580 research outputs found
Q&A: How does jasmonate signaling enable plants to adapt and survive?
Jasmonates (JAs) are a class of plant hormones that play essential roles in response to tissue wounding. They act on gene expression to slow down growth and to redirect metabolism towards producing defense molecules and repairing damage. These responses are systemic and have dramatic impacts on yields, making JAs a very active research area. JAs interact with many other plant hormones and therefore also have essential functions throughout development, notably during plant reproduction, leaf senescence and in response to many biotic and abiotic stresses
Low temperature tunneling current enhancement in silicide/Si Schottky contacts with nanoscale barrier width
The low temperature electrical behavior of adjacent silicide/Si Schottky
contacts with or without dopant segregation is investigated. The electrical
characteristics are very well modeled by thermionic-field emission for
non-segregated contacts separated by micrometer-sized gaps. Still, an excess of
current occurs at low temperature for short contact separations or
dopant-segregated contacts when the voltage applied to the device is
sufficiently high. From two-dimensional self-consistent non-equilibrium Green's
function simulations, the dependence of the Schottky barrier profile on the
applied voltage, unaccounted for in usual thermionic-field emission models, is
found to be the source of this deviation
Fish evacuate smoothly respecting a social bubble
Crowd movements are observed among different species and on different scales,
from insects to mammals, as well as in non-cognitive systems, such as motile
cells. When forced to escape through a narrow opening, most terrestrial animals
behave like granular materials and clogging events decrease the efficiency of
the evacuation. Here, we explore the evacuation behavior of macroscopic,
aquatic agents, neon fish, and challenge their gregarious behavior by forcing
the school through a constricted passage. Using a statistical analysis method
developed for granular matter and applied to crowd evacuation, our results
clearly show that, unlike crowds of people or herds of sheep, no clogging
occurs at the bottleneck. The fish do not collide and wait for a minimum
waiting time between two successive exits, while respecting a social distance.
When the constriction becomes similar to or smaller than their social distance,
the individual domains defined by this cognitive distance are deformed and fish
density increases. We show that the current of escaping fish behaves like a set
of deformable 2D-bubbles, their 2D domain, passing through a constriction.
Schools of fish show that, by respecting social rules, a crowd of individuals
can evacuate without clogging, even in an emergency situation.Comment: 7 pages, 4 figure
Very low effective Schottky barrier height for erbium disilicide contacts on n-Si through arsenic segregation
The segregation of As+ ions implanted into thin Er films deposited on n-Si
substrates is studied after ErSi2-x formation. The same lowering of the
effective Schottky barrier height (SBH) below 0.12 eV is obtained at moderate
annealing temperatures, regardless of the redistribution of As dopants at the
ErSi2-x/Si interface. On the other hand, if the implanted dose is slightly
enhanced, the annealing temperature required to reach sub-0.12-eV effective SBH
can be further reduced. This process enables the formation of very low
effective SBH ErSi2-x/n-Si contacts with a low thermal budget
Modelling the probability of microhabitat formation on trees using cross-sectional data
The rate of TreM formation per unit diameter growth was modelled as a function of tree diameter at breast height (DBH), and the model was calibrated considering cross-sectional observations TreMs on trees of different sizes. The model predicted realistic TreM formation rates at the tree and stand levels in forests dominated by Abies alba and Fagus sylvatica. This approach opens new perspectives to the analysis of forest biodiversity conservation strategies
Challenges in dengue research: A computational perspective
This is the final version of the article. Available from Wiley via the DOI in this record.The dengue virus is now the most widespread arbovirus affecting human populations, causing significant economic and social impact in South America and South-East Asia. Increasing urbanization and globalization, coupled with insufficient resources for control, misguided policies or lack of political will, and expansion of its mosquito vectors are some of the reasons why interventions have so far failed to curb this major public health problem. Computational approaches have elucidated on dengue's population dynamics with the aim to provide not only a better understanding of the evolution and epidemiology of the virus but also robust intervention strategies. It is clear, however, that these have been insufficient to address key aspects of dengue's biology, many of which will play a crucial role for the success of future control programmes, including vaccination. Within a multiscale perspective on this biological system, with the aim of linking evolutionary, ecological and epidemiological thinking, as well as to expand on classic modelling assumptions, we here propose, discuss and exemplify a few major computational avenues—real-time computational analysis of genetic data, phylodynamic modelling frameworks, within-host model frameworks and GPU-accelerated computing. We argue that these emerging approaches should offer valuable research opportunities over the coming years, as previously applied and demonstrated in the context of other pathogens.JL, AW and SG received funding from the European Research Council under the European Union's Seventh Framework Programme (FP7/2007-2013) / ERC grant agreement no. 268904 - DIVERSITY. MR was supported by a Royal Society University Research Fellowship. NRF by a Sir Henry Dale Fellowship jointly funded by the Wellcome Trust and the Royal Society (grant number 204311/Z/16/Z). WT has received funding from a doctoral scholarship from the Engineering and Physical Sciences Research Council (EPSRC) Doctoral Training Partnership
Schottky barrier lowering with the formation of crystalline Er silicide on n-Si upon thermal annealing
The evolution of the Schottky barrier height (SBH) of Er silicide contacts to
n-Si is investigated as a function of the annealing temperature. The SBH is
found to drop substantially from 0.43 eV for the as-deposited sample to reach
0.28 eV, its lowest value, at 450 C. By x-ray diffraction, high resolution
transmission electron microscopy, and x-ray photoelectron spectroscopy, the
decrease in the SBH is shown to be associated with the progressive formation of
crystalline ErSi2-x
Post-treatment follow-up study of abdominal cystic echinococcosis in Tibetan communities of northwest Sichuan Province, China
Background: Human cystic echinococcosis (CE), caused by the larval stage of Echinococcus granulosus, with the liver as the
most frequently affected organ, is known to be highly endemic in Tibetan communities of northwest Sichuan Province.
Antiparasitic treatment with albendazole remains the primary choice for the great majority of patients in this resource-poor
remote area, though surgery is the most common approach for CE therapy that has the potential to remove cysts and lead
to complete cure. The current prospective study aimed to assess the effectiveness of community based use of cyclic
albendazole treatment in Tibetan CE cases, and concurrently monitor the changes of serum specific antibody levels during
treatment.
Methodology/Principal Findings: Ultrasonography was applied for diagnosis and follow-up of CE cases after cyclic
albendazole treatment in Tibetan communities of Sichuan Province during 2006 to 2008, and serum specific IgG antibody
levels against Echinococcus granulosus recombinant antigen B in ELISA was concurrently monitored in these cases. A total of
196 CE cases were identified by ultrasound, of which 37 (18.9%) showed evidence of spontaneous healing/involution of
hepatic cyst(s) with CE4 or CE5 presentations. Of 49 enrolled CE cases for treatment follow-up, 32.7% (16) were considered
to be cured based on B-ultrasound after 6 months to 30 months regular albendazole treatment, 49.0% (24) were improved,
14.3% (7) remained unchanged, and 4.1% (2) became aggravated. In general, patients with CE2 type cysts (daughter cysts
present) needed a longer treatment course for cure (26.4 months), compared to cases with CE1 (univesicular cysts) (20.4
months) or CE3 type (detached cyst membrane or partial degeneration of daughter cysts) (9 months). In addition, the
curative duration was longer in patients with large (.10 cm) cysts (22.3 months), compared to cases with medium (5–
10 cm) cysts (17.3 months) or patients with small (,5 cm) cysts (6 months). At diagnosis, seven (53.8%) of 13 cases with CE1
type cysts without any previous intervention showed negative specific IgG antibody response to E. granulosus recombinant
antigen B (rAgB). However, following 3 months to 18 months albendazole therapy, six of these 7 initially seronegative CE1
cases sero-converted to be specific IgG antibody positive, and concurrently ultrasound scan showed that cysts changed to
CE3a from CE1 type in all the six CE cases. Two major profiles of serum specific IgG antibody dynamics during albendazole
treatment were apparent in CE cases: (i) presenting as initial elevation followed by subsequent decline, or (ii) a persistent
decline. Despite a decline, however, specific antibody levels remained positive in most improved or cured CE cases.
Conclusions: This was the first attempt to follow up community-screened cystic echinococcosis patients after albendazole
therapy using ultrasonography and serology in an endemic Tibetan region. Cyclic albendazole treatment proved to be
effective in the great majority of CE cases in this resource-poor area, but periodic abdominal ultrasound examination was
necessary to guide appropriate treatment. Oral albendazole for over 18 months was more likely to result in CE cure. Poor
drug compliance resulted in less good outcomes. Serology with recombinant antigen B could provide additional limited
information about the effectiveness of albendazole in CE cases. Post-treatment positive specific IgG antibody
seroconversion, in initially seronegative, CE1 patients was considered a good indication for positive therapeutic efficacy
of albendazole
Nuclear rupture at sites of high curvature compromises retention of DNA repair factors.
The nucleus is physically linked to the cytoskeleton, adhesions, and extracellular matrix-all of which sustain forces, but their relationships to DNA damage are obscure. We show that nuclear rupture with cytoplasmic mislocalization of multiple DNA repair factors correlates with high nuclear curvature imposed by an external probe or by cell attachment to either aligned collagen fibers or stiff matrix. Mislocalization is greatly enhanced by lamin A depletion, requires hours for nuclear reentry, and correlates with an increase in pan-nucleoplasmic foci of the DNA damage marker γH2AX. Excess DNA damage is rescued in ruptured nuclei by cooverexpression of multiple DNA repair factors as well as by soft matrix or inhibition of actomyosin tension. Increased contractility has the opposite effect, and stiff tumors with low lamin A indeed exhibit increased nuclear curvature, more frequent nuclear rupture, and excess DNA damage. Additional stresses likely play a role, but the data suggest high curvature promotes nuclear rupture, which compromises retention of DNA repair factors and favors sustained damage
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