Dielectric nano-antennas for strain engineering in atomically thin two-dimensional semiconductors

Atomically thin two-dimensional semiconducting transition metal dichalcogenides (TMDs) can withstand large levels of strain before their irreversible damage occurs. This unique property offers a promising route for control of the optical and electronic properties of TMDs, for instance by depositing them on nano-structured surfaces, where position-dependent strain can be produced on the nano-scale. Here, we demonstrate strain-induced modifications of the optical properties of mono- and bilayer TMD WSe$_2$ placed on photonic nano-antennas made from gallium phosphide (GaP). Photoluminescence (PL) from the strained areas of the TMD layer is enhanced owing to the efficient coupling with the confined optical mode of the nano-antenna. Thus, by following the shift of the PL peak, we deduce the changes in the strain in WSe$_2$ deposited on the nano-antennas of different radii. In agreement with the presented theory, strain up to $\approx 1.4 \%$ is observed for WSe$_2$ monolayers. We also estimate that $>3\%$ strain is achieved in bilayers, accompanied with the emergence of a direct bandgap in this normally indirect-bandgap semiconductor. At cryogenic temperatures, we find evidence of the exciton confinement in the most strained nano-scale parts of the WSe$_2$ layers, as also predicted by our theoretical model. Our results, of direct relevance for both dielectric and plasmonic nano-antennas, show that strain in atomically thin semiconductors can be used as an additional parameter for engineering light-matter interaction in nano-photonic devices

Higher systolic blood pressure in early-mid adulthood is associated with poorer cognitive performance in those with a dominantly inherited Alzheimer's disease mutation but not in non-carriers. Results from the DIAN study

BACKGROUND: The Dominantly Inherited Alzheimer Network (DIAN) is a longitudinal observational study that collects data on cognition, blood pressure (BP), and other variables from autosomal-dominant Alzheimer's disease mutation carriers (MCs) and non-carrier (NC) family members in early to mid-adulthood, providing a unique opportunity to evaluate BP and cognition relationships in these populations. METHOD: We examined cross-sectional and longitudinal relationships between systolic and diastolic BP and cognition in DIAN MC and NC. RESULTS: Data were available from 528 participants, who had a mean age of 38 (SD = 11) and were 42% male and 61% MCs, at a median follow-up of 2 years. Linear-multilevel models found only cross-sectional associations in the MC group between higher systolic BP and poorer performance on language (β = −0.181 [−0.318, −0.044]), episodic memory (−0.212 [−0.375, −0.049]), and a composite cognitive measure (−0.146 [−0.276, −0.015]). In NCs, the relationship was cross-sectional only and present for language alone. DISCUSSION: Higher systolic BP was cross-sectionally but not longitudinally associated with poorer cognition, particularly in MCs. BP may influence cognition gradually, but further longitudinal research is needed

Four patients with a history of acute exacerbations of COPD: implementing the CHEST/Canadian Thoracic Society guidelines for preventing exacerbations

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Combined effects of precipitation and nitrogen deposition on native and invasive winter annual production in California deserts

Primary production in deserts is limited by soil moisture and N availability, and thus is likely to be influenced by both anthropogenic N deposition and precipitation regimes altered as a consequence of climate change. Invasive annual grasses are particularly responsive to increases in N and water availabilities, which may result in competition with native forb communities. Additionally, conditions favoring increased invasive grass production in arid and semi-arid regions can increase fire risk, negatively impacting woody vegetation that is not adapted to fire. We conducted a seeded garden experiment and a 5-year field fertilization experiment to investigate how winter annual production is altered by increasing N supply under a range of water availabilities. The greatest production of invasive grasses and native forbs in the garden experiment occurred under the highest soil N (inorganic N after fertilization = 2.99 g m−2) and highest watering regime, indicating these species are limited by both water and N. A classification and regression tree (CART) analysis on the multi-year field fertilization study showed that winter annual biomass was primarily limited by November–December precipitation. Biomass exceeded the threshold capable of carrying fire when inorganic soil N availability was at least 3.2 g m−2 in piñon-juniper woodland. Due to water limitation in creosote bush scrub, biomass exceeded the fire threshold only under very wet conditions regardless of soil N status. The CART analyses also revealed that percent cover of invasive grasses and native forbs is primarily dependent on the timing and amount of precipitation and secondarily dependent on soil N and site-specific characteristics. In total, our results indicate that areas of high N deposition will be susceptible to grass invasion, particularly in wet years, potentially reducing native species cover and increasing the risk of fire

Fuel Conditions Associated with Native and Exotic Grasses in a Subtropical Dry Forest in Puerto Rico

Exotic grasses capable of increasing frequency and intensity of anthropogenic fire have invaded subtropical and tropical dry forests worldwide. Since many dry forest trees are susceptible to fire, this can result in decline of native species and loss of forest cover. While the contribution of exotic grasses to altered fire regimes has been well documented, the role of native grasses in contributing to fuel loads in dry forest has received little attention. We assessed differences in fuel conditions among native and exotic grasses within a subtropical dry forest preserve in Puerto Rico. We quantified fine fuel loads, fuel continuity, and seasonal changes in percent dead grass among the following grass patch types: (1) native grass with no known history of recent fire, (2) exotic grass that had burned once (single burn), and (3) exotic grass that burns frequently. Sampling was conducted during one wet season (August to October 2008) and again in the following dry season (February to March 2009). Overall, fine fuel loading was highest in native grass, but this was due to woody fuels rather than grass fuels. Percent of dead grass fuels increased with the transition from wet to dry season, and this increase was more pronounced for exotic grasses. Fuel continuity was highest in frequently burned exotic grass. Differences in grass phenology and fuel continuity may contribute to differences in fire frequency among native and exotic grass patches. Fuel management focused on prescribed fire should be used in conjunction with restoration of tree canopy to reduce fuels and limit development of a grass-fire cycle

Risk-stratified approach to breast cancer screening in canada: Women’s knowledge of the legislative context and concerns about discrimination from genetic and other predictive health data

The success of risk-stratified approaches in improving population-based breast cancer screening programs depends in no small part on women’s buy-in. Fear of genetic discrimination (GD) could be a potential barrier to genetic testing uptake as part of risk assessment. Thus, the objective of this study was twofold. First, to evaluate Canadian women’s knowledge of the legislative context governing GD. Second, to assess their concerns about the possible use of breast cancer risk levels by insurance companies or employers. We use a cross-sectional survey of 4293 (age: 30–69) women, conducted in four Canadian provinces (Alberta, British Colombia, Ontario and Québec). Canadian women’s knowledge of the regulatory framework for GD is relatively limited, with some gaps and misconceptions noted. About a third (34.7%) of the participants had a lot of concerns about the use of their health information by employers or insurers; another third had some concerns (31.9%), while 20% had no concerns. There is a need to further educate and inform the Canadian public about GD and the legal protections that exist to prevent it. Enhanced knowledge could facilitate the implementation and uptake of risk prediction informed by genetic factors, such as the risk-stratified approach to breast cancer screening that includes risk levels

Mitochondrial Lactate Dehydrogenase Is Involved in Oxidative-Energy Metabolism in Human Astrocytoma Cells (CCF-STTG1)

Lactate has long been regarded as an end product of anaerobic energy production and its fate in cerebral metabolism has not been precisely delineated. In this report, we demonstrate, for the first time, the ability of a human astrocytic cell line (CCF-STTG1) to consume lactate and to generate ATP via oxidative phosphorylation. 13C-NMR and HPLC analyses aided in the identification of tricarboxylic acid (TCA) cyle metabolites and ATP in the astrocytic mitochondria incubated with lactate. Oxamate, an inhibitor of lactate dehydrogenase (LDH), abolished mitochondrial lactate consumption. Electrophoretic and fluorescence microscopic analyses helped localize LDH in the mitochondria. Taken together, this study implicates lactate as an important contributor to ATP metabolism in the brain, a finding that may significantly change our notion of how this important organ manipulates its energy budget

Purpurogallin-A heme binding component of oak galls

Recently, it has been shown that Purpurogallin (PPG), an orange benztropolone constituent of oak galls and its derivative, CU-CPT22, can compete with the binding of the specific lipoprotein ligand to toll-like receptors (TLRs), which are type I transmembrane proteins. These recognize pathogen-derived macromolecules that play a key role in the innate immune system. This system provides an attractive target for the treatment of various immune disorders. Notably, PPG also interacts with various metals and its mode of action against HIV in vitro may involve inhibition of metal containing integrases. In the current study, an optimised synthesis of PPG is presented together with its gas phase behaviour (probed by mass spectrometry) as well as its redox behaviour with porphyrins such as heme. This interaction may also explain its effects at metal containing integrases within HIV in vitro as well as its action during processing of iron complexes within Plasmodia. This compound could serve as a novel prototype for the synthesis of novel redox active antimalarials

The relationship between the symptoms of female gonococcal infections and serum progesterone level and the genotypes of Neisseria gonorrhoeae multi-antigen sequence type (NG-MAST) in Wuhan, China

The objective of this investigation was to study the relationship between the symptoms of female gonococcal infections and serum progesterone level and the genotypes of Neisseria gonorrhoeae multi-antigen sequence type (NG-MAST) in Wuhan, China. Eighty-one strains of N. gonorrhoeae were harvested from the vaginal discharge of 975 adult females in Wuhan and were genotyped by using NG-MAST. Serum progesterone (P) and estradiol (E2) levels were measured by radio immunoassay (RIA) in 39 gonorrhea-infected patients with slight symptoms (asymptomatic group) and 42 patients with conspicuous symptoms (symptomatic group). The average levels of serum progesterone in the asymptomatic group were significantly higher than in the symptomatic group (p < 0.05), while no significant difference was found in serum estradiol between the two groups. Of 81 wild-type isolates, 50 NG-MAST sequence types were associated with female infections in Wuhan, and N. gonorrhoeae ST2951, ST735, and ST436 were principally found in asymptomatic patients. ST809 and ST369, however, were mainly detected in asymptomatic female subjects. Gonococcal genetic island (GGI)-positive and GGI-negative strains were found in both the asymptomatic group and the symptomatic group. In females with gonococcal infection, high serum progesterone level is associated with the absence of symptoms, but no association was revealed between genotypes and the presence of symptoms. The GGI bears no relation to the absence of symptoms in the patients