288 research outputs found
Decoupling and prices: determinant of dairy farmers’ choices? A model to analyse impacts of the 2003 CAP reform
No full textThe reform of European Common Agricultural Policy (CAP) in 2003 has resulted in substantial changes to the attribution of subsidies to dairy farmers. Moreover, dairy farmers are in also facing an unprecedented situation on the markets with the soaring prices of agricultural raw materials: they sell their products at a higher price (milk, meat and cereals), but must also cope with the increasing prices of concentrates. In this paper1, we discuss cross effects, on the productive strategy of French dairy farms, of the Luxemburg Agreement and the prices variations. A model based on mathematical programming has been privileged to determine how dairy farmers might re-evaluate their systems to identify optimal production plan. While respecting the principle of agent rationality (maximization of profit), the model incorporates the economic risk related to the volatility of the inputs and outputs prices. Thus the model maximises the expected utility of the income while taking into account a set of constraints: regulatory, structural, zootechnical, agronomic and environmental. The model is applied to four types of dairy farms to cope with the diversity of production systems in the west of France (“grazier” type, “semi intensive” type, “milk + cereals” type and “milk + young bulls” type). The model is used to produce quantitative estimations and support reflection through the simulation of the setting up of the Single payment scheme. The sensitivity of the results is discussed by taking into account several options of prices for cereals and livestock products. These may have a strong influence on the structure of the diet and, therefore, on the level of intensification of the forage area. The results show that the implementation of the CAP reform encourages farmers to substitute a part of corn silage by grass in the diet. However, the rising price of agricultural production encourages, on the contrary, farmers to intensify their system in order to free up land for growing cereals. We also observe that a decrease of the young bulls fattening activity to develop cereal crops is also economically profitable.dairy farm, single payment, price variation, Agricultural and Food Policy, Livestock Production/Industries,
Climate Change and invasibility of the Antarctic benthos
No full textBenthic communities living in shallow-shelf habitats in Antarctica (<100-m depth) are archaic in their structure and function. Modern predators, including fast-moving, durophagous (skeleton-crushing) bony fish, sharks, and crabs, are rare or absent; slow-moving invertebrates are the top predators; and epifaunal suspension feeders dominate many soft substratum communities. Cooling temperatures beginning in the late Eocene excluded durophagous predators, ultimately resulting in the endemic living fauna and its unique food-web structure. Although the Southern Ocean is oceanographically isolated, the barriers to biological invasion are primarily physiological rather than geographic. Cold temperatures impose limits to performance that exclude modern predators. Global warming is now removing those physiological barriers, and crabs are reinvading Antarctica. As sea temperatures continue to rise, the invasion of durophagous predators will modernize the shelf benthos and erode the indigenous character of marine life in Antarctica
Megafaunal distribution and biodiversity in a heterogeneous landscape: the iceberg scoured Rockall Bank, NE Atlantic
No full textSpecies distributions are influenced by spatial structure in environmental factors, but the scales at which these dependencies occur and the effect of habitat patch diversity, connectivity and spatial arrangement have rarely been investigated in deep-sea settings. In this study, spatially-limited photographic transects collected from Rockall Bank, Northeast Atlantic, were combined with sidescan and multibeam sonar maps to model spatial patterns in species distribution and biodiversity. Sediment interpretation maps were created and canonical ordination techniques were used to examine relationships between fine-scale sediment characteristics extracted from the digital stills as well as landscape metrics describing the patch mosaic structure of the surrounding areas. Fine-scale sediment characteristics explained 45.1% and 63.8% of the variation in species composition and biodiversity (H′) respectively. This survey effectively captured variation in species distribution resulting from iceberg ploughmarks, occurring at a scale of < 50 m which would normally go undetected by traditional ship-based studies. Our study suggests that fine-scale environmental information is required to capture the spatial heterogeneity of complex seafloor areas in sufficient detail to model species distributions and biodiversity
Synergy and Group Size in Microbial Cooperation
No full textMicrobes produce many molecules that are important for their growth and development, and the exploitation of these secretions by nonproducers has recently become an important paradigm in microbial social evolution. Although the production of these public-goods molecules has been studied intensely, little is known of how the benefits accrued and the costs incurred depend on the quantity of public-goods molecules produced. We focus here on the relationship between the shape of the benefit curve and cellular density, using a model assuming three types of benefit functions: diminishing, accelerating, and sigmoidal (accelerating and then diminishing). We classify the latter two as being synergistic and argue that sigmoidal curves are common in microbial systems. Synergistic benefit curves interact with group sizes to give very different expected evolutionary dynamics. In particular, we show that whether and to what extent microbes evolve to produce public goods depends strongly on group size. We show that synergy can create an "evolutionary trap" that can stymie the establishment and maintenance of cooperation. By allowing density-dependent regulation of production (quorum sensing), we show how this trap may be avoided. We discuss the implications of our results on experimental design.</p
Participant experiences of an internet-based intervention and randomised control trial : interview study
No full textBackground
There are an increasing number of interventions being delivered online, and an expanding body of research to assess the effectiveness of such interventions. Yet, little is known about the motivations for participating in online research. Furthermore, internet interventions and online research studies are characterised by poor adherence and high attrition rates. This study aimed to explore participant motivations for taking part in an online trial of an internet intervention and the reasons for continuing.
Methods
Semi-structured telephone interviews were conducted with twenty members of the intervention arm of an internet-based randomised control trial evaluating an online cognitive behavioural tool to improve mental wellbeing. The qualitative interviews were analysed using the Framework Approach to identify themes and subthemes, through familiarization with the data, identifying a thematic framework, charting, indexing, mapping and interpreting the data.
Results
A number of key themes emerged. Trusted brands were key to participants feeling secure in engaging with the trial due to the association with institutions such as the UK National Health Service and the lead University conducting the research. Participants had a number of motivations for signing up with the study; altruism, low mood and as a replacement for a physical health professional. Participants felt the need for the language used in the intervention to be tailored to them as individuals. The majority of those interviewed also described multiple benefits from the intervention, which could have been a reason for them to persist.
Conclusion
The nascent field of research on internet delivered healthcare needs to take account of participant views, as have been identified in this trial and future studies would benefit from applying its findings
Aspectos biodemográficos de grupos étnicos Macro-Pano de Bolivia y caracterización genética de las poblaciones Aymará, Quechua, Chimane y Mosetén
No full text[spa] La tesis trata de definir algunos aspectos de la situación demográfica y describir la genética poblacional a partir del estudio de haplogrupos del ADN mitocondrial (ADNmt), secuenciación de la región de control d-loop del ADNmt (HVRI), de microsatélites autosómicos, short tandem repeats (STR´s) y microsatélites del cromosoma Y de un grupo de etnias asentadas en el Piedemonte del Departamento del Beni de Bolivia. Las poblaciones Mosetén y Chimane son autóctonas de la zona mientras que las poblaciones Aymará y Quechua deben considerarse colonas en la región ya que su área de poblamiento original se halla en otros departamentos, mayoritariamente andinos.
Las poblaciones autóctonas, si bien presentan una cultura común, pertenecen a grupos lingüísticos claramente diferenciados. Las etnias Mosetén y Chimane son de habla Ge-Pano-Caribe, mientras que las poblaciones Aymará y Quechua pertenecen al stock de lenguas Andinas.
Las poblaciones del Piedemonte andino boliviano son potencialmente muy interesantes en el contexto de la biología y la evolución humana dada su ubicación geográfica a medio camino de la zona andina y la amazónica y por el contexto de su historia.
El piedemonte es una ruta natural de paso entre las dos áreas que presenta una historia demográfica compleja con llegadas migratorias primitivas, influencias incaicas y reducciones franciscanas y jesuíticas que influyeron en la dinámica poblacional de los grupos que allí habitaban y que, en la actualidad, si bien mantienen sus peculiaridades culturales y lingüísticas, poseen un reducido efectivo poblacional. Por otro lado, los movimientos migratorios más recientes de otras poblaciones hacen de la región del Piedemonte una zona excelente para estudiar la diversidad y microdiferenciación de las poblaciones humanas en el continente americano.[eng] The thesis attempts to define the demographic situation of a group of Macro-Panoan linguistic populations living in the Piedmont foothills of the Beni Department (Bolivia) and describe the population genetics of these populations using mitochondrial DNA haplogroups, mtDNA hipervariable region I (HVRI) of the control region, autosomal microsatellites (STR's) and Y-chromosome microsatellites (Y-STR’s).
Moseten and Chimane populations are autochthonous indigenous of the area while Aymara and Quechua populations should be considered new settlers in the region since their original settlements are the Andean Departments.
These two groups of populations belong to distinct linguistic clusters. Chimane Moseten belong to Ge-Pano-Carib speaking group while the Aymara and Quechua populations belong to the Andean language stock.
Populations of the Bolivian piedmont are potentially interesting in the context of biology and human evolution because of its location halfway between the Andes and the Amazon areas and the context of its history.
The piedmont is a natural passage between the two areas with a complex demographic history with primitive migratory arrivals, Inca influences and Franciscan and Jesuit reductions that influenced the population dynamics of the groups who lived in this territory in the past. Populations who live in piedmont nowadays, maintain their linguistic and genetic diversity although they have a reduced effective population. On the other hand, more recent migration of other populations make the region an excellent location to study the diversity and microdifferentiation of human population in the Americas
Rett Syndrome: Revised diagnostic criteria and nomenclature
No full textObjective: Rett syndrome (RTT) is a severe neurodevelopmental disease that affects approximately 1 in 10,000 live female births and is often caused by mutations in Methyl-CpG-binding protein 2 (MECP2). Despite distinct clinical features, the accumulation of clinical and molecular information in recent years has generated considerable confusion regarding the diagnosis of RTT. The purpose of this work was to revise and clarify 2002 consensus criteria for the diagnosis of RTT in anticipation of treatment trials. Method: RettSearch members, representing the majority of the international clinical RTT specialists, participated in an iterative process to come to a consensus on a revised and simplified clinical diagnostic criteria for RTT. Results: The clinical criteria required for the diagnosis of classic and atypical RTT were clarified and simplified. Guidelines for the diagnosis and molecular evaluation of specific variant forms of RTT were developed. Interpretation These revised criteria provide clarity regarding the key features required for the diagnosis of RTT and reinforce the concept that RTT is a clinical diagnosis based on distinct clinical criteria, independent of molecular findings. We recommend that these criteria and guidelines be utilized in any proposed clinical research
Computer assisted knee replacement surgery : is the movement mainstream?
No full textThe first computer-assisted Total Knee Arthroplasty (TKA) was performed in 1997. The FDA approved computer assisted knee arthroplasty systems used in the early 2000s. Since then, surgeons and institutions all over the world have gradually adopted the technology. While the computer holds an importance place in the majority of workspaces across all industries, computer-assisted surgical technique has yet to become the preferred tool of the orthopaedic surgeon. Why has "e-instrumentation" not yet substituted conventional instrumentation in TKA orthopaedic surgery? In this article, we argue that main reasons which oppose the use of this technology are based on inaccurate or misleading observations. We isolated the factors likely to explain such opposition to this innovation: current results of total knee replacement, surgeon age, operative time, system ergonomics, cost for users, and cost for suppliers and "disruptive" innovations. Other factors such as surgeon habits, hospital environment and available assistance for support, although relevant, are not discussed. We assessed the advantages and drawbacks, costs and benefits of this technology to assess whether or not this opposition is justified. Finally, we explored the reasons why such a technology may impel surgeons to use this technique or any "related technologies" in the future. The main factors limiting TKA navigation spreading amongst orthopaedic surgeons are ergonomics and economics. Other factors, such as current TKA outcomes and surgeon's age are fallacious arguments in the rebuttal of CAS system use. Computer assisted knee arthroplasty surgery is not yet mainstream, but TKA will not escape technological progress
Decoupling enzyme catalysis from thermal denaturation
No full textThe equilibrium model (EM) (Daniel et al., 2001) postulates two forms of a folded enzyme, one catalytically active (Eact) and the other inactive (Einact), which interconvert via a fast thermal equilibrium (Keq) (Figure A). This model for enzyme catalysis accounts for experimentally observed time and temperature profiles of enzyme/substrate systems more accurately than the classically derived, single folded-species, model (Figure B). In both models, the denatured species (X) is formed via the kinact process, which is temperature and time-dependent.
(FIgure A) (Figure B) Comparison between the equilibrium model and classical model for enzyme catalysis. For both, the vertical axis is catalytic rate (M s-1), the left-right axis is increasing temperature (K) and the back-front axis is assay duration (s).
The physical basis for the Eact/Einact equilibrium is unknown. To study the equilibrium, the temperature midpoint of the Eact/Einact transition (Teq) has to be separated from the thermostability of the enzyme (Tm) to allow the Einact species to exist in measurable concentrations without exhibiting denaturation.
Mutations were made in a well-studied and NMR-accessible ribonuclease, barnase, to alter the thermostability and/or the Teq of the enzyme activity. The stability properties of each mutant were measured and the activity against two substrates assayed. New models were derived and fitted against wild-type barnase, and an ideal data set, to give insight into alternative irreversible and reversible denaturation pathways. Simulations of these models were developed to benchmark potential dynamics work and explain the movements of species within each model's framework.
Assay data fits to the EM and alternative models show a preference for irreversible denaturation pathways via the Einact species. A mathematically simplified model was also found that accounts for data and could provide an alternative method for determining EM parameters. Although fits of barnase to the EM were statistically good, the denaturation properties could not be reconciled with the literature or experimentally determined values for stability and unfolding. Simulations illustrating how the Eact, Einact and denatured (X) species interact also corroborate this finding.
Despite this discrepancy (in fitted parameters to the EM), it is hypothesised that the Teq and Tm of a disulphide-bridged mutant of barnase have been successfully decoupled. This mutant has been 15N- labelled for future NMR dynamics measurements. New approaches to the EM model are proposed where the separate determination of enzyme thermodynamic properties (e.g., rate and free energy of denaturation) would allow other EM parameters to be fitted independently to each data set
Ki-67 is a PP1-interacting protein that organises the mitotic chromosome periphery
No full textCopyright @ 2014 Booth et al. This article is distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use and redistribution provided that the original author and source are credited.When the nucleolus disassembles during open mitosis, many nucleolar proteins and RNAs associate with chromosomes, establishing a perichromosomal compartment coating the chromosome periphery. At present nothing is known about the function of this poorly characterised compartment. In this study, we report that the nucleolar protein Ki-67 is required for the assembly of the perichromosomal compartment in human cells. Ki-67 is a cell-cycle regulated protein phosphatase 1-binding protein that is involved in phospho-regulation of the nucleolar protein B23/nucleophosmin. Following siRNA depletion of Ki-67, NIFK, B23, nucleolin, and four novel chromosome periphery proteins all fail to associate with the periphery of human chromosomes. Correlative light and electron microscopy (CLEM) images suggest a near-complete loss of the entire perichromosomal compartment. Mitotic chromosome condensation and intrinsic structure appear normal in the absence of the perichromosomal compartment but significant differences in nucleolar reassembly and nuclear organisation are observed in post-mitotic cells
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