1,797 research outputs found
Radiocarbon anomalies suggest late onset of agricultural intensification in the catchment of the southern part of the Yangtze Delta, China
Previously underused information from radiocarbon dates in well-characterised sedimentary sequences in the southern Yangtze Delta, China, is here utilised in reconstruction of patterns of ancient erosion. The southern Yangtze Delta was an important focus of food production in the early Neolithic. Anomalous radiocarbon dates in Holocene sediments from the southern part of the delta are unevenly distributed through time. Two clusters of dates -- in sediments ca. 9,000-7,000 cal. BP and ca. 3,000-1,000 cal. BP -- most likely indicate two periods of intensive erosion and redeposition of organic materials. The older of the two clusters may have been associated with a marked episode of marine transgression, whereas the younger cluster could reflect increasing levels of human disruption of soils and sediments in the catchment. A relatively late increase in anthropogenic soil erosion supports recent archaeological evidence that, following its early Neolithic origins, agricultural expansion and intensification occurred later on the southern Yangtze Delta than previously thought
Influence of foliar application with Moringa oleifera residue fertilizer on growth, and yield quality of leafy vegetables
Biofertilizers produced from organic materials help to promote the growth, and yield quality of crops and is more environmentally friendly than chemical fertilizers. Moringa oleifera is a leafy vegetable whose leaves are also used to make biofertilizers. The use of moringa non-edible parts in biofertilizer preparation remains under-explored. In this study, a procedure to produce moringa foliar biofertilizer (MFB) from non-edible parts was developed. The effect of composting time (3 to 4 months) on the quality of MFB was investigated, and four-month incubation was found suitable for biofertilizers yield with the highest nitrogen content and optimal pH. Furthermore, the influences of MFB doses (20 to 100 mL per Litre) on the growth of lettuce and mustard spinach were studied. The yield of these leafy vegetables was the highest at 100 mL per Litre of MFB spray. Finally, MFB was compared with other commercial foliar sprays, including chitosan fertilizer and seaweed fertilizer. Each foliar treatment was applied every five days until five days before harvest. Plant height, the number of leaves, canopy diameter, leaf area index, actual yield, ascorbic acid content, and Brix were found to be similar in lettuce sprayed with MFB, chitosan, and seaweed fertilizers. In conclusion, the application of MFB promoted the growth and yield of mustard spinach
Is a Two-Day Cardiopulmonary Exercise Test a Valid Tool for The Diagnosis of Post-Exertional Malaise in Long COVID?
A two-day cardiopulmonary exercise testing (CPET) protocol (maximal ramp-incremental cycle test repeated 24hr apart) in myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) patients has suggested that day-2 performance is decreased relative to day-1. This difference has been attributed to post-exertional malaise (PEM), suggesting the two-day CPET as a protocol to investigate PEM in Long COVID (LC) patients. PURPOSE: We aimed to investigate any effects of PEM on exercise performance and cardiorespiratory and perceptual responses to a two-day CPET in LC patients to determine whether the day-1 CPET would impair performance, cardiorespiratory responses or perceptions of exercise at day-2. METHODS: Fifteen LC patients with one or more symptoms persisting for more than three months after their initial infection [n=7 females; n=1 hospitalized; mean(SD); age 53(11) yrs; body mass index 32.2(8.5) kg/m2; time between COVID-19 onset and CPET 13(7) months; forced expiratory volume in 1 second 89(15) %pred; forced vital capacity 92(14) %pred; diffusing capacity of the lungs for carbon monoxide 92(15) %pred; total lung capacity 86(12) %pred] were studied. Prior to any exercise testing, PEM was assessed relative to the past six months using the modified DePaul Symptom Questionnaire (mDSQ) (0-4 symptoms frequency and severity scores). Each performed a two-day CPET protocol; ramp was 10-20 W/min, with the same ramp rate used for the day-1 and day-2 CPET. Peak oxygen uptake, peak work rate, and gas exchange threshold were measured using standard techniques. Ratings of perceived dyspnea and leg effort during cycling were recorded at peak exercise using the modified Borg’s Scale (0-10). One-sample t-tests were used to assess significance of test-retest mean difference. RESULTS: The mDSQ indicated the presence of PEM symptoms in 80% of participants. However, no significant differences between day-1 and day-2 CPET were found in any of the variables assessed. CONCLUSION: The absence of any difference in cardiorespiratory and perceptual responses in 2-day CPET testing, despite patient reported presence of PEM symptoms, suggests that the two-day CPET protocol may not be a valid tool for the diagnosis of PEM in LC patients
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Impact of polystyrene microplastics on Daphnia magna mortality and reproduction in relation to food availability
Microplastics (MPs) in the environment continue to be a growing area of concern in terms of acute and chronic impacts on aquatic life. Whilst increasing numbers of studies are providing important insights into microparticle behaviour and impacts in the marine environment, a paucity of information exists regarding the freshwater environment. This study focusses on the uptake, retention and the impact of 2µm polystyrene MPs in the freshwater cladoceran Daphnia magna in relation to food intake (algae Chlorella vulgaris), with MP size chosen to approximately match the cell size of the algae. Daphnia were exposed to varied concentrations of MPs and algae.
When exposed to a single concentration of MPs Daphnia almost immediately ingested them in large quantities. However, the presence of algae, even at low concentrations, had a significant negative impact on MP uptake that was not in proportion to relative availability. As MP concentrations increased, intake did not if algae were present, even at higher concentrations of MPs. This suggests that Daphnia are selectively avoiding ingesting plastics.
Adult Daphnia exposed to MPs for 21 days showed mortality after 7 days of exposure in all treatments compared to the control. However significant differences were all related to algal concentration rather than to MP concentration. This suggests that where ample food is present, MPs have little effect on adults. There was also no impact on their reproduction.
The neonate toxicity test confirmed previous results that mortality and reproduction was linked to availability of food rather than MP concentrations. This would make sense in light of our suggestion that Daphnia are selectively avoiding ingesting microplastics
Delays in the diagnosis and treatment of tuberculosis patients in Vietnam: a cross-sectional study
<p>Abstract</p> <p>Background</p> <p>Treatment delay is an important indicator of access to tuberculosis diagnosis and treatment. Analyses of patient delay (i.e. time interval between onset of symptoms and first consultation of a health care provider) and health care delay (i.e. time interval between first consultation and start of treatment) can inform policies to improve access. This study assesses the patient, health care provider and total delay in diagnosis and treatment of new smear-positive pulmonary tuberculosis patients, and the risk factors for long delay, in Vietnam.</p> <p>Methods</p> <p>A cross-sectional survey of new patients treated by the National Tuberculosis Control Programme was conducted in 70 randomly selected districts in Vietnam. All consecutively registered patients in one quarter of 2002 were interviewed using a pre-coded structured questionnaire.</p> <p>Results</p> <p>Median (range) delay was 4 weeks (1–48) for total, 3 (1–48) weeks for patient and 1 (0–25) week for health care delay. Patients with long total delay (≥ 12 weeks, 15%) accounted for 49% of the cumulative number of delay-weeks. Independent risk factors (p < 0.05) for long total delay were female sex, middle age, remote setting, residence in the northern or central area, and initial visit to the private sector. For long patient delay (≥ 6 weeks) this was female sex, belonging to an ethnic minority, and living at > 5 km distance from a health facility or in the northern area. For long health care delay (≥ 6 weeks) this was urban setting, residence in the central area and initial visit to a communal health post, TB hospital or the private sector.</p> <p>Conclusion</p> <p>Analyses of patient and treatment delays can indicate target groups and areas for health education and strengthening of the referral system, in particular between the private sector and the NTP.</p
How different are the British in their willingness to move? Evidence from International Social Survey Data
Our paper analyses people's willingness to move (WTM) using data from the 1995 British Social Attitudes Survey and International Social Survey Programme. We identify the personal characteristics and sub-regional indicators that are important in explaining the WTM within Britain. We also find that the WTM is only higher in a few other countries, including the United States. The equivalent desire to move is found to be much lower in Eastern European countries and in several other European Union member states. Compositional effects, such as age and education, are generally important in explaining differences in attitudes towards migration in comparison to other Western economies. However, structural effects such as institutions, history and culture tend to play a more dominant role in explaining differences compared to countries in Central and Eastern Europe
Accreting Millisecond X-Ray Pulsars
Accreting Millisecond X-Ray Pulsars (AMXPs) are astrophysical laboratories
without parallel in the study of extreme physics. In this chapter we review the
past fifteen years of discoveries in the field. We summarize the observations
of the fifteen known AMXPs, with a particular emphasis on the multi-wavelength
observations that have been carried out since the discovery of the first AMXP
in 1998. We review accretion torque theory, the pulse formation process, and
how AMXP observations have changed our view on the interaction of plasma and
magnetic fields in strong gravity. We also explain how the AMXPs have deepened
our understanding of the thermonuclear burst process, in particular the
phenomenon of burst oscillations. We conclude with a discussion of the open
problems that remain to be addressed in the future.Comment: Review to appear in "Timing neutron stars: pulsations, oscillations
and explosions", T. Belloni, M. Mendez, C.M. Zhang Eds., ASSL, Springer;
[revision with literature updated, several typos removed, 1 new AMXP added
Administrative social science data: The challenge of reproducible research
Powerful new social science data resources are emerging. One particularly important source is administrative data, which were originally collected for organisational purposes but often contain information that is suitable for social science research. In this paper we outline the concept of reproducible research in relation to micro-level administrative social science data. Our central claim is that a planned and organised workflow is essential for high quality research using micro-level administrative social science data.
We argue that it is essential for researchers to share research code, because code sharing enables the elements of reproducible research. First, it enables results to be duplicated and therefore allows the accuracy and validity of analyses to be evaluated. Second, it facilitates further tests of the robustness of the original piece of research. Drawing on insights from computer science and other disciplines that have been engaged in e-Research we discuss and advocate the use of Git repositories to provide a useable and effective solution to research code sharing and rendering social science research using micro-level administrative data reproducible
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