Local Optical Probe of Motion and Stress in a multilayer graphene NEMS

Nanoelectromechanical systems (NEMSs) are emerging nanoscale elements at the crossroads between mechanics, optics and electronics, with significant potential for actuation and sensing applications. The reduction of dimensions compared to their micronic counterparts brings new effects including sensitivity to very low mass, resonant frequencies in the radiofrequency range, mechanical non-linearities and observation of quantum mechanical effects. An important issue of NEMS is the understanding of fundamental physical properties conditioning dissipation mechanisms, known to limit mechanical quality factors and to induce aging due to material degradation. There is a need for detection methods tailored for these systems which allow probing motion and stress at the nanometer scale. Here, we show a non-invasive local optical probe for the quantitative measurement of motion and stress within a multilayer graphene NEMS provided by a combination of Fizeau interferences, Raman spectroscopy and electrostatically actuated mirror. Interferometry provides a calibrated measurement of the motion, resulting from an actuation ranging from a quasi-static load up to the mechanical resonance while Raman spectroscopy allows a purely spectral detection of mechanical resonance at the nanoscale. Such spectroscopic detection reveals the coupling between a strained nano-resonator and the energy of an inelastically scattered photon, and thus offers a new approach for optomechanics

Graphene-based ultrathin flat lenses

Flat lenses when compared to curved surface lenses have the advantages of being aberration free and they offer a compact design necessary for a myriad of electro-optical applications. In this paper we present flat and ultra-thin lenses based on graphene, the world’s thinnest known material. Monolayers and low number multilayers of graphene were fabricated into Fresnel zones to produce Fresnel zone plates which utilize the reflection and transmission properties of graphene for their operation. The working of the lens and their performance in the visible and terahertz regimes was analyzed computationally. Experimental measurements were also performed to characterize the lens in the visible regime and a good agreement was obtained with the simulations. The work demonstrates the principle of atom thick graphene-based lenses, with perspectives for ultra-compact integration.HB would like to thank The Leverhulme Trust for the research funding. QD is supported by Bureau of International Cooperation, Chinese Academy of Sciences (121D11KYSB20130013).This is the accepted manuscript. The final version is available from ACS at http://pubs.acs.org/doi/abs/10.1021/ph500197j

Assessing survival in widowers, and controls -A nationwide, six- to nine-year follow-up

To access full text version of this article. Please click on the hyperlink "View/open" at the bottom of this pageThe aim of this study was to assess if widowers had an increased mortality rate during the first 6 to 9 years after the death of their wife, compared initially to an age-matched control group and also compared to the general population of Iceland. The study base was comprised of all 371 men born in 1924-1969 who were widowed in Iceland in 1999-2001 and 357 controls, married men, who were matched by age and residence.The widowers and controls were followed through the years 2002-2007 using information from Statistics Iceland. Mortality rates were compared between the groups and also with the general population. The mortality rate comparisons were: study group vs. control group, on the one hand, and study group vs. general population on the other. Causes of death were also compared between widowers and their wives. A statistically significant increase in mortality in the widowers' group, compared to controls, was observed.Lifestyle-related factors could not be excluded as contributing to cause of death in these cases. Being a widower was related to an increased risk of death for at least 9 years after the death of their wife.Landspitali - National University Hospital in Reykjavik Iceland, Rannis, the Icelandic Centre for Research (provides assistance to Icelandic science & technology, Reykjavik, Iceland), Utfararstofa Islands (a funeral home, Reykjavik, Iceland), Swedish Cancer Society (Cancerfonden), Styrktarsjodur Lifsins samtaka um liknarmedferd (Palliative Care Association, Iceland), Utfarastofa Kirkjugardanna (a funeral home, Reykjavik, Iceland

Among-individual diet variation within a lake trout ecotype: lack of stability of niche use

In a polyphenic species, differences in resource use are expected among ecotypes, and homogeneity in resource use is expected within an ecotype. Yet, using a broad resource spectrum has been identified as a strategy for fishes living in unproductive northern environments, where food is patchily distributed and ephemeral. We investigated whether specialization of trophic resources by individuals occurred within the generalist piscivore ecotype of lake trout from Great Bear Lake, Canada, reflective of a form of diversity. Four distinct dietary patterns of resource use within this lake trout ecotype were detected from fatty acid composition, with some variation linked to spatial patterns within Great Bear Lake. Feeding habits of different groups within the ecotype were not associated with detectable morphological or genetic differentiation, suggesting that behavioral plasticity caused the trophic differences. A low level of genetic differentiation was detected between exceptionally large‐sized individuals and other piscivore individuals. We demonstrated that individual trophic specialization can occur within an ecotype inhabiting a geologically young system (8,000–10,000 yr BP), a lake that sustains high levels of phenotypic diversity of lake trout overall. The characterization of niche use among individuals, as done in this study, is necessary to understand the role that individual variation can play at the beginning of differentiation processes

Epidemiology of liver cirrhosis morbidity and mortality in Iceland

BACKGROUND: The mortality from liver cirrhosis in Iceland is the lowest in the Western world. OBJECTIVE: To study the epidemiology of liver cirrhosis mortality and morbidity in Iceland and to obtain a reliable separation between alcoholic cirrhosis (AC) and non-alcoholic cirrhosis (NAC) by using multiple data sources. METHODS: The study included the whole population of Iceland. Mortality was studied through death certificate data for the period 1951-90 and morbidity (clinical incidence) through hospital, autopsy and biopsy records for the period 1971-90. RESULTS: The average mortality for AC in age group 20 years and older was 8.6 and for NAC 19.2 per 10(6)/year and the average clinical incidence was 22.1 per 10(6)/year for AC and 25.9 per 10(6)/year for NAC. In the morbidity study 44% of cases were due to AC. In the mortality study 24% of cases were due to AC but the data suggested an underreporting of AC for males at a rate of 30%. There was a significant decrease in AC mortality with time but no change in NAC. Average alcohol consumption of inhabitants aged over 15 years increased from 2.1 to 4.9 litres per year (130%) during the period 1951-90. CONCLUSION: The incidence of cirrhosis in Iceland is very low for both AC and NAC, accounting for only 0.2% of total deaths. The reasons are unknown. The low incidence of AC in Iceland is probably partly due to low alcohol consumption. The decreasing incidence of AC despite 130% increase in alcohol consumption is thought to be due to intensive treatment of alcoholism. A low prevalence of hepatitis B and C probably contributes to the low incidence of NAC

The psychometric properties of the Icelandic version of the distress thermometer and problem list.

To access publisher full text version of this article. Please click on the hyperlink in Additional Links field.While a significant number of cancer patients experience distress only a minority are offered appropriate psychosocial interventions. Untreated distress can interfere with compliance to treatment and quality of life. The purpose of this study was to evaluate the psychometric properties and feasibility of the Icelandic translation of the distress thermometer (DT) and problem list, a tool developed to screen for distress in cancer patients.   Participants were 149 cancer patients receiving treatment at outpatient oncology clinics at Landspítali-The National University Hospital of Iceland, mean±SD age 59.06 years ±12.92. Participants answered the DT, HADS and GHQ-30, demographic questions and questions regarding the DT.   Scores on the DT ranged from 0 to 10 with a mean ±SD score of 3.09 ± 2.40, 7.30 ± 4.86 on HADS and 5.28 ± 5.60 on GHQ-30. Significant correlations were between the DT and all categories on the Problem List as well as between the DT and HADS (r = 0.45), and between DT and GHQ-30 (r = 0.57). ROC-analysis supported that a cut-off point of 3 gives the best sensitivity and specificity for the DT predicting depression or anxiety according to the HADS and GHQ. Sixty-nine (48.3%) patients scored < or =2 on DT and 74 (51.7%) scored ≥3.   The Icelandic version of the DT is a valid instrument to screen for distress in clinical practice. The study adds to a growing literature suggesting that this brief instrument may aid in identifying cancer patients suffering from distress and consequently providing appropriate treatment