Isosbestic Points: Theory and Applications

We analyze the sharpness of crossing ("isosbestic") points of a family of curves which are observed in many quantities described by a function f(x,p), where x is a variable (e.g., the frequency) and p a parameter (e.g., the temperature). We show that if a narrow crossing region is observed near x* for a range of parameters p, then f(x,p) can be approximated by a perturbative expression in p for a wide range of x. This allows us, e.g., to extract the temperature dependence of several experimentally obtained quantities, such as the Raman response of HgBa2CuO4+delta, photoemission spectra of thin VO2 films, and the reflectivity of CaCu3Ti4O12, all of which exhibit narrow crossing regions near certain frequencies. We also explain the sharpness of isosbestic points in the optical conductivity of the Falicov-Kimball model and the spectral function of the Hubbard model.Comment: 12 pages, 11 figure

Obrada čelika P2-04BCH kutno kanalnom ekstruzijom (KKE)

The article presents results of investigation of structure and properties of low-carbon steel grade P2-04BCH after application of ECAE at temperature of approx. 290C. The ECAE method leads to significant improvement of strength of investigated material. Investigation of structure was made by combination of TEM and FEG SEM together with EBSD. It was proven the ECAE method enables obtaining of ultra fine-grained ferritic structure formed by recrystallised grains with very low density of dislocations and with a small portion of spheroidised carbides, which occurred usually on the boundaries of ferritic grains.Članak prikazuje rezultate istraživanja strukture i svojstava niskougljičnog čelika kvalitete P2-04BCH nakon kanalno kutne ekstruzije (KKE) pri temperaturi od oko 290°C. Zabilježen je značajan porast čvrstoće materijala. Struktura je ispitana kombinacijom transmisijskog elektronskog mikroskopa (TEM), skenirajućeg elektronskog mikroskopa s emisijom polja (FEG SEM) te elektronskom difrakcijom (EBSD). Dokazano je da se jednakokanalnom kutnom ekstruzijom postiže izuzetno sitnozrnata feritna struktura rekristalizacijom zrna, uz vrlo nisku gustoću dislokacija i mali udio sferičnih karbida s rasporedom, obično na granicama feritnih zrna

Consistent alleviation of abiotic stress with silicon addition: a meta-analysis

1. Hundreds of single species studies have demonstrated the facility of silicon (Si) to alleviate diverse abiotic stresses in plants. Understanding of the mechanisms of Si-mediated stress alleviation is progressing, and several reviews have brought information together. A quantitative assessment of the alleviative capacity of Si, however, which could elucidate plant Si function more broadly, was lacking. 2. We combined the results of 145 experiments, predominantly on agricultural species, in a meta-analysis to statistically assess the responses of stressed plants to Si supply across multiple plant families and abiotic stresses. We interrogated our database to determine whether stressed plants increased in dry mass and net assimilation rate, oxidative stress markers were reduced, antioxidant responses were increased and whether element uptake showed consistent changes when supplied with Si. 3. We demonstrated that across plant families and stress types, Si increases dry weight, assimilation rate and chlorophyll biosynthesis and alleviates oxidative damage in stressed plants. In general, results indicated that plant family (as a proxy for accumulator type) and stress type had significant explanatory power for variation in responses. The consistent reduction in oxidative damage was not mirrored by consistent increases in antioxidant production, indicative of the several different stress alleviation mechanisms in which Si is involved. Silicon addition increased K in shoots, decreased As and Cd in roots and Na and Cd in shoots. Silicon addition did not affect Al, Ca or Mn concentration in shoots and roots of stressed plants. Plants had significantly lower concentrations of Si accumulated in shoots but not in roots when stressed. 4. Meta-analyses showed consistent alleviation by Si of oxidative damage caused by a range of abiotic stresses across diverse species. Our findings indicate that Si is likely to be a useful fertilizer for many crops facing a spectrum of abiotic stresses. Similarities in responses across families provide strong support for a role of Si in the alleviation of abiotic stress in natural systems, where it has barely been explored. We suggest this role may become more important under a changing climate and more experiments using non-agricultural species are now needed

Recording advances for neural prosthetics

An important challenge for neural prosthetics research is to record from populations of neurons over long periods of time, ideally for the lifetime of the patient. Two new advances toward this goal are described, the use of local field potentials (LFPs) and autonomously positioned recording electrodes. LFPs are the composite extracellular potential field from several hundreds of neurons around the electrode tip. LFP recordings can be maintained for longer periods of time than single cell recordings. We find that similar information can be decoded from LFP and spike recordings, with better performance for state decodes with LFPs and, depending on the area, equivalent or slightly less than equivalent performance for signaling the direction of planned movements. Movable electrodes in microdrives can be adjusted in the tissue to optimize recordings, but their movements must be automated to be a practical benefit to patients. We have developed automation algorithms and a meso-scale autonomous electrode testbed, and demonstrated that this system can autonomously isolate and maintain the recorded signal quality of single cells in the cortex of awake, behaving monkeys. These two advances show promise for developing very long term recording for neural prosthetic applications

The role of family functioning and self-esteem in the quality of life of adolescents referred for psychiatric services: a 3-year follow-up.

PurposeTo investigate, in adolescents referred for psychiatric services, the associations of initial self-esteem and family functioning with level and change of quality of life (QoL) over a 3-year period, over and above the effect of their emotional problems.MethodsOf 1648 eligible 13-18 years old patients attending the child and adolescent psychiatric clinic (CAP) at least once, 717 (54.8% females) were enrolled at baseline (a response rate of 43.5%). Self- and parent reports on the McMaster Family Assessment Device were obtained. Adolescents reported self-esteem on the Rosenberg Scale, and emotional problems on the Symptom Check List-5. Adolescents completed the Inventory of Life Quality in Children and Adolescents (ILC). After 3 years, 570 adolescents again completed the ILC, and for 418 adolescents parent information was available. The longitudinal analysis sample of 418 adolescents was representative of the baseline sample for age, gender, emotional problems, and QoL. We used modified growth-model analysis, adjusted for SES, age, gender and time of contact with CAP, where residual variances for ILC at baseline and follow-up were fixed to 0.ResultsA poorer family functioning at baseline, reported by parents, was significantly associated with worsening QoL during the 3 years follow-up period (p = 0.001).ConclusionsParents have important knowledge about their families that may reflect long-term influences on QoL development in adolescent psychiatric patients. Health care providers and policy makers should optimize treatment outcomes by addressing family functioning in adolescents with emotional problems

Struktura i svojstva titana za zubne umetke (implantate)

This paper describes manufacture of nano-structural titanium, its structure and properties. Nano-titanium has higher specific strength properties than ordinary (coarse-grained) titanium. Nano-titanium was produced by the equal-channel angular pressing (ETAP) process. The research it self was focused on physical base of strengthening and softening processes and developments occurring at the grain boundaries during the ECAP process at half-hot temperature. Strength of nano-titanium varies around 960 MPa, grain size around 300 nm.Rad opisuje proizvodnju nanostrukturnog titana te njegovu strukturu i svojstva. Nanotitan se odlikuje višom čvrstoćom od običnog, krupnozrnatog, i proizveden je kanalno kutnim prešanjem (KKP). Samo istraživanje bilo je usmjereno na fizikalne osnove procesa očvršćavanja i omekšavanja na granicama zrna tijekom procesa kanalno kutnim prešanjem (KKP) na srednjim temperaturama. Čvrstoća nanotitana varira oko 960 MPa, a veličina zrna je oko 300 nm

A multi-isotope approach to evaluate the potential of great cormorant eggs for contaminant monitoring

Contaminant monitoring in biota is important for determining environmental status and to detect or prioritize action on hazardous substances. Predators higher up a food chain are often used for monitoring of contaminants that bioaccumulate. However, it is not always possible to find higher predators that are both abundant and have a wide distribution for national or international contaminant monitoring. Great cormorants (Phalocrocorax carbo) are a widespread and increasingly common top predator of fish in fresh, brackish and salt water. We evaluate the suitability of great cormorant eggs as a matrix for contaminant monitoring by using stable isotopes of carbon, nitrogen and sulfur. Despite the fact that cormorants are migratory, egg isotope values showed a significant separation between five breeding colonies in Sweden (1 fresh water lake, 3 Baltic sites and 1 marine site). This high degree of separation indicates that eggs are primarily produced using local resources (not stored body resources) and that contaminants (mercury concentrations in this study) measured in eggs likely reflect levels in fish prey caught close to the breeding area. Compound specific stable isotope analysis was used to estimate cormorant trophic position (TP) and concentrations of mercury in eggs were positively related to TP. The results show that a multi-isotope approach, combined with good ecological diet knowledge allow for meaningful and comparative interpretation of mercury concentrations in biota and that great cormorant eggs appear a suitable matrix to measure locally derived and maternally transferred contaminants

Worldline approach to helicity flip in plane waves

We apply worldline methods to the study of vacuum polarisation effects in plane wave backgrounds, in both scalar and spinor QED. We calculate helicity-flip probabilities to one loop order and treated exactly in the background field, and provide a toolkit of methods for use in investigations of higher-order processes. We also discuss the connections between the worldline, S-matrix, and lightfront approaches to vacuum polarisation effects.Comment: 11 pages, 1 figur

Risk of ischemic heart disease after radiotherapy for ductal carcinoma in situ

The use of adjuvant radiotherapy (RT) in the management of ductal carcinoma in situ (DCIS) is increasing. Left-sided breast irradiation may involve exposure of the heart to ionising radiation, increasing the risk of ischemic heart disease (IHD). We examined the incidence of IHD in a population-based cohort of women with DCIS. The Breast Cancer DataBase Sweden (BCBase) cohort includes women registered with invasive and in situ breast cancers 1992-2012 and age-matched women without a history of breast cancer. In this analysis, 6270 women with DCIS and a comparison cohort of 31,257 women were included. Through linkage with population-based registers, data on comorbidity, socioeconomic status and incidence of IHD was obtained. Hazard ratios (HR) for IHD with 95% confidence intervals (CI) were analysed. Median follow-up time was 8.8 years. The risk of IHD was not increased for women with DCIS versus women in the comparison cohort (HR 0.93; 95% CI 0.82-1.06), after treatment with radiotherapy versus surgery alone (HR 0.77; 95% CI 0.60-0.98) or when analysing RT by laterality (HR 0.85; 95% CI 0.53-1.37 for left-sided versus right-sided RT). The risk of IHD was lower for women with DCIS allocated to RT compared to non-irradiated women and to the comparison cohort, probably due to patient selection. Comparison of RT by laterality did not show any over-risk for irradiation of the left breast.Peer reviewe