939 research outputs found
Techniques for Arbuscular Mycorrhiza Inoculum Reduction
It is well established that arbuscular mycorrhizal (AM) fungi can play a significant role in sustainable crop production and environmental conservation. With the increasing awareness of the ecological significance of mycorrhizas and their diversity, research needs to be directed away from simple records of their occurrence or casual speculation of their function (Smith and Read 1997). Rather, the need is for empirical studies and investigations of the quantitative aspects of the distribution of different types and their contribution to the function of ecosystems.
There is no such thing as a fungal effect or a plant effect, but there is an interaction between both symbionts. This results from the AM fungi and plant community size and structure, soil and climatic conditions, and the interplay between all these factors (Kahiluoto et al. 2000). Consequently, it is readily understood that it is the problems associated with methodology that limit our understanding of the functioning and effects of AM fungi within field communities.
Given the ubiquous presence of AM fungi, a major constraint to the evaluation of the activity of AM colonisation has been the need to account for the indigenous soil native inoculum. This has to be controlled (i.e. reduced or eliminated) if we are to obtain a true control treatment for analysis of arbuscular mycorrhizas in natural substrates. There are various procedures possible for achieving such an objective, and the purpose of this chapter is to provide details of a number of techniques and present some evaluation of their advantages and disadvantages.
Although there have been a large number of experiments to investigated the effectiveness of different sterilization procedures for reducing pathogenic soil fungi, little information is available on their impact on beneficial organisms such as AM fungi. Furthermore, some of the techniques have been shown to affect physical and chemical soil characteristics as well as eliminate soil microorganisms that can interfere with the development of mycorrhizas, and this creates difficulties in the interpretation of results simply in terms of possible mycorrhizal activity.
An important subject is the differentiation of methods that involve sterilization from those focussed on indigenous inoculum reduction. Soil sterilization aims to destroy or eliminate microbial cells while maintaining the existing chemical and physical characteristics of the soil (Wolf and Skipper 1994). Consequently, it is often used for experiments focussed on specific AM fungi, or to establish a negative control in some other types of study. In contrast, the purpose of inoculum reduction techniques is to create a perturbation that will interfere with mycorrhizal formation, although not necessarily eliminating any component group within the inoculum. Such an approach allows the establishment of different degrees of mycorrhizal formation between treatments and the study of relative effects.
Frequently the basic techniques used to achieve complete sterilization or just an inoculum reduction may be similar but the desired outcome is accomplished by adjustments of the dosage or intensity of the treatment. The ultimate choice of methodology for establishing an adequate non-mycorrhizal control depends on the design of the particular experiments, the facilities available and the amount of soil requiring treatment
Short-term efficacy of physical interventions in osteoarthritic knee pain. A systematic review and meta-analysis of randomised placebo-controlled trials.
BACKGROUND: Treatment efficacy of physical agents in osteoarthritis of the knee (OAK) pain has been largely unknown, and this systematic review was aimed at assessing their short-term efficacies for pain relief. METHODS: Systematic review with meta-analysis of efficacy within 1-4 weeks and at follow up at 1-12 weeks after the end of treatment. RESULTS: 36 randomised placebo-controlled trials (RCTs) were identified with 2434 patients where 1391 patients received active treatment. 33 trials satisfied three or more out of five methodological criteria (Jadad scale). The patient sample had a mean age of 65.1 years and mean baseline pain of 62.9 mm on a 100 mm visual analogue scale (VAS). Within 4 weeks of the commencement of treatment manual acupuncture, static magnets and ultrasound therapies did not offer statistically significant short-term pain relief over placebo. Pulsed electromagnetic fields offered a small reduction in pain of 6.9 mm [95% CI: 2.2 to 11.6] (n = 487). Transcutaneous electrical nerve stimulation (TENS, including interferential currents), electro-acupuncture (EA) and low level laser therapy (LLLT) offered clinically relevant pain relieving effects of 18.8 mm [95% CI: 9.6 to 28.1] (n = 414), 21.9 mm [95% CI: 17.3 to 26.5] (n = 73) and 17.7 mm [95% CI: 8.1 to 27.3] (n = 343) on VAS respectively versus placebo control. In a subgroup analysis of trials with assumed optimal doses, short-term efficacy increased to 22.2 mm [95% CI: 18.1 to 26.3] for TENS, and 24.2 mm [95% CI: 17.3 to 31.3] for LLLT on VAS. Follow-up data up to 12 weeks were sparse, but positive effects seemed to persist for at least 4 weeks after the course of LLLT, EA and TENS treatment was stopped. CONCLUSION: TENS, EA and LLLT administered with optimal doses in an intensive 2-4 week treatment regimen, seem to offer clinically relevant short-term pain relief for OAK
What influences national and foreign physicians’ geographic distribution? An analysis of medical doctors’ residence location in Portugal
Background
The debate over physicians’ geographical distribution has attracted the attention of the
economic and public health literature over the last forty years. Nonetheless, it is still to date
unclear what influences physicians’ location, and whether foreign physicians contribute to fill
the geographical gaps left by national doctors in any given country. The present research sets
out to investigate the current distribution of national and international physicians in Portugal, with the objective to understand its determinants and provide an evidence base for policymakers to identify policies to influence it.
Methods
A cross-sectional study of physicians currently registered in Portugal was conducted to describe the population and explore the association of physician residence patterns with relevant personal and municipality characteristics. Data from the Portuguese Medical Council
on physicians’ residence and characteristics were analysed, as well as data from the National Institute of Statistics on municipalities’ population, living standards and health care network.
Descriptive statistics, chi-square tests, negative binomial and logistic regression modelling were applied to determine: (a) municipality characteristics predicting Portuguese and International physicians’ geographical distribution, and; (b) doctors’ characteristics that could
increase the odds of residing outside the country’s metropolitan areas.
Results
There were 39,473 physicians in Portugal in 2008, 51.1% of whom male, and 40.2% between
41 and 55 years of age. They were predominantly Portuguese (90.5%), with Spanish,
Brazilian and African nationalities also represented. Population, Population’s Purchasing
Power, Nurses per capita and Municipality Development Index (MDI) were the municipality
characteristics displaying the strongest association with national physicians’ location. For
foreign physicians, the MDI was not statistically significant, while municipalities’ foreign
population applying for residence appeared to be an additional positive factor in their location
decisions. In general, being foreigner and male resulted to be the physician characteristics
increasing the odds of residing outside the metropolitan areas. However, among the
internationals, older doctors were more likely to reside outside metropolitan areas. Being
Spanish or Brazilian (but not of African origin) was found to increase the odds of being based
outside the Lisbon and Oporto metropolitan areas.
Conclusions
The present study showed the relevance of studying one country’s physician population to
understand the factors driving national and international doctors’ location decisions. A more
nuanced understanding of national and foreign doctors’ location appears to be needed to
design more effective policies to reduce the imbalance of medical services across
geographical areas.The study was supported by a research grant from the Portuguese High Commission for Health to the International Health Department of the Institute of Hygiene and Tropical.
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Associations between diagnostic activity and measures of patient experience in primary care: A cross-sectional ecological study of English general practices
Background: Lower use of endoscopies and urgent referrals for suspected cancer has been linked to poorer outcomes for cancer patients; it is important to examine potential predictors of variable use.
Aim: To examine associations between general practice measures of patient experience and practice use of endoscopies or urgent referrals for suspected cancer.
Design and Setting: Cross-sectional ecological analysis; English general practices
Method: We used data from the General Practice Patient Survey and the Cancer Services Public Health Profiles. After adjustment for practice population characteristics, we examined practice-level associations between use of endoscopy and urgent referrals for suspected cancer, and ability to book an appointment (used as proxy for ease of access), ability to see a preferred doctor (used as proxy for relational continuity), and doctor/nurse communication skills.
Results: Taking into account practice scores for ability to book an appointment, practices rated higher for our proxy measure of relational continuity used urgent referrals and endoscopies less often (e.g. 30% lower urgent referral and a 15% lower gastroscopy rates between practices in the 90th/10th centiles, respectively). In contrast, practices rated higher for doctor communication skills used urgent referrals and endoscopies more often (e.g. 26% higher urgent referral and 17% higher gastroscopy rates, between practices in the 90th/10th centiles, respectively). Cancer patients of practices rated higher for doctor communication skills were less likely to be diagnosed as emergencies (1.7% lower between practices in the 90th compared to the 10th centile).
Conclusions: Practices where patients rate doctor communication highly were more likely to investigate and refer patients urgently but, in contrast, practices where patients could see their preferred doctor more readily were less likely to do so. We discuss the possible implications of these findings for clinical practice.The research was directly supported by Cancer Research UK / National Awareness and Early Diagnosis Initiative (Project Grant No. C18081/A17854); and a Cancer Research UK Advanced Clinician Scientist Fellowship award to GL (No. C18081/A18180). HS is supported in part by the Houston VA HSR&D Center for Innovations in Quality, Effectiveness and Safety (CIN 13–413)
SPATIAL ANALYSE OF LITTERFALL IN A GALLERY FOREST
Matas de galeria possuem grande diversidade gen\ue9tica e desempenham
importantes fun\ue7\uf5es ecol\uf3gicas, como a
prote\ue7\ue3o das nascentes, controle da eros\ue3o e funcionam
como filtros retendo poluentes. A serapilheira, que pode ser usada como
um indicativo de produtividade ecol\uf3gica \ue9 amplamente
coletada por meio de coletores que s\ue3o distribu\ueddos
aleatoriamente em um ecossistema florestal. No entanto, a
distribui\ue7\ue3o da vegeta\ue7\ue3o pode apresentar
depend\ueancia espacial, logo, a produtividade da serapilheira pode
ser mapeada utilizando t\ue9cnicas geoestat\uedsticas o que permite
a delimita\ue7\ue3o de zonas de manejo. Portanto, o objetivo deste
estudo foi avaliar a efici\ueancia de m\ue9todos
geoestat\uedsticos na delimita\ue7\ue3o de zonas de manejo da
produtividade de serapilheira em uma \ue1rea de mata de galeria. O
estudo foi realizado na mata de galeria do c\uf3rrego Lava-p\ue9s
(3 ha) em Ipameri - GO, utilizando-se 60 coletores (cada um com 0,33
m\ub2 de \ue1rea e suspensos a 0,65 m do solo) instalados em uma
malha regular georreferenciada de 32 x 32 m. A serapilheira foi
coletada mensalmente de dezembro de 2011 a novembro de 2012. Todas as
amostras foram separadas manualmente nas fra\ue7\uf5es: folhas
(FF), ramos (FR - galhos e cascas), e estruturas reprodutivas (FER -
flores, frutos e sementes) e foram expressas em kg ha-1. Realizou-se a
an\ue1lise estat\uedstica descritiva e geoestat\uedstica dos
dados. A produtividade de serapilheira para a FF e o total apresentou
forte depend\ueancia espacial. A FR e a FER apresentaram efeito
pepita puro. O mapa dos valores de serapilheira total obtido pelo
m\ue9todo de interpola\ue7\ue3o Krigagem indicaram \ue1reas de
produtividade variando de 900 a 10.900 Kg ha-1ano, evidenciando alta
variabilidade na \ue1rea. Foi poss\uedvel por meio da t\ue9cnica
de interpola\ue7\ue3o krigagem delimitar zonas de manejo da
produtividade de serapilheira na mata de galeria estudada, o que
permitiu o manejo florestal espec\uedfico da serapilheira.The gallery forests have great genetic diversity and important
ecological functions, such as protecting the headwaters, controlling
erosion, and functioning as buffer zones and filtering chemicals.
Litterfall, which can be used as an indicator of ecological
productivity, is widely collected using litter traps that are randomly
distributed in a forest plot. However, vegetation distribution may
present spatial dependence, thus the yield of the litterfall can be
mapped using geostatistical techniques allowing the delineation of
management zones. Therefore, the objective of this study was to
evaluate the efficiency of geostatistical methods using the zoning
management productivity of litterfall on a gallery forest in central
Brazil. The study was conducted on the gallery forest along the
\u2018Lava-p\ue9s\u2019 stream in Goi\ue1s State, Brazil where
the experimental site (3 ha) was structured in a grid of 60 litterfall
traps, each of 0.33 m2 held 0.65 m above the ground, georeferenced,
spaced at 32 x 32 m intervals. Litterfall was monthly collected from
December 2011 to November 2012. All litterfall samples were manually
separated into three fractions: leaves (LE), branch bark (BB), and
reproductive parts (RP) and they were expressed in kg ha-1. Statistical
analyses consisted of data description and geostatistics. The
litterfall of for LE and total showed strong spatial dependence. The BB
and RP showed pure nugget effect. The total litterfall maps obtained by
the Kriging interpolation method indicated zones in the map ranging
from 900 to 10,900 kg ha-1 per yr. The kriging interpolation technique
delineate management zones of productivity in the gallery forest
litterfall studied, which allowed the specific forest management of
litterfall
Photoperiodic Modulation of Circadian Clock and Reproductive Axis Gene Expression in the Pre-Pubertal European Sea Bass Brain
The acquisition of reproductive competence requires the activation of the brain-pituitary-gonad (BPG) axis, which in most vertebrates, including fishes, is initiated by changes in photoperiod. In the European sea bass long-term exposure to continuous light (LL) alters the rhythm of reproductive hormones, delays spermatogenesis and reduces the incidence of precocious males. In contrast, an early shift from long to short photoperiod (AP) accelerates spermatogenesis. However, how photoperiod affects key genes in the brain to trigger the onset of puberty is still largely unknown. Here, we investigated if the integration of the light stimulus by clock proteins is sufficient to activate key genes that trigger the BPG axis in the European sea bass. We found that the clock genes clock, npas2, bmal1 and the BPG genes gnrh, kiss and kissr share conserved transcription factor frameworks in their promoters, suggesting co-regulation. Other gene promoters of the BGP axis were also predicted to be co-regulated by the same frameworks. Co-regulation was confirmed through gene expression analysis of brains from males exposed to LL or AP photoperiod compared to natural conditions: LL fish had suppressed gnrh1, kiss2, galr1b and esr1, while AP fish had stimulated npas2, gnrh1, gnrh2, kiss2, kiss1rb and galr1b compared to NP. It is concluded that fish exposed to different photoperiods present significant expression differences in some clock and reproductive axis related genes well before the first detectable endocrine and morphological responses of the BPG axis.European Community [222719 - LIFECYCLE]; Foundation for Science and Technology of Portugal (FCT) [SFRH/BPD/66742/2009, PEst-C/MAR/LA0015/2011]; Valencian Regional Goverment [Prometeo II/2014/051]; Spanish Ministry of Science and Innovation (MICINN) [CSD 2007-0002]info:eu-repo/semantics/publishedVersio
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