419 research outputs found
Searching for electromagnetic counterpart of LIGO gravitational waves in the Fermi GBM data with ADWO
The Fermi collaboration identified a possible electromagnetic counterpart of
the gravitational wave event of September 14, 2015. Our goal is to provide an
unsupervised data analysis algorithm to identify similar events in Fermi's
Gamma-ray Burst Monitor CTTE data stream. We are looking for signals that are
typically weak. Therefore, they can only be found by a careful analysis of
count rates of all detectors and energy channels simultaneously. Our
Automatized Detector Weight Optimization (ADWO) method consists of a search for
the signal, and a test of its significance. We developed ADWO, a virtual
detector analysis tool for multi-channel multi-detector signals, and performed
successful searches for short transients in the data-streams. We have
identified GRB150522B, as well as possible electromagnetic candidates of the
transients GW150914 and LVT151012. ADWO is an independently developed,
unsupervised data analysis tool that only relies on the raw data of the Fermi
satellite. It can therefore provide a strong, independent test to any
electromagnetic signal accompanying future gravitational wave observations.Comment: 4 pages and 4 figures, A&A Letters accepte
The unitary ability of IQ and indexes in WAIS-IV
Lichtenberger and Kaufman (2009, p. 167) defined unitary ability as âan ability [âŠ] that is represented by a cohesive set of scaled scores, each reflecting slightly different or unique aspects of the abilityâ. Flanagan and Kaufman (2009) and Lichtenberger and Kaufman (2012) used a difference of 23 IQ points between the highest score (Max) and the lowest score (Min) obtained by a subject in the four Indexes of the WAIS-IV to define unitarity of the total IQ score. A similar method has been used to assess the unitary ability of the four Indexes, with a threshold of 5 points. Such difference scores (of 23 for IQ and 5 for Indexes) are considered high and infrequent and the authors therefore conclude that the corresponding Full-Scale IQ score or Index score is uninterpretable. In this paper we argue that these thresholds are inappropriate because they are based on the wrong standard deviation. The main aim of this study was to establish variability thresholds for IQ and the WAIS-IV Indexes for the American standardization sample and to compare these thresholds with those for the Italian standardization sample. We also consider an alternative approach to determining whether an IQ score represents a unitary ability, based on the maximum difference score for the 10 core subtests that contribute to Full-Scale IQ scores
Razvoj i fizikokemijsko vrednovanje farmakosoma diklofenaka
Pharmacosomes are amphiphilic lipid vesicular systems that have shown their potential in improving the bioavailability of poorly water soluble as well as poorly lipophilic drugs. Diclofenac is a poorly water soluble drug and also causes gastrointestinal toxicity. To improve the water solublity of diclofenac, its pharmacosomes (phospholipid complex) have been prepared and evaluated for physicochemical analysis. Diclofenac was complexed with phosphatidylcholine (80 %) in equimolar ratio, in the presence of dichloromethane, by the conventional solvent evaporation technique. Pharmacosomes thus prepared were evaluated for drug solubility, drug content, surface morphology (by scanning electron microscopy), phase transition behaviour (by differential scanning calorimetry), crystallinity (by X-ray powder diffraction) and in vitro dissolution. Pharmacosomes of diclofenac were found to be irregular or disc shaped with rough surfaces in SEM. Drug content was found to be 96.2 1.1 %. DSC thermograms and XRPD data confirmed the formation of the phospholipid complex. Water solubility of the prepared complex was found to be 22.1 ”g mL1 as compared to 10.5 ”g mL1 of diclofenac. This improvement in water solubility in prepared pharmacosomes may result in improved dissolution and lower gastrointestinal toxicity. Pharmacosomes showed 87.8 % while the free diclofenac acid showed a total of only 60.4 % drug release at the end of 10 h of the dissolution study.Farmakosomi su amfifilni lipidni vezikularni sustavi sa sposobnoĆĄÄu poboljĆĄanja bioraspoloĆŸivosti lijekova slabo topljivih u vodi i organskim otapalima. U svrhu poveÄanja topljivosti diklofenaka (ljekovite tvari koja je slabo vodotopljiva, a uzrokuje i gastrointestinalnu toksiÄnost) pripravljeni su i evaluirani njegovi farmakosomi (fosfolipidni kompleksi). Diklofenak je kompleksiran s fosfatidilkolinom (80 %) u ekvimolarnom omjeru, u prisutnosti diklormetana, konvencionalnom metodom evaporacije. Tako pripravljenim farmakosomima ispitivana je topljivost, sadrĆŸaj ljekovite tvari, morfologija povrĆĄine (pomoÄu pretraĆŸne elektronske mikroskopije), ponaĆĄanje pri prijelazu faza (pomoÄu diferencijalne pretraĆŸne kalorimetrije), kristaliniÄnost (rendgenskom analizom praha) i in vitro oslobaÄanje. Farmakosomi diklofenaka su nepravilnog oblika ili u obliku diska te imaju neravnu povrĆĄinu u SEM-u. SadrĆŸaj ljekovite tvari je 96,2 1,1 %. DSC termogrami i XRPD podaci potvrdili su nastajanje fosfolipidnog kompleksa. Topljivost u vodi dobivenih kompleksa bila je 22,1 ”g mL1, a topljivost samog diklofenaka 10,5 ”g mL1. Postignuto poboljĆĄanje topljivosti moĆŸe imati za posljedicu poveÄano oslobaÄanje i manju gastrointestinalnu toksiÄnost. Tijekom 10 h iz farmakosoma se oslobodilo 87,8 %, a iz slobodnog diklofenaka samo 60,4 % ljekovite tvari
Coulomb Blockade and Coherent Single-Cooper-Pair Tunneling in Single Josephson Junctions
We have measured the current-voltage characteristics of small-capacitance
single Josephson junctions at low temperatures (T < 0.04 K), where the strength
of the coupling between the single junction and the electromagnetic environment
was controlled with one-dimensional arrays of dc SQUIDs. We have clearly
observed Coulomb blockade of Cooper-pair tunneling and even a region of
negative differential resistance, when the zero-bias resistance of the SQUID
arrays is much higher than the quantum resistance h/e^2 = 26 kohm. The negative
differential resistance is evidence of coherent single-Cooper-pair tunneling in
the single Josephson junction.Comment: RevTeX, 4 pages with 6 embedded figure
Photoelectric Emission from Interstellar Dust: Grain Charging and Gas Heating
We model the photoelectric emission from and charging of interstellar dust
and obtain photoelectric gas heating efficiencies as a function of grain size
and the relevant ambient conditions. Using realistic grain size distributions,
we evaluate the net gas heating rate for various interstellar environments, and
find less heating for dense regions characterized by R_V=5.5 than for diffuse
regions with R_V=3.1. We provide fitting functions which reproduce our
numerical results for photoelectric heating and recombination cooling for a
wide range of interstellar conditions. In a separate paper we will examine the
implications of these results for the thermal structure of the interstellar
medium. Finally, we investigate the potential importance of photoelectric
heating in H II regions, including the warm ionized medium. We find that
photoelectric heating could be comparable to or exceed heating due to
photoionization of H for high ratios of the radiation intensity to the gas
density. We also find that photoelectric heating by dust can account for the
observed variation of temperature with distance from the galactic midplane in
the warm ionized medium.Comment: 50 pages, including 18 figures; corrected title and abstract field
Monitoring Space Weather: Using Automated, Accurate Neural Network Based Whistler Segmentation for Whistler Inversion
It is challenging, yet important, to measure the - ever-changing - cold electron density in the plasmasphere. The cold electron density inside and outside of the plasmapause is a key parameter for radiation belt dynamics. One indirect measurement is through finding the velocity dispersion relation exhibited by lightning induced whistlers. The main difficulty of the method comes from low signal-to-noise ratios for most of the ground-based whistler components. To provide accurate electron density and L-shell measurements, whistler components need to be detectable in the noisy background, and their characteristics need to be reliably determined. For this reason precise segmentation is needed on a spectrogram image. Here we present a fully automated way to perform such an image segmentation by leveraging the power of convolutional neural networks, a state-of-the-art method for computer vision tasks. Testing the proposed method against a manually, and semi-manually segmented whistler dataset achieved <10% relative electron density prediction error for 80% of the segmented whistler traces, while for the L-shell, the relative error is <5% for 90% of the cases. By segmenting more than 1 million additional real whistler traces from Rothera station Antarctica, logged over 9 years, seasonal changes in the average electron density were found. The variations match previously published findings, and confirm the capabilities of the image segmentation technique
The number of transmission channels through a single-molecule junction
We calculate transmission eigenvalue distributions for Pt-benzene-Pt and
Pt-butadiene-Pt junctions using realistic state-of-the-art many-body
techniques. An effective field theory of interacting -electrons is used to
include screening and van der Waals interactions with the metal electrodes. We
find that the number of dominant transmission channels in a molecular junction
is equal to the degeneracy of the molecular orbital closest to the metal Fermi
level.Comment: 9 pages, 8 figure
Environmental Factors in the Relapse and Recurrence of Inflammatory Bowel Disease:A Review of the Literature
The causes of relapse in patients with Crohn's disease (CD) and ulcerative colitis (UC) are largely unknown. This paper reviews the epidemiological and clinical data on how medications (non-steroidal anti-inflammatory drugs, estrogens and antibiotics), lifestyle factors (smoking, psychological stress, diet and air pollution) may precipitate clinical relapses and recurrence. Potential biological mechanisms include: increasing thrombotic tendency, imbalances in prostaglandin synthesis, alterations in the composition of gut microbiota, and mucosal damage causing increased permeability
Nature of the bonding in metal-silane Ï-complexes
The nature of metal silane Ï-bond interaction has been investigated in several key systems by a range of experimental and computational techniques. The structure of [CpâČMn(CO)2(η2-HSiHPh2)] 1 has been determined by single crystal neutron diffraction, and the geometry at the Si atom is shown to approximate a trigonal bipyramid; salient bond distances and angles are MnâH(1) 1.575(14), SiâH(1) 1.806(14), SiâH(2) 1.501(13) Ă
, and H(1)âSiâH(2) 148.5(8)°. This complex is similar to [CpâČMn(CO)2(η2-HSiFPh2)] 2, whose structure and bonding characteristics have recently been determined by charge density studies based on high-resolution X-ray and neutron diffraction data. The geometry at the Si atom in these Ï-bond complexes is compared with that in other systems containing hypercoordinate silicon. The MnâH distances for 1 and 2 in solution have been estimated using NMR T1 relaxation measurements, giving a value of 1.56(3) Ă
in each case, in excellent agreement with the distances deduced from neutron diffraction. Density functional theory calculations have been employed to explore the bonding in the MnâHâSi unit in 1 and 2 and in the related system [CpâČMn(CO)2(η2-HSiCl3)] 3. These studies support the idea that the oxidative addition of a silane ligand to a transition metal center may be described as an asymmetric process in which the MnâH bond is formed at an early stage, while both the establishment of the MnâSi bond and also the activation of the η2-coordinated SiâH moiety are controlled by the extent of Mn â Ï*(XâSiâH) back-donation, which increases with increasing electron-withdrawing character of the X substituent trans to the metal-coordinated SiâH bond. This delocalized molecular orbital (MO) approach is complemented and supported by combined experimental and theoretical charge density studies: the source function S(r,Ω), which provides a measure of the relative importance of each atomâs contribution to the density at a specific reference point r, clearly shows that all three atoms of the Mn(η2-SiH) moiety contribute to a very similar extent to the density at the MnâSi bond critical point, in pleasing agreement with the MO model. Hence, we advance a consistent and unifying concept which accounts for the degree of SiâH activation in these silane Ï-bond complexes
Superconducting Nanocircuits for Topologically Protected Qubits
For successful realization of a quantum computer, its building blocks
(qubits) should be simultaneously scalable and sufficiently protected from
environmental noise. Recently, a novel approach to the protection of
superconducting qubits has been proposed. The idea is to prevent errors at the
"hardware" level, by building a fault-free (topologically protected) logical
qubit from "faulty" physical qubits with properly engineered interactions
between them. It has been predicted that the decoupling of a protected logical
qubit from local noises would grow exponentially with the number of physical
qubits. Here we report on the proof-of-concept experiments with a prototype
device which consists of twelve physical qubits made of nanoscale Josephson
junctions. We observed that due to properly tuned quantum fluctuations, this
qubit is protected against magnetic flux variations well beyond linear order,
in agreement with theoretical predictions. These results demonstrate the
feasibility of topologically protected superconducting qubits.Comment: 25 pages, 5 figure
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