Communications of the Lunar and Planetary Laboratory, volume 4, part 3 - Ubvrijkl photometry of the bright stars

Multicolor photometric analysis of bright stars - table

Experimental test of a trace formula for two-dimensional dielectric resonators

Resonance spectra of two-dimensional dielectric microwave resonators of circular and square shapes have been measured. The deduced length spectra of periodic orbits were analyzed and a trace formula for dielectric resonators recently proposed by Bogomolny et al. [Phys. Rev. E 78, 056202 (2008)] was tested. The observed deviations between the experimental length spectra and the predictions of the trace formula are attributed to a large number of missing resonances in the measured spectra. We show that by taking into account the systematics of observed and missing resonances the experimental length spectra are fully understood. In particular, a connection between the most long-lived resonances and certain periodic orbits is established experimentally.Comment: 14 pages, 12 figures, 1 tabl

In vivo cranial bone strain and bite force in the agamid lizard Uromastyx geyri

In vivo bone strain data are the most direct evidence of deformation and strain regimes in the vertebrate cranium during feeding and can provide important insights into skull morphology. Strain data have been collected during feeding across a wide range of mammals; in contrast, in vivo cranial bone strain data have been collected from few sauropsid taxa. Here we present bone strain data recorded from the jugal of the herbivorous agamid lizard Uromastyx geyri along with simultaneously recorded bite force. Principal and shear strain magnitudes in Uromastyx geyri were lower than cranial bone strains recorded in Alligator mississippiensis, but higher than those reported from herbivorous mammals. Our results suggest that variations in principal strain orientations in the facial skeleton are largely due to differences in feeding behavior and bite location, whereas food type has little impact on strain orientations. Furthermore, mean principal strain orientations differ between male and female Uromastyx during feeding, potentially because of sexual dimorphism in skull morphology

The Post-Common Envelope and Pre-Cataclysmic Binary PG 1224+309

We have made extensive spectroscopic and photometric observations of PG 1224+309, a close binary containing a DA white dwarf primary and an M4+ secondary. The H alpha line is in emission due to irradiation of the M-star by the hot white dwarf and is seen to vary around the orbit. From the radial velocities of the H alpha line we derive a period of P = 0.258689 +/- 0.000004 days and a semi-amplitude of K_Halpha = 160 +/- 8 km/s. We estimate a correction Delta_K = 21 +/- 2 km/s, where K_M = K_Halpha + Delta_K. Radial velocity variations of the white dwarf reveal a semi-amplitude of K_WD = 112 +/- 14 km/s. The blue spectrum of the white dwarf is well fit by a synthetic spectrum having T_eff = 29,300 K and log(g) = 7.38. The white dwarf contributes 97% of the light at 4500 Angstroms and virtually all of the light blueward of 3800 Angstroms. No eclipses are observed. The mass inferred for the white dwarf depends on the assumed mass of the thin residual hydrogen envelope: 0.40 < M_WD < 0.45 solar masses for hydrogen envelope masses of 0 < M_H < 4.0E-4 solar masses. We argue that the mass of the white dwarf is closer to 0.45 solar masses, hence it appears that the white dwarf has a relatively large residual hydrogen envelope. The mass of the M-star is then M_M = 0.28 +/- 0.05 solar masses, and the inclination is i = 77 +/- 7 degrees. We discuss briefly how PG 1224+309 may be used to constrain theories of close binary star evolution, and the past and future histories of PG 1224+309 itself. The star is both a ``post-common envelope'' star and a ``pre-cataclysmic binary'' star. Mass transfer by Roche-lobe overflow should commence in about 10 Gyr.Comment: 17 pages, 8 figures, AAS LaTeX, to appear in AJ, March 199

Integration of biological control agents and systemic acquired resistance inducers against bacterial spot on tomato

Two strains of plant growth-promoting rhizobacteria, two systemic acquired resistance inducers (harpin and acibenzolar-S-methyl), host-specific unformulated bacteriophages, and two antagonistic bacteria were evaluated for control of tomato bacterial spot incited by Xanthomonas campestris pv. vesicatoria in greenhouse experiments. Untreated plants and plants treated with copper hydroxide were used as controls. The plant growth-promoting rhizobacteria or a tap water control were applied as a drench to the potting mix containing the seedlings, while the other treatments were applied to the foliage using a handheld sprayer. The plant growth-promoting rhizobacteria strains, when applied alone or in combination with other treatments, had no significant effect on bacterial spot intensity. Messenger and the antagonistic bacterial strains, when applied alone, had negligible effects on disease intensity. Unformulated phage or copper bactericide applications were inconsistent in performance under greenhouse conditions against bacterial spot. Although acibenzolar-S-methyl completely prevented occurrence of typical symptoms of the disease, necrotic spots typical of a hypersensitive reaction (HR) were observed on plants treated with acibenzolar-S-methyl alone. Electrolyte leakage and population dynamics experiments confirmed that acibenzolar-S-methyl-treated plants responded to inoculation by eliciting an HR. Application of bacteriophages in combination with acibenzolar-S-methyl suppressed a visible HR and provided excellent disease control. Although we were unable to quantify populations of the bacterium on the leaf surface, indirectly we determined that bacteriophages specific to the target bacterium reduced populations of a tomato race 3 strain of the pathogen on the leaf surface of acibenzolar-S-methyl-treated plants to levels that did not induce a visible HR. Integrated use of acibenzolar-S-m ethyl and phages may complement each other as an alternative management strategy against bacterial spot on tomato

Experimental Test of a Two-dimensional Approximation for Dielectric Microcavities

Open dielectric resonators of different shapes are widely used for the manufacture of microlasers. A precise determination of their resonance frequencies and widths is crucial for their design. Most microlasers have a flat cylindrical geometry, and a two-dimensional approximation, the so-called method of the effective index of refraction, is commonly employed for numerical calculations. Our aim has been an experimental test of the precision and applicability of a model based on this approximation. We performed very thorough and accurate measurements of the resonance frequencies and widths of two passive circular dielectric microwave resonators and found significant deviations from the model predictions. From this we conclude that the model generally fails in the quantitative description of three-dimensional dielectric resonators.Comment: 10 pages, 13 figure

Desenlaces clínicos de los pacientes con diabetes e hiperglucemia de estrés que presentaron infección por SARS-CoV-2

Introduction. Diabetes and stress hyperglycemia (SH) have been related with poorer clinical outcomes in patients infected by SARS-CoV-2 and at risk for severe disease.Objective. To evaluate clinical outcomes in three groups of patients (with diabetes, without diabetes and stress hyperglycemia [SH]) with SARS-CoV-2 infection.Materials and methods. A retrospective cohort study was conducted in Cali-Colombia. Patients aged ≥18 years with a diagnosis of SARS-CoV-2 infection managed in the emergency room, hospitalization or intensive care unit (ICU) between March 2020 and December 2021 were included. Immunocompromised patients and pregnant women were excluded. Patients were classified in three groups: without diabetes, with diabetes and SH. A comparison between the groups was performed. Results. A total of 945 patients were included (59.6% without diabetes, 27% with diabetes and 13.4% with SH). Fifty-five-point three percent required ICU management, with a higher need in patients with SH (89.8%) and diabetes (67.1%), with no difference between these groups (p=0.249). A higher chance of death was seen in SH vs. without diabetes (adjOR= 8.12, 95% CI 5.12-12.88, p&lt;0.01). Frequency of acute respiratory distress syndrome, need for invasive mechanical ventilation, use of vasopressors and inotropes, the need for de novo renal replacement therapy and mortality was higher in patients with metabolic alterations (diabetes and SH). Conclusions. Diabetes and SH are associated to worse clinical outcomes and mortality in patients with COVID-19. These patients should be identified early and considered as high risk at moment of COVID-19 diagnosis that allow to mitigate adverse outcomes.Introducción. La diabetes y la hiperglucemia de estrés (HE) se han relacionado con peores desenlaces clínicos en pacientes infectados por SARS-CoV-2 y con riesgo de enfermedad grave. Objetivo. Evaluar los resultados clínicos en tres grupos de pacientes (con diabetes, sin diabetes e hiperglucemia de estrés [SH]) con infección por SARS-CoV-2.Materiales y métodos. Se realizó un estudio de cohorte retrospectivo en Cali-Colombia. Se incluyeron pacientes ≥18 años con diagnóstico de infección por SARS-CoV-2 atendidos en urgencias, hospitalización o unidad de cuidados intensivos (UCI) entre marzo de 2020 y diciembre de 2021. Se excluyeron pacientes inmunocomprometidos y mujeres embarazadas. Los pacientes fueron clasificados en tres grupos: sin diabetes, con diabetes e HE. Se realizó una comparación entre los grupos.Resultados. Se incluyeron un total de 945 pacientes (59,6% sin diabetes, 27% con diabetes y 13,4% con HE). El 55,3% requirió manejo en UCI, con mayor necesidad en pacientes con HE (89,8%) y diabetes (67,1%), sin diferencia entre estos grupos (p=0,249). Se observó una mayor probabilidad de muerte en HE vs. sin diabetes (adjOR= 8,12, 95% IC 5,12-12,88, p&lt;0,01). La frecuencia de síndrome de distrés respiratorio agudo, necesidad de ventilación mecánica invasiva, uso de vasopresores e inotrópicos, necesidad de terapia de reemplazo renal de novo y la mortalidad fue mayor en pacientes con alteraciones metabólicas (diabetes e HE).Conclusiones. La diabetes y la HE se asociaron a peores resultados clínicos y mortalidad en pacientes con COVID-19. Estos pacientes deben ser identificados tempranamente y considerados de alto riesgo al momento del diagnóstico de COVID-19 que permitan mitigar los desenlaces adversos

Estudio y comparación de distintos tipos de intercambiadores para enfriamiento evaporativo

A fin de mejorar la eficiencia energética de los sistemas de enfriamiento evaporativo se estudian distintos tipos de intercambiadores. En general, los usados corrientemente en la región presentan problemas de degradación, baja relación área/volumen o alta pérdida de carga. Para el estudio se construyeron y ensayaron intercambiadores que puedan superar estos problemas utilizando nuevos materiales y geometrías que no signifiquen costos elevados. Se encontraron los coeficientes de transferencia de calor y masa, el área unitaria y las caídas de presión para cada configuración. Se realizó una comparación técnica y económica a fin de elegir las mejores soluciones.In order to improve the energy efficiency of evaporative cooling systems different types of heat exchangers are studied. In general, the ones currently used in the region present degradation problems, low relation area/volume or high pressure drop. Low cost exchangers that can surpass these problems using new materials and geometries were constructed and tested. The heat and mass transfer coefficients, the unitary area and the pressure drop for each configuration. A technical and economic comparison was made in order to choose the best solutions.Asociación Argentina de Energías Renovables y Medio Ambiente (ASADES

Estudio y comparación de distintos tipos de intercambiadores para enfriamiento evaporativo

A fin de mejorar la eficiencia energética de los sistemas de enfriamiento evaporativo se estudian distintos tipos de intercambiadores. En general, los usados corrientemente en la región presentan problemas de degradación, baja relación área/volumen o alta pérdida de carga. Para el estudio se construyeron y ensayaron intercambiadores que puedan superar estos problemas utilizando nuevos materiales y geometrías que no signifiquen costos elevados. Se encontraron los coeficientes de transferencia de calor y masa, el área unitaria y las caídas de presión para cada configuración. Se realizó una comparación técnica y económica a fin de elegir las mejores soluciones.In order to improve the energy efficiency of evaporative cooling systems different types of heat exchangers are studied. In general, the ones currently used in the region present degradation problems, low relation area/volume or high pressure drop. Low cost exchangers that can surpass these problems using new materials and geometries were constructed and tested. The heat and mass transfer coefficients, the unitary area and the pressure drop for each configuration. A technical and economic comparison was made in order to choose the best solutions.Asociación Argentina de Energías Renovables y Medio Ambiente (ASADES

Estudio y comparación de distintos tipos de intercambiadores para enfriamiento evaporativo

A fin de mejorar la eficiencia energética de los sistemas de enfriamiento evaporativo se estudian distintos tipos de intercambiadores. En general, los usados corrientemente en la región presentan problemas de degradación, baja relación área/volumen o alta pérdida de carga. Para el estudio se construyeron y ensayaron intercambiadores que puedan superar estos problemas utilizando nuevos materiales y geometrías que no signifiquen costos elevados. Se encontraron los coeficientes de transferencia de calor y masa, el área unitaria y las caídas de presión para cada configuración. Se realizó una comparación técnica y económica a fin de elegir las mejores soluciones.In order to improve the energy efficiency of evaporative cooling systems different types of heat exchangers are studied. In general, the ones currently used in the region present degradation problems, low relation area/volume or high pressure drop. Low cost exchangers that can surpass these problems using new materials and geometries were constructed and tested. The heat and mass transfer coefficients, the unitary area and the pressure drop for each configuration. A technical and economic comparison was made in order to choose the best solutions.Asociación Argentina de Energías Renovables y Medio Ambiente (ASADES