728 research outputs found
An explanation of yield differences in three potato cultivars
Under ideal growing conditions, yield is the product of intercepted photosynthetically active radiation (PARi) and its conversion efficiency to dry matter (radiation use efficiency, RUE). For potato (Solanum tuberosum L.) the ability of the leaf to convert the PARi into carbohydrates (source) and the storage capacity of the tubers (sink) affect the potential growth of individual tubers and therefore crop yield. This study describes these mechanisms for three commercial potato cultivars (Bondi, Fraser, and Russet Burbank) grown in non-limiting field conditions. At final harvest Bondi had the largest tuber yield and produced heavier but fewer tubers compared with Fraser and Russet Burbank. All crops had similar total accumulated radiation interception (Rcum), and yield differences were explained by the RUE which was highest for Bondi, lowest for Fraser, with Russet Burbank intermediate. Fraser had the lowest rate of canopy senescence, maintained the lowest specific leaf area (SLA) for most of the period of tuber bulking and maintained the highest dry matter (DM) allocated to leaves at the end of the tuber filling phase. Throughout the crop growing period Bondi had a larger tuber sink compared with Fraser and Russet Burbank. These results suggest that potato tuber production was limited by the “sink strength” and RUE in the lower yield varieties. The larger sink in Bondi, caused by shorter stolons, enabled higher rates of tuber filling which produced the largest tubers in the middle node positions and the highest average tuber weight per plant among these cultivars
Viral load and antibody boosting following herpes zoster diagnosis
BACKGROUND: Acute varicella zoster virus (VZV) replication in shingles is accompanied by VZV antibody boosting. It is unclear whether persisting virus shedding affects antibody levels. OBJECTIVES: To investigate the relationship between VZV viral load and antibody titres in shingles patients during six months following diagnosis and assess whether VZV antibody titre could discriminate patients with recent shingles from healthy population controls. STUDY DESIGN: A prospective study of 63 patients with active zoster. Blood samples were collected at baseline, one, three and six months to measure VZV DNA and IgG antibody titre. We compared VZV antibody titres of zoster patients and 441 controls. RESULTS: In acute zoster, viral load was highest at baseline and declined gradually over the following six months. Mean antibody titres rose fourfold, peaking at one month and remaining above baseline levels throughout the study. Antibody levels at one, three and six months after zoster were moderately correlated with baseline but not subsequent viral load. Regarding use of antibody titres to identify recent shingles, to achieve 80% sensitivity, specificity would be 23.4%, 67.7%, 64.8% and 52.6%, at baseline, visit 2, 3 and 4 respectively, whilst to achieve 80% specificity, sensitivity would be 28.3%, 66.1%, 52.6%, 38.6%, at baseline, visit 2, 3 and 4 respectively. CONCLUSIONS: Clinical VZV reactivation boosted VZV antibody levels and the level of boosting was dependent upon baseline viral replication. While antibody titres could discriminate patients with shingles 1-6 months earlier from blood donor controls, there was a large trade-off between sensitivity and specificity
Recommended from our members
Sacrificing their Careers for their Families? An Analysis of the Family Pay Penalty in Europe
This paper examines the extent of and the mechanisms behind the penalty to motherhood in six European countries. Each country provides different levels of support for maternal employment allowing us to determine institutional effects on labour market outcome. While mothers tend to earn less than non-mothers, the penalty to motherhood is considerably lower in countries with policy support for working mothers. The paper establishes the United Kingdom and West Germany to have the least policy support for working mothers as well as the largest penalties to motherhood
Three-dimensionally Ordered Macroporous Structure Enabled Nanothermite Membrane of Mn2O3/Al
Mn2O3 has been selected to realize nanothermite membrane for the first time in the literature. Mn2O3/Al nanothermite has been synthesized by magnetron sputtering a layer of Al film onto three-dimensionally ordered macroporous (3DOM) Mn2O3 skeleton. The energy release is significantly enhanced owing to the unusual 3DOM structure, which ensures Al and Mn2O3 to integrate compactly in nanoscale and greatly increase effective contact area. The morphology and DSC curve of the nanothermite membrane have been investigated at various aluminizing times. At the optimized aluminizing time of 30 min, energy release reaches a maximum of 2.09 kJ∙g−1, where the Al layer thickness plays a decisive role in the total energy release. This method possesses advantages of high compatibility with MEMS and can be applied to other nanothermite systems easily, which will make great contribution to little-known nanothermite research
Psychopathy to Altruism: Neurobiology of the Selfish–Selfless Spectrum
The age-old philosophical, biological, and social debate over the basic nature of humans as being “universally selfish” or “universally good” continues today highlighting sharply divergent views of natural social order. Here we analyze advances in biology, genetics and neuroscience increasing our understanding of the evolution, features and neurocircuitry of the human brain underlying behavior in the selfish–selfless spectrum. First, we examine evolutionary pressures for selection of altruistic traits in species with protracted periods of dependence on parents and communities for subsistence and acquisition of learned behaviors. Evidence supporting the concept that altruistic potential is a common feature in human populations is developed. To go into greater depth in assessing critical features of the social brain, the two extremes of selfish–selfless behavior, callous unemotional psychopaths and zealous altruists who take extreme measures to help others, are compared on behavioral traits, structural/functional neural features, and the relative contributions of genetic inheritance versus acquired cognitive learning to their mindsets. Evidence from population groups ranging from newborns, adopted children, incarcerated juveniles, twins and mindfulness meditators point to the important role of neuroplasticity and the dopaminergic reward systems in forming and reforming neural circuitry in response to personal experience and cultural influences in determining behavior in the selfish–selfless spectrum. The underlying neural circuitry differs between psychopaths and altruists with emotional processing being profoundly muted in psychopaths and significantly enhanced in altruists. But both groups are characterized by the reward system of the brain shaping behavior. Instead of rigid assignment of human nature as being “universally selfish” or “universally good,” both characterizations are partial truths based on the segments of the selfish–selfless spectrum being examined. In addition, individuals and populations can shift in the behavioral spectrum in response to cognitive therapy and social and cultural experience, and approaches such as mindfulness training for introspection and reward-activating compassion are entering the mainstream of clinical care for managing pain, depression, and stress
Recommended from our members
Public service markets: their economics, institutional oversight and regulation
Public services in the UK have been transformed over the past 25 years with the introduction of market oriented solutions into their provision. This has been characterised by a shift away from state provision to independent providers, and by the introduction of competition and choice. This shift was partly ideologically motivated and partly driven by budget cutting considerations following the financial crisis. As such it has been lacking a comprehensive economic justification or method of analysis. It is now commonly accepted that the language of economic markets is essential to frame arguments about how effectively public services are achieving their intended outcomes.
Using market language and concepts may not always be comfortable for those from a traditional policy-making background. It can nevertheless be very useful when designing investigations into the effectiveness and value for money in the mechanisms of delivery of such services, whenever these services entail a degree of user choice as is currently the case in large parts of health, social care and education (referred to as competition in the market). Our paper wants to provide a conceptual basis on the way of thinking in these terms. We provide a description of the current state and then comment on the desirability of this quasi market approach. Uniquely in the literature, we analyse the expected and desired developments by distinguishing between choice and compulsory merit goods.
In choice merit goods markets many users are unable to choose effectively because of the existence of a number of demand side or supply side market failures. Moreover, conflicts may exist between how service users actually make choices, and policy objectives such as universality or equity which may not be achieved simply by ‘leaving it to the market’.
The users of compulsory merit goods are typically a minority and unable to internalise the full social benefits of their actions; hence it may be welfare-enhancing for society to coerce them ‘consume’ these services. As choice cannot be an objective, the commissioning (competition for the market) or direct provision by the state of such goods may meet public policy objectives more effectively than the market mechanism alone.
Building on these foundations the paper discusses when public service markets are likely to be an effective method of achieving public policy objectives, and when they may not be. Our paper analyses the implications for the institutional and legal framework, funding oversight and regulation of public service markets as a result of their transformation into quasi-markets. The paper concludes with some suggestions for those charged with overseeing public service markets in practice based on this analysis
- …
