Broken Promises

I only very recently have become confident in myself. It took me a while to fi nd my footing, to discover who I was and what I am capable of. To get to where I am now, full of potential and excitement for the future, I had to go through a lot of dark spots. I think my story is one that should be told. I am not writing to brag about myself or make me out to be this heroic, strong figure—I’m writing because I want students that find themselves in similar situations to know that they are not alone

Folding and gating of the outer membrane porin PhoE of Escherichia coli

The cell envelope of Gram-negative bacteria, such as Escherichia coli, consists of a double membrane separated by the periplasm. Due to this architecture, the cell can maintain a microenvironment essential for cell viability. Several outer membrane proteins (OMPs), such as PhoE, are implicated in providing the cell of its nutrients. PhoE functions in the outer membrane as a trimeric pore allowing passive diffusion of preferentially anionic compounds with molecular masses up to 600 Da. OMPs are synthesized in the cytoplasm as precursor proteins with an N-terminal extension, the signal sequence. These precursors are translocated across the inner membrane via the Sec machinery, and the signal sequence is cleaved off. In this thesis we addressed the question whether periplasmic intermediates exists in the biogenesis of OMPs. PhoE is used in our laboratory as a model protein to study the biogenesis of OMPs. Artificial disulfide bonds were constructed within and between PhoE monomers, based upon the known 3D-structure. Formation of these disulfide bonds required the presence of the periplamic DsbA and DsbG proteins, respectively, which catalyze disulfide bonds in unfolded and folded structures, respectively. These findings indicated that folding of the monomer and trimer occurs at least partially in the periplsm. Subsequently, it was demonstrated that the periplamic peptidyl-prolyl cis/trans isomerase SurA functions as a chaperone in the biogenesis of PhoE since folding of a PhoE mutant lacking its proline residues still required the presence of SurA. PhoE monomers are foled as a b-barrel with 16-antiparallel b-strands. These strands are connected by short turns at the periplasmic side and long loop at the surface-exposed side of the membrane. The third loop (L3) is folded into the barrel, thereby forming a constriction at half the height of the membrane. The sequence PEFGG at the tip of L3 is highly conserved in a superfamily of bacterial porins. The L3 is involved in voltage-dependent closing of the pore. In this thesis the channel characteristics of mutant PhoE porins in which either the tip of the constriction loop was connected to the barrel wall or residues within the conserved PEFGG sequence were replaced, were determined. The experiments demonstrated that pore closings are not mediated by a gross movement of L3 within the channel, but by more subtle rearrangements, involving only parts of L3 or the side chains of the charged residues wihtin the constriction zone

Exercise training improves vascular function in adolescents with type 2 diabetes.

The impact of exercise training on vascular health in adolescents with type 2 diabetes has not been previously studied. We hypothesized that exercise training would improve micro- and macrovascular health in adolescents with type 2 diabetes. Thirteen adolescents (13-21 years, 10F) with type 2 diabetes were recruited from Princess Margaret Hospital. Participants were randomized to receive either an exercise program along with standard clinical care (n = 8) or standard care alone (n = 5). Those in the intervention group received 12 weeks of gym-based, personalized, and supervised exercise training. Those in the control group were instructed to maintain usual activity levels. Assessments were conducted at baseline and following week 12. The exercise group was also studied 12 weeks following the conclusion of their program. Assessments consisted of conduit artery endothelial function (flow-mediated dilation, FMD) and microvascular function (cutaneous laser Doppler). Secondary outcomes included body composition (dual-energy X-ray absorptiometry, DXA), glycemic control (whole body insulin sensitivity, M) assessed using the euglycemic-hyperinsulinemic clamp protocol, cardiorespiratory fitness (V˙O2peak), and muscular strength (1RM). Exercise training increased FMD (P < 0.05), microvascular function (P < 0.05), total lean mass (P < 0.05), and muscle strength (P < 0.001). There were no changes in cardiorespiratory fitness, body weight, BMI, or M. In the control group, body weight (P < 0.01), BMI (P < 0.01), and total fat mass (P < 0.05) increased. At week 24, improvements in vascular function were reversed. This study indicates that exercise training can improve both conduit and microvascular endothelial function and health, independent of changes in insulin sensitivity in adolescents with type 2 diabetes

Observaciones de alta resolución del remanente de supernova G308.4-1.4

En este trabajo presentamos nuevas observaciones de alta resolución del remanente de supernova (RSN) G308.4-1.4 usando el interferómetro Australia Telescope Compact Array (ATOA) en los arreglos 6B y 750B. Las observaciones, realizadas con el Compact Array Broadband Backend (CABB) cubren un ancho de banda de 2 GHz a través de 2049 canales, lo que permitió obtener mapas a distintas frecuencias entre 1 y 3 GHz. Se alcanzó una resolución espacial de 9.8" x 9.6" a 2.36 GHz, lo cual mejora en un factor 10 las imágenes publicadas en trabajos previos. Nuestros mapas revelan detalles que no habían sido observados anteriormente, mostrando en particular la estructura interna de dos regiones compactas muy intensas superpuestas a la cáscara elíptica del norte. Utilizando el método T-T plot, estudiamos la distribución de índices espectrales en distintas zonas de este RSN con el fin de determinar la posible vinculación entre las estructuras detectadas, especialmente de las dos regiones compactas cuya relación con el RSN es incierta. También analizamos la polarización asociada a la emisión en radio.In this work we present new high resolution observations of the supernova remnant (SNR) G308.4-1.4 using the Australia Telescope Compact Array (ATCA) in the 6B and 750B arrays. These observations, obtained with the Compact Array Broadband Backend (CABB), span a 2 GHz band width split in 2049 channels. Such configuration allowed us to construct images at different frequencies from 1 to 3 GHz. A spatial resolution of 9.8" x 9.6" was achieved at 2.36 GHz, improving former images in the literature by an order of magnitude. Our maps reveal details not observed previously, showing in particular the internal structure of two bright, compact regions overlapping the northern elliptical shell. Applying the T-T plot method, we estimated the spectral index distribution in different regions throughout the SNR so as to determine a possible link between the observed structures,mainly the two compact regions of uncertain connection with the SNR. We also analyze the polarization of the radio emission.Asociación Argentina de Astronomí

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Abstract:&nbsp; Introduction:&nbsp;From the start of the COVID-19 pandemic, numerous labor categories had to adapt to protect the health of their workers and to be able to continue with their activities. Among them are the Call Centers, who migrated their usual modality to that of teleworking or home office in the workers\u27 home. This caused numerous changes in people\u27s lifestyles, eating habits and levels of physical activity, among others, in an unfavorable epidemiological context.&nbsp;Objective:&nbsp;To describe eating habits, physical activity level and nutritional status of the telephone agents of a Call Center account in the city of Córdoba under the telework modality, in the year 2020.&nbsp;Material and methods:&nbsp;An observational, descriptive and cross-sectional study. Non-probabilistic sample, for convenience, made up of 90 telephone agents from a Call Center account under the telework modality (exclusion criteria: seniority &lt;2 months, workers with sick leave, pregnant women and lactating women). Data collection was carried out using a semi-structured survey form to be completed in an online, self-administered format (Google Forms). It was prepared based on the survey proposed by the Manual de Entornos Saludables&nbsp; and the Cuestionario Internacional de Actividad Física “IPAQ”.&nbsp;Results:&nbsp;85.6% of the sample was represented by the female gender, the mean age was 28.8 ± 5.5 years. 45.6% presented a BMI ≥ 25 Kg / m2 and six out of ten workers perceived an increase in weight since they began to telework. Practically everyone eats at least one meal during their working hours, ultra-processed products being the most chosen and more than half (54.4%) increased their food consumption. 83.5% spent 6 hours or more sitting during a business day.&nbsp;Conclusions:&nbsp;The high proportion of workers with overweight and obesity, the quality of their diet with a prominence of ultra-processed foods and the high time spent sitting, call for the generation of adapted strategies that promote healthy lifestyles in work environments, in order to protect the health and prevent the development of diseases.Resumen:&nbsp; Introducción: A partir del inicio de la pandemia por COVID-19, numerosos rubros laborales debieron adaptarse para proteger la salud de sus trabajadores y poder continuar con sus actividades.&nbsp;Entre ellos se encuentran los Call Centers, quienes migraron su modalidad habitual a la de teletrabajo o home office en el hogar de los trabajadores. Esto ocasionó numerosos cambios en los estilos de vida de las personas, hábitos alimentarios y niveles de actividad física entre otros, en un contexto epidemiológico poco favorable.&nbsp;Objetivo: Describir los hábitos alimentarios, nivel actividad física y el estado nutricional, de los agentes telefónicos de una cuenta de Call Center de la ciudad de Córdoba bajo la modalidad de teletrabajo, en el año 2020.&nbsp;Material y métodos:&nbsp;Estudio de alcance observacional, descriptivo y de corte transversal. Muestra no probabilística, por conveniencia, conformada por 90 agentes telefónicos de una cuenta de Call Center bajo la modalidad de teletrabajo (criterios de exclusión:&nbsp; antigüedad &lt;2 meses, trabajadores con licencia por enfermedad, gestantes y mujeres lactantes). La recolección de datos se llevó a cabo mediante un formulario de encuesta semi-estructurado para ser completado en formato online, autoadministrado (Formularios de Google). El mismo se confeccionó en base a la encuesta propuesta por el Manual de Entornos Saludables y del Cuestionario Internacional de Actividad Física “IPAQ”.&nbsp;&nbsp;&nbsp;Resultados: el 85,6% de la muestra estuvo representada por el género femenino, la media de edad fue de 28,8 ± 5,5 años. El 45,6% presentó un IMC ≥ 25&nbsp;Kg/m2&nbsp;y seis de cada diez trabajadores percibió aumento ponderal desde que comenzó a teletrabajar. Prácticamente todos realizan al menos una comida durante su horario laboral, siendo los productos ultraprocesados los más elegidos y más de la mitad (54,4%) aumentó el consumo de alimentos. El 83,5%&nbsp;pasó 6 horas o más sentado durante un día hábil.&nbsp;Conclusiones: La elevada proporción de trabajadores con sobrepeso y obesidad, la calidad de su alimentación con prominencia de ultraprocesados y el elevado tiempo de permanencia sentado, instan&nbsp;generar estrategias&nbsp;adaptadas que promuevan estilos de vida saludable en los entornos laborales, con el fin de proteger la salud y prevenir el desarrollo de enfermedades.

Molecular environments of the supernova remnant G359.1−0.5

We report new CO observations and a detailed molecular-line study of the mixed morphology supernova remnant G359.1-0.5, which contains six OH (1720 MHz) masers along the radio shell, indicative of shock-cloud interaction. Observations of 12CO and 13CO J:1-0 lines were performed in a ∼38 × 38 arcmin area with the on-the-fly technique using the Kit Peak 12 Meter telescope. The molecular study has revealed the existence of a few clumps with densities ∼103 cm-3 compatible in velocity and position with the OH (1720 MHz) masers. These clumps, in turn, appear to be part of a larger, elongated molecular structure ∼34 arcmin long extending between -12.48 and +1.83 km s-1, adjacent to the western edge of the radio shell. According to the densities and relative position with respect to the masers, we conclude that the CO clouds depict unshocked gas, as observed in other remnants with OH (1720 MHz) masers. In addition, we investigated the distribution of the molecular gas towards the adjacent γ-ray source HESS J1745-303 (Aharonian et al. 2006) but could not find any morphological correlation between the γ-rays and the CO emission at any velocity in this region.Fil: Eppens, Laura Karina. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Instituto Argentino de Radioastronomía. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto Argentino de Radioastronomía; ArgentinaFil: Reynoso, Estela Marta. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; ArgentinaFil: Lazendic Galloway, J. Monash University; AustraliaFil: Combi, Jorge Ariel. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Instituto Argentino de Radioastronomía. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto Argentino de Radioastronomía; ArgentinaFil: Albacete Colombo, Juan Facundo. Universidad Nacional del Comahue; Argentin

Observaciones del remanente de supernova G296.5+10.0 con el satélite XMM-Newton

G296.5+10.0 es un remanente de supernova (RSN) que presenta una morfolog´ıa bilateral de 900×650 en torno a un eje de simetr´ıa perpendicular al plano de la Galaxia en la banda de radio. El remanente muestra dos m´aximos de emisi´on en los extremos sureste y suroeste de la c´ascara de radio. Adem´as, el instrumento de rayos X EXOSAT detect´o una emisi´on extendida entre 0.1-1.2 keV con una distribuci´on axisim´etrica similar a la encontrada en radio, cuyos m´aximos coinciden en posici´on. Adem´as, se detect´o una estrella de neutrones en el centro del RSN que no es visible en la banda de radio. En este trabajo presentamos un mosaico de cinco apuntamientos en direcci´on a G296.5+10.0 usando el instrumento XMM-Newton en el modo full window, mejorando la resoluci´on espacial en un factor 5 con respecto a la mejor imagen obtenida hasta el momento por el instrumento EXOSAT en esta banda de energ´ıa. Estos datos muestran en detalle la emisi´on de rayos X asociada al remanente, donde se observa que la distribuci´on del plasma est´a contenida entre los bordes de radio del RSN. Adem´as, se observa una d´ebil emisi´on de rayos X entre 0.4-2 keV que puede ser bien ajustada con un modelo de una sola temperatura en equilibrio de ionizaci´on. El estudio espectral de este gas de rayos X permiti´o encontrar variaciones en las abundancias de algunos metales. Finalmente, con una estimaci´on de NH y el exceso de color E(B-V) del RSN, calculamos la distancia a la fuente utilizando un modelo de enrojecimiento vs distancia para la Galaxia.G296.5+10.0 is a 900 ×650 -size supernova remnant (SNR) that displays a bilateral distribution in the radio band with the symmetry axis perpendicular to the Galactic Plane. The remnant shows two emission peaks at the South-East and South-West of the radio shell. In addition, the EXOSAT instrument detected an extended X-ray plasma with an axisymmetric distribution between 0.1-1.2 keV, being both the radio and X-ray emission peaks coincident in position. A neutron star was detected at the center of the SNR in the X-ray band but with no radio counterpart. In this work we present an X-ray mosaic of five pointings towards G296.5+10.0 performed with the satellite XMM-Newton in the full window mode, improving the spatial resolution by a factor of 5 as compared to the best image obtained so far by the EXOSAT instrument in this energy band. The XMM-Newton observations show in detail the X-ray emission associated with the remnant, where the distribution of the plasma is observed to be within the outermost radio continuum contours of the remnant. We also noted a weak X-ray emission between 0.4-2 keV that was well fitted using a ionization equilibrium model with a single temperature. Through a spectral X-ray study we found variations in the abundances of some metals. Finally, we calculated the distance to the SNR using NH from our spectral study and a Galactic reddening-distance model.Fil: Eppens, Laura Karina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas; ArgentinaFil: Combi, Jorge Ariel. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; ArgentinaFil: Reynoso, Estela Marta. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; Argentin