2,008 research outputs found
Dynamics of atoms in a time-orbiting-potential trap: Consequences of the classical description
The classical model that describes the motion of an atom in a magnetic trap is solved in order to investigate the relationship between the failure of the usual adiabatic approximation assumption and the physical parameters of the trap. This allows us to evaluate the effect that reversing of the bias field rotation produces on the vertical position of the atomic orbit, a displacement that is closely related to the adiabatic character of the trap motion. The present investigation has been motivated by a similar experimental test previously carried out in the actual magnetic time-orbiting-potential trap. We find that the non-adiabatic effects provided by the classical model are extremely small. Thus, we conclude that the theoretical explanation of the experimental measures requires a quantum description of the dynamics in magnetic traps
Structure of the space of folding protein sequences defined by large language models
Proteins populate a manifold in the high-dimensional sequence space whose
geometrical structure guides their natural evolution. Leveraging
recently-developed structure prediction tools based on transformer models, we
first examine the protein sequence landscape as defined by the folding score
function. This landscape shares characteristics with optimization challenges
encountered in machine learning and constraint satisfaction problems. Our
analysis reveals that natural proteins predominantly reside in wide, flat
minima within this energy landscape. To investigate further, we employ
statistical mechanics algorithms specifically designed to explore regions with
high local entropy in relatively flat landscapes. Our findings indicate that
these specialized algorithms can identify valleys with higher entropy compared
to those found using traditional methods such as Monte Carlo Markov Chains. In
a proof-of-concept case, we find that these highly entropic minima exhibit
significant similarities to natural sequences, especially in critical key sites
and local entropy. Additionally, evaluations through Molecular Dynamics
suggests that the stability of these sequences closely resembles that of
natural proteins. Our tool combines advancements in machine learning and
statistical physics, providing new insights into the exploration of sequence
landscapes where wide, flat minima coexist alongside a majority of narrower
minima
Risk and protective factors for meningococcal disease in adolescents: matched cohort study
Objective: To examine biological and social risk factors for
meningococcal disease in adolescents.
Design: Prospective, population based, matched cohort study
with controls matched for age and sex in 1:1 matching.
Controls were sought from the general practitioner.
Setting: Six contiguous regions of England, which represent
some 65% of the country’s population.
Participants: 15-19 year olds with meningococcal disease
recruited at hospital admission in six regions (representing 65%
of the population of England) from January 1999 to June 2000,
and their matched controls.
Methods: Blood samples and pernasal and throat swabs were
taken from case patients at admission to hospital and from
cases and matched controls at interview. Data on potential risk
factors were gathered by confidential interview. Data were
analysed by using univariate and multivariate conditional
logistic regression.
Results: 144 case control pairs were recruited (74 male (51%);
median age 17.6). 114 cases (79%) were confirmed
microbiologically. Significant independent risk factors for
meningococcal disease were history of preceding illness
(matched odds ratio 2.9, 95% confidence interval 1.4 to 5.9),
intimate kissing with multiple partners (3.7, 1.7 to 8.1), being a
university student (3.4, 1.2 to 10) and preterm birth (3.7, 1.0 to
13.5). Religious observance (0.09, 0.02 to 0.6) and
meningococcal vaccination (0.12, 0.04 to 0.4) were associated
with protection.
Conclusions: Activities and events increasing risk for
meningococcal disease in adolescence are different from in
childhood. Students are at higher risk. Altering personal
behaviours could moderate the risk. However, the development
of further effective meningococcal vaccines remains a key
public health priority
Induction of resistance and enhancing agronomic performance in grapevines under greenhouse and in open fields by applications of plasma activated water
The exposure of water to a cold atmospheric pressure plasma (CAP) enables the production of plasma activated water (PAW), having high content of reactive species, whose applications were tested on grapevine plants, both in greenhouse and in vineyard conditions. Two different CAPs were used
for PAW production, evaluating their effectiveness as a possible mean to control plant diseases. Grapevines infected with yellows associated with the presence of phytoplasmas were treated evaluating qualitative and quantitative yield parameters, phytoplasma presence, and gene expression. The results show the capability of PAW to enhance plant defence mechanisms and, as demonstrated in the field trials, confirmed its ability to improve the health status of the treated
plants. Quantitative (q)RT-PCR analyses allowed to determine the transcription level of genes involved in the plant defence response (phenylalanine ammonia-lyase, pal) and in the plant phytoalexin metabolism of PAW-treated materials. The number of symptomatic grapevine plants in vineyards was significantly reduced by the treatments. Transcriptional and post-transcriptional molecular analyses highlighted the PAW ability to enhance the expression of genes encoding the
main enzymes involved in the phytoalexin biosynthetic pathway (flavonoids and stilbenes). The PAW ability to enhance some of the plant defence mechanisms also improving the health status of the treated plants was therefore experimentally demonstrated. After three years of trials the overall results demonstrated the possible use of PAW to reduce the disease severity, induce plant resistance both in open field and greenhouse, improving plant healthy status and grapevine yield production
Transcriptional profiling of phytoplasma infected plants treated with plasma activated water (PAW).
Background. Phytoplasmas are insect-transmitted plant pathogenic prokaryotes, associated with severe
diseases in agronomic important crops. Management of these diseases has mainly focused on insect vector
chemical control and on infected plant rouging. There is therefore a strong need for effective and friendly
control strategies for phytoplasma-associated diseases and the possibility to use plasma activated water
(PAW) as sustainable and effective method to them was therefore evaluated. PAW is produced by treating
distilled water with atmospheric pressure plasmas, inducing the production of reactive oxygen and nitrogen
species (RONS) and pH reduction. PAW has good potential for bacterial decontamination, degradation of
organic compounds and was shown to positively affect plant growth. Methods. Sterile deionized water (SDW)
was exposed to a nanosecond pulsed dielectric barrier discharge, operating in ambient air for 10 min
treatment with a peak voltage of 19 kV and a pulse repetition frequency of 1 kHz, which induced production of
nitrates, nitrites and peroxides, and a pH decrease. Phytoplasma infected and healthy periwinkles
micropropagated shoots were exposed to PAW for about 25 minutes and gene expression studies were then
performed. The theses used were: shoots treated with PAW, Fosetyl aluminum (as positive control) and SDW
(as negative control), with an exposition of about 25 minutes. Nine shoots for each thesis were then collected
at 6 different times after treatment and stored at -80\ub0C. Quantitative RT-PCR analyses were carried out to
determine the expression level of genes involved in the plant defense response. Parallel experiments were
carried out treating grapevine plants in vineyards previously tested for the phytoplasma presence. Treatments
were performed for three years injecting into the plant vascular tissues 10-20 ml of PAW or sterile distilled
water (as control) on each selected plant for a total of 60 plants (40 with phytoplasmas and 20 without
phytoplasmas). Results. Overexpression of selected genes involved in the phytoalexin metabolism was
detected in the periwinkles micropropagated shoots treated with PAW in comparison with the shoots treated
with Fosetyl-Al and distilled water. In the field trials, in a relevant number of cases, the PAW-treated
symptomatic plants showed reduction of symptoms, while the SDW-treated and untreated plants did not show
symptom reduction. No phytotoxicity was observed in the PAW treated grapevine and periwinkle plants.
Conclusion. The results obtained showed the capability of PAW to enhance plant defence mechanisms and,
as demonstrated in the field trials, confirmed its ability to improve the health status of the treated plant
The quantum non-linear Schrodinger model with point-like defect
We establish a family of point-like impurities which preserve the quantum
integrability of the non-linear Schrodinger model in 1+1 space-time dimensions.
We briefly describe the construction of the exact second quantized solution of
this model in terms of an appropriate reflection-transmission algebra. The
basic physical properties of the solution, including the space-time symmetry of
the bulk scattering matrix, are also discussed.Comment: Comments on the integrability and the impurity free limit adde
An innovative agro-forestry supply chain for residual biomass : physicochemical characterisation of biochar from olive and hazelnut pellets
Concerns about climate change and food productivity have spurred interest in biochar, a form of charred organic material typically used in agriculture to improve soil productivity and as a means of carbon sequestration. An innovative approach in agriculture is the use of agro-forestry waste for the production of soil fertilisers for agricultural purposes and as a source of energy. A common agricultural practice is to burn crop residues in the field to produce ashes that can be used as soil fertilisers. This approach is able to supply plants with certain nutrients, such as Ca, K, Mg, Na, B, S, and Mo. However, the low concentration of N and P in the ashes, together with the occasional presence of heavy metals (Ni, Pb, Cd, Se, Al, etc.), has a negative effect on soil and, therefore, crop productivity. This work describes the opportunity to create an innovative supply chain from agricultural waste biomass. Olive (Olea europaea) and hazelnut (Corylus avellana) pruning residues represent a major component of biomass waste in the area of Viterbo (Italy). In this study, we evaluated the production of biochar from these residues. Furthermore, a physicochemical characterisation of the produced biochar was performed to assess the quality of the two biochars according to the standards of the European Biochar Certificate (EBC). The results of this study indicate the cost-effective production of high-quality biochar from olive and hazelnut biomass residues
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