641 research outputs found

    Estimation of production trend of the depik, Rasbora tawarensis (Teleostei, Cyprinidae), in Lake Laut Tawar, Indonesia

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    The objective of the present study was to evaluate the production trend of the depik (Rasbora tawarensis) during the last two decades in Lake Laut Tawar. The production trend was examined based on the catch per unit efforts. The direct sampling, fishermen catches collection and fishermen interview were conducted to collect actual fish catches. The results showed that the depik, R. tawarensis production (indicated by the catch-per-unit effort (CPUE)) was seasonally dependent where the CPUE was higher in the rainy season compared to dry season. In addition, the CPUE was higher in the new moon according to lunar cycle. The production of depik in particular and fishes of Lake Laut Tawar in general are declining dramatically during the last two decades. The decrease in the water levels, destructive fishing gears, the presence of introduced species and pollution are the main reasons suggested for this phenomenon.</p

    A hop-count based positioning algorithm for wireless ad-hoc networks

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    We propose a range-free localization algorithm for a wireless ad-hoc network utilizing the hop-count metric’s ability to indicate proximity to anchors (i.e., nodes with known positions). In traditional sense, hop-count generally means the number of intermediate routers a datagram has to go through between its source and the destination node. We analytically show that hop-count could be used to indicate proximity relative to an anchor node. Our proposed algorithm is computationally feasible for resource constrained wireless ad-hoc nodes, and gives reasonable accuracy. We perform both real experiments and simulations to evaluate the algorithm’s performance. Experimental results show that our algorithm outperforms similar proximity based algorithms utilizing received signal strength and expected transmission count. We also analyze the impact of various parameters like the number of anchor nodes, placements of anchor nodes and varying transmission powers of the nodes on the hop-count based localization algorithm’s performance through simulation

    Thin-Film Metamaterials called Sculptured Thin Films

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    Morphology and performance are conjointed attributes of metamaterials, of which sculptured thin films (STFs) are examples. STFs are assemblies of nanowires that can be fabricated from many different materials, typically via physical vapor deposition onto rotating substrates. The curvilinear--nanowire morphology of STFs is determined by the substrate motions during fabrication. The optical properties, especially, can be tailored by varying the morphology of STFs. In many cases prototype devices have been fabricated for various optical, thermal, chemical, and biological applications.Comment: to be published in Proc. ICTP School on Metamaterials (Augsut 2009, Sibiu, Romania

    Data sharing in DHT based P2P systems

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    International audienceThe evolution of peer-to-peer (P2P) systems triggered the building of large scale distributed applications. The main application domain is data sharing across a very large number of highly autonomous participants. Building such data sharing systems is particularly challenging because of the "extreme" characteristics of P2P infrastructures: massive distribution, high churn rate, no global control, potentially untrusted participants... This article focuses on declarative querying support, query optimization and data privacy on a major class of P2P systems, that based on Distributed Hash Table (P2P DHT). The usual approaches and the algorithms used by classic distributed systems and databases forproviding data privacy and querying services are not well suited to P2P DHT systems. A considerable amount of work was required to adapt them for the new challenges such systems present. This paper describes the most important solutions found. It also identies important future research trends in data management in P2P DHT systems

    Mice with reduced DAT levels recreate seasonal-induced switching between states in bipolar disorder.

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    Developing novel therapeutics for bipolar disorder (BD) has been hampered by limited mechanistic knowledge how sufferers switch between mania and depression-how the same brain can switch between extreme states-described as the "holy grail" of BD research. Strong evidence implicates seasonally-induced switching between states, with mania associated with summer-onset, depression with winter-onset. Determining mechanisms of and sensitivity to such switching is required. C57BL/6J and dopamine transporter hypomorphic (DAT-HY 50% expression) mice performed a battery of psychiatry-relevant behavioral tasks following 2-week housing in chambers under seasonally relevant photoperiod extremes. Summer-like and winter-like photoperiod exposure induced mania-relevant and depression-relevant behaviors respectively in mice. This behavioral switch paralleled neurotransmitter switching from dopamine to somatostatin in hypothalamic neurons (receiving direct input from the photoperiod-processing center, the suprachiasmatic nucleus). Mice with reduced DAT expression exhibited hypersensitivity to these summer-like and winter-like photoperiods, including more extreme mania-relevant (including reward sensitivity during reinforcement learning), and depression-relevant (including punishment-sensitivity and loss-sensitivity during reinforcement learning) behaviors. DAT mRNA levels switched in wildtype littermate mice across photoperiods, an effect not replicated in DAT hypomorphic mice. This inability to adjust DAT levels to match photoperiod-induced neurotransmitter switching as a homeostatic control likely contributes to the susceptibility of DAT hypormophic mice to these switching photoperiods. These data reveal the potential contribution of photoperiod-induced neuroplasticity within an identified circuit of the hypothalamus, linked with reduced DAT function, underlying switching between states in BD. Further investigations of the circuit will likely identify novel therapeutic targets to block switching between states

    Clinical implications of lowering episcleral venous pressure in the management of glaucoma and the use of Rho kinase inhibitors

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    There has been limited success in both measuring and modifying episcleral venous pressure (EVP) in clinical practice. Understanding the potential role of EVP in the management of glaucoma for different patients may allow for more individualized treatment approaches. To explore the clinical implications of lowering EVP, an international group of 9 glaucoma experts (the ENGAGE Global Expert Working Group) convened to bridge the gap between the current literature and evidence with clinical opinion and best practices. This review summarizes insights from the group on the effect of current medical therapies on EVP and its potential impact. It also discusses unmet investigational needs to enhance the understanding of EVP, as well as the challenges associated with the measurement and treatment of EVP. Regardless of the relatively modest EVP reductions achieved with current treatments, EVP lowering may have clinical significance in patients with glaucoma, particularly those with low intraocular pressure (IOP). Those who might benefit include patients with elevated EVP; normal-tension glaucoma; undergoing trabecular meshwork bypass surgery, goniotomy, or selective laser trabeculoplasty; or requiring additional IOP lowering to the low teens or with a lower-than-usual target IOP

    2017 HRS/EHRA/ECAS/APHRS/SOLAECE expert consensus statement on catheter and surgical ablation of atrial fibrillation: executive summary.

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    Systems genetics identifies a role for Cacna2d1 regulation in elevated intraocular pressure and glaucoma susceptibility

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    Glaucoma is a multi-factorial blinding disease in which genetic factors play an important role. Elevated intraocular pressure is a highly heritable risk factor for primary open angle glaucoma and currently the only target for glaucoma therapy. Our study helps to better understand underlying genetic and molecular mechanisms that regulate intraocular pressure, and identifies a new candidate gene, Cacna2d1, that modulates intraocular pressure and a promising therapeutic, pregabalin, which binds to CACNA2D1 protein and lowers intraocular pressure significantly. Because our study utilizes a genetically diverse population of mice with kno

    How to diagnose the cause of sudden cardiac arrest

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    Sudden cardiac death or sudden cardiac arrest (SCA) is defined as natural death that occurs within an hour of the onset of acute symptoms or during sleep due to a primary cardiac cause. Most cases of SCA are attributable to coronary artery disease, with occult cardiomyopathy or inheritable arrhythmic syndromes accounting for a minority of SCA. Diagnosing the cause of SCA has potential implications for the patient and the family, and demands a comprehensive approach. This review summarizes the potential causes of SCA and outlines a systematic diagnostic approach to the SCA survivor. (Cardiol J 2011; 18, 2: 210-216
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