613 research outputs found
Extended Definition of Capacity in Airport Systems
Nowadays the main airports throughout the world are suffering because their capacity are getting close to saturation
due to the air traffic which is still increasing besides the economic crisis and oil prices. In addition, the forecasts
predict an increase in air traffic of at least 3.6% until 2020. This situation makes very important to come up with
solutions to alleviate capacity congestions in the main airports throughout the world. Capacity has been perceived
traditionally as the factor to be addressed in airport systems and it is faced through a technical perspective. In this
paper we propose to change the mind-set and view capacity of airport systems taking other factors than pure
technical ones. The discussion is illustrated with the example of Schiphol Airport
The Smallest Molecular Switch
Ab-initio total energy calculations reveal benzene-dithiolate (BDT) molecules
on a gold surface, contacted by a monoatomic gold STM tip to have two classes
of low energy conformations with differing symmetries. Lateral motion of the
tip or excitation of the molecule cause it to change from one conformation
class to the other and to switch between a strongly and a weakly conducting
state. Thus, surprisingly, despite their apparent simplicity these Au/BDT/Au
nanowires are shown to be electrically bi-stable switches, the smallest
two-terminal molecular switches to date. Experiments with a conventional or
novel self-assembled STM are proposed to test these predictions.Comment: 8 pages, 3 figure
Common patterns of morbidity and multi-morbidity and their impact on health-related quality of life: evidence from a national survey.
BACKGROUND: There is limited evidence about the impact of specific patterns of multi-morbidity on health-related quality of life (HRQoL) from large samples of adult subjects. METHODS: We used data from the English General Practice Patient Survey 2011-2012. We defined multi-morbidity as the presence of two or more of 12 self-reported conditions or another (unspecified) long-term health problem. We investigated differences in HRQoL (EQ-5D scores) associated with combinations of these conditions after adjusting for age, gender, ethnicity, socio-economic deprivation and the presence of a recent illness or injury. Analyses were based on 831,537 responses from patients aged 18 years or older in 8,254 primary care practices in England. RESULTS: Of respondents, 23 % reported two or more chronic conditions (ranging from 7 % of those under 45 years of age to 51 % of those 65 years or older). Multi-morbidity was more common among women, White individuals and respondents from socio-economically deprived areas. Neurological problems, mental health problems, arthritis and long-term back problem were associated with the greatest HRQoL deficits. The presence of three or more conditions was commonly associated with greater reduction in quality of life than that implied by the sum of the differences associated with the individual conditions. The decline in quality of life associated with an additional condition in people with two and three physical conditions was less for older people than for younger people. Multi-morbidity was associated with a substantially worse HRQoL in diabetes than in other long-term conditions. With the exception of neurological conditions, the presence of a comorbid mental health problem had a more adverse effect on HRQoL than any single comorbid physical condition. CONCLUSION: Patients with multi-morbid diabetes, arthritis, neurological, or long-term mental health problems have significantly lower quality of life than other people. People with long-term health conditions require integrated mental and physical healthcare services
Stated preferences for anti-malarial drug characteristics in Zomba, a malaria endemic area of Malawi
Background
The evidence on determinants of individuals’ choices for anti-malarial drug treatments is scarce. This study sought to measure the strength of preference for adult antimalarial drug treatment attributes of heads of urban, rural and peri-urban households in a resource-limited malaria-endemic area of sub-Saharan Africa.
Methods
Discrete choice experiments were conducted with 508 heads of household interviewed face-to-face for a household population survey of health-seeking behavior in Zomba District, Malawi. The interviews were held in Chichewa and the choice experiment questions were presented with cartoon aids. The anti-malarial drug attributes included in the stated preference experiment were: speed of fever resolution, side effects (pruritus) risk, protection (duration of prophylactic effect), price, duration of treatment course and recommendation by a health professional. Sixteen treatment profiles from a fractional factorial design by orthogonal array were paired into choice scenarios, and scenarios were randomly assigned to participants so that each participant was presented with a series of eight pairwise choice scenarios. Respondents had the option to state indifference between the two profiles or decline to choose. Data were analysed in a mixed logit model, with normally distributed coefficients for all six attributes.
Results
The sex ratio was balanced in urban areas, whereas 63% of participants in rural areas were male. The proportion of individuals with no education was considerably higher in the rural group (25%) than in the urban (5%) and peri-urban (6%) groups. All attributes investigated had the expected influence, and traded-off in most respondents’ choices. There were heterogeneous effects of price, pruritus risk, treatment recommendation by a professional, and duration of prophylaxis across respondents, only partly explained by their differences in education, household per capita expenditure, sex and age. Individuals´ demand elasticity (simulated median, inter-quartile range) was highest (most responsive) to speed of symptom resolution (0.88, 0.80-0.89) and pruritus risk (0.25, 0.08-0.62).
Conclusions
Most adult antimalarial users are willing to use treatments without recommendation from health professional, and may be influenced by price. Future studies should investigate the magnitude of differences in price and treatment attribute sensitivity between adult anti-malarial drug users in rural, peri-urban and urban areas in order to determine optimal price subsidies
Shear Modulus of an Elastic Solid under External Pressure as a function of Temperature: The case of Helium
The energy of a dislocation loop in a continuum elastic solid under pressure
is considered within the framework of classical mechanics. For a circular loop,
this is a function with a maximum at pressures that are well within reach of
experimental conditions for solid helium suggesting, in this case, that
dislocation loops can be generated by a pressure-assisted thermally activated
process. It is also pointed out that pinned dislocations segments can alter the
shear response of solid helium, by an amount consistent with current
measurements, without any unpinning.Comment: 5 pages, 3 figure
Patrón de comportamiento tipo A, ira y enfermedades cardiovasculares (ECV) en población urbana chilena
Diaz, EM (Moyano Diaz, Emilio)1; Icaza, G (Icaza, Gloria); Mujica, V (Mujica, Veronica); Nunez, L (Nunez, Loreto); Leiva, E (Leiva, Elba); Vasquez, M (Vasquez, Marcela); Palomo, I (Palomo, Ivan)A worldwide raise in the number of cardiovascular disease (CVD) and the existence of a higher percentage in Maule (Chile) than the national media, and increased attention in the analysis of psychological factors motivate to analyze the Type A Behavior Pattern (TABP) and anger in relation to CVD. The sample was 1007 adults between 18 and 74 years old (citizens of Talca, Chile), mostly women. They provided information about their demographic details, eating habits and lifestyle, answered the Novaco's Anger inventory and the Retiro Scale of Type A Behavior (RSTAB), and also were taken measurements like weight, body mass index and blood pressure and blood tests related to risk factors to traditional cardiovascular diseases. The results show Overall, that the participants appear highly sedentary (79.9%) with relatively high levels of tabaquism (53.6%), and hypercholesterolemia (44.5%), overweight (40.7%) and obesity (32.6%). A quarter of the sample also presents hyperglycemic indexes, hypertension and TABP unequally distributed by sex. The absence of PCTA (or PCTB presence) appeared mostly associated with traditional cardiovascular risk factors (CRF). Regarding anger, women present more high than men (2.1% against 0.3%; c(2)(3) = 27.99,p<.0001), decreasing for both sexes with age, while also befall stroke by sex
Life expectancy and mortality in 363 cities of Latin America
The significant challenges to equity in health in the Region of the Americas, as detailed in the report of the Pan American Health Organization Independent Commission on Equity and Health Inequalities in the Americas, gave original impetus to this Special Issue on Equity in Health by the Pan American Journal of Public Health. The report, Just Societies: Health Equity and Dignified Lives, analyzed a vast body of evidence that indicated the overwhelming inequalities in the Region that relate to three factors: structural drivers, conditions of daily life, and governance for health equity (taking action). Highlighting the continued realities of the interrelationship between social and health inequities in the Americas is by no means new. However, since early 2020 this interrelationship has been further exposed and exacerbated by the unprecedented COVID-19 pandemic, which is testing governments, communities, economies, and individuals in ways previously unimagined in their scope and intensity. The crisis is exposing underlying inequalities in health and the cost of inaction to address this long-standing social injustice, and the COVID-19 response is even reversing improvements in social and health indicators made in the last two decades
The contribution of the Chirality-Induced Spin Selectivity (CISS) effect to the dispersion interaction between chiral molecules
Dispersion interactions are one of the components of van der Waals forces,
which play a key role in the understanding of intermolecular interactions in
many physical, chemical and biological processes. The theory of dispersion
forces was developed by London in the early years of quantum mechanics.
However, it was only in the 1960s that it was recognized that for molecules
lacking an inversion center such as chiral and helical molecules, there are
chirality-sensitive corrections to the dispersion forces proportional to the
rotatory power known from the theory of circular dichroism and with the same
distance scaling law R-6 as the London energy. The discovery of the
Chirality-Induced Spin Selectivity (CISS) effect in recent years has led to an
additional twist in the study of chiral molecular systems, showing a close
relation between spin and molecular geometry. Motivated by it, we propose in
this investigation that there may exist additional contributions to the
dispersion energy related to intermolecular, induced spin-orbit (ISOC)
interactions. Within a second-order perturbative approach, these forces
manifest as an effective intermolecular spin-spin exchange interaction.
Although they are weaker than the standard London forces, the ISOC interactions
turn out to be nevertheless not negligible and display the same R
distance scaling. Our results suggest that classical force field descriptions
of van-der Waals interactions may require additional modifications to include
the effects discussed here.Comment: 21 pages, 2 figure
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