4,644 research outputs found
Enhanced signal of astrophysical tau neutrinos propagating through Earth
Earth absorbs \nue and \numu of energies above about 100 TeV. As is
well-known, although \nutau will also disappear through charged-current
interactions, the \nutau flux will be regenerated by prompt tau decays. We
show that this process also produces relatively large fluxes of secondary
\nube and \nubmu, greatly enhancing the detectability of the initial
\nutau. This is particularly important because at these energies \nutau is
a significant fraction of the expected astrophysical neutrino flux, and only a
tiny portion of the atmospheric neutrino flux.Comment: Four pages, two inline figure
COVID-19 as a Possible Cause of Functional Exhaustion of CD4 and CD8 T-cells and Persistent Cause of Methicillin-Sensitive Staphylococcus aureus Bacteremia.
We report a case of a 73-year-old male with a history of diabetes mellitus, osteomyelitis, methicillin-sensitive Staphylococcus aureus (MSSA) bacteremia who recently completed an extended intravenous course of cefazolin eight days back, and presented with MSSA bacteremia complicated by epidural abscess, endocarditis, and aortic root abscess. Meanwhile, the patient was tested positive for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) by reverse transcription-polymerase chain reaction (RT-PCR). Even with aggressive antibiotic treatment, the patient remained bacteremic and developed endocarditis with a worsening aortic root abscess. We suspect coronavirus disease 2019 (COVID-19) as a cause for the infectious paradox and will discuss the possible mechanisms in this case report
Tracing very high energy neutrinos from cosmological distances in ice
Astrophysical sources of ultrahigh energy neutrinos yield tau neutrino fluxes
due to neutrino oscillations. We study in detail the contribution of tau
neutrinos with energies above PeV relative to the contribution of the other
flavors. We consider several different initial neutrino fluxes and include tau
neutrino regeneration in transit through the Earth and energy loss of charged
leptons. We discuss signals of tau neutrinos in detectors such as IceCube, RICE
and ANITA.Comment: 27 pages, 19 figure
Mutations and mechanism: how PINK1 may contribute to risk of sporadic Parkinson's disease
This scientific commentary refers to
‘Heterozygous PINK1 p.G411S increases
risk of Parkinson’s disease
via a dominant-negative mechanism’,
by Puschmann et al. (doi:10.1093/
brain/aww261)
Trans-arterial therapy for Fibrolamellar carcinoma: A case report and literature review
Introduction: Fibrolamellar carcinoma (FLC) is a rare pathologically distinct primary liver cancer. Surgical resection is the only treatment associated with prolonged survival. Trans-arterial embolization (TAE), which is a recognised treatment for hepatocellular carcinoma has been used to treat FLC. We present a case and performed a literature review of patients with FLC treated with TAE.
Case presentation: We present a 19-year old female with a large potentially resectable FLC which was initially treated with trans-arterial chemo-embolization (TACE) with drug eluting beads. The TACE was followed by surgical resection. Histology confirmed tumour necrosis related to the previous TACE.
Discussion & literature review: We identified seven case reports and one case series of TAE for FLC. TAE was either used as a neo-adjuvant therapy to facilitate subsequent tumour resection or as a palliative treatment modality. We propose an algorithm for the treatment of FLC that includes TAE.
Conclusion: The rarity of FLC and the paucity of data precludes establishing clear evidence-based standards of care. We propose an algorithm for the treatment of FLC. The establishment of an international registry may facilitate the collection of better quality evidence
Steady two dimensional free-surface flow over semi-infinite and finite-length corrugations in an open channel
Free-surface flow past a semi-infinite or a finite length corrugation in an otherwise flat and horizontal open channel is considered. Numerical solutions for the steady flow problem are computed using both a weakly nonlinear and fully nonlinear model. The new solutions are classified in terms of a depth-based Froude number and the four classical flow types (supercritical, subcritical, generalised hydraulic rise and hydraulic rise) for flow over a small bump. While there is no hydraulic fall solution for semi-infinite topography, we provide strong numerical evidence that such a solution does exist in the case of a finite length corrugation. Numerical solutions are also found for the other flow types for either semi-infinite or finite length corrugation. For subcritical flow over a semi-infinite corrugation, the free-surface profile is found to be quasiperiodic in nature. A discussion of the new results is made with reference to the classical problem of flow over a bump
PCA Encrypted Short Acoustic Data Inculcated in Digital Color Images
We propose develop a generalized algorithm for hiding audio signal using image steganography. The authors suggest transmitting short audio messages camouflaged in digital images using Principal Component Analysis (PCA) as an encryption technique. The quantum of principal components required to represent the audio signal by removing the redundancies is a measure of the magnitude of the Eigen values. The aforementioned technique follows a dual task of encryption and in turn also compresses the audio data, sufficient enough to be buried in the image. A 57Kb audio signal is decipher from the Stego image with a high PSNR of 47.49 and a correspondingly low mse of 3.3266 × 1
Synthetic Analogues of the Snail Toxin 6-Bromo-2-mercaptotryptamine Dimer (BrMT) Reveal That Lipid Bilayer Perturbation Does Not Underlie Its Modulation of Voltage-Gated Potassium Channels
Drugs do not act solely by canonical ligand–receptor binding interactions. Amphiphilic drugs partition into membranes, thereby perturbing bulk lipid bilayer properties and possibly altering the function of membrane proteins. Distinguishing membrane perturbation from more direct protein–ligand interactions is an ongoing challenge in chemical biology. Herein, we present one strategy for doing so, using dimeric 6-bromo-2-mercaptotryptamine (BrMT) and synthetic analogues. BrMT is a chemically unstable marine snail toxin that has unique effects on voltage-gated K+ channel proteins, making it an attractive medicinal chemistry lead. BrMT is amphiphilic and perturbs lipid bilayers, raising the question of whether its action against K+ channels is merely a manifestation of membrane perturbation. To determine whether medicinal chemistry approaches to improve BrMT might be viable, we synthesized BrMT and 11 analogues and determined their activities in parallel assays measuring K+ channel activity and lipid bilayer properties. Structure–activity relationships were determined for modulation of the Kv1.4 channel, bilayer partitioning, and bilayer perturbation. Neither membrane partitioning nor bilayer perturbation correlates with K+ channel modulation. We conclude that BrMT’s membrane interactions are not critical for its inhibition of Kv1.4 activation. Further, we found that alkyl or ether linkages can replace the chemically labile disulfide bond in the BrMT pharmacophore, and we identified additional regions of the scaffold that are amenable to chemical modification. Our work demonstrates a strategy for determining if drugs act by specific interactions or bilayer-dependent mechanisms, and chemically stable modulators of Kv1 channels are reported
The (un)resolved X-ray background in the Lockman Hole
Most of the soft and a growing fraction of the harder X-ray background has
been resolved into emission from point sources, yet the resolved fraction above
7 keV has only been poorly constrained. We use ~700 ks of XMM-Newton
observations of the Lockman Hole and a photometric approach to estimate the
total flux attributable to resolved sources in a number of different energy
bands. We find the resolved fraction of the X-ray background to be ~90 per cent
below 2 keV but it decreases rapidly at higher energies with the resolved
fraction above ~7 keV being only ~50 per cent. The integrated X-ray spectrum
from detected sources has a slope of Gamma~1.75, much softer than the Gamma=1.4
of the total background spectrum. The unresolved background component has the
spectral signature of highly obscured AGN.Comment: 6 pages, 6 figures, MNRAS Letters, in press, changed to reflect
accepted versio
Comparison of human uterine cervical electrical impedance measurements derived using two tetrapolar probes of different sizes
BACKGROUND
We sought to compare uterine cervical electrical impedance spectroscopy measurements employing two probes of different sizes, and to employ a finite element model to predict and compare the fraction of electrical current derived from subepithelial stromal tissue.
METHODS
Cervical impedance was measured in 12 subjects during early pregnancy using 2 different sizes of the probes on each subject.
RESULTS
Mean cervical resistivity was significantly higher (5.4 vs. 2.8 Ωm; p < 0.001) with the smaller probe in the frequency rage of 4–819 kHz. There was no difference in the short-term intra-observer variability between the two probes. The cervical impedance measurements derived in vivo followed the pattern predicted by the finite element model.
CONCLUSION
Inter-electrode distance on the probes for measuring cervical impedance influences the tissue resistivity values obtained. Determining the appropriate probe size is necessary when conducting clinical studies of resistivity of the cervix and other human tissues
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