165 research outputs found
Pyrenophora tritici-repentis, Causal Agent of Tan Spot: A Review of Intraspecific Genetic Diversity
In some countries where the wheat is cultivated, the biological adversities are led by foliar disease. These diseases have emerged as a serious problem in many areas where the wheat is the principal crop. In the last few years, minimum tillage has been considered advantageous to soil conservation, but it leads to a loss of available nutrients and a potential increase in necrotic pathogens whose saprophytic stage lives in the straw of the crop (Annone, 1985). Establishment of the crop under this management can be affected by pathogens of this type. Leaf spotting diseases can be caused by one or a combination of leaf spotting pathogens (Table 1). Leaf spotting diseases affect wheat grown reduce the photosynthetic area of leaves resulting in reduced grain filling and lower yields; particularly when the top two leaves (penultimate and flag leaves) are severely infected. The most of these diseases are similar in host symptomatology, disease cycle, life cycles of pathogens and types of damage induced. Whitin of these pathogens the Ascomycota fungus, Pyrenophora tritici-repentis (Ptr) (Died.) Drechs. It is a facultative pathogen whose asexual stage is Drechslera tritici-repentis (Dtr) (Died.). This pathogen is the causal agent of tan spot of wheat
Entropy of the Nordic electricity market: anomalous scaling, spikes, and mean-reversion
The electricity market is a very peculiar market due to the large variety of
phenomena that can affect the spot price. However, this market still shows many
typical features of other speculative (commodity) markets like, for instance,
data clustering and mean reversion. We apply the diffusion entropy analysis
(DEA) to the Nordic spot electricity market (Nord Pool). We study the waiting
time statistics between consecutive spot price spikes and find it to show
anomalous scaling characterized by a decaying power-law. The exponent observed
in data follows a quite robust relationship with the one implied by the DEA
analysis. We also in terms of the DEA revisit topics like clustering,
mean-reversion and periodicities. We finally propose a GARCH inspired model but
for the price itself. Models in the context of stochastic volatility processes
appear under this scope to have a feasible description.Comment: 16 pages, 7 figure
Cytomegalovirus infection in HIV-infected patients in the era of combination antiretroviral therapy
Background: Cytomegalovirus infection dramatically decreased with the introduction of antiretroviral therapy. Whether incidence, clinical characteristics and prognosis of cytomegalovirus in HIV infected patients, has changed over time is. scarcely known. Methods: Retrospective single-center study. Patients included in this study were all HIV infected patients that went to our center for any disease, and were diagnosed with cytomegalovirus, during the period 2004-2015. epidemiological, clinical and laboratory patients variables were collected in a clinical database. Clinical characteristics, incidence of cytomegalovirus and predictors of mortality during the study were assessed. Results were considered statistically significant when p < 0.05. All statistical analyses were calculated by SPSS version 20.0 (Chicago, IL,USA). Results: Fifty-six cases of cytomegalovirus infection, in HIV infected patients were identified during the study period (incidence rate-1.7 cases per 1000 persons/year). The most frequent presentation was systemic illness in 43% of cases. Of note,no patients presented with ophthalmic manifestations. The 30-days mortality was 18%. Predictors of mortality were, in the univariate analysis, admission to the intensive care unit OR 32.4 (3.65-287.06) p = 0.0001, and mechanic ventilation 84 OR (8.27-853.12) p = 0.0001, and ART OR 4.1 (0.97-17.31) p = 0.044. These variables were assessed by multivariate analysis, and only mechanical ventilation was statistically significant (p < 0.05) CONCLUSION: Incidence of cytomegalovirus infection was higher than described in the antiretroviral therapy era. Clinical presentation has changed. Mechanic ventilation predicted mortality
Disposition of Federally Owned Surpluses
PDZ domains are scaffolding modules in protein-protein interactions that mediate numerous physiological functions by interacting canonically with the C-terminus or non-canonically with an internal motif of protein ligands. A conserved carboxylate-binding site in the PDZ domain facilitates binding via backbone hydrogen bonds; however, little is known about the role of these hydrogen bonds due to experimental challenges with backbone mutations. Here we address this interaction by generating semisynthetic PDZ domains containing backbone amide-to-ester mutations and evaluating the importance of individual hydrogen bonds for ligand binding. We observe substantial and differential effects upon amide-to-ester mutation in PDZ2 of postsynaptic density protein 95 and other PDZ domains, suggesting that hydrogen bonding at the carboxylate-binding site contributes to both affinity and selectivity. In particular, the hydrogen-bonding pattern is surprisingly different between the non-canonical and canonical interaction. Our data provide a detailed understanding of the role of hydrogen bonds in protein-protein interactions
Factors affecting calcium oxalate dihydrate fragmented calculi regrowth
BACKGROUND: The use of extracorporeal shock wave lithotripsy (ESWL) to treat calcium oxalate dihydrate (COD) renal calculi gives excellent fragmentation results. However, the retention of post-ESWL fragments within the kidney remains an important health problem. This study examined the effect of various urinary conditions and crystallization inhibitors on the regrowth of spontaneously-passed post-ESWL COD calculi fragments. METHODS: Post-ESWL COD calculi fragments were incubated in chambers containing synthetic urine varying in pH and calcium concentration: pH = 5.5 normocalciuria (3.75 mM), pH = 5.5 hypercalciuria (6.25 mM), pH = 6.5 normocalciuria (3.75 mM) or pH = 6.5 hypercalciuria (6.25 mM). Fragment growth was evaluated by measuring increases in weight. Fragment growth was standardized by calculating the relative mass increase. RESULTS: Calcium oxalate monohydrate (COM) crystals formed on COD renal calculi fragments under all conditions. Under pH = 5.5 normocalciuria conditions, only COM crystals formed (growth rate = 0.22 ± 0.04 μg/mg·h). Under pH = 5.5 hypercalciuria and under pH = 6.5 normocalciuria conditions, COM crystals and a small number of new COD crystals formed (growth rate = 0.32 ± 0.03 μg/mg·h and 0.35 ± 0.05 μg/mg·h, respectively). Under pH = 6.5 hypercalciuria conditions, large amounts of COD, COM, hydroxyapatite and brushite crystals formed (growth rate = 3.87 ± 0. 34 μg/mg·h). A study of three crystallization inhibitors demonstrated that phytate completely inhibited fragment growth (2.27 μM at pH = 5.5 and 4.55 μM at pH = 6.5, both under hypercalciuria conditions), while 69.0 μM pyrophosphate caused an 87% reduction in mass under pH = 6.5 hypercalciuria conditions. In contrast, 5.29 mM citrate did not inhibit fragment mass increase under pH = 6.5 hypercalciuria conditions. CONCLUSION: The growth rate of COD calculi fragments under pH = 6.5 hypercalciuria conditions was approximately ten times that observed under the other three conditions. This observation suggests COD calculi residual fragments in the kidneys together with hypercalciuria and high urinary pH values may be a risk factor for stone growth. The study also showed the effectiveness of specific crystallization inhibitors in slowing calculi fragment growth
Market Imitation and Win-Stay Lose-Shift Strategies Emerge as Unintended Patterns in Market Direction Guesses.
Decisions made in our everyday lives are based on a wide variety of information so it is generally very difficult to assess what are the strategies that guide us. Stock market provides a rich environment to study how people make decisions since responding to market uncertainty needs a constant update of these strategies. For this purpose, we run a lab-in-the-field experiment where volunteers are given a controlled set of financial information -based on real data from worldwide financial indices- and they are required to guess whether the market price would go "up" or "down" in each situation. From the data collected we explore basic statistical traits, behavioural biases and emerging strategies. In particular, we detect unintended patterns of behavior through consistent actions, which can be interpreted as Market Imitation and Win-Stay Lose-Shift emerging strategies, with Market Imitation being the most dominant. We also observe that these strategies are affected by external factors: the expert advice, the lack of information or an information overload reinforce the use of these intuitive strategies, while the probability to follow them significantly decreases when subjects spends more time to make a decision. The cohort analysis shows that women and children are more prone to use such strategies although their performance is not undermined. Our results are of interest for better handling clients expectations of trading companies, to avoid behavioural anomalies in financial analysts decisions and to improve not only the design of markets but also the trading digital interfaces where information is set down. Strategies and behavioural biases observed can also be translated into new agent based modelling or stochastic price dynamics to better understand financial bubbles or the effects of asymmetric risk perception to price drops
Probability distribution of returns in the exponential Ornstein-Uhlenbeck model
We analyze the problem of the analytical characterization of the probability
distribution of financial returns in the exponential Ornstein-Uhlenbeck model
with stochastic volatility. In this model the prices are driven by a Geometric
Brownian motion, whose diffusion coefficient is expressed through an
exponential function of an hidden variable Y governed by a mean-reverting
process. We derive closed-form expressions for the probability distribution and
its characteristic function in two limit cases. In the first one the
fluctuations of Y are larger than the volatility normal level, while the second
one corresponds to the assumption of a small stationary value for the variance
of Y. Theoretical results are tested numerically by intensive use of Monte
Carlo simulations. The effectiveness of the analytical predictions is checked
via a careful analysis of the parameters involved in the numerical
implementation of the Euler-Maruyama scheme and is tested on a data set of
financial indexes. In particular, we discuss results for the German DAX30 and
Dow Jones Euro Stoxx 50, finding a good agreement between the empirical data
and the theoretical description.Comment: 26 pages, 9 figures and 3 tables. New section with real data analysis
and related references added, some minor typos corrected. Accepted for
publication on JSTA
Improving Scientific Knowledge of Mallorca Channel Seamounts (Western Mediterranean) within the Framework of Natura 2000 Network
The scientific exploration of Mallorca Channel seamounts (western Mediterranean) is
improving the knowledge of the Ses Olives (SO), Ausias March (AM), and Emile Baudot (EB)
seamounts for their inclusion in the Natura 2000 network. The aims are to map and characterize
benthic species and habitats by means of a geological and biological multidisciplinary approach:
high-resolution acoustics, sediment and rock dredges, beam trawl, bottom trawl, and underwater
imagery. Among the seamounts, 15 different morphological features were differentiated, highlighting
the presence of 4000 pockmarks, which are seafloor rounded depressions indicators of focused
fluid flow escapes, usually gas and/or water, from beneath the seabed sediments. So far, a total of
547 species or taxa have been inventoried, with sponges, fishes, mollusks, and crustaceans the most
diverse groups including new taxa and new geographical records. Up to 29 categories of benthic
habitats have been found, highlighting those included in the Habitats Directive: maërl beds on the
summits of AM and EB, pockmarks around the seamounts and coral reefs in their rocky escarpments
as well as fields of Isidella elongata on sedimentary bathyal bottoms. Trawling is the main demersal
fishery developed around SO and AM, which are targeted to deep water crustaceans: Parapenaeus
longirostris, Nephrops norvegicus, and Aristeus antennatus. This study provides scientific information
for the proposal of the Mallorca Channel seamounts as a Site of Community Importance and for its
final declaration as a Special Area of Conservation
Exploring Health Science Students’ Notions on Organ Donation and Transplantation: A Multicenter Study
The knowledge acquired during university education about organ donation and transplantation (ODT) decisively influences the information future health professionals transmit. This is important in ODT where the participation of the general public is essential to obtain organs. Objective: To determine notions of Spanish medicine and nursing students on ODT and its relationship with attitude toward ODT. Methods and Design: and design. We conducted a sociologic, multicenter, and observational study. The population for our study consisted of medical and nursing students in Spanish universities. Our database was the Collaborative International Donor Project, stratified by geographic area and academic course. A validated questionnaire (PCID-DTO-RIOS) was self-administered and completed anonymously. Our sample consisted of 9598 medical and 10, 566 nursing students (99% confidence interval; precision of ±1%), stratified by geographic area and year of study. Results: The completion rate for our study was 90%. Only 20% (n=3640) of students thought their notions on ODT were good; 41% (n=7531) thought their notions were normal; 36% (n=6550) thought their notions were scarce. Comparing groups, there were differences between those who believed that their notions on ODT were good (44% nursing vs 56% medical students; P < .000), and those who believed it scarce (54% nursing vs 46% medical students; P < .000). Notions on ODT were related with attitude toward the donation of one''s own organs: those who considered their notions were good were more in favor then those who considered it scarce (88% vs 72%; P < .000). Conclusion: Only 20% of Spanish medical and nursing students thought their notions on ODT were good. Having good knowledge is related to a favorable attitude towards ODT. Receiving specific information on the subject could improve their knowledge about ODT during their training
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