Report on "Scheduling in a factory"

In order to carry out their orders of shoe soles, this company has a number of tasks T_1, ..., T_n of different lengths to be assigned to groups of machines. Each group is operated by one worker (two in one case), and an operation cycle corresponds to injection, cooling, and removal of the sole. The time taken at each step varies from one order to another, and when starting a new task a machine needs to be tuned, which takes some extra time. Machines are working in parallel. At the moment the assignment is carried out empirically, and the problem proposed is to optimize the procedure

Buying In: Positional Competition, Schools, Income Inequality, and Housing Consumption

Social scientists have suggested that a key sociobehavioral consequence of rising inequality is intensifying market competition for advantageous positions in the opportunity structure, such as residences that afford access to high-quality public schools. We assess empirical implications of inequality-fueled positional competition theories (PCTs) by analyzing the relationships between metropolitan income inequality, households’ efforts to secure residential positions in desirable school districts, and housing consumption behavior. We assemble a unique data set, which contains longitudinal information on household finances, residences, and geographic locations from the Panel Study of Income Dynamics; information on the quality of the school attendance areas in which these households reside; and information about the local real estate market. We find that greater inequality is associated with steeper housing price premia for residences in desirable areas, more pronounced social class sorting on school quality when relocating, and greater salience of schools relative to other housing amenities in families’ housing expenditure functions. Families in high-inequality regions exhibit modestly greater willingness to pay more (relative to their own incomes) for a given improvement in school desirability. The analysis brings important empirical nuance to oft-invoked but untested theories about positional competition as a mechanism by which inequality affects behaviors, consumption, and markets

Note on the diameter of otolith nucleus as a characteristic of the population groups of anchovy, Engraulis encrasicolus (Linnaeus, 1758), of the Cantabrian Sea and Galicia

The diameters of the nuclei of anchovy, Engraulis encrasicolus (Linnaeus, 1758), otoliths collected in 1995 and 1998 in the eastern Cantabrian Sea, the western Cantabrian Sea and Galicia (northwest Spain) have been measured to check possible differences in their length and, if they existed, whether they were characteristic of a different growth rate of the population groups of this species. Significant differences among the three regions were found. Although our results must be considered only preliminary, they seem to indicate that such differences can be characteristics of the population groups described in the regions studied.Se ha medido el diámetro del núcleo de otolitos de anchoa, Engraulis encrasicolus (Linnaeus, 1758), recogidos en el Cantábrico oriental, en el occidental y en Galicia durante 1995 y 1998 para comprobar si existían diferencias en su longitud y, si era así, si estas diferencias eran características de los grupos de población de la especie. Los resultados muestran diferencias significativas entre las tres regiones y, aunque deben considerarse solamente como preliminares, parecen indicar que estas diferencias pueden ser propias de los grupos de población de anchoa descritos en las regiones estudiadas.Instituto Español de Oceanografí

Serum folic acid is reduced in patients with Alzheimer's disease

CONTEXTO: Deficiência de vitaminas do complexo B tem sido associada a deterioração cognitiva e quadros demenciais em idosos. OBJETIVO: Neste trabalho, foi avaliado se pacientes com doença de Alzheimer (DA) e com comprometimento cognitivo leve (CCL) apresentam níveis séricos de ácido fólico e cobalamina (vitamina B12) menores que idosos controles. MÉTODOS: Foram recrutados 146 idosos (40 com DA, 56 com CCL e 49 idosos controles) para este estudo. Os níveis séricos de ácido fólico e vitamina B12 foram avaliados pelo método de eletroquimioluminescência. RESULTADOS: Os pacientes com DA apresentaram redução estatisticamente significativa nos níveis de ácido fólico em relação aos idosos com CCL e controles (p = 0,02). Esses resultados mantiveram-se estatisticamente significativos após controlar por variáveis sociodemográficas e desempenho cognitivo. Não se observaram diferenças estatisticamente significativas nos níveis de vitamina B12 nem em variáveis hematológicas entre os grupos. CONCLUSÃO: Esses resultados reforçam a importância de anormalidades em aspectos nutricionais, em particular do metabolismo de um-carbono, na fisiopatologia da DA.BACKGROUND: Complex B vitamin deficiency has been associated to cognitive impairment and dementing disorders in the elderly. OBJECTIVE: This work aims to assess whether patients with Alzheimer's disease (AD) and mild cognitive impairment (MCI) have lower levels of folic acid and cobalamin (vitamin B12) compared to age and gender-matched controls. METHODS: One hundred and forty six elderly subjects (40 AD, 56 MCI and 49 healthy older adults) were recruited for this study. Serum folic acid and vitamin B12 levels were measured by electrochemoluminescence. RESULTS: Compared to MCI and healthy controls a statistically significant reduction in serum concentrations of folic acid in AD patients was found (p = 0.02). This result remained statistically significant after controlling for socio-demographic and cognitive performance variables (p = 0.01). No significant differences were found in serum concentrations of vitamin B12 in patients with AD, MCI and healthy controls. No significant changes in hematologic parameters were observed across these diagnostic groups. DISCUSSION: The present study provides additional evidence that folic acid is reduced in patients with AD and reinforces the importance of nutritional changes, in particular the one-carbon metabolism, in the physiopathology of AD

Density-functional calculation of ionization energies of current-carrying atomic states

Current-density-functional theory is used to calculate ionization energies of current-carrying atomic states. A perturbative approximation to full current-density-functional theory is implemented for the first time, and found to be numerically feasible. Different parametrizations for the current-dependence of the density functional are critically compared. Orbital currents in open-shell atoms turn out to produce a small shift in the ionization energies. We find that modern density functionals have reached an accuracy at which small current-related terms appearing in open-shell configurations are not negligible anymore compared to the remaining difference to experiment.Comment: 7 pages, 2 tables, accepted by Phys. Rev.

Regulation of the T-type Ca²⁺ channel Cav3.2 by hydrogen sulfide: Emerging controversies concerning the role of H₂S in nociception

Ion channels represent a large and growing family of target proteins regulated by gasotransmitters such as nitric oxide, carbon monoxide and, as described more recently, hydrogen sulfide. Indeed, many of the biological actions of these gases can be accounted for by their ability to modulate ion channel activity. Here, we report recent evidence that H₂S is a modulator of low voltage-activated T-type Ca²⁺ channels, and discriminates between the different subtypes of T-type Ca²⁺ channel in that it selectively modulates Cav3.2, whilst Cav3.1 and Cav3.3 are unaffected. At high concentrations, H₂S augments Cav3.2 currents, an observation which has led to the suggestion that H₂S exerts its pro-nociceptive effects via this channel, since Cav3.2 plays a central role in sensory nerve excitability. However, at more physiological concentrations, H₂S is seen to inhibit Cav3.2. This inhibitory action requires the presence of the redox-sensitive, extracellular region of the channel which is responsible for tonic metal ion binding and which particularly distinguishes this channel isoform from Cav3.1 and 3.3. Further studies indicate that H₂S may act in a novel manner to alter channel activity by potentiating the zinc sensitivity/affinity of this binding site. This review discusses the different reports of H₂S modulation of T-type Ca²⁺ channels, and how such varying effects may impact on nociception given the role of this channel in sensory activity. This subject remains controversial, and future studies are required before the impact of T-type Ca²⁺ channel modulation by H₂S might be exploited as a novel approach to pain management