4,064 research outputs found

    Remote photothermal actuation for calibration of in-phase and quadrature readout in a mechanically amplified Fabry-PĆ©rot accelerometer

    Get PDF
    A mechanically amplified Fabry-PeĢrot optical accelerometer is reported in which photothermal actuation is used to calibrate the in-phase and quadrature (I&Q) readout. The Fabry-PeĢrot interferometer (FPI) is formed between a gold-coated silicon mirror, situated in the middle of a V-beam amplifier, and the end surface of a cleaved optical fiber. On the opposite side of the silicon mirror, a further cleaved optical fiber transmits near-infrared laser light (Ī» = 785 nm), which is absorbed by the uncoated silicon causing heating. The thermal expansion of the V-beam is translated into an amplified change in cavity length of the FPI, large enough for the 2Ļ€-phase variation necessary for I&Q calibration. A simple 1D thermal analysis of the structure has been developed to predict the relationship between laser power and change in cavity length. A device having a V-beam of length 1.8 mm, width 20 Ī¼m, and angle 2 Ā° was found to undergo a cavity length change of 785 nm at 30 mW input power. The device response was approximately linear for input accelerations from 0.01 to 15 g. The noise was measured to be ~ 60 Ī¼g/āˆšHz from 100 Hz to 3.0 kHz, whereas the limit of detection was 47.7 mg from dc to 3.0 kHz

    Fifty years of oil exploration in Nigeria: The paradox of plenty

    Get PDF
    It is expected that countries with an abundance of natural resources should prosper. Yet over many years, it has been observed that nations rich in oil, gas, or mineral resources have been disadvantaged in the drive for economic progress. The concept of resource curse which refers to theobservation that nations with rich endowments of natural resources [oil as in the case of Nigeria] often dramatically under perform economically relative to what one would expect was used in this study. The methods employed in data collection, primarily from secondary sources include; literature review of NNPC publications, national dailies and newsmagazines; internet reports on OPEC, oil production in Nigeria, etc. Descriptive statistic was used in data analysis. The results revealed that the oil wealth was initially well applied towards the development of the country. Overtime, successive governments began to mismanage it and a situation like this had given rise to other contemporary oil nations overtaking Nigeria. The consequence is that the early gains of oil disappeared in the face of declining quality of general infrastructure across the country. The growingreliance of the country on oil and gas alone may undermine the democratic structure-rule of law, political stability [as in the case of militancy in the Niger Delta region], government effectiveness and the fight against corruptio

    Testing non-autonomous antimalarial gene drive effectors using self-eliminating drivers in the African mosquito vector Anopheles gambiae

    Get PDF
    Gene drives for mosquito population modification are novel tools for malaria control. Strategies to safely test antimalarial effectors in the field are required. Here, we modified the Anopheles gambiae zpg locus to host a CRISPR/Cas9 integral gene drive allele (zpgD) and characterized its behaviour and resistance profile. We found that zpgD dominantly sterilizes females but can induce efficient drive at other loci when it itself encounters resistance. We combined zpgD with multiple previously characterized non-autonomous payload drives and found that, as zpgD self-eliminates, it leads to conversion of mosquito cage populations at these loci. Our results demonstrate how self-eliminating drivers could allow safe testing of non-autonomous effector-traits by local population modification. They also suggest that after engendering resistance, gene drives intended for population suppression could nevertheless serve to propagate subsequently released non-autonomous payload genes, allowing modification of vector populations initially targeted for suppression

    SCN5A allelic expression imbalance in African-Americans heterozygous for the common variant p.Ser1103Tyr

    Get PDF
    <p>Abstract</p> <p>Background</p> <p>Heterozygous and homozygous carriers of <it>SCN5A</it>-p.Ser1103Tyr, a common genetic variant with functional effects among African-Americans, have an increased risk of sudden death. We hypothesized that some heterozygous carriers may have unequal expression of wild-type and variant alleles and secondarily that predominance of the variant gene copy could further increase risk for sudden death in this population.</p> <p>Methods</p> <p>We quantified allele-specific expression of <it>SCN5A</it>-p.Ser1103Tyr by real-time reverse-transcription polymerase chain reaction (RT-PCR) in heart tissue from heterozygous African-American infants, who died from sudden infant death syndrome (SIDS) or from other causes, to test for allelic expression imbalance.</p> <p>Results</p> <p>We observed significant allelic expression imbalance in 13 of 26 (50%) African-American infant hearts heterozygous for <it>SCN5A</it>-p.Ser1103Tyr, and a significant (p < 0.0001) bimodal distribution of log<sub>2 </sub>allelic expression ratios. However, <b>t</b>here were no significant differences in the mean log<sub>2 </sub>allelic expression ratios in hearts of infants dying from SIDS as compared to infants dying from other causes and no significant difference in the proportion of cases with greater expression of the variant allele.</p> <p>Conclusions</p> <p>Our data provide evidence that <it>SCN5A </it>allelic expression imbalance occurs in African-Americans heterozygous for p.Ser1103Tyr, but this phenomenon alone does not appear to be a marker for risk of SIDS.</p

    Protection against Experimental Melioidosis with a Synthetic manno-Heptopyranose Hexasaccharide Glycoconjugate

    Get PDF
    This is the final version of the article. Available from the publisher via the DOI in this record.Melioidosis is an emerging infectious disease caused by Burkholderia pseudomallei and is associated with high morbidity and mortality rates in endemic areas. Antibiotic treatment is protracted and not always successful; even with appropriate therapy, up to 40% of individuals presenting with melioidosis in Thailand succumb to infection. In these circumstances, an effective vaccine has the potential to have a dramatic impact on both the scale and the severity of disease. Currently, no vaccines are licensed for human use. A leading vaccine candidate is the capsular polysaccharide consisting of a homopolymer of unbranched 1ā†’3 linked 2-O-acetyl-6-deoxy-Ī²-d-manno-heptopyranose. Here, we present the chemical synthesis of this challenging antigen using a novel modular disaccharide assembly approach. The resulting hexasaccharide was coupled to the nontoxic Hc domain of tetanus toxin as a carrier protein to promote recruitment of T-cell help and provide a scaffold for antigen display. Mice immunized with the glycoconjugate developed IgM and IgG responses capable of recognizing native capsule, and were protected against infection with over 120 Ɨ LD50 of B. pseudomallei strain K96243. This is the first report of the chemical synthesis of an immunologically relevant and protective hexasaccharide fragment of the capsular polysaccharide of B. pseudomallei and serves as the rational starting point for the development of an effective licensed vaccine for this emerging infectious disease.This work was funded by the United Kingdom Ministry of Defence. The mass spectral data described here were acquired on an Orbitrap Fusion mass spectrometer funded by National Institutes of Health grant 1S10OD010645-01A1

    Low alanine aminotransferase and higher cardiovascular events in type 2 diabetes: analysis of the Fenofibrate Intervention and Event Lowering in Diabetes (FIELD) study

    Get PDF
    Aims Non-alcoholic fatty liver disease (NAFLD) is common in type 2 diabetes and associated with higher risk of cardiovascular disease. This study aimed to determine whether alanine aminotransferase (ALT) or gamma-glutamyltransferase (GGT), as markers of liver health and NAFLD, might predict cardiovascular events in this population. Methods Data from the Fenofibrate Intervention and Event Lowering in Diabetes (FIELD) study were analysed to examine the relationship between liver enzymes and incident cardiovascular events (nonfatal myocardial infarction, stroke, coronary and other cardiovascular death, coronary or carotid revascularization) over 5 years. Results ALT had a linear inverse relationship with the first cardiovascular event on study. After adjustment, for every standard deviation higher baseline ALT (13.2U/L), the risk of an event was 7%(95%CI 4ā€“13, P=0.02) lower. Participants with ALT below and above the reference range 8ā€“41 U/L for women and 9ā€“59 U/L for men, had a hazard ratio of an event of 1.86(95%CI, 1.12ā€“3.09) and 0.65(95%CI, 0.49ā€“0.87), respectively (P=0.001). No relationship was found for GGT. Conclusions The data may indicate that in type 2 diabetes ā€” associated with higher ALT due to prevalent NAFLD ā€” lower ALT is a marker of hepatic or systemic frailty rather than health

    Discrete wavelet transform de-noising in eukaryotic gene splicing

    Get PDF
    <p>Abstract</p> <p>Background</p> <p>This paper compares the most common digital signal processing methods of exon prediction in eukaryotes, and also proposes a technique for noise suppression in exon prediction. The specimen used here which has relevance in medical research, has been taken from the public genomic database - GenBank.</p> <p>Methods</p> <p>Here exon prediction has been done using the digital signal processing methods viz. binary method, EIIP (electron-ion interaction psuedopotential) method and filter methods. Under filter method two filter designs, and two approaches using these two designs have been tried. The discrete wavelet transform has been used for de-noising of the exon plots.</p> <p>Results</p> <p>Results of exon prediction based on the methods mentioned above, which give values closest to the ones found in the NCBI database are given here. The exon plot de-noised using discrete wavelet transform is also given.</p> <p>Conclusion</p> <p>Alterations to the proven methods as done by the authors, improves performance of exon prediction algorithms. Also it has been proven that the discrete wavelet transform is an effective tool for de-noising which can be used with exon prediction algorithms.</p
    • ā€¦
    corecore