20,276 research outputs found
Multivariable Scaling for the Anomalous Hall Effect
We derive a general scaling relation for the anomalous Hall effect in
ferromagnetic metals involving multiple competing scattering mechanisms,
described by a quadratic hypersurface in the space spanned by the partial
resistivities. We also present experimental findings, which show strong
deviation from previously found scaling forms when different scattering
mechanism compete in strength but can be nicely explained by our theory
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Reply to Nathamgari et al.: Nanopore electroporation for intracellular delivery of biological macromolecules.
Hot Spine Loops and the Nature of a Late-Phase Solar Flare
The fan-spine magnetic topology is believed to be responsible for many
curious features in solar explosive events. A spine field line links distinct
flux domains, but direct observation of such feature has been rare. Here we
report a unique event observed by the Solar Dynamic Observatory where a set of
hot coronal loops (over 10 MK) connected to a quasi-circular chromospheric
ribbon at one end and a remote brightening at the other. Magnetic field
extrapolation suggests these loops are partly tracer of the evolving spine
field line. Continuous slipping- and null-point-type reconnections were likely
at work, energizing the loop plasma and transferring magnetic flux within and
across the fan quasi-separatrix layer. We argue that the initial reconnection
is of the "breakout" type, which then transitioned to a more violent flare
reconnection with an eruption from the fan dome. Significant magnetic field
changes are expected and indeed ensued. This event also features an
extreme-ultraviolet (EUV) late phase, i.e. a delayed secondary emission peak in
warm EUV lines (about 2-7 MK). We show that this peak comes from the cooling of
large post-reconnection loops beside and above the compact fan, a direct
product of eruption in such topological settings. The long cooling time of the
large arcades contributes to the long delay; additional heating may also be
required. Our result demonstrates the critical nature of cross-scale magnetic
coupling - topological change in a sub-system may lead to explosions on a much
larger scale.Comment: Accepted for publication in ApJ. Animations linked from pd
Hormad1 mutation disrupts synaptonemal complex formation, recombination, and chromosome segregation in mammalian meiosis
Meiosis is unique to germ cells and essential for reproduction. During the first meiotic division, homologous chromosomes pair, recombine, and form chiasmata. The homologues connect via axial elements and numerous transverse filaments to form the synaptonemal complex. The synaptonemal complex is a critical component for chromosome pairing, segregation, and recombination. We previously identified a novel germ cell-specific HORMA domain encoding gene, Hormad1, a member of the synaptonemal complex and a mammalian counterpart to the yeast meiotic HORMA domain protein Hop1. Hormad1 is essential for mammalian gametogenesis as knockout male and female mice are infertile. Hormad1 deficient (Hormad1-/-) testes exhibit meiotic arrest in the early pachytene stage, and synaptonemal complexes cannot be visualized by electron microscopy. Hormad1 deficiency does not affect localization of other synaptonemal complex proteins, SYCP2 and SYCP3, but disrupts homologous chromosome pairing. Double stranded break formation and early recombination events are disrupted in Hormad1-/- testes and ovaries as shown by the drastic decrease in the γH2AX, DMC1, RAD51, and RPA foci. HORMAD1 co-localizes with cH2AX to the sex body during pachytene. BRCA1, ATR, and γH2AX co-localize to the sex body and participate in meiotic sex chromosome inactivation and transcriptional silencing. Hormad1 deficiency abolishes γH2AX, ATR, and BRCA1 localization to the sex chromosomes and causes transcriptional de-repression on the X chromosome. Unlike testes, Hormad1-/- ovaries have seemingly normal ovarian folliculogenesis after puberty. However, embryos generated from Hormad1-/- oocytes are hyper- and hypodiploid at the 2 cell and 8 cell stage, and they arrest at the blastocyst stage. HORMAD1 is therefore a critical component of the synaptonemal complex that affects synapsis, recombination, and meiotic sex chromosome inactivation and transcriptional silencing. © 2010 Shin et al
Induction chemotherapy for squamous cell carcinomas of the oral cavity: A cumulative meta-analysis
Induction chemotherapy (ICT) is a controversial treatment for head and neck squamous cell carcinomas (HNSCC). Despite numerous randomized controlled trials (RCTs), a majority do not have enough statistical power alone to conclude ICT’s treatment value among oral squamous carcinoma patients (OSCC) since many addressed HNSCC as one entity instead of by specific subtypes. By performing a systematic review and cumulative meta-analysis, we aim to determine the benefits of ICT in OSCC therapy. A literature search identified for RCTs comparing OSCC patients who received ICT against those without. Log-hazard ratio, and relative risk were used for comparison. Heterogeneity was determined using the I2 statistic package. The primary endpoint was overall survival (OS), followed by disease-free survival (DFS), locoregional recurrence (LRR) and distant metastasis (DM) as secondary endpoints. RESULTS: 27 randomized trials were included for analysis (n = 2872 patients). The shortest median follow-up was 15 months whereas the longest was 11.5 years. ICT does not improve OS (HR = 0.947, 95% CI 0.85–1.05, p = 0.318), DFS (RR = 1.05, 95% CI 0.92–1.21, p = 0.462) and DM (RR = 0.626, CI 95% 0.361–1.086, p = 0.096) compared to locoregional treatment alone. However, there was a significant improvement to LRR (RR = 0.778, 95% CI 0.622–0.972, p = 0.027). There is no evidence ICT improves survival outcomes for OSCC patients. However, ICT reduces locoregional recurrence of OSCC, which may need further verification.preprin
Drosophila Bruce Can Potently Suppress Rpr- and Grim-Dependent but Not Hid-Dependent Cell Death
Bruce is a large protein (530 kDa) that contains an N-terminal baculovirus IAP repeat (BIR) and a C-terminal ubiquitin conjugation domain (E2) 1, 2. BRUCE upregulation occurs in some cancers and contributes to the resistance of these cells to DNA-damaging chemotherapeutic drugs [2]. However, it is still unknown whether Bruce inhibits apoptosis directly or instead plays some other more indirect role in mediating chemoresistance, perhaps by promoting drug export, decreasing the efficacy of DNA damage-dependent cell death signaling, or by promoting DNA repair. Here, we demonstrate, using gain-of-function and deletion alleles, that Drosophila Bruce (dBruce) can potently inhibit cell death induced by the essential Drosophila cell death activators Reaper (Rpr) and Grim but not Head involution defective (Hid). The dBruce BIR domain is not sufficient for this activity, and the E2 domain is likely required. dBruce does not promote Rpr or Grim degradation directly, but its antiapoptotic actions do require that their N termini, required for interaction with DIAP1 BIR2, be intact. dBruce does not block the activity of the apical cell death caspase Dronc or the proapoptotic Bcl-2 family member Debcl/Drob-1/dBorg-1/Dbok. Together, these results argue that dBruce can regulate cell death at a novel point
Constraints on B--->pi,K transition form factors from exclusive semileptonic D-meson decays
According to the heavy-quark flavour symmetry, the transition
form factors could be related to the corresponding ones of D-meson decays near
the zero recoil point. With the recent precisely measured exclusive
semileptonic decays and , we perform a
phenomenological study of transition form factors based on this
symmetry. Using BK, BZ and Series Expansion parameterizations of the form
factor slope, we extrapolate transition form factors from
to . It is found that, although being consistent with
each other within error bars, the central values of our results for form factors at , , are much smaller than
predictions of the QCD light-cone sum rules, but are in good agreements with
the ones extracted from hadronic B-meson decays within the SCET framework.
Moreover, smaller form factors are also favored by the QCD factorization
approach for hadronic B-meson decays.Comment: 19 pages, no figure, 5 table
Does the 2D Hubbard Model Really Show d-Wave Superconductivity?
Some issues concerning the question if the two-dimensional Hubbard model
really show d-wave superconductivity are briefly discussed.Comment: Revtex, no figure
Energy Momentum Pseudo-Tensor of Relic Gravitational Wave in Expanding Universe
We study the energy-momentum pseudo-tensor of gravitational wave, and examine
the one introduced by Landau-Lifshitz for a general gravitational field and the
effective one recently used in literature. In short wavelength limit after
Brill-Hartle average, both lead to the same gauge invariant stress tensor of
gravitational wave. For relic gravitational waves in the expanding universe, we
examine two forms of pressure, and , and trace the
origin of their difference to a coupling between gravitational waves and the
background matter. The difference is shown to be negligibly small for most of
cosmic expansion stages starting from inflation. We demonstrate that the wave
equation is equivalent to the energy conservation equation using the pressure
that includes the mentioned coupling.Comment: 15 pages, no figure, Accepted by PR
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