1,189 research outputs found
Pressure dependence of the Shubnikov-de Haas oscillation pectrum of beta''-(BEDT-TTF)4(NH4)[Cr(C2O4)3].DMF
The Shubnikov-de Haas (SdH) oscillation spectra of the
beta''-(BEDT-TTF)4(NH4)[Cr(C2O4)\_3].DMF organic metal have been studied in
pulsed magnetic fields of up to either 36 T at ambient pressure or 50 T under
hydrostatic pressures of up to 1 GPa. The ambient pressure SdH oscillation
spectra can be accounted for by up to six fundamental frequencies which points
to a rather complex Fermi surface (FS). A noticeable pressure-induced
modification of the FS topology is evidenced since the number of frequencies
observed in the spectra progressively decreases as the pressure increases.
Above 0.8 GPa, only three compensated orbits are observed, as it is the case
for several other isostructural salts of the same family at ambient pressure.
Contrary to other organic metals, of which the FS can be regarded as a network
of orbits, no frequency combinations are observed for the studied salt, likely
due to high magnetic breakdown gap values or (and) high disorder level
evidenced by Dingle temperatures as large as about 7 K.Comment: To be published in European Physical Journal
de Haas-van Alphen oscillations in the underdoped cuprate YBaCuO
The de Haas-van Alphen effect was observed in the underdoped cuprate
YBaCuO via a torque technique in pulsed magnetic fields up to
59 T. Above an irreversibility field of 30 T, the magnetization exhibits
clear quantum oscillations with a single frequency of 540 T and a cyclotron
mass of 1.76 times the free electron mass, in excellent agreement with
previously observed Shubnikov-de Haas oscillations. The oscillations obey the
standard Lifshitz-Kosevich formula of Fermi-liquid theory. This thermodynamic
observation of quantum oscillations confirms the existence of a well-defined,
close and coherent, Fermi surface in the pseudogap phase of cuprates.Comment: published versio
Cell cultures harbouring constructs of different pig promoter polymorphisms show different transcriptional efficiency in gene reporter systems
AbstractProduction traits variability among and within breeds, differences among developmental stages or the response to different environments are in part due to genetic factors that affect gene expression. Within the context of an Italian FIRB project, whose objective is to identify genes and molecular mechanisms affecting meat quality and production traits in pig, we studied the promoter regions of candidate genes selected on the basis of their physiological role in animal tissue development or composition. Genomic DNA was isolated from liver or muscle tissue of individuals belonging to Large White and Casertana breed. PCR primers were designed to amplify 5' upstream region of SCD (Stearoyl-CoA Desaturase), LDLR (Low Density Lipoprotein Receptor), LEP (Leptin), MSTN (Myostatin), ACTA1 (Alpha-actin) and HFABP (Heart Fatty Acid Binding Protein) genes using sequences available at NCBI. A total of 19 single nucleotide polymorphisms (SNPs) not previously described were characterised. Some haplotypes, harbou..
Shubnikov-de Haas oscillations in YBa_2Cu_4O_8
We report the observation of Shubnikov-de Haas oscillations in the underdoped
cuprate superconductor YBaCuO (Y124). For field aligned along the
c-axis, the frequency of the oscillations is T, which corresponds
to % of the total area of the first Brillouin zone. The effective
mass of the quasiparticles on this orbit is measured to be times
the free electron mass. Both the frequency and mass are comparable to those
recently observed for ortho-II YBaCuO (Y123-II). We show that
although small Fermi surface pockets may be expected from band structure
calculations in Y123-II, no such pockets are predicted for Y124. Our results
therefore imply that these small pockets are a generic feature of the copper
oxide plane in underdoped cuprates.Comment: v2: Version of paper accepted for publication in Physical Review
Letters. Only minor changes to the text and reference
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Consumers’ acceptance and preferences for nutrition-modified and functional dairy products: a systematic review
This systematic literature review collects and summarizes research on consumer acceptance and preferences for nutrition-modified and functional dairy products, to reconcile, and expand upon, the findings of previous studies. We find that female consumers show high acceptance for some functional dairy products, such as yogurt enriched with calcium, fiber and probiotics. Acceptance for functional dairy products increases among consumers with higher diet/health related knowledge, as well as with aging. General interest in health, food-neophobia and perceived self-efficacy seem also to contribute shaping the acceptance for functional dairy products. Furthermore, products with “natural” matches between carriers and ingredients have the highest level of acceptance among consumers. Last, we find that brand familiarity drives consumers with low interest in health to increase their acceptance and preference for health enhanced dairy products, such as probiotic yogurts, or those with a general function claim
Sexual behaviours, HIV testing, and the proportion of men at risk of transmitting and acquiring HIV in London, UK, 2000-13: a serial cross-sectional study
BACKGROUND: HIV incidence in men who have sex with men (MSM) in the UK has remained unchanged over the past decade despite increases in HIV testing and antiretroviral therapy (ART) coverage. In this study, we examine trends in sexual behaviours and HIV testing in MSM and explore the risk of transmitting and acquiring HIV.
METHODS: In this serial cross-sectional study, we obtained data from ten cross-sectional surveys done between 2000 and 2013, consisting of anonymous self-administered questionnaires and oral HIV antibody testing in MSM recruited in gay social venues in London, UK. Data were collected between October and January for all survey years up to 2008 and between February and August thereafter. All men older than 16 years were eligible to take part and fieldworkers attempted to approach all MSM in each venue and recorded refusal rates. Data were collected on demographic and sexual behavioural characteristics. We analysed trends over time using linear, logistic, and quantile regression.
FINDINGS: Of 13 861 questionnaires collected between 2000 and 2013, we excluded 1985 (124 had completed the survey previously or were heterosexual reporting no anal intercourse in the past year, and 1861 did not provide samples for antibody testing). Of the 11 876 eligible MSM recruited, 1512 (13%) were HIV positive, with no significant trend in HIV positivity over time. 35% (531 of 1505) of HIV-positive MSM had undiagnosed infection, which decreased non-linearly over time from 34% (45 of 131) to 24% (25 of 106; p=0·01), while recent HIV testing (ie, in the past year) increased from 26% (263 of 997) to 60% (467 of 777; p<0·0001). The increase in recent testing in undiagnosed men (from 29% to 67%, p<0·0001) and HIV-negative men (from 26% to 62%, p<0·0001) suggests that undiagnosed infection might increasingly be recently acquired infection. The proportion of MSM reporting unprotected anal intercourse (UAI) in the past year increased from 43% (513 of 1187) to 53% (394 of 749; p<0·0001) and serosorting (exclusively) increased from 18% (207 of 1132) to 28% (177 of 6369; p<0·0001). 268 (2%) of 11 570 participants had undiagnosed HIV and reported UAI in the past year were at risk of transmitting HIV. Additionally 259 (2%) had diagnosed infection and reported UAI and non-exclusive serosorting in the past year. Although we did not collect data on antiretroviral therapy or viral load, surveillance data suggests that a small proportion of men with diagnosed infection will have detectable viral load and hence might also be at risk of transmitting HIV. 2633 (25%) of 10 364 participants were at high risk of acquiring HIV (defined as HIV-negative MSM either reporting one or more casual UAI partners in the past year or not exclusively serosorting). The proportions of MSM at risk of transmission or acquisition changed little over time (p=0·96 for MSM potentially at risk of transmission and p=0·275 for MSM at high risk of acquiring HIV). Undiagnosed men reporting UAI and diagnosed men not exclusively serosorting had consistently higher partner numbers than did other MSM over the period (median ranged from one to three across surveys in undiagnosed men reporting UAI, two to ten in diagnosed men not exclusively serosorting, and none to two in other men).
INTERPRETATION: An increasing proportion of undiagnosed HIV infections in MSM in London might have been recently acquired, which is when people are likely to be most infectious. High UAI partner numbers of MSM at risk of transmitting HIV and the absence of a significant decrease in the proportion of men at high risk of acquiring the infection might explain the sustained HIV incidence. Implementation of combination prevention interventions comprising both behavioural and biological interventions to reduce community-wide risk is crucial to move towards eradication of HIV.
FUNDING: Public Health England
SOS1 over-expression in genital skin fibroblasts from hirsute women: a putative role of the SOS1/RAS pathway in the pathogenesis of hirsutism.
Hirsutism is the development of androgen-dependent terminal body hair in women in places in which terminal hair are normally not found. It is often associated with hyperandrogenemia and/or polycystic ovary syndrome (PCOS), but the existence of uncommom hirsutism forms that are not related to altered androgen plasma levels lead also to the definition of - idiopathic hirsutism. Although the pathophysiology of hirsutism has been linked to increasing 5-alpha reductase (SRD5A) activity and to an alteration of the androgen receptor (AR) transcriptional machinery, many aspects remain unclear. In particular, the relationships between androgens and local factors are poorly understood. In the present paper, we selected for a genital skin biopsy, 8 women affected with severe hirsutism (Ferriman-Gallway score greater than 25) but with normal plasma androgen levels, with the exception of slightly higher serum 3alpha-diol-glucuronide levels, and 6 healthy controls and analyzed their androgen- and insulin-specific transcriptional profile using a specific custom low density microarray (AndroChip 2, GPL9164). We identified the over-expression of the Son of Sevenless-1 (SOS1) gene in all of the hirsute skin fibroblast primary cell cultures compared to control healthy women. Since SOS1 is a guanine nucleotide exchange factor that couples receptor tyrosine kinases to the RAS signaling pathway that controls cell proliferation and differentiation, we further analyzed SOS1 expression, protein level and RAS signaling activation pathway in an in vitro model (NHDF, normal human dermal fibroblast cell line). NHDF treated for 24 h with different concentrations of DHT and T showed an increase in SOS1 levels (both mRNA and protein) and also an activation of the RAS pathway. Our in vivo and in vitro data represent a novel preliminary observation that factors activating SOS1 could act as local proliferative modulators linked to the androgen pathway in the pilosebaceous unit. SOS1 over-expression may play a role in the regulation of the RAS/mitogen-activated protein kinase pathway in the skin, in the hair follicle proliferation and cell cycle, suggesting new perspectives in understanding the pathogenesis of idiopathic hirsutism
Plasmonic mediated nucleation of resonant nano-cavities in metallic layers
We predict plasmonic mediated nucleation of pancake shaped resonant
nano-cavities in metallic layers that are penetrable to laser fields. The
underlying physics is that the cavity provides a narrow plasmonic resonance
that maximizes its polarizability in an external field. The resonance yields a
significant energy gain making the formation of such cavities highly favorable.
Possible implications include nano-optics and generation of the dielectric bits
in conductive films that underlie the existing optical recording phase change
technology.Comment: 4 pages, 3 figure
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