3,110 research outputs found
VHE Gamma-ray Afterglow Emission from Nearby GRBs
Gamma-ray Bursts (GRBs) are among the potential extragalactic sources of
very-high-energy (VHE) gamma-rays. We discuss the prospects of detecting VHE
gamma-rays with current ground-based Cherenkov instruments during the afterglow
phase. Using the fireball model, we calculate the synchrotron self-Compton
(SSC) emission from forward-shock electrons. The modeled results are compared
with the observational afterglow data taken with and/or the sensitivity level
of ground-based VHE instruments (e.g. STACEE, H.E.S.S., MAGIC, VERITAS, and
Whipple). We find that modeled SSC emission from bright and nearby bursts such
as GRB 030329 are detectable by these instruments even with a delayed
observation time of ~10 hours.Comment: Proceeding of "Heidelberg International Symposium on High Energy
Gamma-Ray Astronomy", held in Heidelberg, 7-11 July 2008, submitted to AIP
Conference Proceedings. 4 pages, 3 figures, 1 tabl
Potential anti-inflammatory and anti-cancer properties of farnesol
© 2018 by the authors. Farnesol, an acyclic sesquiterpene alcohol, is predominantly found in essential oils of various plants in nature. It has been reported to exhibit anti-cancer and anti-inflammatory effects, and also alleviate allergic asthma, gliosis, and edema. In numerous tumor cell lines, farnesol can modulate various tumorigenic proteins and/or modulates diverse signal transduction cascades. It can also induce apoptosis and downregulate cell proliferation, angiogenesis, and cell survival. To exert its anti-inflammatory/anti-oncogenic effects, farnesol can modulate Ras protein and nuclear factor kappa-light-chain-enhancer of activated B cells activation to downregulate the expression of various inflammatory mediators such as cyclooxygenase-2, inducible nitric oxide synthase, tumor necrosis factor alpha, and interleukin-6. In this review, we describe the potential mechanisms of action underlying the therapeutic effects of farnesol against cancers and inflammatory disorders. Furthermore, these findings support the clinical development of farnesol as a potential pharmacological agent in clinical studies
Parvovirus B19 infection presenting with severe erythroid aplastic crisis during pregnancy in a woman with autoimmune hemolytic anemia and alpha-thalassemia trait: a case report
Molecular targets modulated by fangchinoline in tumor cells and preclinical models
© 2018 MDPI AG. All rights reserved. Despite tremendous progress made during the last few decades in the treatment options for cancer, compounds isolated from Mother Nature remain the mainstay for therapy of various malignancies. Fangchinoline, initially isolated from the dried root of Stephaniae tetrandrine, has been found to exhibit diverse pharmacological effects including significant anticancer activities both in tumor cell lines and selected preclinical models. This alkaloid appears to act by modulating the activation of various important oncogenic molecules involved in tumorigenesis leading to a significant decrease in aberrant proliferation, survival and metastasis of tumor cells. This mini-review briefly describes the potential effects of fangchinoline on important hallmarks of cancer and highlights the molecular targets modulated by this alkaloid in various tumor cell lines and preclinical models
Thermal Emission from Warm Dust in the Most Distant Quasars
We report new continuum observations of fourteen z~6 quasars at 250 GHz and
fourteen quasars at 1.4 GHz. We summarize all recent millimeter and radio
observations of the sample of the thirty-three quasars known with
5.71<=z<=6.43, and present a study of the rest frame far-infrared (FIR)
properties of this sample. These quasars were observed with the Max Plank
Millimeter Bolometer Array (MAMBO) at 250 GHz with mJy sensitivity, and 30% of
them were detected. We also recover the average 250 GHz flux density of the
MAMBO undetected sources at 4 sigma, by stacking the on-source measurements.
The derived mean radio-to-UV spectral energy distributions (SEDs) of the full
sample and the 250 GHz non-detections show no significant difference from that
of lower-redshift optical quasars. Obvious FIR excesses are seen in the
individual SEDs of the strong 250 GHz detections, with FIR-to-radio emission
ratios consistent with that of typical star forming galaxies. Most 250
GHz-detected sources follow the L_{FIR}--L_{bol} relationship derived from a
sample of local IR luminous quasars (L_{IR}>10^{12}L_{\odot}), while the
average L_{FIR}/L_{bol} ratio of the non-detections is consistent with that of
the optically-selected PG quasars. The MAMBO detections also tend to have
weaker Ly\alpha emission than the non-detected sources. We discuss possible FIR
dust heating sources, and critically assess the possibility of active star
formation in the host galaxies of the z~6 quasars. The average star formation
rate of the MAMBO non-detections is likely to be less than a few hundred
M_{\odot} yr^{-1}, but in the strong detections, the host galaxy star formation
is probably at a rate of \gtrsim10^{3} M_{\odot} yr^{-1}, which dominates the
FIR dust heating.Comment: 32 pages with 6 figures; ApJ, in press; Added references; Corrected
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Is keV ion induced pattern formation on Si(001) caused by metal impurities?
We present ion beam erosion experiments performed in ultra high vacuum using
a differentially pumped ion source and taking care that the ion beam hits the
Si(001) sample only. Under these conditions no ion beam patterns form on Si for
angles below 45 degrees with respect to the global surface normal using 2 keV
Kr ions and fluences of 2 x 10^22 ions/m^2. In fact, the ion beam induces a
smoothening of preformed patterns. Simultaneous sputter deposition of stainless
steel in this angular range creates a variety of patterns, similar to those
previously ascribed to clean ion beam induced destabilization of the surface
profile. Only for grazing incidence with incident angles between 60 degrees and
83 degrees pronounced ion beam patterns form. It appears that the angular
dependent stability of Si(001) against pattern formation under clean ion beam
erosion conditions is related to the angular dependence of the sputtering
yield, and not primarily to a curvature dependent yield as invoked frequently
in continuum theory models.Comment: 15 pages, 7 figures. This is an author-created, un-copyedited version
of an article published in Nanotechnology. IOP Publishing Ltd is not
responsible for any errors or omissions in this version of the manuscript or
any version derived from i
Criteria for the experimental observation of multi-dimensional optical solitons in saturable media
Criteria for experimental observation of multi-dimensional optical solitons
in media with saturable refractive nonlinearities are developed. The criteria
are applied to actual material parameters (characterizing the cubic
self-focusing and quintic self-defocusing nonlinearities, two-photon loss, and
optical-damage threshold) for various glasses. This way, we identify operation
windows for soliton formation in these glasses. It is found that two-photon
absorption sets stringent limits on the windows. We conclude that, while a
well-defined window of parameters exists for two-dimensional solitons (spatial
or spatiotemporal), for their three-dimensional spatiotemporal counterparts
such a window \emph{does not} exist, due to the nonlinear loss in glasses.Comment: 8 pages, to appear in Phys. Rev.
Heat Capacity of Protein Folding
We construct a Hamiltonian for a single domain protein where the contact
enthalpy and the chain entropy decrease linearly with the number of native
contacts. The hydration effect upon protein unfolding is included by modeling
water as ideal dipoles that are ordered around the unfolded surfaces, where the
influence of these surfaces, covered with an ``ice-like'' shell of water, is
represented by an effective field that directs the water dipoles. An
intermolecular pair interaction between water molecules is also introduced. The
heat capacity of the model exhibits the common feature of small globular
proteins, two peaks corresponding to cold and warm unfolding, respectively. By
introducing vibrational modes, we obtain quantitatively good accordance with
experiments.Comment: 14 pages, LaTex, 4 figure
A Novel Bioluminescent Protease Assay Using Engineered Firefly Luciferase
Proteases play important roles in a variety of disease processes. Understanding their biological functions underpins the efforts of drug discovery. We have developed a bioluminescent protease assay using a circularly permuted form of firefly luciferase, wherein the native enzyme termini were joined by a peptide containing a protease site of interest. Protease cleavage of these mutant luciferases greatly activates the enzyme, typically over 100 fold. The mutant luciferase substrates are easily generated by molecular cloning and cell-free translation reactions and thus the protease substrates do not need to be chemically synthesized or purchased. The assay has broad applicability using a variety of proteases and their cognate sites and can sensitively detect protease activity. In this report we further demonstrate its utility for the evaluation of protease recognition sequence specificity and subsequent establishment of an optimized assay for the identification and characterization of protease inhibitors using high throughput screening
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