1,370 research outputs found
Self-reported illness among Boston-area international travelers: A prospective study
This is the Accepted Manuscript version and was published in final edited form as: Travel Med Infect Dis. 2016 ; 14(6): 604–613. doi:10.1016/j.tmaid.2016.09.009.BACKGROUND: The Boston Area Travel Medicine Network surveyed travelers on travel-related health problems.
METHODS: Travelers were recruited 2009-2011 during pre-travel consultation at three clinics. The investigation included pre-travel data, weekly during-travel diaries, and a post-travel questionnaire. We analyzed demographics, trip characteristics, health problems experienced, and assessed the relationship between influenza vaccination, influenza prevention advice, and respiratory symptoms.
RESULTS:Of 987 enrolled travelers, 628 (64%) completed all surveys, of which 400 (64%) reported health problems during and/or after travel; median trip duration was 12 days. Diarrhea affected the most people during travel (172) while runny/stuffy nose affected the most people after travel (95). Of those with health problems during travel, 25% stopped or altered plans; 1% were hospitalized. After travel, 21% stopped planned activities, 23% sought physician or other health advice; one traveler was hospitalized. Travelers who received influenza vaccination and influenza prevention advice had lower rates of respiratory symptoms than those that received influenza prevention advice alone (18% vs 28%, P = 0.03).
CONCLUSIONS:A large proportion of Boston-area travelers reported health problems despite pre-travel consultation, resulting in inconveniences. The combination of influenza prevention advice and influenza immunization was associated with fewer respiratory symptoms than those who received influenza prevention advice alone
Vortex Matter Transition in BiSrCaCuO under Tilted Fields
Vortex phase diagram under tilted fields from the axis in
BiSrCaCuO is studied by local magnetization
hysteresis measurements using Hall probes. When the field is applied at large
angles from the axis, an anomaly () other than the well-known
peak effect () are found at fields below . The angular dependence of
the field is nonmonotonic and clearly different from that of
and depends on the oxygen content of the crystal. The results suggest existence
of a vortex matter transition under tilted fields. Possible mechanisms of the
transition are discussed.Comment: Revtex, 4 pages, some corrections are adde
Investigating The Vortex Melting Phenomenon In BSCCO Crystals Using Magneto-Optical Imaging Technique
Using a novel differential magneto-optical imaging technique we investigate
the phenomenon of vortex lattice melting in crystals of Bi_2Sr_2CaCu_2O_8
(BSCCO). The images of melting reveal complex patterns in the formation and
evolution of the vortex solid-liquid interface with varying field (H) or
temperature (T). We believe that the complex melting patterns are due to a
random distribution of material disorder or inhomogeneities across the sample,
which create fluctuations in the local melting temperature or field value. To
study the fluctuations in the local melting temperature / field, we have
constructed maps of the melting landscape T_m(H,r), viz., the melting
temperature (T_m) at a given location (r) in the sample at a given field (H). A
study of these melting landscapes reveals an unexpected feature: the melting
landscape is not fixed, but changes rather dramatically with varying field and
temperature along the melting line. It is concluded that the changes in both
the scale and shape of the landscape result from the competing contributions of
different types of quenched disorder which have opposite effects on the local
melting transition.Comment: Paper presented at the International Symposium on Advances in
Superconductivity & Magnetism: Materials, Mechanisms & Devices September
25-28, 2001, Mangalore, India. Symposium proceedings will be published in a
special issue of Pramana - Journal of Physic
Characterisation of cohesive powders for bulk handling and DEM modelling
The flow behaviour of granular materials is relevant for many industrial applications including the pharmaceutical, chemical, consumer goods and food industries. A key issue is the accurate characterisation of these powders under different loading conditions and flow regimes, for example in mixers, pneumatic conveyors and silo filling and discharge.
This paper explores the experimental aspects of cohesive powder handling at different compaction levels and flow regimes, namely inertial and quasi-static regimes. So far, laboratory element test set-ups capable of defining the full stress states at very low compaction levels have not been fully explored in literature. In contrast the mechanical behaviour of cohesive powders under relatively high consolidation stress (several kPa upward) can be carefully measured using element tests such as biaxial test, true triaxial and hollow cylinder tests. However in practice these tests are expensive and slow to conduct and are almost never performed for many industrial applications requiring material characterisation. Here we investigate simpler techniques that could be used for filling this important gap with the focus of providing test data for model calibration and simulation validation in line with the spirit of the European Commission funded PARDEM Marie Curie ITN Project.
We perform particle and bulk characterisation on limestone powder with 4.7µm and 31.3 µm mean particle size, detergent powder with differences in formulation, cocoa powder with low and high fat content - relevant for different industrial applications. Of particular significance is the 4.7µm limestone powder which is the PARDEM reference powder that have been created and extensively used in a collaborative European PARDEM Project (www.pardem.eu).
In the inertial, low consolidation stress regimes - more relevant for powder transport and conveying applications - we present experimental findings on the flowability and avalanching behaviour of the reference material in a rotating drum. On the other hand, in the quasi-static, higher consolidation regime, we perform shear tests with the Edinburgh Powder Tester (EPT), an extended uniaxial tester and the commercially available Freeman FT4 Powder Rheometer. For macroscopic quantities, we report the unconfined yield strength as a function of applied stress. These material characteristics provide important scientific insights for developing innovative solutions for cohesive powder handling problems. From these experiments and for best practice guideline, we highlight subtle issues associated with the experimental setup and measurements. The experiments lead to a rich quantitative description of the flow behaviour and failure properties of the materials which provide the material data for DEM model calibration and validation
The London theory of the crossing-vortex lattice in highly anisotropic layered superconductors
A novel description of Josephson vortices (JVs) crossed by the pancake
vortices (PVs) is proposed on the basis of the anisotropic London theory. The
field distribution of a JV and its energy have been calculated for both dense
() PV lattices with distance
between PVs, and the nonlinear JV core size . It is shown that the
``shifted'' PV lattice (PVs displaced mainly along JVs in the crossing vortex
lattice structure), formed in high out-of-plane magnetic fields transforms into
the PV lattice ``trapped'' by the JV sublattice at a certain field, lower than
, where is the flux quantum, is the
anisotropy parameter and is the distance between CuO planes.
With further decreasing , the free energy of the crossing vortex lattice
structure (PV and JV sublattices coexist separately) can exceed the free energy
of the tilted lattice (common PV-JV vortex structure) in the case of with the in-plane penetration depth if the low
() or high ()
in-plane magnetic field is applied. It means that the crossing vortex structure
is realized in the intermediate field orientations, while the tilted vortex
lattice can exist if the magnetic field is aligned near the -axis and the
-plane as well. In the intermediate in-plane fields
, the
crossing vortex structure with the ``trapped'' PV sublattice seems to settle in
until the lock-in transition occurs since this structure has the lower energy
with respect to the tilted vortex structure in the magnetic field
oriented near the -plane.Comment: 15 pages, 6 figures, accepted for publication in PR
Justification of Filter Selection for Robot Balancing in Conditions of Limited Computational Resources
The paper considers the problem of mathematical filter selection, used for balancing of wheeled robot in conditions of limited computational resources. The solution based on complementary filter is proposed
Possible new vortex matter phases in BSCCO
The vortex matter phase diagram of BSCCO crystals is analyzed by
investigating vortex penetration through the surface barrier in the presence of
a transport current. The strength of the effective surface barrier, its
nonlinearity, and asymmetry are used to identify a possible new ordered phase
above the first-order transition. This technique also allows sensitive
determination of the depinning temperature. The solid phase below the
first-order transition is apparently subdivided into two phases by a vertical
line extending from the multicritical point.Comment: 11 pages, 3 figures, accepted for publication in PR
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SETD3 is an actin histidine methyltransferase that prevents primary dystocia.
For more than 50 years, the methylation of mammalian actin at histidine 73 has been known to occur1. Despite the pervasiveness of His73 methylation, which we find is conserved in several model animals and plants, its function remains unclear and the enzyme that generates this modification is unknown. Here we identify SET domain protein 3 (SETD3) as the physiological actin His73 methyltransferase. Structural studies reveal that an extensive network of interactions clamps the actin peptide onto the surface of SETD3 to orient His73 correctly within the catalytic pocket and to facilitate methyl transfer. His73 methylation reduces the nucleotide-exchange rate on actin monomers and modestly accelerates the assembly of actin filaments. Mice that lack SETD3 show complete loss of actin His73 methylation in several tissues, and quantitative proteomics analysis shows that actin His73 methylation is the only detectable physiological substrate of SETD3. SETD3-deficient female mice have severely decreased litter sizes owing to primary maternal dystocia that is refractory to ecbolic induction agents. Furthermore, depletion of SETD3 impairs signal-induced contraction in primary human uterine smooth muscle cells. Together, our results identify a mammalian histidine methyltransferase and uncover a pivotal role for SETD3 and actin His73 methylation in the regulation of smooth muscle contractility. Our data also support the broader hypothesis that protein histidine methylation acts as a common regulatory mechanism
c-axis penetration depth in BiSrCaCuO single crystals measured by ac-susceptibility and cavity perturbation technique
The -axis penetration depth in
BiSrCaCuO (BSCCO) single crystals as a function of
temperature has been determined using two techniques, namely, measurements of
the ac-susceptibility at a frequency of 100 kHz and the surface impedance at
9.4 GHz. Both techniques yield an almost linear function
in the temperature range T<0.5 T_c.
Electrodynamic analysis of the impedance anisotropy has allowed us to estimate
m in BSCCO crystals overdoped with oxygen
( K) and m at the optimal doping
level ( K).Comment: 5 pages, 4 figure
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