Effects of brood manipulation costs on optimal sex allocation in social hymenoptera.

In eusocial Hymenoptera, queens and workers are in conflict over optimal sex allocation. Sex ratio theory, while generating predictions on the extent of this conflict under a wide range of conditions, has largely neglected the fact that worker control of investment almost certainly requires the manipulation of brood sex ratio. This manipulation is likely to incur costs, for example, if workers eliminate male larvae or rear more females as sexuals rather than workers. In this article, we present a model of sex ratio evolution under worker control that incorporates costs of brood manipulation. We assume cost to be a continuous, increasing function of the magnitude of sex ratio manipulation. We demonstrate that costs counterselect sex ratio biasing, which leads to less female-biased population sex ratios than expected on the basis of relatedness asymmetry. Furthermore, differently shaped cost functions lead to different equilibria of manipulation at the colony level. While linear and accelerating cost functions generate monomorphic equilibria, decelerating costs lead to a process of evolutionary branching and hence split sex ratios.

Kenny syndrome: evidence for idiopathic hypoparathyroidism in two patients and for abnormal parathyroid hormone in one.

We report three unrelated patients with Kenny syndrome. Clinical symptoms included severe dwarfism, with internal cortical thickening and medullary stenosis of the tubular bones, normal bone age, macrocephaly, absent diploic space, delayed closure of the anterior fontanel, and normal intelligence; two of the patients had hyperopia and papillary edema. The patients also had episodic hypocalcemic tetany and low serum levels of magnesium. In two patients the diagnosis of idiopathic hypoparathyroidism was established on the basis of undetectable serum parathyroid hormone (PTH) levels (N- and C-terminal RIAs); one of these had normal urinary cyclic adenosine monophosphate (cAMP) response to exogenous PTH. Circulating calcitonin was undetectable in either patient. In a third patient, who had abnormal body proportions, serum levels of PTH were increased in an RIA detecting predominantly intact PTH (N-RIA) and undetectable in another RIA recognizing carboxy-terminal fragments (C-RIA). Administration of PTH promptly increased urinary cAMP excretion. In this patient, serum levels of calcitonin were increased, whereas values for 25-OHD and 1,25(OH)2D were normal.

Steady-state brain glucose transport kinetics re-evaluated with a four-state conformational model.

Glucose supply from blood to brain occurs through facilitative transporter proteins. A near linear relation between brain and plasma glucose has been experimentally determined and described by a reversible model of enzyme kinetics. A conformational four-state exchange model accounting for trans-acceleration and asymmetry of the carrier was included in a recently developed multi-compartmental model of glucose transport. Based on this model, we demonstrate that brain glucose (G(brain)) as function of plasma glucose (G(plasma)) can be described by a single analytical equation namely comprising three kinetic compartments: blood, endothelial cells and brain. Transport was described by four parameters: apparent half saturation constant K(t), apparent maximum rate constant T(max), glucose consumption rate CMR(glc), and the iso-inhibition constant K(ii) that suggests G(brain) as inhibitor of the isomerisation of the unloaded carrier. Previous published data, where G(brain) was quantified as a function of plasma glucose by either biochemical methods or NMR spectroscopy, were used to determine the aforementioned kinetic parameters. Glucose transport was characterized by K(t) ranging from 1.5 to 3.5 mM, T(max)/CMR(glc) from 4.6 to 5.6, and K(ii) from 51 to 149 mM. It was noteworthy that K(t) was on the order of a few mM, as previously determined from the reversible model. The conformational four-state exchange model of glucose transport into the brain includes both efflux and transport inhibition by G(brain), predicting that G(brain) eventually approaches a maximum concentration. However, since K(ii) largely exceeds G(plasma), iso-inhibition is unlikely to be of substantial importance for plasma glucose below 25 mM. As a consequence, the reversible model can account for most experimental observations under euglycaemia and moderate cases of hypo- and hyperglycaemia.

Tetania secundaria a raquitismo carencial.

Hypocalcemia is an uncommon illness in children. In developed countries the incidence of rickets has decreased significantly, although last years this pathology is increasing at the expense of immigration. Its etiology is due to different factors such as low sun exposure, inadequate clothing and bad feeding and excessive contributions in phytates, exclusive breastfeeding and genetic factors. We report a case of a teenager 13 year old from Pakistan, who consulted for myoclonus, paresthesias, hand midwife and asymmetry walking. The laboratory emphasizes hypocalcemia deficit of 25 (OH) D and increased parathyroid hormone. Administration of calcium and vitamin D along with changes in his diet normalized clinical and laboratory parameters. Due to increased migration, the lack of sun exposure and inadequate supply this disease which was almost forgotten will appear another time.

Investment, duration, and exit strategies for corporate and independent venture capital-backed start-ups

We propose a model of investment, duration, and exit strategies for start-ups backed by venture capital (VC) funds that accounts for the high level of uncertainty, the asymmetry of information between insiders and outsiders, and the discount rate. Our analysis predicts that start-ups backed by corporate VC funds remain for a longer period of time before exiting and receive larger investment amounts than those financed by independent VC funds. Although a longer duration leads to a higher likelihood of an exit through an acquisition, a larger investment increases the probability of an IPO exit. These predictions find strong empirical support.

Central corneal thickness, intraocular pressure, and degree of myopia in an adult myopic population aged 20 to 40 years in southeast Spain: determination and relationships.

Objective: To determine the values of, and study the relationships among, central corneal thickness (CCT), intraocular pressure (IOP), and degree of myopia (DM) in an adult myopic population aged 20 to 40 years in Almeria (southeast Spain). To our knowledge this is first study of this kind in this region. Methods: An observational, descriptive, cross-sectional study was done in which a sample of 310 myopic patients (620 eyes) aged 20 to 40 years was selected by gender- and age-stratified sampling, which was proportionally fixed to the size of the population strata for which a 20% prevalence of myopia, 5% epsilon, and a 95% confidence interval were hypothesized. We studied IOP, CCT, and DM and their relationships by calculating the mean, standard deviation, 95% confidence interval for the mean, median, Fisher’s asymmetry coefficient, range (maximum, minimum), and the Brown-Forsythe’s robust test for each variable (IOP, CCT, and DM). Results: In the adult myopic population of Almeria aged 20 to 40 years (mean of 29.8), the mean overall CCT was 550.12 μm. The corneas of men were thicker than those of women (P = 0.014). CCT was stable as no significant differences were seen in the 20- to 40-year-old subjects’ CCT values. The mean overall IOP was 13.60 mmHg. Men had a higher IOP than women (P = 0.002). Subjects over 30 years (13.83) had a higher IOP than those under 30 (13.38) (P = 0.04). The mean overall DM was −4.18 diopters. Men had less myopia than women (P < 0.001). Myopia was stable in the 20- to 40-year-old study population (P = 0.089). A linear relationship was found between CCT and IOP (R2 = 0.152, P ≤ 0.001). CCT influenced the IOP value by 15.2%. However no linear relationship between DM and IOP, or between CCT and DM, was found. Conclusions: CCT was found to be similar to that reported in other studies in different populations. IOP tends to increase after the age of 30 and is not accounted for by alterations in CCT values.

Variability of the relative afferent pupillary defect.

PURPOSE: Afferent asymmetry of visual function is detectable in both normal and pathologic conditions. With a computerized test, we assessed the variability in measuring afferent asymmetry of the pupillary light reflex, that is, the relative afferent pupillary defect. METHODS: In ten normal subjects, pupillary responses to an alternating light stimulus were recorded with computerized infrared pupillography. The relative afferent pupillary defect for each test was determined by using a new computer analysis. The 95% confidence interval of each determination of relative afferent pupillary defect was used to represent the short-term fluctuation in its measurement. To optimize the test for clinical use, we studied the influence of stimulus intensity, duration, and number on the variability of the relative afferent pupillary defect. RESULTS: When the relative afferent pupillary defect was based on only a few light alternations (stimulus pairs), there was excessive variability in its measurement (95% confidence interval > 0.5 log units). With approximately 200 stimulus pairs, the 95% confidence interval was reduced to less than 0.1 log unit (relative afferent pupillary defect +/- 0.05 log unit). Also, there was less variability when the dark interval between alternating light stimulation was less than one second. CONCLUSIONS: Computerized infrared pupillography can standardize the alternating light test and minimize the error in quantifying a relative afferent pupillary defect. A reproducible relative afferent pupillary defect measurement is desirable for defining afferent injury and following the course of disease.

Drugs, schizotypy and cognition: Cognitive attenuations seem more consistently associated with substance use than schizotypal symptoms

Psychosis is a debilitating disease, causing harm to the individual and society. Since early detection of the disease is associated with a more benign course, factors are warranted that enable the early detection of psychosis. In the present thesis we will be focusing on two potential risk factors, namely schizotypy and drug use. The schizotypy concept, originally developed by Meehl (1962), states that schizophrenia symptoms exist on a spectrum, with symptoms ranging from the most severe in patients with schizophrenia to the least affected individual in the general population. Along the schizophrenia spectrum cognitive impairments are commonly found, for instance reduced hemispheric asymmetry or frontal lobe functions. The second risk factor (drug use), affects similar cognitive functions as those attenuated along the schizophrenia spectrum, and drug use is elevated in schizophrenia and people scoring high on schizotypy. Therefore, we set out to investigate whether cognitive attenuations formerly allocated to schizotypal symptoms could have been influenced by elevated substance use in this population. To test this idea, we assessed various drugs (nicotine, cannabis, mephedrone, general substance dependence) and schizotypy symptoms (O-LIFE), and measured either hemispheric asymmetry of function (left hemisphere dominance for language, and right hemisphere dominance for facial processing) or functions largely relying on the frontal lobes (such as cognitive flexibility, working memory, verbal short-term memory, verbal learning and verbal fluency). Results of all studies suggest that it is mostly drugs, and not schizotypy in general that predict cognitive functioning. Therefore, cognitive attenuations subscribed to schizotypy dimensions are likely to have been affected by enhanced drug use. Future studies should extend the list of potential risk factors (e.g. depression and IQ) to acquire a comprehensive overview of the most reliable predictors of disadvantageous cognitive profiles.

Capital cities of federations. On the way to analysing the normative base of their asymmetrical status

Federal Capitals often have special statutes. Compared with member states, they often enjoy a lower degree of self-government and a lesser share in the governing of the federation. Why do actors choose such devices, and how can they be justified in a liberal democracy? Surprisingly, the burgeoning literature on asymmetric federalism (to which our research group has contributed significantly) has overlooked this important feature of a de iure asymmetry, perhaps because political theory up to now has concentrated on cases of multicultural and plurinational federations. However, comparative literature is also rare. This paper is the first step to filling in this gap by comparing some federal capitals. The Federal District model (Washington) is compared to capitals organized as member-states (Berlin and Brussels), and capitals that are cities belonging to a single member state (Ottawa in Ontario). The different features of de iure asymmetry will thereby be highlighted. Some light will be shed on the possible motives, reasons and justifications for the choice of each respective status. The paper opens the door to further research on such status questions by analysing public and parliamentary debates, for example. It paves the way for more thorough research. Sicne the author has been awarded a grant by the Institut d’Estudis Autonòmics, this research will be carried out soon.

Federalism and democracy. The case of minority nations: a federalist deficit

In this chapter, after pointing out the different logics that lie behind the familiar ideas of democracy and federalism, I have dealt with the case of plurinational federal democracies. Having put forward a double criterion of an empirical nature with which to differentiate between the existence of minority nations within plurinational democracies (section 2), I suggest three theoretical criteria for the political accommodation of these democracies. In the following section, I show the agonistic nature of the normative discussion of the political accommodation of this kind of democracies, which bring monist and pluralist versions of the demos of the polity into conflict (section 3.1), as well as a number of conclusions which are the result of a comparative study of 19 federal and regional democracies using four analytical axes: the uninational/plurinational axis; the unitarianism-federalism axis; the centralisation-decentralisation axis; and the symmetry-asymmetry axis (section 3.2). This analysis reveals shortcomings in the constitutional recognition of national pluralism in federal and regional cases with a large number of federated units/regions with political autonomy; a lower degree of constitutional federalism and a greater asymmetry in the federated entities or regions of plurinational democracies. It also reveals difficulties to establish clear formulas in these democracies in order to encourage a “federalism of trust” based on the participation and protection of national minorities in the shared government of plurinational federations/regional states. Actually, there is a federal deficit in this kind polities according to normative liberal-democratic patterns and to what comparative analysis show. Finally, this chapter advocates the need for a greater normative and institutional refinement in plurinational federal democracies. In order to achieve this, it is necessary to introduce a deeper form of “ethical” pluralism -which displays normative agonistic trends, as well as a more “confederal/asymmetrical” perspective, congruent with the national pluralism of these kind of polities.

Perfusion abnormalities in hemimegalencephaly

INTRODUCTION: Cerebrovascular changes are rarely discussed in patients with hemimegalencephaly. These alterations have previously been associated with epileptical activity. CASE: We report the case of a 36-week gestation neonate presenting with total right hemimegalencephaly, as demonstrated by a magnetic resonance imaging (MRI) performed in the first days of life. Perfusion-weighted imaging displayed a clear hypervascularization of the right hemisphere. Diffusion-tensor imaging showed an arrangement of white matter fibers concentrically around the ventricle on the right hemisphere. AngioMRI showed an obvious asymmetry in the size of the middle cerebral arteries, with the right middle cerebral artery being prominent. The baby was free of clinical seizures during his first week of life. An electroencephalogram at that time displayed an asymmetric background activity, but no electrical seizures. CONCLUSION: Perfusion anomalies in hemimegalencephaly may not necessarily be related to epileptical activity, but may be related to vessel alterations.

Does Reasoning Enhance Learning?

Utilizing the well-known Ultimatum Game, this note presents the following phenomenon. If we start with simple stimulus-response agents, learning through naive reinforcement, and then grant them some introspective capabilities, we get outcomes that are not closer but farther away from the fully introspective game-theoretic approach. The cause of this is the following: there is an asymmetry in the information that agents can deduce from their experience, and this leads to a bias in their learning process.

The Law of Impersonal Transactions: Meaning and Difficulties

Most economic interactions happen in a context of sequential exchange in which innocent third parties suffer information asymmetry with respect to previous "originative" contracts. The law reduces transaction costs by protecting these third parties but preserves some element of consent by property right holders to avoid damaging property enforcement-e.g., it is they as principals who authorize agents in originative contracts. Judicial verifiability of these originative contracts is obtained either as an automatic byproduct of transactions or, when these would have remained private, by requiring them to be made public. Protecting third parties produces a sort of legal commodity which is easy to trade impersonally, improving the allocation and specialization of resources. Historical delay in generalizing this legal commoditization paradigm is attributed to path dependency-the law first developed for personal trade-and an unbalance in vested interests, as luddite legal professionals face weak public bureaucracies.

Asymmetric information and trade policy

Economists understand protectionism as a costly mechanism to redistribute from the average citizen to special-interest groups; yet political platforms that deviate from free trade have surprising popular appeal. I present an explanation based on heterogeneous information across citizens whose voting decision has an intensive margin. For each politician and each sector, the optimal trade-policy choice caters to the preferences of those voters who are more likely to be informed of that proposal. An overall protectionist bias emerges because in every industry producers are better informed than consumers. This asymmetry emerges in equilibrium because co-workers share industry-specific knwoledge, and because producers have greater incentives to engage in costly learning about their sector. My model implies that more widespread information about trade policy for an industry is associated with lower protection. Cross-sectoral evidence on U.S. non-tariff barriers and newspaper coverage is consistent with this prediction.

Heterozigosidade e assimetria do número de hâmulos em operárias adultas de Apis mellifera (Hymenoptera, Apidae)

Heterozygosity and hammuli number asymmetry in adult workers of Apis mellifera (Hymenoptera, Apidae). Relationship between individual heterozygosity at particular loci (Mdh-1, Hk-1 ou Pgm-1) or average heterozygosity of the colony and asymmetry of the hammuli number of right and left wings was verified on adult workers of five Africanized and five European colonies of Apis mellifera. Our results demonstrated the importance of statistical tests to verify the type of asymmetry of the character studied and they did not validate the assumption that uni or multiloci heterozygosity has a positive effect on developmental stability.