597 research outputs found
As pequenas brocas do cupuacu, Xyleborus sp. e Hypocryphalus sp. (Coleoptera: Scolytidae): danos e indicacoes de manejo em sistemas agroflorestais de Rondonia.
Trabalho desenvolvido em dois sistemas Agroflorestais na zona rural de Porto Velho - Rondonia. Num deles, ocupando area de 0,6ha, foram plantados cupuacu e bandarra(Schilozobium amazonicum), alem de outras duas especies madeireiras, teca (Tectona grandis) e mogno (Swietenia macrophylla). No outro sistema com area de 1,3ha foram plantadaos cupuacu, pupunha e banana. Alem destas, o sistema recebeu as especies madeireiras: teca, mogno, cedro (Cedrela odorata), ipe (Tabebuia), cerejeira (Torresea acreana, freijo (Cordia sp) e copaiba (Copaifera multijuga). Considerou-se o ataque de Xyleborus sp e Hypocrypahlus sp em relacao as condicoes de cultivo implementadas para o cupuacu em Rondonia. Traz indicacoes de manejo de cultivo em sistemas agroflorestais em areas de "derruba & queima", onde a presenca de tocos(madeira morta) e frequente e significativa.bitstream/item/56213/1/Circ.T-270001.pd
Bandwidth renormalization due to the intersite Coulomb interaction
The theory of correlated electrons is currently moving beyond the
paradigmatic Hubbard , towards the investigation of intersite Coulomb
interactions. Recent investigations have revealed that these interactions are
relevant for the quantitative description of realistic materials. Physically,
intersite interactions are responsible for two rather different effects:
screening and bandwidth renormalization. We use a variational principle to
disentangle the roles of these two processes and study how appropriate the
recently proposed Fock treatment of intersite interactions is in correlated
systems. The magnitude of this effect in graphene is calculated based on cRPA
values of the intersite interaction. We also observe that the most interesting
charge fluctuation phenomena actually occur at elevated temperatures,
substantially higher than studied in previous investigations.Comment: New appendix on benzen
Melt block copolymerization of ε-caprolactone and L-lactide
AB block copolymers of ε-caprolactone and (L)-lactide could be prepared by ring-opening polymerization in the melt at 110°C using stannous octoate as a catalyst and ethanol as an initiator provided ε-caprolactone was polymerized first. Ethanol initiated the polymerization of ε-caprolactone producing a polymer with ε-caprolactone derived hydroxyl end groups which after addition of L-lactide in the second step of the polymerization initiated the ring-opening copolymerization of L-lactide. The number-average molecular weights of the poly(ε-caprolactone) blocks varied from 1.5 to 5.2 × 103, while those of the poly(L-lactide) blocks ranged from 17.4 to 49.7 × 103. The polydispersities of the block copolymers varied from 1.16 to 1.27. The number-average molecular weights of the polymers were controlled by the monomer/hydroxyl group ratio, and were independent on the monomer/stannous octoate ratio within the range of experimental conditions studied. When L-lactide was polymerized first, followed by copolymerization of ε-caprolactone, random copolymers were obtained. The formation of random copolymers was attributed to the occurrence of transesterification reactions. These side reactions were caused by the ε-caprolactone derived hydroxyl end groups generated during the copolymerization of ε-caprolactone with pre-polymers of L-lactide. The polymerization proceeds through an ester alcoholysis reaction mechanism, in which the stannous octoate activated ester groups of the monomers react with hydroxyl groups
Effect of Fluticasone propionate Aqueous Nasal Spray Treatment on Platelet Activating Factor and Eicosanoid Production By nasal Mucosa in Patients with A house Dust Mite Allergy
The relationship between the release of platelet activating factor
(PAF), leukotriene C4/D4/EE
(LTC4/D4/E4) and prostaglandin D2 (PGD2)
from nasal mucosa in vivo was examined in 24 rhinitis patients
allergic to the house dust mite (HDM). During a double blind placebo
controlled cross-over study 200 μg fluticasone propionate aqueous
nasal spray (FPANS) was administered twice daily for two weeks. In
response to allergen provocation (100, 1 000, 10 000 Bu/ml) and
during the 9.5 h after this challenge the nasal fluid was obtained
by washing the nose with saline and the levels of PAF, LTC4/D4/E4 and
PGD2, as indicators of mediator release, were measured at the
following time-points: baseline (t = − 1/2), allergen provocation with
10 000 Bu/ml (t = 0), 3.5 and 7.5 h (late phase). After allergen
provocation the levels of the mediators increased in the nasal
fluids of placebo treated patients (x-fold increase to baseline:
PAF, 15; LTC4/D4/E4, 12; PGD2, 1.5). In fluids of patients treated
with FPANS these levels tended to decrease. At the time of
provocation the levels of PAF, LTC4/D4/E4 and PGD2 showed a significant
correlation. The results indicate that these mediators can be used
as markers of allergic reactions against house dust mites and that
fluticasone propionate aqueous nasal spray tended to reduce the
release of mediators of inflammation correlated with beneficial
effects on clinical symptoms in this type of allergic reactions
Parity transitions in the superconducting ground state of hybrid InSb-Al Coulomb islands
The number of electrons in small metallic or semiconducting islands is
quantized. When tunnelling is enabled via opaque barriers this number can
change by an integer. In superconductors the addition is in units of two
electron charges (2e), reflecting that the Cooper pair condensate must have an
even parity. This ground state (GS) is foundational for all superconducting
qubit devices. Here, we study a hybrid superconducting-semiconducting island
and find three typical GS evolutions in a parallel magnetic field: a robust
2e-periodic even-parity GS, a transition to a 2e-periodic odd-parity GS,and a
transition from a 2e- to a 1e-periodic GS. The 2e-periodic odd-parity GS
persistent in gate-voltage occurs when a spin-resolved subgap state crosses
zero energy. For our 1e-periodic GSs we explicitly show the origin being a
single zero-energy state gapped from the continuum, i.e. compatible with an
Andreev bound states stabilized at zero energy or the presence of Majorana zero
modes
Molecular characterization and identification of proteins regulated by Hfq in Neisseria meningitidis
Hfq is a highly conserved pleiotropically acting prokaryotic RNA-binding protein involved in the post-transcriptional regulation of many stress-responsive genes by small RNAs. In this study, we show that Hfq of the strictly human pathogen Neisseria meningitidis is involved in the regulation of expression of components involved in general metabolic pathways, iron metabolism and virulence. A meningococcal hfq deletion strain (H44/76Δhfq) is impaired in growth in nutrient-rich media and does not grow at all in nutrient-limiting medium. The growth defect was complemented by expression of hfq in trans. Using proteomics, the expression of 28 proteins was found to be significantly affected upon deletion of hfq. Of these, 20 proteins are involved in general metabolism, among them seven iron-responsive genes. Two proteins (PilE, TspA) are involved in adherence to human cells, a step crucial for the onset of disease. One of the differentially expressed proteins, GdhA, was identified as an essential virulence factor for establishment of sepsis in an animal model, studied earlier. These results show that in N. meningitidis Hfq is involved in the regulation of a variety of components contributing to the survival and establishment of meningococcal disease
Quantized Majorana conductance
Majorana zero-modes hold great promise for topological quantum computing.
Tunnelling spectroscopy in electrical transport is the primary tool to identify
the presence of Majorana zero-modes, for instance as a zero-bias peak (ZBP) in
differential-conductance. The Majorana ZBP-height is predicted to be quantized
at the universal conductance value of 2e2/h at zero temperature. Interestingly,
this quantization is a direct consequence of the famous Majorana symmetry,
'particle equals antiparticle'. The Majorana symmetry protects the quantization
against disorder, interactions, and variations in the tunnel coupling. Previous
experiments, however, have shown ZBPs much smaller than 2e2/h, with a recent
observation of a peak-height close to 2e2/h. Here, we report a quantized
conductance plateau at 2e2/h in the zero-bias conductance measured in InSb
semiconductor nanowires covered with an Al superconducting shell. Our
ZBP-height remains constant despite changing parameters such as the magnetic
field and tunnel coupling, i.e. a quantized conductance plateau. We distinguish
this quantized Majorana peak from possible non-Majorana origins, by
investigating its robustness on electric and magnetic fields as well as its
temperature dependence. The observation of a quantized conductance plateau
strongly supports the existence of non-Abelian Majorana zero-modes in the
system, consequently paving the way for future braiding experiments.Comment: 5 figure
Electric field tunable superconductor-semiconductor coupling in Majorana nanowires
We study the effect of external electric fields on
superconductor-semiconductor coupling by measuring the electron transport in
InSb semiconductor nanowires coupled to an epitaxially grown Al superconductor.
We find that the gate voltage induced electric fields can greatly modify the
coupling strength, which has consequences for the proximity induced
superconducting gap, effective g-factor, and spin-orbit coupling, which all
play a key role in understanding Majorana physics. We further show that level
repulsion due to spin-orbit coupling in a finite size system can lead to
seemingly stable zero bias conductance peaks, which mimic the behavior of
Majorana zero modes. Our results improve the understanding of realistic
Majorana nanowire systems.Comment: 10 pages, 5 figures, supplemental information as ancillary fil
Low vitamin D status is associated with more depressive symptoms in Dutch older adults
Purpose: The existence of vitamin D receptors in the brain points to a possible role of vitamin D in brain function. We examined the association of vitamin D status and vitamin D-related genetic make-up with depressive symptoms amongst 2839 Dutch older adults aged ≥65 years. Methods: 25-Hydroxyvitamin D (25(OH)D) was measured, and five ‘vitamin D-related genes’ were selected. Depressive symptoms were measured with the 15-point Geriatric Depression Scale. Results were expressed as the relative risk of the score of depressive symptoms by quartiles of 25(OH)D concentration or number of affected alleles, using the lowest quartile or minor allele group as reference. Results: A clear cross-sectional and pr
β-Cell Replication Is Increased in Donor Organs From Young Patients After Prolonged Life Support
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