1,460 research outputs found
Environmental drivers of distribution and reef development of the Mediterranean coral Cladocora caespitosa
Cladocora caespitosa is the only Mediterranean scleractinian similar to tropical reef-building corals. While this species is part of the recent fossil history of the Mediterranean Sea, it is currently considered endangered due to its decline during the last decades. Environmental factors affecting the distribution and persistence of extensive bank reefs of this endemic species across its whole geographic range are poorly understood. In this study, we examined the environmental response of C. caespitosa and its main types of assemblages using ecological niche modeling and ordination analysis. We also predicted other suitable areas for the occurrence of the species and assessed the conservation effectiveness of Mediterranean marine protected areas (MPAs) for this coral. We found that phosphate concentration and wave height were factors affecting both the occurrence of this versatile species and the distribution of its extensive bioconstructions in the Mediterranean Sea. A set of factors (diffuse attenuation coefficient, calcite and nitrate concentrations, mean wave height, sea surface temperature, and shape of the coast) likely act as environmental barriers preventing the species from expansion to the Atlantic Ocean and the Black Sea. Uncertainties in our large-scale statistical results and departures from previous physiological and ecological studies are also discussed under an integrative perspective. This study reveals that Mediterranean MPAs encompass eight of the ten banks and 16 of the 21 beds of C. caespitosa. Preservation of water clarity by avoiding phosphate discharges may improve the protection of this emblematic species.Spanish Ministry of Economy and Competitiveness [CTM2014-57949-R]info:eu-repo/semantics/publishedVersio
Photon deflection by a Coulomb field in noncommutative QED
In noncommutative QED photons present self-interactions in the form of triple
and quartic interactions. The triple interaction implies that, even though the
photon is electrically neutral, it will deflect when in the presence of an
electromagnetic field. If detected, such deflection would be an undoubted
signal of noncommutative space-time. In this work we derive the general
expression for the deflection of a photon by any electromagnetic field. As an
application we consider the case of the deflection of a photon by an external
static Coulomb field.Comment: 07 pages, some typos corrected, accepted for publication in JP
Experiences of maltreatment in childhood and attention to facial emotions in healthy young women
Using reaction-time measures, research on the relationship between childhood maltreatment and biased attention to emotional stimuli in adults has obtained inconsistent results. To help clarify this issue, we conducted an eye-tracking study on the link between childhood maltreatment and allocation of attention to facial emotions analyzing gaze behavior in addition to manual reactions. In contrast to prior investigations, we excluded individuals with tendencies to minimize maltreatment experiences from analyses. Gaze behavior and manual response time of 58 healthy women were examined in a dot-probe task in which pairs of emotional (happy, sad, or disgusted) and neutral faces were presented. In our analyses, participants’ affectivity, level of alexithymia, and intelligence were controlled. Entry time and dwell time on facial expressions were used as indicators of attention allocation. Childhood maltreatment showed no effect on response latencies but was associated with shorter entry times on emotional faces and shorter dwell time on disgusted faces. Experiences of childhood maltreatment seem to be linked to an increased early vigilance to emotional social signals and to an attentional avoidance of hostile facial expressions at a later stage of perception. The present results suggest a vigilance-avoidance pattern of attention allocation associated with childhood maltreatment
Effect of Aging on the Reversibility of Pu(IV) Sorption to Goethite
Designing safe remediation and disposal strategies for plutonium (Pu) requires understanding the sorption affinity of Pu for soil minerals. Sorption of Pu(IV) was examined with respect to aging for a goethite system using batch sorption experiments. Sorption of Pu(IV) to iron oxides has been observed to be strong, rapid, and possibly irreversible or hysteretic. These observations may be explained by aging, a surface chemical process happening after initial sorption which causes a change in contaminant surface speciation over time. Measurements of Pu(IV) sorption are often complicated by oxidative leaching of Pu(IV) as Pu(V). Desferrioxamine B (DFOB) is a complexant capable of competing with the proposed strong surface complexes. Additionally, DFOB minimizes oxidative leaching by forming strong Pu(IV)-DFOB complexes, thereby stabilizing Pu(IV) as the dominant aqueous oxidation state. Pu(IV) was reacted in suspensions of 0.1g/L goethite and 10mM NaCl spanning pH 4–7 for various lengths of time (1,6,15,34 and 116 days). Supernatant was replaced with a 1.7µM DFOB solution and, after 34 more days, analyzed for aqueous Pu by liquid scintillation counting. Modeling sorption curves in FITEQL yielded logK values which increased from 0.078 to 0.953 over 116 days, indicating Pu(IV) sorption onto goethite becomes less reversible with aging
Food intake of European adolescents in the light of different food-based dietary guidelines : results of the HELENA (Healthy Lifestyle in Europe by Nutrition in Adolescence) study
Objective: Since inadequate food consumption patterns during adolescence are not only linked with the occurrence of obesity in youth but also with the subsequent risk of developing diseases in adulthood, the establishment and maintenance of a healthy diet early in life is of great public health importance. Therefore, the aim of the present study was to describe and evaluate the food consumption of a well-characterized sample of European adolescents against food-based dietary guidelines for the first time.
Design: The HELENA (Healthy Lifestyle in Europe by Nutrition in Adolescence) Study is a cross-sectional study, whose main objective was to obtain comparable data on a variety of nutritional and health-related parameters in adolescents aged 12.5-17.5 years.
Setting: Ten cities in Europe.
Subjects: The initial sample consisted of more than 3000 European adolescents. Among these, 1593 adolescents (54% female) had sufficient and plausible dietary data on energy and food intakes from two 24 h recalls using the HELENA-DIAT software.
Results: Food intake of adolescents in Europe is not optimal compared with the two food-based dietary guidelines, Optimized Mixed Diet and Food Guide Pyramid, examined in this study. Adolescents eat half of the recommended amount of fruit and vegetables and less than two-thirds of the recommended amount of milk (and milk products), but consume much more meat (and meat products), fats and sweets than recommended. However, median total energy intake may be estimated to be nearly in line with the recommendations.
Conclusion: The results urge the need to improve the dietary habits of adolescents in order to maintain health in later life
Coping with anxiety: Brain structural correlates of vigilance and cognitive avoidance
Background: Individuals differ in their dispositional coping behavior when they are confronted with anxiety-provoking situations. Cognitive avoidance is characterized by a withdrawal from threatening information, whereas vigilance denotes the intensive search for threat-related information. Functional neuroimaging studies indicate alterations in brain responsivity to emotional stimuli as a function of cognitive avoidant and vigilant coping, but findings are partially discrepant. Studies on structural correlates of coping styles are scarce. Materials and Methods: By using structural magnetic resonance imaging, the present study examined the relationship between brain gray matter volume and coping strategies in 114 healthy individuals. Individual differences in vigilance and cognitive avoidance were measured by the Mainz Coping Inventory. Results: Exploratory whole-brain analyses were conducted. Cognitive avoidant coping significantly predicted reduced gray matter volume in the bilateral thalamus, whereas vigilant coping was associated with volumetric increases in the bilateral thalamus. These relationships remained significant when controlling for a potential influence of age, sex, depressive symptoms, and trait anxiety. Discussion: Our findings indicate that dispositional strategies to deal with anxiety-provoking situations are related to volumetric alterations in the thalamus, a brain structure that has been implicated in the mediation of attentional processes and alertness, and the anticipation of harm. The dispositional tendency to monitor the environment for potential threats (i.e., vigilance), appears to be associated with volumetric increases in the thalamus, whereas the dispositional inclination to divert one’s attention away from distressing stimuli (i.e., cognitive avoidance) seems to go along with reductions in thalamic gray matter density
Theory of Electric Field-Induced Photoluminescence Quenching in Disordered Molecular Solids
The dynamics of excitons in disordered molecular solids is studied
theoretically, taking into account migration between different sites,
recombination, and dissociation into free charge carriers in the presence of an
electric field. The theory is applied to interpret the results of electric
field-induced photoluminescence (PL) quenching experiments on molecularly doped
polymers by Deussen et al. [Chem. Phys. 207, 147 (1996)]. Using an
intermolecular dissociation mechanism, the dependence of the PL quenching on
the electric field strength and the dopant concentration, and the time
evolution of the transient PL quenching can be well described. The results
constitute additional proof of the distinct exciton dissociation mechanisms in
conjugated polymer blends and molecularly doped polymers.Comment: 4 pages RevTeX, 3 Postscript figure
Using Subsystem MT2 for Complete Mass Determinations in Decay Chains with Missing Energy at Hadron Colliders
We propose to use the MT2 concept to measure the masses of all particles in
SUSY-like events with two unobservable, identical particles. To this end we
generalize the usual notion of MT2 and define a new MT2(n,p,c) variable, which
can be applied to various subsystem topologies, as well as the full event
topology. We derive analytic formulas for its endpoint MT2{max}(n,p,c) as a
function of the unknown test mass Mc of the final particle in the subchain and
the transverse momentum pT due to radiation from the initial state. We show
that the endpoint functions MT2{max}(n,p,c)(Mc,pT) may exhibit three different
types of kinks and discuss the origin of each type. We prove that the subsystem
MT2(n,p,c) variables by themselves already yield a sufficient number of
measurements for a complete determination of the mass spectrum (including the
overall mass scale). As an illustration, we consider the simple case of a decay
chain with up to three heavy particles, X2 -> X1 -> X0, which is rather
problematic for all other mass measurement methods. We propose three different
MT2-based methods, each of which allows a complete determination of the masses
of particles X0, X1 and X2. The first method only uses MT2(n,p,c) endpoint
measurements at a single fixed value of the test mass Mc. In the second method
the unknown mass spectrum is fitted to one or more endpoint functions
MT2{max}(n,p,c)(Mc,pT) exhibiting a kink. The third method is hybrid, combining
MT2 endpoints with measurements of kinematic edges in invariant mass
distributions. As a practical application of our methods, we show that the
dilepton W+W- and tt-bar samples at the Tevatron can be used for an independent
determination of the masses of the top quark, the W boson and the neutrino,
without any prior assumptions.Comment: 47 pages, 9 figures. revised version, published in JHEP. Major
addition: a new appendix with the complete set of formulas for the MT2
endpoints as functions of the upstream transverse momentum pT and test mass
M
Validation of the Berlin Grading System for moyamoya angiopathy with the use of [15O]H2O PET
The Berlin Grading System assesses clinical severity of moyamoya angiopathy (MMA) by combining MRI, DSA, and cerebrovascular reserve capacity (CVRC). Our aim was to validate this grading system using [O-15]H2O PET for CVRC. We retrospectively identified bilateral MMA patients who underwent [O-15]H2O PET examination and were treated surgically at our department. Each hemisphere was classified using the Suzuki and Berlin Grading System. Preoperative symptoms and perioperative ischemias were collected, and a logistic regression analysis was performed. A total of 100 hemispheres in 50 MMA patients (36 women, 14 men) were included. Using the Berlin Grading System, 2 (2.8%) of 71 symptomatic hemispheres were categorized as grade I, 14 (19.7%) as grade II, and 55 (77.5%) as grade III. The 29 asymptomatic hemispheres were characterized as grade I in 7 (24.1%) hemispheres, grade II in 12 (41.4%), and grade III in 10 (34.5%) hemispheres. Berlin grades were independent factors for identifying hemispheres as symptomatic and higher grades correlated with increasing proportion of symptomatic hemispheres (p < 0.01). The Suzuki grading did not correlate with preoperative symptoms (p = 0.26). Perioperative ischemic complications occurred in 8 of 88 operated hemispheres. Overall, complications did not occur in any of the grade I hemispheres, but in 9.1% (n = 2 of 22) and 9.8% (n = 6 of 61) of grade II and III hemispheres, respectively. In this study, we validated the Berlin Grading System with the use of [O-15]H2O PET for CVRC as it could stratify preoperative symptomatology. Furthermore, we highlighted its relevance for predicting perioperative ischemic complications
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