564 research outputs found

    Force Distributions in Frictional Granular Media

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    We report a joint experimental and theoretical investigation of the probability distribution functions (pdf's) of the normal and tangential (frictional) forces in amorphous frictional media. We consider both the joint pdf of normal and tangential forces together, and the marginal pdf's of normal forces separately and tangential forces separately. A maximum entropy formalism is utilized for all these cases after identifying the appropriate constraints. Excellent agreements with both experimental and simulational data are reported. The proposed joint pdf (which appears new to the literature) predicts giant slip events at low pressures, again in agreement with observations.Comment: 13 pages, 15 figure

    Hydrodynamic signatures of stationary Marangoni-driven surfactant transport

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    We experimentally study steady Marangoni-driven surfactant transport on the interface of a deep water layer. Using hydrodynamic measurements, and without using any knowledge of the surfactant physico-chemical properties, we show that sodium dodecyl sulphate and Tergitol 15-S-9 introduced in low concentrations result in a flow driven by adsorbed surfactant. At higher surfactant concentration, the flow is dominated by the dissolved surfactant. Using Camphoric acid, whose properties are {\it a priori} unknown, we demonstrate this method's efficacy by showing its spreading is adsorption dominated

    Method for Cooling Nanostructures to Microkelvin Temperatures

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    We propose a new scheme aimed at cooling nanostructures to microkelvin temperatures, based on the well established technique of adiabatic nuclear demagnetization: we attach each device measurement lead to an individual nuclear refrigerator, allowing efficient thermal contact to a microkelvin bath. On a prototype consisting of a parallel network of nuclear refrigerators, temperatures of 1\sim 1\,mK simultaneously on ten measurement leads have been reached upon demagnetization, thus completing the first steps toward ultracold nanostructures.Comment: 4 pages, 3 (color) figure

    An Algorithm on Generalized Un Sharp Masking for Sharpness and Contrast of an Exploratory Data Model

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    In the applications like medical radiography enhancing movie features and observing the planets it is necessary to enhance the contrast and sharpness of an image. The model proposes a generalized unsharp masking algorithm using the exploratory data model as a unified framework. The proposed algorithm is designed as to solve simultaneously enhancing contrast and sharpness by means of individual treatment of the model component and the residual, reducing the halo effect by means of an edge-preserving filter, solving the out of range problem by means of log ratio and tangent operations. Here is a new system called the tangent system which is based upon a specific bargeman divergence. Experimental results show that the proposed algorithm is able to significantly improve the contrast and sharpness of an image. Using this algorithm user can adjust the two parameters the contrast and sharpness to have desired output

    Pembuatan Program Ekstraksi Dan Penentuan Posisi Satelit Dari File Navigation Rinex Versi 2.10

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    In positioning using the GPS the first step that we must do is calculating the satellite position during the observation. The precision of a point in a GPS survey is affected by the precision of the satellite position that recorded in the observation, the higher number of the satellite that is being recorded the more precise of the position can be. In surveying using GPS, GPS receiver will receive informations related to the satellite that is being observed. These information is given in navigation message, and the content of the message usually related to the satellite orbit's component (Kepler's element) and time correction satellite's component. To obtain the navigation message data in a standard format we can convert the measuring result of the GPS to the RINEX ver. 2.10 format. From the format we can get time reference data when epoch (Epoch, a0, a1, a2, and Toe), pertubation parameters satellite (Idot, Delta_N (∆n), Ωdot (Ω), CRS, CRC, CUS, CUC, CIC, and CIS), and keplerian parameters (Eccentricity (e), i0, Ω0, M0, ω, Sqrt_a (√a)), then from the data we made it into GPS satellite positioning program using visual basic language. The result is an extraction program and satellite position's calculation, then the calculation's result of satellite position using FMP 1.0 is being compared with the precise ephemerides provided by IGS, the result of the comparison shows that this program is effective to be used in observation with interval of 4 hours to to

    Pitting corrosion studies on Ti6Al4V alloy weldments in marine environment

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    1179-1182Titanium and its alloys are widely used owing to their high strength-to-weight ratio, good tensile strength, and resistance to corrosion. The Ti6Al4V alloy is called the workhorse among the titanium alloys owing to its wide application. Even though the Ti6Al4V alloy is immune to corrosion, improper welding conditions lead to contamination, making the weldments prone to stress corrosion cracking (SCC). These weldments are susceptible to SCC if they show sensitivity to pitting. This study examines the effect of welding conditions on the pitting corrosion behavior of 3 mm thick plates of Ti6Al4V alloy. The Ti6Al4V weldments were fabricated using fusion welding methods, namely, the gas tungsten arc welding (GTAW) and laser beam welding (LBW) techniques. The pitting corrosion studies were carried out by a potentiodynamic polarization technique, using non-deaerated 3.5% NaCl solution of pH 7, to create a marine corrosion environment. The pitting corrosion studies yielded good results as there was corrosion resistance in weldments fabricated under controlled conditions

    In vivo acquisition and risk of inter-species spread of blaKPC-3-plasmid from Klebsiella pneumoniae to Serratia marcescens in the lower respiratory tract

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    In recent years, Serratia marcescens has emerged as an important agent of hospital-acquired infections, such as pneumonia, urinary tract infection, septicaemia and meningitis, particularly in vulnerable patients. Compared to Klebsiella pneumoniae and Escherichia coli, S. marcescens is less commonly associated with blaKPC genes, yet few cases of plasmid transmission at the gastrointestinal level from K. pneumoniae carbapenemase (KPC)-producing Enterobacterales to S. marcescens have been described. Here we report a case of in vivo acquisition, during a 3-month period of hospitalization in the intensive care unit, of a blaKPC-3 gene carried by a pKpQIL-IT plasmid, and its probable transmission at the bronchial level among different species of Enterobacterales, including K. pneumoniae and S. marcescens. By using whole genome sequence analyses we were able provide insight into the dynamics of carbapenem-resistance determinants acquisition in the lower respiratory tract, a novel anatomical region for such plasmid transmission events, that usually involve the gastrointestinal tract. The co-presence at the same time of both wild-type and resistant Enterobacterales could have been the critical factor leading to the spread of plasmids harbouring carbapenem-resistance genes, of particular importance during surveillance screenings. The possibility of such an event may have significant consequences in terms of antimicrobial treatment, with a potential limitation of therapeutic options, thereby further complicating the clinical management of high-risk critically ill patients

    Intra-instar larval cannibalism in Anopheles gambiae (s.s.) and Anopheles stephensi (Diptera: Culicidae)

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    BACKGROUND: Cannibalism has been observed in a wide range of animal taxa and its importance in persistence and stability of populations has been documented. In anopheline malaria vectors the inter-instar cannibalism between fourth- and first-instar larvae (L4-L1) has been shown in several species, while intra-instar cannibalism remains poorly investigated. In this study we tested the occurrence of intra-instar cannibalism within larvae of second-, third- and fourth-instar (L2, L3 and L4) of Anopheles gambiae (s.s.) and An. stephensi. Experiments were set up under laboratory conditions and the effects of larval density, duration of the contact period among larvae and the presence of an older larva (i.e. a potential cannibal of bigger size) on cannibalism rate were analysed. Cannibalism was assessed by computing the number of missing larvae after 24 and 48 h from the beginning of the experiments and further documented by records with a GoPro videocamera. RESULTS: Intra-instar cannibalism was observed in all larval instars of both species with higher frequency in An. gambiae (s.s.) than in An. stephensi. In both species the total number of cannibalistic events increased from 0-24 to 0-48 h. The density affected the cannibalism rate, but its effect was related to the larval instar and to the presence of older larvae. Interestingly, the lower cannibalism rate between L4 larvae was observed at the highest density and the cannibalism rate between L3 larvae decreased when one L4 was added. CONCLUSIONS: The present study provides experimental evidence of intra-instar cannibalism in the malaria vectors An. gambiae (s.s.) and An. stephensi and highlights the possible occurrence of complex interactions between all larval instars potentially present in the breeding sites. We hypothesize that the high density and the presence of a potential cannibal of bigger size could affect the readiness to attack conspecifics, resulting into low risk larval behavior and lower cannibalism rate. The understanding of cannibalistic behavior and the factors affecting it is of utmost importance for malaria vectors, as nutrition during larval development can strongly affect the fitness of adult female mosquitoes and ultimately their vector ability

    OPTIMIZATION AND MODELLING OF EN8 STEEL SURFACE ADAPTATION USING TAGUCHI TECHNIQUE

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    The assignment of latest machining industries is decreased lead time and increase manufacturing fee an excellent manner to hold their competitiveness. The mechanical production industries are often challenged for reaching better productiveness and awesome products in an effort to stay competitive. Turning way, a machining method utilized in a manufacturing business enterprise. The way of turning is encouraged via identified factors collectively with lowering pace, the intensity of decreasing, feed charge, the geometry of reducing tool, & reducing situations and plenty of others. In the machining operations, attaining the popular surface tremendous of a machined product is a clearly tough task. This is because of the reality that remarkable is quite recommended through approach parameters right now or not directly. However, the quantity of a tremendous have an impact on of method parameters those are precise for one of kind responses. In this thesis, the effect of insert nose radius and the machining parameters which together with the slicing velocity, feed price, and lowering fluids on ground roughness in a turning operation are investigated by manner of the usage of the Taguchi optimization technique. Three-d modelling has become completed through PRO ENGINEER parametric software. The assessment is performed with the aid of ANSYS

    Description of klebsiella spallanzanii sp. Nov. and of klebsiella pasteurii sp. nov

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    Klebsiella oxytoca causes opportunistic human infections and post-antibiotic haemorrhagic diarrhoea. This Enterobacteriaceae species is genetically heterogeneous and is currently subdivided into seven phylogroups (Ko1 to Ko4, Ko6 to Ko8). Here we investigated the taxonomic status of phylogroups Ko3 and Ko4. Genomic sequence-based phylogenetic analyses demonstrate that Ko3 and Ko4 formed well-defined sequence clusters related to, but distinct from, Klebsiella michiganensis (Ko1), Klebsiella oxytoca (Ko2), K. huaxiensis (Ko8) and K. grimontii (Ko6). The average nucleotide identity of Ko3 and Ko4 were 90.7% with K. huaxiensis and 95.5% with K. grimontii, respectively. In addition, three strains of K. huaxiensis, a species so far described based on a single strain from a urinary tract infection patient in China, were isolated from cattle and human faeces. Biochemical and MALDI-ToF mass spectrometry analysis allowed differentiating Ko3, Ko4 and Ko8 from the other K. oxytoca species. Based on these results, we propose the names Klebsiella spallanzanii for the Ko3 phylogroup, with SPARK_775_C1T (CIP 111695T, DSM 109531T) as type strain, and Klebsiella pasteurii for Ko4, with SPARK_836_C1T (CIP 111696T, DSM 109530T) as type strain. Strains of K. spallanzanii were isolated from human urine, cow faeces and farm surfaces, while strains of K. pasteurii were found in faecal carriage from humans, cows and turtles
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