Density of states in graphene with vacancies: midgap power law and frozen multifractality

The density of states ϱ(E) of graphene is investigated numerically and within the self-consistent T-matrix approximation in the presence of vacancies within the tight binding model. The focus is on compensated disorder, where the concentration of vacancies n(A) and n(B) in both sublattices is the same. Formally, this model belongs to the chiral symmetry class BDI. The onlinear sigma model predicts for BDI a Gade-type singularity ϱ(E)∼|E|(-1)exp[-|log(E)|(-1/x)]. Our numerical data are comparable to this result in a preasymptotic regime that gives way, however, at even lower energies to ϱ(E)∼E(-1)|log(E)|(-x̃), 1≤x̃<2. We take this finding as evidence that, similar to the case of dirty d-wave superconductors, generic bipartite random hopping models may also exhibit unconventional (strong-coupling) fixed points for certain kinds of randomly placed scatterers if these are strong enough. Our research suggests that graphene with (effective) vacancy disorder is a physical representative of such systems.

Effectiveness of peer-based healthy living lesson plans on anthropometric measures and physical activity in elementary school students: a cluster randomized trial

IMPORTANCE

Schools are considered an attractive setting to promote healthy living behaviors in children, but previous school-based interventions aimed at preventing weight gain in children have yielded mixed results. Novel school-based approaches are needed to modify healthy living behaviors and attenuate weight gain in children.

OBJECTIVE

To assess the effectiveness of a peer-led healthy living program called Healthy Buddies on weight gain and its determinants when disseminated at the provincial level to elementary school students.

DESIGN, SETTING, AND PARTICIPANTS

Cluster-randomized effectiveness trial performed during the 2009-2010 school year. Baseline and follow-up measurements were made in October 2009 and May 2010, respectively. The study was performed in 19 elementary schools in Manitoba, Canada, and included 647 elementary school students aged 6 to 12 years (48% girls).

INTERVENTION

Schools were randomized to receive regular curriculum or Healthy Buddies lesson plans. Lesson plans were delivered by older (9- to 12-year-old) elementary school students to the younger (6- to 8-year-old) peers and targeted 3 components of health: physical activity, healthy eating, and self-esteem and body image.

MAIN OUTCOMES AND MEASURES

The primary outcome measures were the change in waist circumference and body mass index z score. Secondary outcomes included physical activity (steps per day), cardiorespiratory fitness, self-efficacy, healthy living knowledge, and self-reported dietary intake.

RESULTS

At baseline, 36% of children were overweight or obese and 11% achieved the recommended 13,500 steps per day. Intention-to-treat analyses showed that waist circumference declined significantly in the intervention group relative to controls: -1.42 cm (-2.68 to -0.17; P = .03). Reductions in waist circumference were particularly significant for children who were younger, overweight or obese, or attending First Nations schools. No difference in body mass index z score was observed between groups. Self-efficacy, healthy living knowledge, and dietary intake significantly improved in younger peers who received the intervention compared with students from control schools. No differences were observed in daily step counts or cardiorespiratory fitness between the groups.

CONCLUSIONS AND RELEVANCE

The implementation of Healthy Buddies lesson plans delivered by older peers within an elementary school setting is an effective method for attenuating increases in central adiposity and improving knowledge of healthy living behaviors among elementary school students. Improvements were achieved with parallel improvements in diet quality, self-efficacy, and knowledge of healthy living.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT01979978.

[Bladder cancer screening with urine-based tumour markers - occupational medical experience]

OBJECTIVE

Bladder cancer responds favourably to treatment and has a good survival rate, provided it is diagnosed at an early stage. Established methods exist for the early detection, however, their specificity and positive predictive value are not yet satisfactory. Innovative markers have been proposed, but still require validation in prospective studies. We provide a literature-based short overview on the currently available and some proposed markers for the early detection of bladder cancer and evaluate the need for validation in further studies. We further provide some first results of such a recently finished study in an occupational setting.

MATERIAL AND METHODS

We conducted a prospective screening study over seven years in 1610 males with former occupational exposure to carcinogenic aromatic amines. Annual bladder cancer screening according to statutory requirements was offered. In addition to the regularly performed check for hematuria and urine cytology, the markers NMP22, UroVysion™ and survivin were performed in voided urine samples of the participants. Positive findings (not for survivin) were further followed through urethrocystoscopy.

RESULTS AND CONCLUSIONS

A total of 7219 urine samples were screened. During the study period 16 incidental and 4 recurrent bladder tumours, thereof three papillomas, occurred in a total of 19 participants. 14 out of twenty tumours were marker-positive, and all but two were early stage findings. Cell-based markers (cytology, UroVysion™) und molecular markers (NMP22, survivin) were largely complementary, thus acting as a "multi-marker panel". Eight of the tumours were identified by a positive cytology. Six tumours were not detected by any of the tumour markers. The results will be further evaluated through the inclusion of confounding factors, which have so far rarely been examined in other studies. This may lead to the development of tiered diagnostic strategies with the aim to reduce the number of invasive diagnostic procedures in the future.

[Burn trauma--Part 2. Anesthesiological, surgical and intensive care management]

After initial stabilization of burn victims at the scene and in the trauma room, a tight cooperation and communication between anesthesiologists, plastic surgeons and intensive care specialists is needed for further therapy. Interdisciplinary communication about preoperative planning, timing of necrectomy and intensive care therapy is vital regarding functional and aesthetic outcome and survival rate. During burn surgery attention has to be paid to excessive blood loss and the danger of hypothermia. The main problems of intensive care therapy involve the evaluation of volume status, high demands for analgesia and sedation, high incidence of septic multiorgan failure and therapy and prophylaxis of the effects of hypermetabolism.

Geochemistry and toxicity of sediment porewater in a salt-impacted urban stormwater detention pond

A comprehensive study was carried out to investigate the impacts of road salts on the benthic compartment of a small urban detention facility, Rouge River Pond. Although the pond is an engineered water body, it is representative of many small urban lakes, ponds and wetlands, which receive road runoff and are probable high impact areas. Specific objectives of the study were to document the porewater chemistry of an aquatic system affected by elevated salt concentrations and to carry out a toxicological assessment of sediment porewater to determine what factors may cause porewater toxicity. The results indicate that the sediment porewater may itself attain high salt concentrations. The computations show that increased chloride levels have important implications on the Cd complexation, augmenting its concentration in porewater. The toxicity tests suggest that the toxicity in porewater is caused by metals or other toxic chemicals, rather than high levels of chloride.

Outcome and predictors of interstitial radiosurgery in the treatment of gelastic epilepsy

BACKGROUND

Gelastic epilepsy due to hypothalamic hamartomas is usually a severe condition encompassing both epileptic seizures and an epileptic encephalopathy associated with behavioral and cognitive impairments. Here we report the effects of interstitial radiosurgery in the treatment of this generally pharmacoresistant epilepsy syndrome.

METHODS

Twenty-four consecutive patients (3-46 years of age, 7 women, mean age 21.9 years, mean duration of epilepsy 17.6 years) with gelastic epilepsy due to MR-ascertained hypothalamic hamartoma and a minimum follow-up period of 1 year were included in this evaluation. Treatment was performed by interstitial radiosurgery using stereotactically implanted (125)I seeds. Effects of treatment on seizure frequency and possible side effects were assessed prospectively. Factors influencing outcome and side effects were analyzed statistically.

RESULTS

After a mean 24-month follow-up period following the last radiosurgical treatment, 11/24 patients were seizure free or had seizure reduction of at least 90% (Engel class I and II), in some cases only after repeated treatment. The duration of epilepsy prior to radiosurgery negatively influenced outcome. Treatment was well tolerated in most patients. Headache, fatigue, and lethargy were transient side effects associated with the development of brain edema extending from the implantation site in five patients. Four patients had a weight gain of more than 5 kg which was severe in two patients. The majority of those patients whose cognitive functions initially deteriorated showed subsequent recovery of cognitive functions, but episodic memory in two patients showed persistent decline at 1 year follow-up. Longer disease duration increased the risk for cognitive side effects, and larger hamartoma size and eccentric seed positioning increased the risk for radiogenic brain edema. Neither perioperative mortality nor neurologic impairments, visual field defects, or endocrinologic disturbances were encountered following treatment.

CONCLUSION

Interstitial radiosurgery was efficacious in significantly improving gelastic epilepsy in about half of the patients treated in this series. Weight gain may occur as a side effect, whereas other severe side effects reported following microsurgical removal of the hamartoma were absent. The study results strongly suggest early causal treatment, as chances for seizure control are higher and the risk for cognitive side effects is lower in patients with shorter disease duration.

The Wada test in Austrian, Dutch, German, and Swiss epilepsy centers from 2000 to 2005: a review of 1421 procedures

Twenty-six Austrian, Dutch, German, and Swiss epilepsy centers were asked to report on use of the Wada test (intracarotid amobarbital procedure, IAP) from 2000 to 2005 and to give their opinion regarding its role in the presurgical diagnosis of epilepsy. Sixteen of the 23 centers providing information had performed 1421 Wada tests, predominantly the classic bilateral procedure (73%). A slight nonsignificant decrease over time in Wada test frequency, despite slightly increasing numbers of resective procedures, could be observed. Complication rates were relatively low (1.09%; 0.36% with permanent deficit). Test protocols were similar even though no universal standard protocol exists. Clinicians rated the Wada test as having good reliability and validity for language determination, whereas they questioned its reliability and validity for memory lateralization. Several noninvasive functional imaging techniques are already in use. However, clinicians currently do not want to rely solely on noninvasive functional imaging in all patients.

Occurrence of alkylphenolic substances in a Great Lakes coastal marsh, Cootes Paradise, ON, Canada

Occurrence and fate of alkylphenols (APs), known endocrine disruptors, were investigated in a Great Lakes coastal wetland, Cootes Paradise, ON. The wetland, which receives discharges from a Wastewater Treatment Plant (WTP) and several Combined Sewer Overflows (CSOs), is an important spawning ground for fish and crucial habitat for other fauna. Elevated concentrations of nonylphenol ethoxylates (NPEs) and their degradation product nonylphenol (NP) were found in water and sediment samples near the sources. Since transfer of APs through the food chain is of concern, we compared their concentrations in invertebrates from clean and contaminated sites. The results reveal transfer of alkylphenolics from sediments to biota and their accumulation in the invertebrate tissue, particularly the highly hydrophobic 4-NP, whose concentrations ranged from 1.9 to 6.3 microg g(-1). To our knowledge, this is the first study to evaluate AP concentrations in tissue of benthic invertebrates under real environmental conditions.

Assessment of cognitive functions before and after stereotactic interstitial radiosurgery of hypothalamic hamartomas in patients with gelastic seizures

We assessed cognitive functions before and 3 months after interstitial radiotherapy in 14 patients with gelastic seizures caused by hypothalamic hamartoma. Cognitive functioning was assessed before temporary implantation of (125)I-seed and 3 months after seed explantation. Performance was compared with that of a selected control group of conservatively treated patients with symptomatic focal epilepsy tested before add-on treatment with a new antiepileptic drug and after reaching steady state. No short-term negative side effects of the interstitial radiosurgery could be observed for the domains of attention and executive functions and verbal and figural memory performance. Cognitive development of the patients treated with seeds was comparable to that of the control group at both assessments. Thus, the stereotactic implantation of (125)I-seeds in this patient group with gelastic seizures caused by hypothalamic hamartoma provides a well-tolerated minimally invasive method in the treatment of this severe epileptic syndrome without negative cognitive side effects.