Corresponding states law for a generalized Lennard-Jones potential.

It was recently shown that vapor-liquid coexistence densities derived from Mie and Yukawa models collapse to define a single master curve when represented against the difference between the reduced second virial coefficient at the corresponding temperature and that at the critical point. In this work, we further test this proposal for another generalization of the Lennard-Jones pair potential. This is carried out for vapor-liquid coexistence densities, surface tension, and vapor pressure, along a temperature window set below the critical point. For this purpose, we perform molecular dynamics simulations by varying the potential softness parameter to produce from very short to intermediate attractive ranges. We observed all properties to collapse and yield master curves. Moreover, the vapor-liquid curve is found to share the exact shape of the Mie and attractive Yukawa. Furthermore, the surface tension and the logarithm of the vapor pressure are linear functions of this difference of reduced second virial coefficients.

Electron drift velocities in He and water mixtures: measurements and an assessment of the water vapour cross-section sets.

The drift velocity of electrons in mixtures of gaseous water and helium is measured over the range of reduced electric fields 0.1-300 Td using a pulsed-Townsend technique. Admixtures of 1% and 2% water to helium are found to produce negative differential conductivity (NDC), despite NDC being absent from the pure gases. The measured drift velocities are used as a further discriminative assessment on the accuracy and completeness of a recently proposed set of electron-water vapour cross-sections [K. F. Ness, R. E. Robson, M. J. Brunger, and R. D. White, J. Chem. Phys. 136, 024318 (2012)]. A refinement of the momentum transfer cross-section for electron-water vapour scattering is presented, which ensures self-consistency with the measured drift velocities in mixtures with helium to within approximately 5% over the range of reduced fields considered.

[Chronic obstructive pulmonary disease in the setting of hospital at home. Study of 522 episodes]. / Enfermedad pulmonar obstructiva crónica en hospitalización a domicilio. Estudio de 522 casos.

OBJECTIVES: To assess the effectiveness, respiratory status, services of origin and outcome of patient with exacerbated COPD attended in Hospital at Home (HaH) regimen. PATIENT AND METHOD: Study of patients with an exacerbated COPD in HaH from Vitoria-Gasteiz, Spain during the period March 1999-October 2004, in whom hospital admission had been recommended after medical assessment. We studied: age, gender, patient's stay, oxygen-saturation or arterial blood gas analysis, FEV1 (basal), dyspnea status (basal and current), coexisting diseases, exacerbation causes, Services of origin, use of home nebulizers and oxygen therapy, intravenous drugs, course (discharges/admissions/deaths). We analyzed the number of visits to the Emergency Department and hospital admissions 90 days before and after discharge from Hospital at home. RESULTS: A total of 302 patients who generated 522 cases with exacerbated COPD were accepted, 81% of whom are men. Means stay was 11 days (0-111). Three hundred ninety six (76%) of the cases were discharge from HaH, 111 (21%) had to be hospitalized for different reasons, on 13 (2.5%) died. Of these, 43% came from the Respiratory Department and 39% from the Emergency one. Mean FEV1 was 45.4. A total of 89% of the patients had dyspnea 4/4 and 34% 3/4 when seen and 9% of the patients had pneumonia. During the 90 days following discharge from Hospital at Home, the number of visits to the Emergency Department and the rate of hospital admissions decreased significantly (p < 0.001). CONCLUSIONS: Our data confirm that Hospital at Home is a good alternative to conventional hospital admission for the management of patients with exaxerbated COPD.

Enfermedad pulmonar obstructiva crónica en hospitalización a domicilio. Estudio de 522 casos / Chronic obstructive pulmonary disease in the setting of hospital at home. Study of 522 episodes

Objetivos. Analizar la efectividad, situación respiratoria, servicios de procedencia, causas de reingreso y evolución de pacientes con enfermedad pulmonar obstructiva crónica (EPOC) agudizada en una Unidad de Hospitalización a Domicilio (HaD). Pacientes y método. Estudio de pacientes con EPOC agudizada atendidos en la Unidad de HaD de Vitoria-Gasteiz entre marzo de 1999 y octubre de 2004, donde el ingreso hospitalario es recomendado tras valoración médica. Variables estudiadas: edad, sexo, estancia media, saturación de oxígeno o gasometría arterial, volumen espiratorio forzado en el primer segundo (FEV1) basal, grado de disnea (basal y actual), enfermedades coexistentes, causas de la agudización, servicios de procedencia, utilización de nebulizadores, oxigenoterapia y medicación intravenosa y evolución (altas/ingresos/fallecimientos). Analizamos el número de visitas a Urgencias y los ingresos hospitalarios 3 meses antes y 3 meses después de la intervención de HaD. Resultados. Trescientos dos pacientes que generaron 522 casos con EPOC agudizada fueron aceptados. El 81% eran hombres. La mediana de la estancia fue de 11 días (rango: 1-111). En 396 (76%) casos se dio el alta desde HaD. Ciento once (21%) tuvieron que ser hospitalizados por diferentes causas y 13 (2,5%) fallecieron. El 43 % procedían del Servicio Respiratorio y el 39% de Urgencias. El FEV1 medio fue de 45,4. El 89% de los pacientes tenían disnea 3-4/4 en el momento de ser atendidos. El 9% de los pacientes tuvieron neumonía. Durante los 90 días posteriores al alta por HaD el número de visitas a Urgencias y de ingresos disminuyó significativamente (p < 0,001). Conclusiones. Nuestros datos confirman que la HaD es una buena alternativa a la hospitalización convencional para el manejo de pacientes con EPOC agudizada (AU)

Objectives. To assess the effectiveness, respiratory status, services of origin and outcome of patient with exacerbated COPD attended in Hospital at Home (HaH) regimen. Patient and method. Study of patients with an exacerbated COPD in HaH from Vitoria-Gasteiz, Spain during the period March 1999-October 2004, in whom hospital admission had been recommended after medical assessment. We studied: age, gender, patient's stay, oxygen-saturation or arterial blood gas analysis, FEV1 (basal), dyspnea status (basal and current), coexisting diseases, exacerbation causes, Services of origin, use of home nebulizers and oxygen therapy, intravenous drugs, course (discharges/admissions/deaths). We analyzed the number of visits to the Emergency Department and hospital admissions 90 days before and after discharge from Hospital at home. Results. A total of 302 patients who generated 522 cases with exacerbated COPD were accepted, 81% of whom are men. Means stay was 11 days (0-111). Three hundred ninety six (76%) of the cases were discharge from HaH, 111 (21%) had to be hospitalized for different reasons, on 13 (2.5%) died. Of these, 43% came from the Respiratory Department and 39% from the Emergency one. Mean FEV1 was 45.4. A total of 89% of the patients had dyspnea 4/4 and 34% 3/4 when seen and 9% of the patients had pneumonia. During the 90 days following discharge from Hospital at Home, the number of visits to the Emergency Department and the rate of hospital admissions decreased significantly (p < 0.001). Conclusions. Our data confirm that Hospital at Home is a good alternative to conventional hospital admission for the management of patients with exaxerbated COPD (AU)

Electron drift velocities in mixtures of helium and xenon and experimental verification of corrections to Blanc's law.

Measurements of electron drift velocities were performed in pure Xe and He and in a number of mixtures ranging up to 70% of Xe. The data were obtained by using a pulsed Townsend technique over the density-normalized electric field strength E/N between 1 and 100 Td . Even for pure gases there are no data in the entire range covered here, and these data represent an extension of accurate drift velocities to higher E/N. A selection of well-established cross sections for low energies, which was extended to higher energies, led to a reasonably good agreement of the calculated transport coefficients with the available data. At the same time we have applied the standard (common E/N) Blanc's law and two forms of common mean energy (CME, due to Chiflykian) procedures. Blanc's law fails for most mixtures at low and moderate E/N, while the CME procedure is capable of following the experimental data for the mixtures much more closely, and even predicting the negative differential conductivity region when such effect does not exist for pure gases. Thus the present paper also represents an experimental test of procedures to correct the standard Blanc's law. Finally, we have used the data for two mixtures to obtain results for the third mixture and in all cases this procedure gave excellent results even though only the standard Blanc's law was used in the process.

Ion mobilities in Xe/Ne and other rare-gas mixtures.

The ion mobility or drift velocity data important for modeling glow discharges in rare gas mixtures are not generally available, nor are the ion-neutral scattering cross sections needed to calculate these data. In this paper we propose a set of cross sections for Xe+ and Ne+ collisions with Xe and Ne atoms. Ion mobilities at 300 K calculated using this cross section set in a Monte Carlo simulation are reported for reduced field strengths, E/N, up to 1500 x 10(-21) V m(2), in pure gases and in Xe/Ne mixtures containing 5% and 20% Xe/Ne, which are mixtures of interest for plasma display panels (PDPs). The calculated Xe+ mobilities depend strongly on the mixture composition, but the Ne+ mobility varies only slightly with increasing Xe in the mixture over the range studied here. The mobilities in pure gases compare well with available experimental values, and mobilities in gas mixtures at low E/N compare well with our recent measurements which will be published separately. Results from these calculations of ion mobilities are used to evaluate the predictions of Blanc's law and of the mixture rule proposed by Mason and Hahn [Phys. Rev. A 5, 438 (1972)] for determining the ion mobilities in mixtures from a knowledge of the mobilities in each of the pure gases. The mixture rule of Mason and Hahn is accurate to better than 10% at high field strengths over a wide range of conditions of interest for modeling PDPs. We conclude that a good estimate of ion mobilities at high E/N in Xe/Ne and other binary rare gas mixtures can be obtained using this mixture rule combined with known values of mobilities in parent gases and with the Langevin form for mobility of rare gas ions ion in other gases. This conclusion is supported by results in Ar/Ne mixtures which are also presented here.

Motion of SF+x (x=1-3,5) and ion conversion in SF6-N2 mixtures.

This paper reports on the mass-analyzed measurement of the drift velocity of the positive SF6 daughter ions, SF+x (x=1-3,5) in the mixture of SF6 with N2 for SF6 concentrations of 10% and 50%. A double mass spectrometer-drift tube was used for these measurements. The density-normalized electric field intensity E/N, was varied from 30 to 360 Td (1 Td=10(-17) V cm(2)). We have found an increasingly monotonic dependence of the drift velocity with E/N, and an inverse dependence of the above parameter with the decrease of the SF6 content in the mixture. A test of Blanc's law for the zero-field reduced mobilities of the above ions shows a fair qualitative agreement. No drift velocities of these ionic species could be measured in pure N2, since we found that these ions reacted strongly with the nitrogen molecules. The cases for SF+3 and SF+5 are discussed. A similar behavior was observed for the nitrogen ions drifting in pure SF6.

N+ charge transfer and N+2 dissociation in N2 at swarm energies.

This paper reports a drift-tube-mass-spectrometer measurement of the relative abundances of N+ and N+2 in pure nitrogen, over a ratio of electric field to gas density, E/N, from 800 to 7200 Td [1 townsend (Td)=10(-17) V cm(2)]. A proposed charge transfer dissociation scheme between the above two ions and N2 allowed us to obtain spatial rate coefficients for charge transfer and dissociation over the E/N range 800-2800 Td. Using previously measured cross sections for the above processes, and assuming a Maxwellian distribution of ion velocities, we calculated the reaction coefficients, which were found to be in good agreement with our measured values. In particular, the present results support the trend toward fairly high charge transfer cross section values for N+ energies above 10 eV. In the overlap range between 2.4 and 7.2 kTd, our concentration ratio [N(+)/N(+)(2)] is about five times smaller than that measured previously from a diffuse Townsend discharge in which electron impact is involved in addition to N+2 collisional dissociation with N2, but has the same trend. Thus it seems that, besides N+2 dissociation by electron impact, collisional dissociation becomes important at elevated values of E/N. In connection with previous discharge work in nitrogen, the present study may help explain the enhanced cathode yields observed.

Considerations for conducting epidemiologic case-control studies of cancer in developing countries.

The challenges involved in conducting epidemiologic studies of cancer in developing countries can be and often are unique. This article reports on our experience in performing a case-control study of invasive cervical cancer in four Latin American countries (Columbia, Costa Rica, Mexico, and Panama), the summary medical results of which have been published in a previous issue of this journal (1). The study involved a number of principal activities--mainly selecting, conducting interviews with, and obtaining appropriate biologic specimens from 759 cervical cancer patients, 1,467 matched female controls, and 689 male sex partners of monogamous female subjects. This presentation provides an overview of the planning and methods used to select the subjects, conduct the survey work, and obtain complete and effectively unbiased data. It also points out some of the important advantages and disadvantages of working in developing areas similar to those serving as locales for this study.

[Incidence and characteristics of Q fever in a community habitat]. / Incidencia y características de la fiebre Q en un hábitat comarcal.

Q fever is more common in our country than is usually thought, as shown by the diagnostic incidence curve, which approached an exponential rather than lineal function. Sixty cases were diagnosed between 1985 and October 1989. The disease predominated in middle aged males. The suspect epidemiologic contacts did not have any significance. Q fever was more frequent during autumn. Its usual clinical presentation was pneumonia (75%), commonly associated with a flu-like syndrome. Liver was commonly involved (66.6%), although in a mild degree. One of the patients had chronic Q fever, with granulomatous and hepatic, but not endocardial, involvement. The diagnosis was based on seroconversion detected by indirect immunofluorescence. As a rule, the course of the disease was favorable independently from therapy.