Search

Funding Information: The authors would like to thank the MCAM and Rover Environmental Monitoring Station Teams. Comments and suggestions by the M. Battalio and M. Mischna were very useful and are gratefully acknowledged. The authors also thank support from the Spanish Ministry of Science, Innovation and Universities, project No RTI2018-098728-B-C31, and the Instituto Nacional de Técnica Aeroespacial. A portion of this work was performed at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with NASA. The US coauthors performed their work under sponsorship from NASA's Mars Science Laboratory project. Funding Information: The authors would like to thank the MCAM and Rover Environmental Monitoring Station Teams. Comments and suggestions by the M. Battalio and M. Mischna were very useful and are gratefully acknowledged. The authors also thank support from the Spanish Ministry of Science, Innovation and Universities, project No RTI2018‐098728‐B‐C31, and the Instituto Nacional de Técnica Aeroespacial. A portion of this work was performed at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with NASA. The US coauthors performed their work under sponsorship from NASA's Mars Science Laboratory project. Publisher Copyright: © 2022. The Authors. Modeling and observations have long demonstrated that Martian dust storms strongly interfere with global circulation patterns and change the diurnal and semidiurnal pressure variability as well as oscillations with periods greater than one sol associated with planetary waves. As of early 2022, five Mars years of pressure data have been collected by the Curiosity Rover in Gale crater with the Rover Environmental Monitoring Station (REMS). A combination of signal filtering techniques is used to search for pressure signatures that might warn large-scale dust storms reaching Gale. The analysis combines an exploration of changes in both baroclinic waves and thermal tides for the first time to our knowledge. Focusing on the periods preceding local opacity increases as detected by Curiosity's Mastcam observations, the pressure analysis shows changes in the coupling between the diurnal pressure tide and quasi-diurnal Kelvin wave, as well as in the temporal evolution of baroclinic waves that are harbingers of the larger dust storms. Changes in the phasing between Kelvin waves and diurnal tides are found to be precursors for the growth phase of periods Z (defined here as Ls ∼ 120°–160°), A (Ls ∼ 190°–240°), and C (Ls ∼ 300°–335°) dust storms. Changes in multi-sol pressure oscillations also help predict the occurrence of A, B (Ls ∼ 245°–295°), and C storms. The specific pressure oscillations preceding each storm period are likely to be signatures of the large-scale circulation patterns that enable the growth and propagation of the storm fronts.

Long-run evolution of B chromosomes is mainly made up by an evolutionary arms race between these selfish genetic elements and the standard genome. The suppression of B drive is one of the clearest expressions of genome defense against B chromosomes. After drive neutralization, the B is condemned to extinction unless a new variant showing drive can emerge and replace it. This paper reports the first empirical evidence for the substitution of a neutralized B variant by a new selfish B variant. Such a polymorphism regeneration has recently taken place in a natural population of the grasshopper Eyprepocnemis plorans.

The chemisorption of CO on the atop site of Pt(111) has been simulated by a Pt4 cluster model. Ab initio self consistent field (SCF) and complete active space self consistent field (CASSCF) cluster model wave functions have been obtained for the electronic ground state. Likewise, ab initio SCF wavefunctions have been obtained for two other electronic states. The optimum geometry and vibrational frequencies of chemisorbed CO are reported for the three states. The interaction energy and vibrational shift of chemisorbed CO, with respect to free gas phase CO, have been analyzed for the three electronic states. This analysis is carried out by means of the constrained space orbital variation (CSOV) method. In all cases the bond is found to be dominated by σ donation and π back-donation, known as Blyholder's mechanism. This mechanism is further supported by SCF calculations on a larger, Pt13, cluster model. For both clusters, the CSOV analysis of the vibrational frequency definitely shows that, contrary to previous recent studies, a major contribution to the experimentally observed vibrational shift comes from the π back-donation mechanism. However, we found that, contrary to common belief, σ donation also acts to lower the CO frequency and not to increase it. Physical reasons for such unexpected behaviour are given.

The electrostatic potential distribution above the Pt(100), Pt(110) and Pt(111) surfaces has been studied using finite cluster model representations of the surfaces and their ab initio Hartree-Fock electron densities. From the different distributions it is seen that electrostatic effects are not substantial for Pt(100), minor but significant for Pt(110) and quite important for Pt(111). The minima of the electrostatic potential always appear at the more coordinated sites, four-fold for Pt(100) and Pt(110) and threefold for Pt(111), indicating that, up to first order, electrophilic adsorbates will prefer to approach the high coordinated surface sites.

An ab initio one-electron approach has been used to study the geometry and order of stabilities of Pt 3 and Pt 4 clusters. For the valence shell the Schrodinger equation is exactly solved in a rather large basis set, the effect of d electrons is modelled by a core polarization potential, and core—core corrections are also included. Results for Pt 3 are in good agreement with recent ab initio calculations which explicitly include the Pt 5d electrons. For Pt 4 the most stable structure is predicted to be a rhombus, as expected from comparison with other metal tetramers.

Virtual Worlds present a 3D space to the user. However, input devices are typically 2D. This unnatural mapping reduces the engagement of the experience. We are exploring using Wii controllers to provide 3D gesture-based input to the 3D virtual world, Second Life. By evaluating its usability, we found that gesture-based interfaces are appealing and natural for hand gestures such as wave but difficult to map to facial expressions.

To investigate collagen turnover and proliferation in dermal fibroblasts from patients with systemic sclerosis (SSc) and their relationship with disease duration and cellular subpopulations, SSc patients were grouped by disease duration (less than 2.5 years or more than 7 years). Control and SSc fibroblasts were obtained from skin biopsies. Collagen biosynthesis was determined by [14C]-proline uptake. Type I/III collagens, gelatinolytic activity, and tissue inhibitors of metalloproteinases (TIMP)-1 and -2 were evaluated by electrophoresis, zymography, and enzyme-linked immunosorbent assay, respectively. Total collagen synthesis and the levels of alpha1(I), alpha2(I), and alpha1(III) chains, as well as TIMP-1 and proliferation were increased in fibroblasts only from patients with early-stage SSc. Gelatinolytic activity did not vary among the groups. This metabolic condition favors a higher local fibroblast population and is characterized by a heterogeneous clonal response in which the majority exhibited higher levels of collagen and TIMP-1 synthesis as well as an increase in their proliferation patterns involving hyper-reactive fibroblast subsets.

Population-based surveillance and a case-control study were conducted in Abancay, Peru, to estimate the burden of disease and to determine risk factors for sporadic lymphocutaneous sporotrichosis (LS). Laboratory records from local hospitals were reviewed for the years of 1997 and 1998, and prospective surveillance was conducted for the period of September 1998 through September 1999. A case-control study was conducted with 2 matched control subjects per case patient. The mean annual incidence was 98 cases per 100,000 persons. Children had an incidence 3 times higher than that for adults and were more likely to have LS lesions on the face and neck. Identified risk factors included owning a cat, playing in crop fields, having a dirt floor in the house, working mainly outdoors, and having a ceiling made of raw wood or conditions associated with a lower socioeconomic status. Decreased environmental exposure, such wearing protective clothing during construction activities for adults or limiting contact with cats and soil for children, and improvements in living spaces may decrease the incidence of LS.

Cryptococcus neoformans tiene 2 variedades: neoformans y gattii. El primero afecta a pacientes inmunosuprimidos y la variedad gattii produce enfermedad en individuos aparentemente sanos originando compromiso neurológico. En nuestro país no se realizan pruebas bioquímicas diferenciales, por lo que este estudio permitió estandarizar un método de tipificación de las variedades en cepas de C. neoformans de origen clínico mantenidas en el Instituto Nacional de Salud del Perú (INS). Entre abril de 1997 y diciembre de 1998, el INS recibió 18 cepas de C. neoformans aisladas de pacientes con SIDA. La confirmación de las especies fue realizada según métodos convencionales: observación de levaduras encapsuladas, prueba de la urea, asimilación de carbohidratos y tolerancia a la temperatura. Adicionalmente se verificó la ausencia de la enzima nitrato reductasa y se realizó la prueba de la fenoloxidasa modificada. Las 18 cepas fueron tipificadas como variedad neoformans usando el agar CGB. No se encontró ninguna cepa de variedad gattii. Cryptococcus neoformans has two varieties: neoformans and gattii. The first one affects mainly immunosuppressed patients and the latter causes neurological lesions. Differential biochemical tests are not performed in Peru, so this study was able to standardize a typification method among C. neoformans strain varieties from clinical origin that were maintained at the National Institute of Health (INS) of Peru. Between April 1997 and December 1998, INS received 18 C. neoformans strains isolated from AIDS patients. Confirmation of the species was performed according to conventional methods: encapsulated yeast observation, urease test, carbohydrate assimilation and temperature toleration. Additionally, the absence of the nitrate reductase enzyme was verified and the modified fenoloxidase test was performed, too. All 18 strains were typified as neoformans by means of CGB. No gattii strains were found.

To investigate the spontaneous cytokine gene expression in fibroblasts from patients with diffuse cutaneous systemic sclerosis. Their pattern of expression was correlated with the production of collagen.Fibroblasts were obtained from skin biopsies of nine patients diagnosed with systemic sclerosis (mean 16 +/- 8.7 years of disease duration) and ten control individuals. The cytokine gene expression was detected by coupled reverse transcriptase polymerase chain reaction for interleukins 1 beta, 6, 8, tumour necrosis factor-alpha, and transforming growth factor beta. In addition, collagen synthesis was measured by [14C]-proline uptake in fibroblast cultures.All fibroblast samples from patients expressed the interleukin-6 gene (p = 0.04 compared with controls). Eight of the nine patients expressed interleukin-8 (p = 0.02 compared with controls). Four of them expressed also transforming growth factor beta and two more weakly expressed the tumour necrosis factor-alpha gene. Only one patient showed transcription for the interleukin-1 beta gene. In accordance with such immune activation, collagen synthesis was higher in fibroblasts from patients with systemic sclerosis (p = 0.028) as compared with normal controls. Indeed, a positive correlation was found between the expression of IL-6 gene and collagen production (rs = 1).The constitutive expression of IL-6 and IL-8 genes by fibroblasts may play an important role in the perpetuation of local immune dysregulation, thus leading to a permanent fibroblast activation in patients with systemic sclerosis.

The mycoplasmas comprise a discrete group of microorganisms that are known to exert a range of effects upon cells derived from the immune system. Some of these interactions turn out to be immunomodulatory, such as polyclonal stimulation of T and B cells or enhancement of the cytolytic potential of macrophages, NK cells and T lymphocytes. Immunologically committed cells, when infected with mycoplasmas, can also increase the production of cytokines (IL-1, IL-2, IL-4 and IL-6), interferon (IFN) gamma, tumor necrosis factor-alpha (TNF-alpha) and colony-stimulating factors (particularly GM-CSF). Moreover, mycoplasmas are potent inductors of cytokine secretion by fibroblasts in culture. Since growth factors are determinants for the activation and proliferation of immunocompetent cells in vitro, we decided to investigate if these effects are concordant with the finding of mycoplasma contamination. In order to address this question, we compared the pattern of lymphokine secretion by normal-derived human fibroblasts in culture with and without Mycoplasma spp. contamination. We found those human fibroblasts that have been contaminated with mycoplasma show production of IL-13 at the transcriptional level. This effect coincides with discrete morphological changes as compared to uncontaminated human fibroblasts. This is the first report to acknowledge that mycoplasma contamination can induce mRNA expression for IL-13 in cultured human fibroblasts.

The analysis of ab initio cluster model wavefunctions shows that the bonding of CO on Pt(111) is of covalent nature being well described by the Blyholder mechanism. However, the NO Cu(111) interaction is found to be dominantly ionic. This ionic nature of the bond has important consequences as an avoided crossing between two electronic states of ionic and neutral character. The existence of this avoided crossing interaction indicates that the process is non-adiabatic. While this is a well known phenomenon in molecular physics, to the authors' best knowledge, this is the first time it is shown to happen in a gassurface reaction.

Ab initio self-consistent field and complete active space self-consistent field cluster-model wave functions have been obtained for a CO-${\mathrm{Pt}}_{4}$ cluster model simulating the atop interaction of CO on Pt(111). The origin of the vibrational shift between free and chemisorbed CO has been investigated by means of the constrained space orbital variation method. This analysis shows that the vibrational shift is the result of several effects. First, there is a large positive shift due to Pauli repulsion, and second various negative contributions; these are substrate polarization, \ensuremath{\sigma} donation, and \ensuremath{\pi} back donation, respectively. This theoretical analysis shows that the mechanism suggested by Blyholder is, in fact, the one responsible for the observed vibrational shift.