500 research outputs found
Precision of the determination of focal depth from the spectral ratio of Love/Rayleigh surface waves
The precision with which the focal depth may be determined using Love/Rayleigh-wave spectral ratios depends on the accuracy of the models for Earth structure and for source mechanism used in the focal depth calculations. Estimates of the precision of the focal depth determination are obtained using the partial derivatives of Love/Rayleigh spectral ratios with respect to the parameters: focal depth, shear velocity, dip angle, and slip angle. We find that errors caused by imprecise knowledge of any of these parameters can be important in practice
Feed size and texture influence propionic and butyric acid concentrations and Escherichia coli populations in the pig gastrointestinal tract
Natural approaches are now being considered to replace antimicrobials to reduce the risk of antimicrobial resistance development. This has put the new emphasis on using diet to control bacterial infections in pigs, some of which having recently demonstrated a zoonotic disease potential
On Words with the Zero Palindromic Defect
We study the set of finite words with zero palindromic defect, i.e., words
rich in palindromes. This set is factorial, but not recurrent. We focus on
description of pairs of rich words which cannot occur simultaneously as factors
of a longer rich word
Evaluation of building envelope retrofit techniques for reducing energy needs for space cooling.
One of the fastest growing sources of new energy demand is space cooling. According to EU-studies a four-fold growth in air-conditioned space is likely to take place between 1990 and 2020. The energy savings achievable in the end-use space cooling depend on a number of variables related to the building envelope, the plants and to some extent the behaviour of occupants. They are hence complex to evaluate and consequently often underrepresented in energy efficiency programmes and National Plans.
This paper is based on some preliminary results of the IEE project KeepCool 2. It discusses in particular:
a methodology for bottom-up assessment of the energy savings related to "sustainable summer comfort" solutions; reference base case building typologies are analyzed in 5 European climates, and dynamic simulations are used to calculate the reductions in the energy need for cooling which can be achieved by specific retrofit actions (e.g. additions of effective solar protections, increased thermal insulation, night ventilation, increase of active mass by PCM, low solar absorbance surfaces,...); situations where mechanical cooling can be avoided are evaluated using the Adaptive Comfort model, according to the norm EN 15251.
case studies of buildings with good summer comfort and low energy consumption performances, according to the ten steps of the KC2 procedure.
the analysis of case studies of "comfort policies" adopted by public and private bodies to ensure summer comfort with low energy consumption (commitments to give priority to heat load reductions instead of introducing mechanical cooling, relaxed dress codes, low thermal insulation chairs, local air velocity increase)
Vitamin B6 deficiency experimentally-induced bone and joint disorder: microscopic, radiographic and biochemical evidence
In the present study the effect of pyridoxine deficiency on the utrastructure and morphology of bone and its metabolism was examined in the rapidly growing chick. Pyridoxine-deficient animals had tibias of reduced dry weight and cortical thickness. Histomorphometry demonstrated a disproportionately high eroded surface, lower amount of osteoid tissue and reduced mineralized trabecular width. Anterior-posterior radiographs of the tibiotarsometatarsal joint showed reduced secondary ossification centres and coarse trabeculation. Decalcified metaphyseal cartilage showed irregular trabeculas and a markedly reduced amount of Fast-green counterstain matrix suggesting that there is less collagen present and in turn less availability for matrix to be laid down for later calcification. Plasma activity of the bone alkaline phosphatase isoenzyme (EC) 3. 1.3.1) was decreased. Plasma Ca and PO4 levels did not vary. The present bone study referring to a pseudo-lathyritic state in which collagen maturation is not completely achieved supports the hypothesis that pyridoxine is an essential nutrient for the connective tissue matri
Sea ice and biological production variability reconstructed in the Adélie Basin, East Antarctica, during the late Holocene
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Effects of energy correlations and superexchange on charge transport and exciton formation in amorphous molecular semiconductors:an ab initio study
In this study, we investigate on the basis of ab initio calculations how the morphology, molecular on-site energies, reorganization energies, and charge transfer integral distribution affect the hopping charge transport and the exciton formation process in disordered organic semiconductors. We focus on three materials applied frequently in organic light-emitting diodes: α-NPD, TCTA, and Spiro-DPVBi. Spatially correlated disorder and, more importantly, superexchange contributions to the transfer integrals, are found to give rise to a significant increase of the electric field dependence of the electron and hole mobility. Furthermore, a material-specific correlation is found between the HOMO and LUMO energy on each specific molecular site. For α-NPD and TCTA, we find a positive correlation between the HOMO and LUMO energies, dominated by a Coulombic contribution to the energies. In contrast, Spiro-DPVBi shows a negative correlation, dominated by a conformational contribution. The size and sign of this correlation have a strong influence on the exciton formation rate
Ab initio modeling of steady-state and time-dependent charge transport in hole-only α-NPD devices
We present an ab initio modeling study of steady-state and time-dependent charge transport in hole-only devices of the amorphous molecular semiconductor αâNPDâ[N,N âČ âDi(1ânaphthyl)âN,N âČ âdiphenylâ(1,1 âČ âbiphenyl)â4,4 âČ âdiamine] αâNPDâ[N,NâČ-Di(1ânaphthyl)-N,NâČ-diphenyl-(1,1âČ-biphenyl)-4,4âČ-diamine]. The study is based on the microscopic information obtained from atomistic simulations of the morphology and density functional theory calculations of the molecular hole energies, reorganization energies, and transfer integrals. Using stochastic approaches, the microscopic information obtained in simulation boxes at a length scale of âŒ10ânm is expanded and employed in one-dimensional (1D) and three-dimensional (3D) master-equation modeling of the charge transport at the device scale of âŒ100ânm. Without any fit parameter, predicted current density-voltage and impedance spectroscopy data obtained with the 3D modeling are in very good agreement with measured data on devices with different α-NPD layer thicknesses in a wide range of temperatures, bias voltages, and frequencies. Similarly good results are obtained with the computationally much more efficient 1D modeling after optimizing a hopping prefacto
Multivariate risks and depth-trimmed regions
We describe a general framework for measuring risks, where the risk measure
takes values in an abstract cone. It is shown that this approach naturally
includes the classical risk measures and set-valued risk measures and yields a
natural definition of vector-valued risk measures. Several main constructions
of risk measures are described in this abstract axiomatic framework.
It is shown that the concept of depth-trimmed (or central) regions from the
multivariate statistics is closely related to the definition of risk measures.
In particular, the halfspace trimming corresponds to the Value-at-Risk, while
the zonoid trimming yields the expected shortfall. In the abstract framework,
it is shown how to establish a both-ways correspondence between risk measures
and depth-trimmed regions. It is also demonstrated how the lattice structure of
the space of risk values influences this relationship.Comment: 26 pages. Substantially revised version with a number of new results
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Impact of mash feeding versus pellets on propionic/butyric acid levels and on total Escherichia coli load in the gastrointestinal tract of growing pigs
Feed characteristics may influence
the bacterial community composition and metabolic
activities in the pig gastrointestinal tract, known to be
associated with positive effects on the gut. Use of mash
feed is associated with reduced Salmonella excretion,
but little is known of its effect on the Escherichia coli
population or of the mechanism of action. Our objectives
were to assess the effect of feed texture combined
with feed particle size on VFA profiles and levels,
total E. coli count, and the presence of genes encoding
virulence factors of pathogenic E. coli strains in the
digestive tract along with their impact on pig performance
of fattening pigs. Pigs (n = 840) on a commercial
farm received mash or pellet diets of different particle
sizes during the fattening period. Caecal and colon contents
from 164 pigs were sampled at the slaughterhouse
for enumeration of E. coli by quantitative PCR (qPCR)
and for VFA quantification by capillary gas chromatography.
The yccT gene was used to enumerate total E.
coli. Improved pig performances associated with pellet
texture and a 500-ÎŒm size were observed. Caecal (P =
0.02) and colon (P < 0.01) propionic acid concentrations
were lower for pigs receiving pellet rather than
mash feed. Similarly, caecal (P = 0.01) and colon (P <
0.001) butyric acid concentrations were also lower for
pigs receiving pellet rather than mash feed, as determined
by capillary gas chromatography. Moreover,
caecal (P = 0.03) and colon (P < 0.001) butyric acid
concentrations were higher for pigs receiving a feed
with a 1,250-ÎŒm particle size rather than a 500-ÎŒm
particle size. On the other hand, total caecal and colon
E. coli levels were higher for pigs receiving pellet feed
than for those receiving mash feed. For total E. coli
enumeration, caecal (P < 0.01) and colon (P < 0.01)
yccT gene copies were higher for pigs receiving pellet
rather than mash feed. No effect of particle size on
fatty acid concentrations or on E. coli numbers was
observed. Virulence gene quantification revealed no
trend. Taken together, results showed that mash feed
is associated with lower growth performance but with
favorable intestinal changes linked to VFA levels and E.
coli reduction in the intestine
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