6,458 research outputs found
The Effects of Lesions in the Dorsolateral Pons on the Coordination of Swallowing and Breathing in Awake Goats
The purpose of this retrospective study was to gain insight into the contribution of the dorsolateral pons to the coordination of swallowing and breathing in awake goats. In 4 goats, cannulas were chronically implanted bilaterally through the lateral (LPBN) and medial (MPBN) parabrachial nuclei just dorsal to the Kölliker–Fuse nucleus (KFN). After \u3e2 weeks recovery from this surgery, the goats were studied for 5½ h on a control day, and on separate days after receiving 1 and 10 μl injections of ibotenic acid (IA) separated by 1 week. The frequency of swallows did not change during the control and 1 μl IA studies, but after injection of 10 μl IA, there was a transient 65% increase in frequency of swallows (P \u3c 0.05). Under control conditions swallows occurred throughout the respiratory cycle, where late-E swallows accounted for 67.6% of swallows. The distribution of swallow occurrence throughout the respiratory cycle was unaffected by IA injections. Consistent with the concept that swallowing is dominant over breathing, we found that swallows increased inspiratory (TI) and expiratory (TE) time and decreased tidal volume (VT) of the breath of the swallow (n) and/or the subsequent (n + 1) breath. Injections of 10 μl IA attenuated the normal increases in TI and TE and further attenuated VT of the n breath. Additionally, E and I swallows reset respiratory rhythm, but injection of 1 or 10 μl IA progressively attenuated this resetting, suggesting a decreased dominance over respiratory motor output with increasing IA injections. Post mortem histological analysis revealed about 50% fewer (P \u3c 0.05) neurons remained in the KFN, LPBN, and MPBN in lesioned compared to control goats. We conclude that dorsolateral pontine nuclei have a modulatory role in a hypothesized holarchical neural network regulating swallowing and breathing particularly contributing to the normal dominance of swallowing over breathing in both rhythm and motor pattern generation
Polarization fluctuations in insulators and metals: New and old theories merge
The ground-state fluctuation of polarization P is finite in insulators and
divergent in metals, owing to the SWM sum rule [I. Souza, T. Wilkens, and R. M.
Martin, Phys. Rev. B 62, 1666 (2000)]. This is a virtue of periodic (i.e.
transverse) BCs. I show that within any other boundary conditions the P
fluctuation is finite even in metals, and a generalized sum rule applies. The
boundary-condition dependence is a pure correlation effect, not present at the
independent-particle level. In the longitudinal case div P = -rho, and one
equivalently addresses charge fluctuations: the generalized sum rule reduces
then to a well known result of many-body theory.Comment: 4 pages, no figur
Nonlinearities in Conservative Growth Equations
Using the dynamic renormalization group (DRG) technique, we analyze general
nonlinearities in a conservative nonlinear growth equation with non-conserved
gaussian white noise. We show that they fall in two classes only: the
Edwards-Wilkinson and Lai-Das Sarma types, by explicitly computing the
associated amputated two and three point functions at the first order in
perturbation parameter(s). We further generalize this analysis to higher order
nonlinearities and also suggest a physically meaningful geometric
interpretation of the same.Comment: REVTEX, will appear in Phys Rev E Rapid Comm. February 1996, .ps
figure file available upon request to [email protected]
Asymmetric Thermal Lineshape Broadening in a Gapped 3-Dimensional Antiferromagnet - Evidence for Strong Correlations at Finite Temperature
It is widely believed that magnetic excitations become increasingly
incoherent as temperature is raised due to random collisions which limit their
lifetime. This picture is based on spin-wave calculations for gapless magnets
in 2 and 3 dimensions and is observed experimentally as a symmetric Lorentzian
broadening in energy. Here, we investigate a three-dimensional dimer
antiferromagnet and find unexpectedly that the broadening is asymmetric -
indicating that far from thermal decoherence, the excitations behave
collectively like a strongly correlated gas. This result suggests that a
temperature activated coherent state of quasi-particles is not confined to
special cases like the highly dimerized spin-1/2 chain but is found generally
in dimerized antiferromagnets of all dimensionalities and perhaps gapped
magnets in general
Distributed Edge Connectivity in Sublinear Time
We present the first sublinear-time algorithm for a distributed
message-passing network sto compute its edge connectivity exactly in
the CONGEST model, as long as there are no parallel edges. Our algorithm takes
time to compute and a
cut of cardinality with high probability, where and are the
number of nodes and the diameter of the network, respectively, and
hides polylogarithmic factors. This running time is sublinear in (i.e.
) whenever is. Previous sublinear-time
distributed algorithms can solve this problem either (i) exactly only when
[Thurimella PODC'95; Pritchard, Thurimella, ACM
Trans. Algorithms'11; Nanongkai, Su, DISC'14] or (ii) approximately [Ghaffari,
Kuhn, DISC'13; Nanongkai, Su, DISC'14].
To achieve this we develop and combine several new techniques. First, we
design the first distributed algorithm that can compute a -edge connectivity
certificate for any in time .
Second, we show that by combining the recent distributed expander decomposition
technique of [Chang, Pettie, Zhang, SODA'19] with techniques from the
sequential deterministic edge connectivity algorithm of [Kawarabayashi, Thorup,
STOC'15], we can decompose the network into a sublinear number of clusters with
small average diameter and without any mincut separating a cluster (except the
`trivial' ones). Finally, by extending the tree packing technique from [Karger
STOC'96], we can find the minimum cut in time proportional to the number of
components. As a byproduct of this technique, we obtain an -time
algorithm for computing exact minimum cut for weighted graphs.Comment: Accepted at 51st ACM Symposium on Theory of Computing (STOC 2019
Mid-Infrared Imaging of NGC 6334 I
We present high-resolution (<0.5") mid-infrared Keck II images of individual
sources in the central region of NGC 6334 I. We compare these images to images
at a variety of other wavelengths from the near infrared to cm radio continuum
and speculate on the nature of the NGC 6334 I sources. We assert that the
cometary shape of the UCHII region here, NGC 6334 F, is due to a champagne-like
flow from a source on the edge of a molecular clump and not a due to a bow
shock caused by the supersonic motion of the UCHII region through the
interstellar medium. The mid-infrared emission in concentrated into an arc of
dust that define the boundary between the UCHII region and the molecular clump.
This dust arc contains a majority of the masers in the region. We discuss the
nature of the four near-infrared sources associated with IRS-I 1, and suggest
that one of the sources, IRS1E, is responsible for the heating and ionizing of
the UCHII region and the mid-infrared dust arc. Infrared source IRS-I 2, which
has been thought to be a circumstellar disk associated with a linear
distribution of methanol masers, is found not to be directly coincident with
the masers and elongated at a much different position angle. IRS-I 3 is found
to be a extended source of mid-infrared emission coming from a cluster of young
dusty sources seen in the near-infrared.Comment: Accepted for publication by the Astrophysical Journal, 27 pages, 9
figure
A New Method of Measuring 81Kr and 85Kr Abundances in Environmental Samples
We demonstrate a new method for determining the 81Kr/Kr ratio in
environmental samples based upon two measurements: the 85Kr/81Kr ratio measured
by Atom Trap Trace Analysis (ATTA) and the 85Kr/Kr ratio measured by Low-Level
Counting (LLC). This method can be used to determine the mean residence time of
groundwater in the range of 10^5 - 10^6 a. It requires a sample of 100 micro-l
STP of Kr extracted from approximately two tons of water. With modern
atmospheric Kr samples, we demonstrate that the ratios measured by ATTA and LLC
are directly proportional to each other within the measurement error of +/-
10%; we calibrate the 81Kr/Kr ratio of modern air measured using this method;
and we show that the 81Kr/Kr ratios of samples extracted from air before and
after the development of the nuclear industry are identical within the
measurement error
Patritumab or Placebo Plus Cetuximab and Platinum-Based Therapy in Squamous Cell Carcinoma of the Head and Neck (SCCHN): a Phase 2 Study
BACKGROUND: P is a fully human monoclonal antibody against human epidermal growth factor receptor 3. P blocks activation by the ligand, heregulin (HRG), inducing receptor internalization. Evidence is growing that HRG presence determines disease progression and survival; in a phase 2 study in non–small-cell lung cancer, P + erlotinib increased progression-free survival (PFS) in high HRG mRNA expression (HRG-high) patients. A phase 1b study in SCCHN demonstrated safety, tolerability and tumor response of P + C + cisplatin or carboplatin and informed the P phase 2 dose. January 2016 (N = 15) response rate = 47%; best responses = 3 complete response (CR), 4 partial response (PR) and 8 stable disease (SD). This phase 2 study (NCT02633800) evaluates first-line P + C + platinum (P arm) vs. PBO + C + platinum (PBO arm) in recurrent and/or metastatic (R/M) SCCHN. The primary objective is to evaluate PFS in the HRG-high population (P vs. PBO arms). METHODS: This is arandomized, controlled, double-blind first-line study in Europe. Patients aged ≥ 18 years with confirmed R/M SCCHN, ECOG performance status ≤ 1 and documented HRG expression (per archived or fresh biopsies) are eligible. The primary efficacy endpoint is PFS. Secondary endpoints include overall survival, overall response rate, pharmacokinetics and safety (including human antihuman antibody incidence). Approximately 105 patients will be stratified 2:1 by HRG status (70 high; 35 low), and then randomized 1:1 to the P or PBO arm. All patients will receive either intravenous P (18mg/kg loading dose [LD]; 9mg/kg maintenance dose [MD] every 3 weeks [q3w]) or PBO, and C (400mg/m2 LD; 250mg/m2 MD weekly) + ≤ 6 cycles of cisplatin (100mg/m2 q3w) or carboplatin (area under the curve of 5). Patients demonstrating CR, PR or SD will be treated with P/PBO + C + ≤ 6 cycles platinum for the study duration (until all patients have died or ≥ 13 months postrandomization of last patient); those benefiting may continue treatment uninterrupted in an open-label extension phase until progressive disease, toxicity or withdrawal. Survival status will be obtained ≥ 13 months after discontinuation. The first patient was dosed December 2015 and enrollment is open. Clinical trial information: NCT0263380
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