1,888 research outputs found

    A new perspective on the Ī“13C signal preserved in speleothems using LCā€“IRMS analysis of bulk organic matter and compound specific stable isotope analysis

    Get PDF
    The analysis of Ī“13C in speleothem calcite is established as a palaeoenvironmental proxy, but records can often be complex to interpret due to multiple controls on the signal. Here we present a novel palaeoenvironmental application of non-purgeable organic carbon (NPOC) Ī“13C analysis and compound-specific isotope analysis (CSIA) to speleothems, and compare the resultant signals to a conventional calcite Ī“13C record. By accessing the carbon pool held in molecular organic matter, we are able for the first time to produce stable isotope records complementary to the CO2-derived signal from the speleothem calcite, and begin to identify separate ecological and climatic controls. In this sample from north-west Scotland, the calcite Ī“13C record and the NPOC Ī“13C both show fluctuations at a period of increasing wetness and change from birch woodland to more open peatland, the NPOC signal having a strong correlation with biomarkers for vegetation change. We interpret an inverse correlation between the NPOC and CO2 Ī“13C signals as primarily driven by changes in soil conditions impacting upon microbial activity, with decreased activity leading to a reduction in 13C enrichment of the residual organic matter (the NPOC fraction), and an increase in Ī“13C in the CO2 pool (calcite) due to a decrease in respired 12C. This opens the way for the application of parallel analyses to distinguish between soil conditions and vegetation parameters as the primary control on a record, and highlights the advantage of combining both inorganic and organic geochemical techniques in the palaeoenvironmental interpretation of stable carbon isotopic record

    The Relationship Between the Mid-Point and Most-Prominent Point on the Labial Curve of Upper Anterior Teeth

    Get PDF
    Objectives: This study investigates coincidence of the most-prominent point and the mid-point on upper anterior teeth in relation to the use of straight-wire appliances. Materials and Methods: Alginate impressions of the upper jaw were obtained from forty Caucasian patients. Impressions were cast using hard dental stone. The teeth on each upper study model (canine to canine) were marked along the facial axis of the clinical crown (FACC line) then separated using a very thin diamond disc. Each tooth was mounted on a glass slide using sticky wax and cut into two halves down this FACC line. Images were acquired of the sections and a straight line connecting the gingival margin and the incisal edge was drawn on the flat cut surfaces (now the proximal crosssectional view). From this line, perpendicular lines were drawn at the mid-point and most prominent point to the labial curve. Coincidence rate was calculated or whether the most prominent point was gingival or incisal to the mid-point. Results: Approximately 80% of upper central incisors had coincident mid- and most-prominent points. Upper lateral incisors and canine teeth had approximately 50% coincidence. The vast majority of cases without coincidence showed the most-prominent point incisal to the mid-point for all tooth kinds with just 5% or less gingival. Conclusions: The high proportions of non-coincident examples found suggest that clinicians should be aware of individual variation and that this may possibly effect 3rd order alignment. </jats:p

    Dietary Patterns Associated with Alzheimer?s Disease and Related Chronic Disease Risk: A Review

    Get PDF
    The worldā€™s population is growing older due to improved healthcare and nutrition. As a result, Alzheimerā€™s disease (AD) prevalence is rapidly increasing. The focus of the current research climate is shifting from understanding AD pathology and diagnosis to primary prevention and intervention strategies. Diet represents one potential intervention strategy accessible to all. Accumulating evidence suggests diet plays a major role in risk and development of AD and AD-related chronic diseases of the periphery like cardiovascular disease (CVD) and diabetes. This paper reviews studies that have explored the relationship between ā€œa prioriā€ dietary patterns, AD and AD-related chronic disease risk. The dietary patterns we will review are the healthy eating index, healthy diet indicator, recommended food score, and the Mediterranean diet (MeDi). Our review of the literature suggests a generally positive association between healthy diet patterns, AD and AD-related chronic disease risk; however the magnitude of the protective effect is modest in many studies. Consequently, we can only confidently conclude that the MeDi is associated with reduced AD risk, and further studies on the remaining indices need to be carried out. It is our opinion that a combination of dietary scores could predict overall dietary quality and chronic disease risk to a greater extent than one score individually. Analysis in multi-ethnic cohorts, investigating combinations of scores must be completed before firm conclusions can be reached on the ideal combination of scores. Obtaining further insight into the association between dietary patterns, AD and AD-related chronic disease risk may help in prioritizing public health efforts and provide a stronger basis for recommendations to improve dietary patterns

    Intake of products containing anthocyanins, flavanols, and flavanones, and cognitive function: A narrative review

    Get PDF
    The purpose of this review is to examine human research studies published within the past 6 years which evaluate the role of anthocyanin, flavanol, and flavanone consumption in cognitive function, and to discuss potential mechanisms of action underlying any observed benefits. Evidence to date suggests the consumption of flavonoid-rich foods, such as berries and cocoa, may have the potential to limit, or even reverse, age-related declines in cognition. Over the last 6 years, the flavonoid subgroups of anthocyanins, flavanols, and flavanones have been shown to be beneficial in terms of conferring neuroprotection. The mechanisms by which flavonoids positively modulate cognitive function are yet to be fully elucidated. Postulated mechanisms include both direct actions such as receptor activation, neurotrophin release and intracellular signaling pathway modulation, and indirect actions such as enhancement of cerebral blood flow. Further intervention studies conducted in diverse populations with sufficient sample sizes and long durations are required to examine the effect of consumption of flavonoid groups on clinically relevant cognitive outcomes. As populations continue to focus on adopting healthy aging strategies, dietary interventions with flavonoids remains a promising avenue for future research. However, many questions are still to be answered, including identifying appropriate dosage, timeframes for intake, as well as the best form of flavonoids, before definitive conclusions can be drawn about the extent to which their consumption can protect the aging brain

    Compression ultrasonography for false femoral artery aneurysms: Hypocoagulability is a cause of failure

    Get PDF
    Objectives:false femoral artery aneurysm is an occasional complication of percutaneous cardiovascular radiological procedures. Compression ultrasonography causes thrombosis non-invasively, reducing need for operative intervention. The technique fails in a proportion of cases. Analysis was undertaken to identify causes of failure.Design:prospective open study.Materials and Methods:patients presenting with false femoral artery aneurysm since 1984 were identified from a computerised database (BIPAS). Since 1993 compression ultrasonography has been performed as first line treatment according to a standard protocol. Prospectively collected ultrasonographic data and case notes were reviewed to identify causes of failed compression.Results:false femoral artery aneurysm occurred as a complication in 32/26 687 (0.12%) cardiovascular radiological procedures. Eighteen aneurysms were treated by compression. The technique was successful in 11/18 (61%) cases but primary failure occurred in seven cases. Six out of seven had bleeding abnormalities (Chi-squared analysis with Yates correction 10.55, p=0.0012), four were anticoagulated and compression was subsequently successful following reversal of warfarin therapy in three of these patients. In 4/18 cases surgical repair was necessary.Conclusions:compression ultrasonography is an effective treatment of false femoral aneurysms, however, hypocoagulability is a significant cause of failure. For patients in whom anticoagulation cannot be reversed, primary surgical repair should be considered

    Novel cell types, neurosecretory cells, and body plan of the early-diverging metazoan Trichoplax adhaerens.

    Get PDF
    BACKGROUND: Trichoplax adhaerens is the best-known member of the phylum Placozoa, one of the earliest-diverging metazoan phyla. It is a small disk-shaped animal that glides on surfaces in warm oceans to feed on algae. Prior anatomical studies of Trichoplax revealed that it has a simple three-layered organization with four somatic cell types. RESULTS: We reinvestigate the cellular organization of Trichoplax using advanced freezing and microscopy techniques to identify localize and count cells. Six somatic cell types are deployed in stereotyped positions. A thick ventral plate, comprising the majority of the cells, includes ciliated epithelial cells, newly identified lipophil cells packed with large lipid granules, and gland cells. Lipophils project deep into the interior, where they alternate with regularly spaced fiber cells whose branches contact all other cell types, including cells of the dorsal and ventral epithelium. Crystal cells, each containing a birefringent crystal, are arrayed around the rim. Gland cells express several proteins typical of neurosecretory cells, and a subset of them, around the rim, also expresses an FMRFamide-like neuropeptide. CONCLUSIONS: Structural analysis of Trichoplax with significantly improved techniques provides an advance in understanding its cell types and their distributions. We find two previously undetected cell types, lipohil and crystal cells, and an organized body plan in which different cell types are arranged in distinct patterns. The composition of gland cells suggests that they are neurosecretory cells and could control locomotor and feeding behavior

    One Dimensional Chain with Long Range Hopping

    Full text link
    The one-dimensional (1D) tight binding model with random nearest neighbor hopping is known to have a singularity of the density of states and of the localization length at the band center. We study numerically the effects of random long range (power-law) hopping with an ensemble averaged magnitude \expectation{|t_{ij}|} \propto |i-j|^{-\sigma} in the 1D chain, while maintaining the particle-hole symmetry present in the nearest neighbor model. We find, in agreement with results of position space renormalization group techniques applied to the random XY spin chain with power-law interactions, that there is a change of behavior when the power-law exponent Ļƒ\sigma becomes smaller than 2

    Resistance training enhances delayed memory in healthy middle-aged and older adults: A randomised controlled trial

    Get PDF
    Objectives High-intensity exercise is a potential therapeutic tool to postpone or prevent the onset of cognitive decline. However, there is a lack of sufficient evidence regarding the longitudinal effects of structured resistance training on cognitive function in healthy adults. The purpose of this study was to investigate the effect of two ecologically valid, intense 12-week resistance training programs on cognitive function in late middle-aged adults. Design Single-site parallel randomised controlled trial at the Department of Exercise Science strength and conditioning laboratory. Groups allocated by minimisation randomisation. Methods Forty-five healthy adults (age rangeā€‰=ā€‰41-69 years) were enrolled and randomised into A.) high-load, long rest resistance training (nā€‰=ā€‰14), or B.) moderate-load, short rest resistance training (nā€‰=ā€‰15) twice per week for 12 weeks, or a non-exercising control (nā€‰=ā€‰16). Follow-up within 7 days. Data were collected September 2016-December 2017. Cognitive function assessed using the CogState computerised battery. Assessors were blinded to participant group allocation. Secondary outcomes were maximal muscle strength and body composition. Results Forty-four participants were analysed in 2018. Delayed verbal memory performance was improved (pā€‰=ā€‰0.02) in resistance training groups (gā€‰=ā€‰0.67-0.79) when compared to the control group, with no differences between training groups. Likewise, increases in maximal muscle strength were observed (pā€‰<ā€‰0.01) in resistance training groups when compared to the control group, with no differences between training groups. No differences in body composition were observed. There were no adverse events or side-effects of the intervention. Conclusions 12 weeks of intense resistance training improves delayed verbal memory irrespective of training design (i.e., high-load vs. moderate-load)
    • ā€¦
    corecore