The essential role of the brain in maintaining energy homeostasis has motivated the drive to define the neural circuitry that integrates external and internal stimuli to enact appropriate and consequential metabolic and behavioral responses. The hypothalamus has received significant attention in this regard given its ability to influence feeding behavior, yet organisms rely on a much broader diversity and distribution of neuronal networks to regulate both energy intake and expenditure. Because energy balance is a fundamental determinant of survival and success of an organism, it is not surprising that emerging data connect circuits controlling feeding and energy balance with higher brain functions and degenerative processes. In this review, we will highlight both classically defined and emerging aspects of brain control of energy homeostasis.

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This paper considers the importance of countervailing power, manifested as the effects of increased retail concentration on consumer prices and welfare within a market setting where imperfectly competitive retailers negotiate intermediate prices with a monopoly supplier. Only when retailer services are regarded as very close substitutes do final prices fall following a reduction in the number of retailers. Even in these circumstances, the social benefits of countervailing power may not be realised as the supplier may seek to protect its profits by using a refusal to supply restraint to engage in exclusive trading.

Consumer choice is increasingly recognised as a crucial factor in competition policy. To illustrate the implications of such choice we present an investment model of the switching choice in the UK residential natural gas market and examine responses to a specially commissioned survey of nearly seven hundred consumers, identifying search and switching costs. Through an assessment of the savings which consumers say they require to switch supplier, together with an evaluation of consumer switching behaviour, we deduce that the incumbent retained considerable market power, suggesting that some continued regulation may be necessary.Markets for goods previously provided by a single supplier have been opened up to competition across the world. But how competitive do they become in practice? We believe this article to be a forerunner amongst academic empirical studies of this question for a major consumer industry, formerly the province of a monopoly supplier and now opened fully to competition, namely the UK domestic natural gas market. 1 As such, it provides a useful example of the development of competition in a market and the importance of consumer behaviour in determining the extent to which any market may become competitive. The role of consumer behaviour in competition policy is increasingly recognised (Prendergast, 2002;Waterson, 2003) and is particularly crucial in markets where choice has only recently become available.Our article uses specially gathered information in the UK natural gas supply market to examine how residential consumers exercised choice, as it first became available, and the policy implications of their decisions. Through a * We acknowledge funding from the Leverhulme Trust for this research, part of a larger project

Across the European Union, concentration in food retailing at the national level has been increasing for some time, but increasingly multinational retailers have been extending their international reach. In the process, aggregate concentration has risen sharply over the last few years. In addition, the presence of buyer groups, representing different retail interests, adds to the characterisation of procurement markets as highly concentrated. Also at the aggregate level, cross‐border buyer alliances amongst large retailers have emerged. We consider the implications of these features for the changing patterns of retail competition and the impact on food producers, supplier competition and economic welfare.

Sensory perception modulates lifespan across taxa, presumably due to alterations in physiological homeostasis after central nervous system integration. The coordinating circuitry of this control, however, remains unknown. Here, we used the Drosophila melanogaster gustatory system to dissect one component of sensory regulation of aging. We found that loss of the critical water sensor, pickpocket 28 (ppk28), altered metabolic homeostasis to promote internal lipid and water stores and extended healthy lifespan. Additionally, loss of ppk28 increased neuronal glucagon-like adipokinetic hormone (AKH) signaling, and the AKH receptor was necessary for ppk28 mutant effects. Furthermore, activation of AKH-producing cells alone was sufficient to enhance longevity, suggesting that a perceived lack of water availability triggers a metabolic shift that promotes the production of metabolic water and increases lifespan via AKH signaling. This work provides an example of how discrete gustatory signals recruit nutrient-dependent endocrine systems to coordinate metabolic homeostasis, thereby influencing long-term health and aging.taste | adipokinetic hormone signaling S ensory signaling systems are potent modulators of organismal metabolism and lifespan (1-6) but the mechanisms by which sensory inputs are transduced into relevant physiological outputs remain poorly understood. For even the simplest organisms, an extensive array of sensory stimuli-including chemical, mechanical, thermal, and visual cues-must be properly transduced and integrated to ensure a reliable response to environmental quality. In the nematode Caenorhabditis elegans, sensory neurons alone may accomplish these tasks. They express multiple sensory receptors, which provide simple integrative capabilities to the cell, and they secrete neuropeptides, which can direct cell-nonautonomous responses in peripheral tissues (7). The fruit fly, Drosophila melanogaster, however, is similar to mammals in that sensory neurons are often highly specialized, and elaborate mechanisms of sensory integration and interpretation are performed by specialized processing centers in the central brain (8). Once decoded, sensory signals are presumably relayed to neuroendocrine centers to stimulate appropriate actions in peripheral tissues. Whereas the release of endocrine molecules, including insulinlike peptides, via central nervous system (CNS) control has emerged as a critical regulator of aging across model organisms, the extent to which sensory signals impact such systems, and the underlying neurocircuitry involved, are unknown (9-11).The Drosophila system is a powerful tool for elucidating evolutionarily conserved aspects of neural circuitry that link sensory information to a variety of behavioral and metabolic responses. Although comprised of only ∼100,000 neurons, the fly brain is sufficiently complex to share many aspects of structure and function with humans and mice. This, along with the ability to manipulate neuronal activity in a temporally and spatially controlled manner, ha...

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Chain‐stores now dominate most areas of retailing. While retailers may operate nationally or even internationally, the markets they compete in are largely local. How should they best operate pricing policy in respect of the different markets served—price uniformly across the local markets or on a local basis according to market conditions? We model this by allowing local market differences, with retail markets differing by their size and the number of players present. We show that practising price discrimination is not always best for a chain‐store. Competitive conditions exist under which uniform pricing can raise profits.