12,086 research outputs found
Estimation of the gravitational wave polarizations from a non template search
Gravitational wave astronomy is just beginning, after the recent success of
the four direct detections of binary black hole (BBH) mergers, the first
observation from a binary neutron star inspiral and with the expectation of
many more events to come. Given the possibility to detect waves from not
perfectly modeled astrophysical processes, it is fundamental to be ready to
calculate the polarization waveforms in the case of searches using non-template
algorithms. In such case, the waveform polarizations are the only quantities
that contain direct information about the generating process. We present the
performance of a new valuable tool to estimate the inverse solution of
gravitational wave transient signals, starting from the analysis of the signal
properties of a non-template algorithm that is open to a wider class of
gravitational signals not covered by template algorithms. We highlight the
contributions to the wave polarization associated with the detector response,
the sky localization and the polarization angle of the source. In this paper we
present the performances of such method and its implications by using two main
classes of transient signals, resembling the limiting case for most simple and
complicated morphologies. Performances are encouraging, for the tested
waveforms: the correlation between the original and the reconstructed waveforms
spans from better than 80% for simple morphologies to better than 50% for
complicated ones. For a not-template search this results can be considered
satisfactory to reconstruct the astrophysical progenitor
Reversible and irreversible dynamics of a qubit interacting with a small environment
We analyze the dynamics of a system qubit interacting by means a sequence of
pairwise collisions with an environment consisting of just two qubits. We show
that the density operator of the qubits approaches a common time averaged
equilibrium state, characterized by large fluctuations, only for a random
sequence of collisions. For a regular sequence of collisions the qubitstates of
the system and of the reservoir undergo instantaneous periodic oscillations and
do not relax to a common state. Furthermore we show that pure bipartite
entanglement is developed only when at least two qubits are initially in the
same purestate while otherwise also genuine multipartite entanglement builds
up.Comment: 5 pages, 4 figure
Impact of noise on a dynamical system: prediction and uncertainties from a swarm-optimized neural network
In this study, an artificial neural network (ANN) based on particle swarm
optimization (PSO) was developed for the time series prediction. The hybrid
ANN+PSO algorithm was applied on Mackey--Glass chaotic time series in the
short-term . The performance prediction was evaluated and compared with
another studies available in the literature. Also, we presented properties of
the dynamical system via the study of chaotic behaviour obtained from the
predicted time series. Next, the hybrid ANN+PSO algorithm was complemented with
a Gaussian stochastic procedure (called {\it stochastic} hybrid ANN+PSO) in
order to obtain a new estimator of the predictions, which also allowed us to
compute uncertainties of predictions for noisy Mackey--Glass chaotic time
series. Thus, we studied the impact of noise for several cases with a white
noise level () from 0.01 to 0.1.Comment: 11 pages, 8 figure
Renin-angiotensin-aldosterone system (RAAS) and its pharmacologic modulation
O sistema-renina-angiotensina-aldosterona (SRAA) é um sistema neuroendócrino complexo
responsável pela modulação do equilÃbrio hidroelectrolÃtico e regulação da pressão
arterial. Através das suas múltiplas interacções contribui para a protecção do tecido
endotelial, cardÃaco, cerebral e renal. Adicionalmente, regula ainda a resposta do endotélio
à inflamação e lesão. A sua activação crónica/desregulação induz hipertensão e perpetuação
de uma cascata pró-inflamatória, pró-trombótica e aterogénica, que está na base da
lesão de vários órgãos-alvo (coração, cérebro, rim, endotélio). Consequentemente, o SRAA
constitui um alvo terapêutico importante nestas situações. O artigo aborda a fisiologia,
patofisiologia e mecanismos de modulação farmacológica do SRAA. The renin-angiotensin-aldosterone system (RAAS) is a neuroendocrine complex system
that regulates the modulation of salt and water homeostasis, and regulation of blood
pressure. Through its multiple interactions it protects the endothelium, heart, brain and
kidney. In addition, the RAAS regulates the vascular response to injury and inflammation.
Chronic activation/dysregulation of the RAAS leads to hypertension and perpetuates a
cascade of proinflammatory, prothrombotic and atherogenic effects associated with endorgan
damage (heart, brain, kidney, endothelium). Consequently, the RAAS is an important
therapeutic target in these situations. This article presents an overview of physiology,
pathophysiology and pharmacologic modulation of the RAAS
Inflorescence initiation in grapes - response to plant growth regulators
Young pot-grown vines of Riesling grapes (Vitis vinifera L.) were treated, via roots, with gibberellin A3 (GA3), indole acetic acid (IAA), 6-benzyl-amino purine (BAP) and abscisic acid (ABA) in a factorial experiment. Seven 100 ml applications at 50 μM were applied at regular intervals. In a second experiment GA3, IAA, indole butyric acid (IBA), naphthalene acetic acid (NAA), and 2,4-dichlorophenoxy acetic acid (2,4 - D) were injected into the trunks of field-grown Riesling vines 3 weeks after bud burst. Auxins induced more leaf primordia, tendrils and inflorescences and reduced internode length in the buds of treated vines examined the following winter. The rate of formation (plastochrone) was also increased. Flowers appearing on shoots the following spring were more numerous on treated vines. GA3 had opposite effects to auxins on all the above. ABA and BAP reduced the production of tendrils, inflorescences and leaf primordia in the bud - although much less than GA3 - however, when applied with GA3, they reduced its deleterious effects on these organs. Examination of buds revealed a variety of bud forms. Buds which had more inflorescences and primordial leaves were from mature vines, especially if treated with auxin-like compounds. Young vines had fewer leaf primordia and fewer inflorescences, a situation also found in GA3 - treated older plants. Treatments or conditions which favoured more fruitful buds also tended to reduce the plastochrone and it is suggested that the two phenomena are causally related.
Limitation of entanglement due to spatial qubit separation
We consider spatially separated qubits coupled to a thermal bosonic field
that causes pure dephasing. Our focus is on the entanglement of two Bell states
which for vanishing separation are known as robust and fragile entangled
states. The reduced two-qubit dynamics is solved exactly and explicitly. Our
results allow us to gain information about the robustness of two-qubit
decoherence-free subspaces with respect to physical parameters such as
temperature, qubit-bath coupling strength and spatial separation of the qubits.
Moreover, we clarify the relation between single-qubit coherence and two-qubit
entanglement and identify parameter regimes in which the terms robust and
fragile are no longer appropriate.Comment: 7 pages, 3 figures; revised version, accepted for publication in
Europhys. Let
Revised Predictions of Neutrino Fluxes from Pulsar Wind Nebulae
Several pulsar wind nebulae (PWN) have been detected in the TeV band in the last decade. TeV emission is typically interpreted in a purely leptonic scenario, but this often requires that the magnetic field in the nebula be much lower than the equipartition value, as well as the assumption of an enhanced density of target radiation at IR frequencies. In this work, we consider the possibility that, in addition to the relativistic electrons and positrons, relativistic hadrons are also present in these nebulae. Assuming that some of the emitted TeV photons are of hadronic origin, we compute the associated flux of ∼1-100 TeV neutrinos. We use IceCube non-detection to put constraints on the fraction of TeV photons that might be contributed by hadrons and estimate the number of neutrino events that can be expected from these sources in ANTARES and KM3Net
Metastatic tumors to the stomach: clinical and endoscopic features.
AIM: To evaluate the clinical and endoscopic patterns in a large series of patients with metastatic tumors in the stomach. METHODS: A total of 64 patients with gastric metastases from solid malignant tumors were retrospectively examined between 1990 and 2005. The clinicopathological findings were reviewed along with tumor characteristics such as endoscopic pattern, location, size and origin of the primary sites. RESULTS: Common indications for endoscopy were anemia, bleeding and epigastric pain. Metastases presented as solitary (62.5%) or multiple (37.5%) tumors were mainly located in the middle or upper third of stomach. The main primary metastatic tumors were from breast and lung cancer and malignant melanoma. CONCLUSION: As the prognosis of cancer patients has been improving gradually, gastrointestinal (GI) metastases will be encountered more often. Endoscopic examinations should be conducted carefully in patients with malignancies, and endoscopic biopsies and information on the patient's clinical history are useful for correct diagnosis of gastric metastases
Implant Site Nexplanon Reaction?
Nexplanon (Schering-Plough Limited/Merck Sharp & Dohme Limited (MSD)) is a long active reversible contraceptive method that provides effective contraception for 3 years. It consists of a single, flexible, rod-shaped implant, containing 68 mg etonogestrel. It is 4 cm long, consists of an ethylene vinyl acetate copolymer, a non-absorbable material, and also contains 15 mg of barium sulfate, which makes it visible by X-ray. We describe a case of a 39-year-old woman who experienced a local reaction to the barium sulfate in Nexplanon. She was given medical treatment, but only the removal of the implant resolved the symptoms. After removal there was gradual improvement and 72 h later the patient was asymptomatic. Allergic reaction to barium sulfate is extremely rare: until now, there have only been two cases associated with Nexplanon described in the literature
- …