and they transition less frequently to these stages. Additionally, we showed that the next sleep stage and its duration can be optimally predicted by the prior 2 stages and age. Our results demonstrate the potential benefit of big data and Bayesian network approaches in quantifying static and dynamic architecture of normal sleep

    Expression of a single major histocompatibility complex locus controls the immune complex locus controls the immune response to poly-L-(tyrosine, glutamic acid)-poly-DL-alanine—poly-L-lysine

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    Genetic control of the immune response linked to the major histocompatibility (H-2) complex in the mouse has been described for synthetic polypeptide antigens and for low doses of native proteins. The phenomenon is well documented(1,2). Extensive screening of intra-H-2 crossover-derived recombinant strains has localized H-2-linked immune response (Ir) genes to the I-immune response region of the H-2 complex (3). For most antigens, Ir genes are autosomal, dominant, and they segregate as single loci. It is not known whether these crossover-defined loci respresent single genes with multiple alleles or clusters of tightly linked genes (4). In 1972, Stimpfling and Durham (5) postulated that two interacting loci within the H-2 complex were required for the response to the alloantigen, H-2.2 (6), and, in 1975, Dorf et. al. (7) observed a responder phenotype in a recombinant derived from two strains which were nonresponders to the synthetic linear terpolymer, L-glutamic acid, L-lysine, L-phenylaline (GLPhe). Analysis of additional recombinants and complementation tests with F(1) hybrids clearly demonstrated that genes in two intra-I-region loci controlled the immune response to GLPhe. Subsequently, requirement for genes mapping in two intra-I-region loci were reported for porcine LDH(B)(8), the alloantigen Thy-1.1 (9), and for the synthetic terpolymers L-glutamic acid, L-lysine, L-tyrosine and L-glutamic acid, L-lysine, L- leucine (6,10). Demonstration that responses to both synthetic polypeptide and native protein antigens can be controlled by genes in two distinct I-region loci prompted speculation that the phenotypic expression of two I-region genes is a general phenomenon which may provide the key for understanding the mechanism of Ir gene function and cellular collaboration in the immune response. Benacerraf and Dorf (10) have shown that Ir gene complementation is often more effective in the cis than in the trans configuration. This concept is further supported by the data reported for GLPhe (10-12) which indicate that both of the complementing genes must be expressed in each of the cell types participating in the interaction. Failure to detect complementation for the majority of antigens under H-2-linked Ir-gene control might be attributed to the limited number of available intra-I- region recombinant strains

    Overlapping functionality of the Pht proteins in zinc homeostasis of streptococcus pneumoniae

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    Streptococcus pneumoniae is a globally significant pathogen that causes a range of diseases, including pneumonia, sepsis, meningitis, and otitis media. Its ability to cause disease depends upon the acquisition of nutrients from its environment, including transition metal ions such as zinc. The pneumococcus employs a number of surface proteins to achieve this, among which are four highly similar polyhistidine triad (Pht) proteins. It has previously been established that these proteins collectively aid in the delivery of zinc to the ABC transporter substrate-binding protein AdcAII. Here we have investigated the contribution of each individual Pht protein to pneumococcal zinc homeostasis by analyzing mutant strains expressing only one of the four pht genes. Under conditions of low zinc availability, each of these mutants showed superior growth and zinc accumulation profiles relative to a mutant strain lacking all four genes, indicating that any of the four Pht proteins are able to facilitate delivery of zinc to AdcAII. However, optimal growth and zinc accumulation in vitro and pneumococcal survival and proliferation in vivo required production of all four Pht proteins, indicating that, despite their overlapping functionality, the proteins are not dispensable without incurring a fitness cost. We also show that surface-attached forms of the Pht proteins are required for zinc recruitment and that they do not contribute to defense against extracellular zinc stress

    Self-similar structure and experimental signatures of suprathermal ion distribution in inertial confinement fusion implosions

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    The distribution function of suprathermal ions is found to be self-similar under conditions relevant to inertial confinement fusion hot-spots. By utilizing this feature, interference between the hydro-instabilities and kinetic effects is for the first time assessed quantitatively to find that the instabilities substantially aggravate the fusion reactivity reduction. The ion tail depletion is also shown to lower the experimentally inferred ion temperature, a novel kinetic effect that may explain the discrepancy between the exploding pusher experiments and rad-hydro simulations and contribute to the observation that temperature inferred from DD reaction products is lower than from DT at National Ignition Facility.Comment: Revised version accepted for publication in PRL. "Copyright (2015) by the American Physical Society.

    The first histidine triad motif of phtd is critical for zinc homeostasis in Streptococcus pneumoniae

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    Streptococcus pneumoniae is the world's foremost human pathogen. Acquisition of the first row transition metal ion zinc is essential for pneumococcal colonization and disease. Zinc is acquired via the ATP-binding cassette transporter AdcCB and two zinc-binding proteins, AdcA and AdcAII. We have previously shown that AdcAII is reliant upon the polyhistidine triad (Pht) proteins to aid in zinc recruitment. Pht proteins generally contain five histidine (His) triad motifs that are believed to facilitate zinc binding and therefore play a significant role in pneumococcal metal ion homeostasis. However, the importance and potential redundancy of these motifs have not been addressed. We examined the effects of mutating each of the five His triad motifs of PhtD. The combination of in vitro growth assays, active zinc uptake, and PhtD expression studies show that the His triad closest to the protein's amino terminus is the most important for zinc acquisition. Intriguingly, in vivo competitive infection studies investigating the amino- and carboxyl-terminal His triad mutants indicate that the motifs have similar importance in colonization. Collectively, our new insights into the contributions of the individual His triad motifs of PhtD, and by extension the other Pht proteins, highlight the crucial role of the first His triad site in zinc acquisition. This study also suggests that the Pht proteins likely play a role beyond zinc acquisition in pneumococcal virulence

    Effects of tumour necrosis factor-α on BrdU incorporation in cultured human enterocytes

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    Bromodeoxyuridine incorporation is a useful method for studying the pattern of DNA synthesis in proliferating cells. The distribution pattern of incorporated BrdU in villus enterocytes of duodenal explants was analysed after exposure to TNFα in organ culture. TNFα caused a consistent, low level uptake of BrdU in the portion of the nucleus close to the nuclear membrane, this pattern was absent from the control cultures. As these epithelial cells are terminally arrested in G0, the BrdU incorporation was thought not to be due to S phase DNA synthesis, but rather a response to the cytotoxic influence of TNFα. Microtitre plate proliferation assays of cell density and DNA synthesis were devised to study the effects of TNFα on confluent monolayers of the human foetal jejunal cell line I407 and the mouse fibrosarcoma cell line L929. Both cell lines showed a similar response to TNFα. Exposure to TNFα alone did not reduce cell numbers but did cause a significant increase in DNA synthesis (p < 0.05). When cycloheximtde was added in tandem with TNFα there was a significant reduction in cell number (p < 0.001) and level of DNA synthesis (p < 0.01) indicative of cell death. The DNA of cells exposed to TNFα and cycloheximide was fragmented when viewed on an electrophoresis gel. The results show that BrdU incorporation might be a good indicator of damage to the DNA of cells after cytotoxic insult. TNFα may be responsible for villus enterocyte damage in enteropathies such as coeliac disease and GVHR of the small bowel

    GENETIC CONTROL OF THE IMMUNE RESPONSE : MAPPING OF THEIR-1 LOCUS

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    Eleven strains of mice bearing recombinant H-2 chromosomes derived from known crossover events between known H-2 types were immunized with a series of branched, multichain, synthetic polypeptide antigens [(T,G)-A--L, (H,G)-A--L, and (Phe,G)-A--L]. Results with nine of the eleven H-2 recombinants indicated that the gene(s) controlling immune response to these synthetic polypeptides (Ir-1) is on the centromeric or H-2K part of the recombinant H-2 chromosome. Results with two of the eleven recombinant H-2 chromosomes indicated that Ir-1 was on the telomeric or H-2D part of the recombinant H-2 chromosome. Both of these recombinants were derived from crossovers between the H-2K locus and the Ss-Slp locus near the center of the H-2 region. One of these recombinants, H-2y, was derived from a known single crossover event. These results indicate that Ir-1 lies near the center of the H-2 region between the H-2K locus and the Ss-Slp locus. The results of a four-point linkage test were consistent with these results. In 484 offspring of a cross designed to detect recombinants between H-2 and Ir-1, only two putative recombinants were detected. Both of these recombinants were confirmed by progeny testing. Extensive analysis of one of them has shown that the crossover event occurred within the H-2 region. (Testing of the second recombinant is currently under way.) Thus, in the linkage test, recombinants between H-2 and Ir-1 are in fact intra-H-2 crossovers. These results permit assignment of Ir-1 to a position between the H-2K locus and the Ss-Slp locus

    Phylogeographic structure of the pygmy shrew: revisiting the roles of southern and northern refugia in Europe

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    Southern and northern glacial refugia are considered paradigms that explain the complex phylogeographic patterns and processes of European biota. Here, we provide a revisited statistical phylogeographic analysis of the pygmy shrew Sorex minutus Linnaeus, 1766 (Eulipotyphla, Soricidae) examining the genetic diversity, genetic differentiation and demographic history in the Mediterranean peninsulas and in Western and Central Europe. The results showed support for genetically distinct and diverse phylogeographic groups consistent with southern and northern glacial refugia, as expected from previous studies, but also identified geographical barriers concordant with glaciated mountain ranges during the Last Glacial Maximum (LGM), early diversification events dated between the Upper Pleistocene and Lower Holocene for the main phylogeographic groups, and recent (post-LGM) patterns of demographic expansions. This study is the most comprehensive investigation of this species to date, and the results have implications for the conservation of intraspecific diversity and the preservation of the evolutionary potential of S. minutus
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