145 research outputs found
Coexistence of ferro- and antiferromagnetic order in Mn-doped NiMnGa
Ni-Mn-Ga is interesting as a prototype of a magnetic shape-memory alloy
showing large magnetic field induced strains. We present here results for the
magnetic ordering of Mn-rich Ni-Mn-Ga alloys based on both experiments and
theory. Experimental trends for the composition dependence of the magnetization
are measured by a vibrating sample magnetometer (VSM) in magnetic fields of up
to several tesla and at low temperatures. The saturation magnetization has a
maximum near the stoichiometric composition and it decreases with increasing Mn
content. This unexpected behaviour is interpreted via first-principles
calculations within the density-functional theory. We show that extra Mn atoms
are antiferromagnetically aligned to the other moments, which explains the
dependence of the magnetization on composition. In addition, the effect of Mn
doping on the stabilization of the structural phases and on the magnetic
anisotropy energy is demonstrated.Comment: 4 pages, 3 figure
Infection control : point prevalence study versus incidence study in Polish long-term care facilities in 2009-2010 in the Małopolska Region
OBJECTIVE: The objective of this study was to evaluate the epidemiology of infection in Polish long-term care facilities (LTCFs) and to analyse the capabilities and legitimacy of implementing continuous targeted surveillance. METHODS: The study investigated the relationship between the presence of infection and health status, tested using a point prevalence study (PPS) and incidence study. A 1-day PPS was carried out in October 2009, with prospective continuous surveillance between December 2009 and November 2010. Infections were defined according to McGeer’s criteria. RESULTS: The surveillance encompassed 193 people. The prevalence was 14.0 % in residential homes (RHs) and 18.7 % in the nursing home (NH). Various types of infections (in the PPS) were observed significantly more frequently in patients with asthma, wounds, atherosclerosis of lower extremities, tracheotomy tubes and conditions in patients hospitalised in intensive care units (ICUs) up to 1 year before the PPS day. The incidence rate was 2.7/1,000 patient days (pds). CONCLUSIONS: The factors determined to be important for the risk of infection (in the continuous study) include the general status of patients, expressed using Barthel, abbreviated mental and Katz scales, as well as limited physical activity, stool incontinence and urinary catheterisation. In the PPS study, only a slight relationship was shown between the general status of residents and the risk of infection. None of the general status scales used clinically were shown to be helpful in estimating that risk, similarly to the five-point physical activity scale. Prospective continuous surveillance shows a possibility of limiting the range of infection control in the LTCFs within targeted surveillance in a population of patients that requires intensive nursing procedures. As a marker, one could point to the low score in the Barthel or Katz scales or low physical activity/bedridden persons
Study of the 3He-eta system in d-p collisions at COSY-11
We present preliminary results from dp --> 3He X (X=pi0,eta) measurements
near the eta production threshold. The data were taken during a slow ramping of
the COSY internal deuteron beam scattered on a proton target. The 3He ejectiles
were registered with the COSY-11 detection setup. The ongoing data analysis
should deliver high precision data for the dp --> 3He eta total and
differential cross sections for the excess energies in the range from threshold
up to 9 MeV. The preliminary excitation function for the reaction dp --> 3He
pi0 does not show any structure which could originate from the decay of 3He-eta
bound state. We present also a threshold excitation curve for the dp --> 3He X
channel. Contrary to corresponding results from SATURNE we see no cusp in the
vicinity of the eta threshold.Comment: 8 pages; 5 figures; Talk at Eta05 Workshop on Production and Decay of
eta and eta-prime Mesons, Cracow, Poland, 15-18 Sep 2005; Acta Phys. Slovaca,
in prin
Non-equilibrium emission of complex fragments from p+Au collisions at 2.5 GeV proton beam energy
Energy and angular dependence of double differential cross sections
d/ddE was measured for reactions induced by 2.5 GeV protons
on Au target with isotopic identification of light products (H, He, Li, Be, and
B) and with elemental identification of heavier intermediate mass fragments (C,
N, O, F, Ne, Na, Mg, and Al). It was found that two different reaction
mechanisms give comparable contributions to the cross sections. The
intranuclear cascade of nucleon-nucleon collisions followed by evaporation from
an equilibrated residuum describes low energy part of the energy distributions
whereas another reaction mechanism is responsible for high energy part of the
spectra of composite particles. Phenomenological model description of the
differential cross sections by isotropic emission from two moving sources led
to a very good description of all measured data. Values of the extracted
parameters of the emitting sources are compatible with the hypothesis claiming
that the high energy particles emerge from pre-equilibrium processes consisting
in a breakup of the target into three groups of nucleons; small, fast and hot
fireball of 8 nucleons, and two larger, excited prefragments, which
emits the light charged particles and intermediate mass fragments. The smaller
of them contains 20 nucleons and moves with velocity larger than the CM
velocity of the proton projectile and the target. The heavier prefragment
behaves similarly as the heavy residuum of the intranuclear cascade of
nucleon-nucleon collisions. %The mass and charge dependence of the total
production cross %sections was extracted from the above analysis for all
observed %reaction products. This dependence follows the power low behavior
%(A or Z)
Drift chamber with a c-shaped frame
We present the construction of a planar drift chamber with wires stretched
between two arms of a c-shaped aluminium frame. The special shape of the frame
allows to extendthe momentum acceptance of the COSY-11 detection system towards
lower momenta without suppressing the high momentum particles. The proposed
design allows for construction of tracking detectors covering small angles with
respect to the beam, which can be installed and removed without dismounting the
beam-pipe. For a three-dimensional track reconstruction a computer code was
developed using a simple algorithm of hit preselection.Comment: submitted to Nucl. Instr. & Meth
Modulated Martensite: Why it forms and why it deforms easily
Diffusionless phase transitions are at the core of the multifunctionality of
(magnetic) shape memory alloys, ferroelectrics and multiferroics. Giant strain
effects under external fields are obtained in low symmetric modulated
martensitic phases. We outline the origin of modulated phases, their connection
with tetragonal martensite and consequences for their functional properties by
analysing the martensitic microstructure of epitaxial Ni-Mn-Ga films from the
atomic to macroscale. Geometrical constraints at an austenite-martensite phase
boundary act down to the atomic scale. Hence a martensitic microstructure of
nanotwinned tetragonal martensite can form. Coarsening of twin variants can
reduce twin boundary energy, a process we could follow from the atomic to the
millimetre scale. Coarsening is a fractal process, proceeding in discrete steps
by doubling twin periodicity. The collective defect energy results in a
substantial hysteresis, which allows retaining modulated martensite as a
metastable phase at room temperature. In this metastable state elastic energy
is released by the formation of a 'twins within twins' microstructure which can
be observed from the nanometre to millimetre scale. This hierarchical twinning
results in mesoscopic twin boundaries which are diffuse, in contrast to the
common atomically sharp twin boundaries of tetragonal martensite. We suggest
that observed extraordinarily high mobility of such mesoscopic twin boundaries
originates from their diffuse nature which renders pinning by atomistic point
defects ineffective.Comment: 34 pages, 8 figure
Human intestinal tissue tropism of intimin epsilon O103 Escherichia coli
Human intestinal in vitro organ culture was used to assess the tissue tropism of human isolates of Escherichia coli O103:H2 and O103:H- that express intimin F. Both strains showed tropism for follicle associated epithelium and limited adhesion to other regions of the small and large intestine. This is similar to the tissue tropism shown by intimin gamma enterohaemorrhagic (EHEC) O157:H7, but distinct from that of intimin a enteropathogenic (EPEC) O127:H6. (C) 2002 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserve
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