1,716 research outputs found

    The connections of party brokers

    Get PDF
    Seminal models of clientelism assert that parties value brokers for their strong downward ties to voters. Despite its dominance, scholars have not empirically scrutinized key assumptions of this theory due to the challenges of measuring brokers' network connections. We analyze unique data from three sources-Ghana's voter register, a handmade catalogue of local elites, and a large-scale survey of aspiring party brokers. We show that the observable implications of the standard model do not hold: brokers know surprisingly few voters, brokers with more downward connections are not the most active or effective, and parties do not select the brokers who know the most voters. Instead, brokers with the most upward connections to local elites appear to be the most valuable to parties. We build inductively from these results to develop an alternative theory of brokers, proposing that many parties value "problem solvers" over "monitors.

    Creation of entangled states in coupled quantum dots via adiabatic rapid passage

    Full text link
    Quantum state preparation through external control is fundamental to established methods in quantum information processing and in studies of dynamics. In this respect, excitons in semiconductor quantum dots (QDs) are of particular interest since their coupling to light allows them to be driven into a specified state using the coherent interaction with a tuned optical field such as an external laser pulse. We propose a protocol, based on adiabatic rapid passage, for the creation of entangled states in an ensemble of pairwise coupled two-level systems, such as an ensemble of QD molecules. We show by quantitative analysis using realistic parameters for semiconductor QDs that this method is feasible where other approaches are unavailable. Furthermore, this scheme can be generically transferred to some other physical systems including circuit QED, nuclear and electron spins in solid-state environments, and photonic coupled cavities.Comment: 10 pages, 2 figures. Added reference, minor changes. Discussion, results and conclusions unchange

    Reduced Atlantic variability in the mid-Pliocene

    Get PDF
    This study evaluates interannual-to-decadal sea surface temperature (SST) variability in the mid-Pliocene Warm Period within the Pliocene Model Intercomparison Project (PlioMIP). Our results show significantly reduced variability at low latitudes and mid-latitudes in the mid-Pliocene in comparison to the pre-industrial climate. At high latitudes of both hemispheres, the SST variability has increased. Latitudinal changes are likely driven by changes in the meridional SST gradient. Results with respect to the main Atlantic SST modes of variability show that the Atlantic Multidecadal Variability shifts southward and expands eastward due to a southward shift in the North Atlantic Drift position. The Atlantic Meridional Mode amplitude weakens due to increased SST gradient between its two poles. The South Atlantic Subtropical Dipole significantly shifts its southwestern pole towards the South American coast. Moreover, all Atlantic modes of variability have shifted their respective frequencies towards lower values. Our analyses on the PlioMIP simulation results provide a useful constraint in future projections associated with a warmer world when assessing Atlantic SST variability

    Effects of temperature and salinity on four species of northeastern Atlantic scyphistomae (Cnidaria Scyphozoa)

    Get PDF
    This work was funded by the MASTS pooling initiative (Marine Alliance for Science and Technology for Scotland), and we gratefully acknowledge that support. MASTS is funded by the Scottish Funding Council (grant reference HR09011) and contributing institutions. C.L.W. is also grateful to the US/UK Fulbright Commission and the University of St Andrews for their financial support.Laboratory incubation experiments were conducted to examine the effects of different temperatures (4, 9, 14, 19, 23°C) and salinities (21, 27, 34) on survival and asexual reproduction of scyphistomae of Cyanea capillata, C. lamarckii, Chrysaora hysoscella, and Aurelia aurita in order to better understand how climate variability may affect the timing and magnitude of jellyfish blooms. Significant mortality was observed only for C. capillata and Ch. hysoscella at the highest and lowest temperatures, respectively, but temperature and salinity significantly affected the asexual reproductive output for all species. As temperature increased, production rates of podocysts increased and, if produced, progeny scyphistomae by side budding also increased. However, strobilation rates, and therefore the mean number of ephyrae produced, decreased when scyphistomae were exposed to elevated temperatures. These results provide a mechanistic explanation for why ephyrae of these species tend to be produced during colder periods of the year whilst summer and early autumn are probably important periods for increasing the numbers of scyphistomae in natural populations.PostprintPeer reviewe

    Regional variations in the ocean response to tropical cyclones: Ocean mixing versus low cloud suppression

    Get PDF
    Tropical cyclones (TCs) tend to cool sea surface temperature (SST) via enhanced vertical mixing and evaporative fluxes. This cooling is substantially reduced in the subtropics, especially in the northeastern Pacific where the occurrence of TCs can warm the ocean surface. Here we investigate the cause of this anomalous warming by analyzing the local oceanic features and TC-induced anomalies of SST, surface fluxes, and cloud fraction using satellite and in situ data. We find that TCs tend to suppress low clouds at the margins of the tropical ocean warm pool, enhancing shortwave radiative surface fluxes within the first week following storm passage, which, combined with spatial variations in ocean thermal structure, can produce a ~1°C near-surface warming in the northeastern Pacific. These findings, supported by high-resolution Earth system model simulations, point to potential connections between TCs, ocean temperature, and low cloud distributions that can influence tropical surface heat budgets

    Talking therapy: The allopathic nihilation of homoeopathy through conceptual translation and a new medical language

    Get PDF
    The 19th century saw the development of an eclectic medical marketplace in both the United Kingdom and the United States, with mesmerists, herbalists and hydrotherapists amongst the plethora of medical ‘sectarians’ offering mainstream (or ‘allopathic’) medicine stiff competition. Foremost amongst these competitors were homoeopaths, a group of practitioners who followed Samuel Hahnemann (1982[1810]) in prescribing highly dilute doses of single-drug substances at infrequent intervals according to the ‘law of similars’ (like cures like). The theoretical sophistication of homoeopathy, compared to other medical sectarian systems, alongside its institutional growth after the mid-19th-century cholera epidemics, led to homoeopathy presenting a challenge to allopathy that the latter could not ignore. Whilst the subsequent decline of homoeopathy at the beginning of the 20th century was the result of multiple factors, including developments within medical education, the Progressive movement, and wider socio-economic changes, this article focuses on allopathy’s response to homoeopathy’s conceptual challenge. Using the theoretical framework of Berger and Luckmann (1991[1966]) and taking a Tory historiographical approach (Fuller, 2002) to recover more fully 19th-century homoeopathic knowledge, this article demonstrates how increasingly sophisticated ‘nihilative’ strategies were ultimately successful in neutralising homoeopathy and that homoeopaths were defeated by allopaths (rather than disproven) at the conceptual level. In this process, the therapeutic use of ‘nosodes’ (live disease products) and the language of bacteriology were pivotal. For their part, homoeopaths failed to mount a counter-attack against allopaths with an explanatory framework available to them

    Quantifying Global Drivers of Zoonotic Bat Viruses: A Process-based Perspective

    Get PDF
    Emerging infectious diseases (EIDs), particularly zoonoses, represent a significant threat to global health. Emergence is often driven by anthropogenic activity (e.g. travel, land use change). Although disease emergence frameworks suggest multiple steps from initial zoonotic transmission to human-to-human spread, there have been few attempts to empirically model specific steps. We create a process-based framework to separate out components of individual emergence steps. We focus on early emergence and expand the first step, zoonotic transmission, into processes of generation of pathogen richness, transmission opportunity and establishment, each with their own hypothesised drivers. Using this structure, we build a spatial empirical model of these drivers, taking bat viruses shared with humans as a case study. We show that drivers of both viral richness (host diversity and climatic variability) and transmission opportunity (human population density, bushmeat hunting and livestock production) are associated with virus sharing between humans and bats. We also show spatial heterogeneity between the global patterns of these two processes, suggesting high priority locations for pathogen discovery and surveillance in wildlife may not necessarily coincide with those for public health intervention. Finally, we offer direction for future studies of zoonotic EIDs by highlighting the importance of the processes underlying their emergence

    Compilation of an Arabic Children’s Corpus

    Get PDF
    Inspired by the Oxford Children's Corpus, we have developed a prototype corpus of Arabic texts written and/or selected for children. Our Arabic Children's Corpus of 2950 documents and nearly 2 million words has been collected manually from the web during a 3-month project. It is of high quality, and contains a range of different children's genres based on sources located, including classic tales from The Arabian Nights, and popular fictional characters such as Goha. We anticipate that the current and subsequent versions of our corpus will lead to interesting studies in text classification, language use, and ideology in children's texts

    Thermoregulation and mucosal immunity : the effects of environmental extremes

    Get PDF
    The main objectives of this thesis were to: 1. investigate the effects of acute and chronic hypoxia on human thermoregulation and mucosal immunity, specifically salivary immunoglobulin A (s-IgA) and salivary alpha-amylase during mild cold exposure at rest (Chapter 4 and 5), 2. identify the effectiveness of four practical field re-warming methods for the field treatment of cold casualties on thermoregulation and metabolism (Chapter 6), 3. examine the s-IgA response during and following mild hypothermia (Chapter 7) and 4. determine the efficacy of three field protection methods for the prevention of heat loss in non-shivering cold casualties using an in vitro torso model exposed to - 18.5°C, 0°C and 18.5°C for four hours (Chapter 8). Two hours of exposure to a simulated high altitude of 4000m, regardless of hypoxic acclimatisation, did not alter core or mean skin temperature during cold exposure. Nonetheless, hypoxia reduced metabolic heat production which may cause thermoregulatory implications during longer bouts of cold exposure. Chronic hypoxia reduced thermal sensitivity to the cold which may lead individuals to neglect appropriate behavioural thermoregulation and increase the risk of local and whole body cold injuries. Given s-IgA responses were unaffected by hypoxia in the cold before and following the 18 day mountaineering expedition suggests individuals are not at risk from URTI upon arrival to altitude. During a three hour ‘awaiting rescue’ scenario following cold water immersion to reduce core temperature, a triple layered, metallised survival product with cells to trap heat and self-activating chemical heat pads was more superior at re-warming cold individuals compared to other methods tested. The insulative attribute of this survival bag may reduce possible shivering-induced fatigue and the subsequent increase in heat loss during more prolonged periods of cold exposure (> 4 hours). A reduction in core temperature (≥ 1.5°C) resulting from cold water immersion and subsequent cold air exposure suppressed the usual daily s-IgA response which may increase susceptibility to illness and infection (i.e. URTI, common colds, influenza) if re-warming is not initiated immediately. A non-shivering, in vitro torso model demonstrated that a triple-layered, metallised survival product with cells to trap heat and self-activating chemical heat pads was the most superior of three field cold protection methods to reduce heat loss during exposure to a variety of ambient temperatures (- 18.5°C, 0°C and 18.5°C) for four hours. It would appear when individuals experience cold stress at sea level or altitude, a triple-layered, metallised survival product with cells to trap heat and self-activating chemical heat pads may be the optimal light-weight field treatment to counteract the potential onset of hypothermia. For nonshivering casualties, this survival product may greatly reduce heat loss creating a longer survival time while waiting for evacuation to superior medical treatments (e.g. hospitals). The overall aim of this thesis was to clarify the immediate health risks for individuals exposed to the extreme environments of cold and/or hypoxia, and if simple countermeasures which can be easily administered, offer suitable protection in the field to reduce such risks. The key message of this thesis is that individuals exposing themselves to cold and/or hypoxia when un-acclimatised to such conditions should carry self-administering survival bags and follow a specific programme of monitoring thermoregulation and upper respiratory symptoms in order to remain free of illness (e.g. rhinovirus, bronchitis) and peripheral or central cold injury (e.g. hypothermia and frostbite)

    The Limited Role of Mutually Unbiased Product Bases in Dimension Six

    Full text link
    We show that a complete set of seven mutually unbiased bases in dimension six, if it exists, cannot contain more than one product basis.Comment: 8 pages, identical to published versio
    • …
    corecore