4,459 research outputs found
General no-go condition for stochastic pumping
The control of chemical dynamics requires understanding the effect of
time-dependent transition rates between states of chemo-mechanical molecular
configurations. Pumping refers to generating a net current, e.g. per period in
the time-dependence, through a cycle of consecutive states. The working of
artificial machines or synthesized molecular motors depends on it. In this
paper we give short and simple proofs of no-go theorems, some of which appeared
before but here with essential extensions to non-Markovian dynamics, including
the study of the diffusion limit. It allows to exclude certain protocols in the
working of chemical motors where only the depth of the energy well is changed
in time and not the barrier height between pairs of states. We also show how
pre-existing steady state currents are in general modified with a
multiplicative factor when this time-dependence is turned on.Comment: 8 pages; v2: minor changes, 1 reference adde
Review of emergency obstetric hysterectomies at a tertiary care hospital
Background: Emergency obstetric hysterectomy refers to surgical removal of pregnant or recently pregnant uterus with the pregnancy in utero or due to complications of delivery. This surgery is usually done as a last resort in life threatening obstetric hemorrhage. Objective of present study was to determine the incidence, sociodemographic and obstetric factors and indications associated with emergency obstetric hysterectomies.
Methods: A retrospective, analytical study was conducted over a period of five years in the department of obstetrics and Gynecology of Government Medical college Thiruvananthapuram. Kerala. All cases of obstetric hysterectomy done during the study period in this hospital were analysed after getting approval from the institutional ethical committee.
Results: During the study period there were total number of 78613 deliveries in SATH. Emergency obstetric hysterectomy was done for 86 cases. Obstetric hysterectomy rate in SATH during the study period was 0.109% or 1.09/1000 deliveries. Atonic postpartum hemorrhage (55%) was the most common indication followed by placenta praevia (27%). Majority were referred cases.
Conclusions: Emergency obstetric hysterectomy can be a lifesaving procedure when other medical and surgical methods fail to control obstetric hemorrhage. This study highlights the unpredictable need of this procedure, need for identifying the at-risk cases and early referral to higher center
How accurate are satellite estimates of precipitation over the north Indian Ocean?
Following the launch of the Global Precipitation Measurement (GPM) Core Observatory in early 2014, motivated from the successful Tropical Rainfall Measurement Mission (TRMM) satellite, an advanced and sophisticated global multi-satellite precipitation product – Integrated Multi- satellitE Retrievals for GPM (IMERG) was released at finer spatio-temporal scales. This precipitation product has been upgraded recently after several refinements and supposed to be superior to other existing global or quasi-global multi-satellite precipitation estimates. In the present study, IMERG precipitation is comprehensively evaluated for the first time against moored buoy observations over the north Indian Ocean at hourly scale for the study period of March 2014 to December 2015. IMERG precipitation performs considerably better over the Bay of Bengal than the Arabian Sea in both detection and estimation. The systematic error in IMERG is appreciably lower by about 14%, however, it generally overestimates in-situ precipitation and also exhibits noticeable false alarms. Furthermore, IMERG essentially shows an improvement over the TRMM Multi-satellite Precipitation Analysis (TMPA) at a daily scale over the north Indian Ocean. IMERG precipitation estimates show overall promising error characteristics, but there is still a need of substantial efforts for improvement in the satellite-based precipitation estimation algorithms especially over data sparse regions such as north Indian Ocean
Archimedes' law and its corrections for an active particle in a granular sea
We study the origin of buoyancy forces acting on a larger particle moving in
a granular medium subject to horizontal shaking and its corrections before
fluidization. In the fluid limit Archimedes' law is verified; before the limit
memory effects counteract buoyancy, as also found experimentally. The origin of
the friction is an excluded volume effect between active particles, which we
study more exactly for a random walker in a random environment. The same
excluded volume effect is also responsible for the mutual attraction between
bodies moving in the granular medium. Our theoretical modeling proceeds via an
asymmetric exclusion process, i.e., via a dissipative lattice gas dynamics
simulating the position degrees of freedom of a low density granular sea.Comment: 22 pages,5 figure
Double Carbon−Hydrogen Activation of 2-Vinylpyridine: Synthesis of Tri- and Pentanuclear Clusters Containing the μ-NC\u3csub\u3e5\u3c/sub\u3eH\u3csub\u3e4\u3c/sub\u3eCH═C Ligand
Reactions of 2-vinylpyridine with the triruthenium complexes [Ru3(CO)12] and [Ru3(CO)10(μ-dppm)] leads to a previously unknown double carbon−hydrogen bond activation of the β-carbon of the vinyl group to afford the pentaruthenium and triruthenium complexes [Ru5(CO)14(μ4-C5H4CH═C)(μ-H)2] (1) and [Ru3Cl(CO)5(μ-CO)(μ-dppm)(μ3-NC5H4CH═C)(μ-H)] (2), respectively. Crystal structures reveal two different forms of bridging of the dimetalated 2-vinylpyridyl ligand, capping a square face in 1 and a triangular face in 2
BMI from nutritional surveillance of 8-9 years old children in Tuscany (Italy)
Introduction. The latest increase in childhood obesity focused attention on the important consequences that this phenomenon may have on public health in relationship to the increasing risk that an obese child may become an obese adult. To deal with this problem, there is necessary to assess systematically the distribution of childhood nutritional status at different levels: international, regional and local. In this paper are presented data on underweight, overweight and obesity prevalence in third grade primary school children, aged 8/9 years in Tuscany (2008) and its distribution in relationship to the demographic breadth of their place of residence.
Methods. Data from statistic sample of 2109 (1.091 males, 1.018 females), 8/9 years school-children were collected; weight and height were measured using standardised personnel and instruments. Exact month age was calculated between the data of measurement and that of birth. Body Mass Index (BMI) classes were calculated using Cole et al.?s epidemiologic cut-off for children and adolescents. Residence areas were divided into four classes based on the number of inhabitants ( inf. 10.000; 10.000-50.000; > 50.000; > 50.000 metropolitan).
Results. The prevalence of underweight was 0.88% (0.76% in males and 1.01% in females), the prevalence of overweight was 23.43% (22.33% in males and 24.65% in females), the prevalence
of obese was 7.95% (9.08% in males, 6.70% in females). The lowest prevalence of obese (6.46%) was found in towns with over 50.000 residents (metropolitan).
Conclusion. The obesity prevalence in Tuscany children is still lower than that of the Italian National Survey, while the overweight prevalence it?s the same. Obesity prevalence (10.71%) is higher in municipalities with low residents number ( inf. 10.000)
Monitoramento da extração de areia nos municípios não pertencentes ao Zoneamento Ambiental Minerário do trecho paulista da várzea do rio Paraíba do Sul.
Remote sensing techniques can significantly contribute to environmental monitoring of the low cost mineral extraction of sand pits. This study aims to evaluate the increase of sand pits mining activity between the period of 2004 to 2009, in municipalities of the Paraiba do Sul basin of São Paulo State, Brazil, that are not included in the mineral zoning of this basin. Visual interpretation of Landsat-5 (Thematic Mapper ? TM sensor) images indicated areas of sand extraction for the municipalities of Aparecida, Cachoeira Paulista and Roseira with an annual average increase of 10.1 ha, 20.5 ha and 33.5 ha, respectively. The municipality with the highest percentage of sand mining area increase was Lorena (233%). Results presented in this study can be used to justify the mineral zoning expansion to these municipalities
Aqua{6,6′-dimethoxy-2,2′-[ethane-1,2-diylbis(nitrilomethylidyne)]diphenolato}(4-hydroxybenzoato)manganese(III)
The title compound, [Mn(C18H18N2O4)(C7H5O3)(H2O)], was synthesized by a template reaction of ethane-1,2-diamine and 3-methoxysalicylaldehyde in presence of manganese(II) 4-hydroxybenzoate. The Jahn–Teller-distorted manganese(III) centre has an octahedral geometry. Extensive O—H⋯O hydrogen-bonding interactions generate a two-dimensional sheet structure parallel to (103)
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