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The angular distribution of the sky radiance determines the energy generation of solar power technologies as well as the ultraviolet (UV) doses delivered to the biosphere. The sky-diffuse radiance distribution depends on the wavelength, the solar elevation, and the atmospheric conditions. Here, we report on ground-based measurements of the all-sky radiance at three sites in the Southern Hemisphere across a transect of about 5,000 km: Santiago (33°S, a mid-latitude city of 6 million inhabitants with endemic poor air quality), King George Island (62°S, at the northern tip of the Antarctic Peninsula, one of the cloudiest regions on Earth), and Union Glacier (79°S, a snow-covered glacier in the vast interior of Western Antarctica). The sites were strategically selected for studying the influence of urban aerosols, frequent and thick clouds, and extremely high albedo on the sky-diffuse radiance distribution. Our results show that, due to changing site-specific atmospheric conditions, the characterization of the weather-driven sky radiance distribution may require ground-based measurements.

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Percutaneous surgery is the treatment of choice of isolated aortic coarctation in adults However, when there are other heart problems related to aortic coarctation, its surgical management may vary. We report a 41-year-old male presenting with aortic coarctation associated with severe, symptomatic, bicuspid aortic valve lesions and significant left ventricular dysfunction. He underwent open heart surgery for the surgical resolution of these problems. One year after surgery the results are satisfactory with no evidence of postoperative complications and a significant improvement of patient symptoms and left ventricular function.

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The SLC5/STAC histidine kinases comprise a recently identified family of sensor proteins in two-component signal transduction systems (TCSTS), in which the signaling domain is fused to an SLC5 solute symporter domain through a STAC domain. Only two members of this family have been characterized experimentally, the CrbS/R system that regulates acetate utilization in Vibrio and Pseudomonas, and the CbrA/B system that regulates the utilization of histidine in Pseudomonas and glucose in Azotobacter. In an attempt to expand the characterized members of this family beyond the Gammaproteobacteria, we identified two putative TCSTS in the Alphaproteobacterium Sinorhizobium fredii NGR234 whose sensor histidine kinases belong to the SLC5/STAC family. Using reverse genetics, we were able to identify the first TCSTS as a CrbS/R homolog that is also needed for growth on acetate, while the second TCSTS, RpuS/R, is a novel system required for optimal growth on pyruvate. Using RNAseq and transcriptional fusions, we determined that in S. fredii the RpuS/R system upregulates the expression of an operon coding for the pyruvate symporter MctP when pyruvate is the sole carbon source. In addition, we identified a conserved DNA sequence motif in the putative promoter region of the mctP operon that is essential for the RpuR-mediated transcriptional activation of genes under pyruvate-utilizing conditions. Finally, we show that S. fredii mutants lacking these TCSTS are affected in nodulation, producing fewer nodules than the parent strain and at a slower rate.

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Percutaneous surgery is the treatment of choice of isolated aortic coarctation in adults However, when there are other heart problems related to aortic coarctation, its surgical management may vary. We report a 41-year-old male presenting with aortic coarctation associated with severe, symptomatic, bicuspid aortic valve lesions and significant left ventricular dysfunction. He underwent open heart surgery for the surgical resolution of these problems. One year after surgery the results are satisfactory with no evidence of postoperative complications and a significant improvement of patient symptoms and left ventricular function.

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Black carbon (BC) from fossil fuel and biomass combustion darkens the snow and makes it melt sooner. The BC footprint of research activities and tourism in Antarctica has likely increased as human presence in the continent has surged in recent decades. Here, we report on measurements of the BC concentration in snow samples from 28 sites across a transect of about 2,000 km from the northern tip of Antarctica (62°S) to the southern Ellsworth Mountains (79°S). Our surveys show that BC content in snow surrounding research facilities and popular shore tourist-landing sites is considerably above background levels measured elsewhere in the continent. The resulting radiative forcing is accelerating snow melting and shrinking the snowpack on BC-impacted areas on the Antarctic Peninsula and associated archipelagos by up to 23 mm water equivalent (w.e.) every summer.

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Attributable to the Montreal Protocol, the most successful environmental treaty ever, human-made ozone-depleting substances are declining and the stratospheric Antarctic ozone layer is recovering. However, the Antarctic ozone hole continues to occur every year, with the severity of ozone loss strongly modulated by meteorological conditions. In late November and early December 2020, we measured at the northern tip of the Antarctic Peninsula the highest ultraviolet (UV) irradiances recorded in the Antarctic continent in more than two decades. On Dec. 2nd, the noon-time UV index on King George Island peaked at 14.3, very close to the largest UV index ever recorded in the continent. On Dec. 3rd, the erythemal daily dose at the same site was among the highest on Earth, only comparable to those recorded at high altitude sites in the Atacama Desert, near the Tropic of Capricorn. Here we show that, despite the Antarctic ozone recovery observed in early spring, the conditions that favor these extreme surface UV events persist in late spring, when the biologically effective UV radiation is more consequential. These conditions include long-lasting ozone holes (attributable to the polar vortex dynamics) that often bring ozone-depleted air over the Antarctic Peninsula in late spring. The fact that these conditions have been occurring at about the same frequency during the last two decades explains the persistence of extreme surface UV events in Antarctica.

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Surface albedo is an important forcing parameter that drives the radiative energy budget as it determines the fraction of the downwelling solar irradiance that the surface reflects. Here we report on ground-based measurements of the spectral albedo (350-2200 nm) carried out at 20 sites across a North-South transect of approximately 1300 km in the Atacama Desert, from latitude 18° S to latitude 30° S. These spectral measurements were used to evaluate remote sensing estimates of the albedo derived from the Moderate Resolution Imaging Spectroradiometer (MODIS). We found that the relative mean bias error (RMBE) of MODIS-derived estimates was within ± 5% of ground-based measurements in most of the Atacama Desert (18-27° S). Although the correlation between MODIS-derived estimates and ground-based measurements remained relatively high (R= 0.94), RMBE values were slightly larger in the southernmost part of the desert (27-30° S). Both MODIS-derived data and ground-based measurements show that the albedo at some bright spots in the Atacama Desert may be high enough (up to 0.25 in visible range) for considerably boosting the performance of bifacial photovoltaic technologies (6-12%).

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Predicting radiative forcing due to Antarctic stratospheric ozone recovery requires detecting changes in the ozone vertical distribution. In this endeavor, the Limb Profiler of the Ozone Mapping and Profiler Suite (OMPS-LP), aboard the Suomi NPP satellite, has played a key role providing ozone profiles over Antarctica since 2011. Here, we compare ozone profiles derived from OMPS-LP data (version 2.5 algorithm) with balloon-borne ozonesondes launched from 8 Antarctic stations over the period 2012-2020. Comparisons focus on the layer from 12.5 to 27.5 km and include ozone profiles retrieved during the Sudden Stratospheric Warming (SSW) event registered in Spring 2019. We found that, over the period December-January-February-March, the root mean square error (RMSE) tends to be larger (about 20%) in the lower stratosphere (12.5-17.5 km) and smaller (about 10%) within higher layers (17.5-27.5 km). During the ozone hole season (September-October-November), RMSE values rise up to 40% within the layer from 12.5 to 22 km. Nevertheless, relative to balloon-borne measurements, the mean bias error of OMPS-derived Antarctic ozone profiles is generally lower than 0.3 ppmv, regardless of the season.

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INTRODUCCIÓN: El dispositivo MyVal balón-expandible (Meril Life Sciences, India) fue recientemente aprobado en Chile y la Unión Europea para uso comercial. El objetivo del presente estudio fue proveer datos de eficacia y seguridad temprana y de mediano plazo en pacientes portadores de estenosis aórtica (EA) severa de alto riesgo quirúrgico sometidos a reemplazo valvular aórtico percutáneo (RVAP) con dispositivo MyVal. MATERIAL Y MÉTODOS: Se enrolaron retrospectivamente todos los pacientes con EA severa sintomática de alto riesgo según criterio del ´heart team´ local, sometidos a RVAP usando prótesis MyVal en Hospital San Borja Arriarán. RESULTADOS: La población quedó compuesta por 14 sujetos tratados entre Octubre 2018 y Noviembre 2019. La población tuvo una edad media de 82,5±7,8 años y elevado perfil de riesgo (puntaje STS promedio 11,6±5,1% de mortalidad a 30 días). Se logró éxito de dispositivo y procedimiento en 12 pacientes (86%) con caída sustancial de la gradiente aórtica media, persistente a 6 meses de seguimiento sin insuficiencia aórtica más que leve. Ocurrió falla de dispositivo en 2 pacientes, una debida a falla de entrega y otra por embolización a ventrículo, esta última con resultado de muerte. En términos de complicaciones, ocurrió una muerte precoz atribuida a disección/ruptura de aorta y 2 hemorragias mayores. La tasa de marcapasos ascendió a 3 pacientes, 23% considerando todos quienes recibieron implante. CONCLUSIÓN: El presente registro cuestiona la seguridad de MyVal en el tratamiento percutáneo de la EA severa de alto riesgo. Sin embargo, una vez logrado un implante exitoso MyVal muestra adecuados parámetros de funcionamiento, persistentes a un plazo mediano de seguimiento.

BACKGROUND: The recently approved balloon expandable MyVal (Meril Life Sciences, India) transcatheter aortic valve replacement (TAVR) prosthesis is available for commercial use in Chile and the European Union. The aim of this study is to provide early and mid-term data on the safety and efficacy of patients with severe aortic stenosis (AS) at high surgical risk undergoing TAVR using the MyVal device. METHODS: All patients with symptomatic severe AS at high surgical risk undergoing intended TAVR with MyVal prosthesis at San Borja-Arriarán Hospital entered to a retrospective registry. RESULTS: Between October 2018 and November 2019, 14 patients entered to the registry. The mean age was 82.5±7.8 years-old with a high-surgical riskprofile (mean STS score of 11.6±5.1% for 30-day mortality). Device and procedural success were achieved in 12 patients (86%) with substantial decrease in the mean aortic gradient, persistent at 6 months follow-up, all with mild or trace aortic regurgitation. Device failure occurred in 2 patients, one due to failed delivery and other due to device embolization into the left ventricle, which resulted in patient death. There were one death attributed aortic dissection/rupture and two major bleeding episodes. Three patients receiving MyVal implant required the implantation of a permanent pacemaker (23%). CONCLUSION: The present registry rises a question upon the safety of the MyVal TAVR device in high-risk AS. However, once a successfully implant was achieved the MyVal prosthesis showed an adequate performance to mid-term follow-up.

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The Andean snowpack is the primary source of water for many communities in South America. We have used Landsat imagery over the period 1986-2018 in order to assess the changes in the snow cover extent across a north-south transect of approximately 2,500 km (18°-40°S). Despite the significant interannual variability, here we show that the dry-season snow cover extent declined across the entire study area at an average rate of about -12% per decade. We also show that this decreasing trend is mainly driven by changes in the El Niño Southern Oscillation (ENSO), especially at latitudes lower than 34°S. At higher latitudes (34°-40°S), where the El Niño signal is weaker, snow cover losses appear to be also influenced by the poleward migration of the westerly winds associated with the positive trend in the Southern Annular Mode (SAM).

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Background Robot-assisted minimally invasive heart surgery is an effective alternative when compared with classical approaches. It has a low mortality and postoperative complications and its long-term durability is comparable with conventional techniques. Aim: To report short- and long-term results with the use of a robot-assisted transthoracic approach. Patients and Methods: Review of patients undergoing heart surgery between 2015 and 2019 using a robot assisted minimally invasive technique in a single center. We analyzed demographic characteristics, surgical and early ultrasound results. Results: Thirteen procedures were reviewed, nine mitral valve repairs (MVR) in patients aged 61 ± 21 years (seven males) and four atrial septal defect (ASD) closures in patients aged from 24 to 52 years (three men). For MVR, the average extracorporeal circulation and myocardial ischemia times were 120 ± 20.9 and 89 ± 21 minutes, respectively. The median hospitalization was four days. Two cases of MVR had postoperative complications. There was no mortality. All cases showed improvement in their symptoms. Ultrasound findings showed no postoperative mitral insufficiency except in one case. Conclusions: We report very good results in both complex mitral repair and CIA closure, comparable to centers with high standards in minimally invasive robot-assisted heart surgery.

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The snowpack is an important source of water for many Andean communities. Because of its importance, elemental and mineralogical composition analysis of the Andean snow is a worthwhile effort. In this study, we conducted a chemical composition analysis (major and trace elements, mineralogy, and chemical enrichment) of surface snow sampled at 21 sites across a transect of about 2,500 km in the Chilean Andes (18-41°S). Our results enabled us to identify five depositional environments: (i) sites 1-3 (in the Atacama Desert, 18-26°S) with relatively high concentrations of metals, high abundance of quartz and low presence of arsenates, (ii) sites 4-8 (in northern Chile, 29-32°S) with relatively high abundance of quartz and low presence of metals and arsenates, (iii) sites 9-12 (in central Chile, 33-35°S) with anthropogenic enrichment of metals, relatively high values of quartz and low abundance of arsenates, (iv) sites 13-14 (also in central Chile, 35-37°S) with relatively high values of quartz and low presence of metals and arsenates, and v) sites 15-21 (in southern Chile, 37-41°S) with relatively high abundance of arsenates and low presence of metals and quartz. We found significant anthropogenic enrichment at sites close to Santiago (a major city of 6 million inhabitants) and in the Atacama Desert (that hosts several major copper mines).

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Background Robot-assisted minimally invasive heart surgery is an effective alternative when compared with classical approaches. It has a low mortality and postoperative complications and its long-term durability is comparable with conventional techniques. AIM: To report short- and long-term results with the use of a robot-assisted transthoracic approach. PATIENTS AND METHODS: Review of patients undergoing heart surgery between 2015 and 2019 using a robot assisted minimally invasive technique in a single center. We analyzed demographic characteristics, surgical and early ultrasound results. RESULTS: Thirteen procedures were reviewed, nine mitral valve repairs (MVR) in patients aged 61 ± 21 years (seven males) and four atrial septal defect (ASD) closures in patients aged from 24 to 52 years (three men). For MVR, the average extracorporeal circulation and myocardial ischemia times were 120 ± 20.9 and 89 ± 21 minutes, respectively. The median hospitalization was four days. Two cases of MVR had postoperative complications. There was no mortality. All cases showed improvement in their symptoms. Ultrasound findings showed no postoperative mitral insufficiency except in one case. CONCLUSIONS: We report very good results in both complex mitral repair and CIA closure, comparable to centers with high standards in minimally invasive robot-assisted heart surgery.

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Resumen: El Síndrome de Austrian, corresponde al cuadro clínico descrito por Robert Austrian en 1957, definido por la triada de Neumonía, Endocarditis Infecciosa (EI) y Meningitis, causado por Streptococcus pneumoniae. En la mayoría de los casos el vicio valvular presente, es la insuficiencia valvular aórtica, cuyo tratamiento médico y resolución quirúrgica de acuerdo con su gravedad, deben ser realizados precoz y oportunamente. Un paciente de 51 años, sin antecedentes de valvulopatía, con historia de poli consumo de alcohol y cocaína comenzó dos semanas previo a su ingreso hospitalario con síndrome febril, neumonía, y meningitis bacteriana por Streptococcus pneumoniae. Sus hemocultivos fueron negativos. El ecocardiograma transesofágico (ETE) fue compatible con EI valvular aórtica con insuficiencia moderada a severa. Se trató como EI a microorganismo desconocido y se efectuó un reemplazo valvular aórtico electivo con prótesis biológica a la 5° semana después de terminado el tratamiento médico antibiótico, cuyo resultado fue exitoso.

Abstract: A syndrome including Infective endocarditis, pneumonia and Meningitis caused by S pneumoniae was described by Robert Austrian in 1957. The aortic valve is affected in most cases. Medical followed by surgical treatment should be promptly implemented. The clinical case of a 51 year old man with a history of multiple drug consumption developing fever, pneumonia, and meningitis caused by S pneumoniae is presented. Blood cultures were negative and trans esophageal echocardiography showed aortic valve vegetations and moderate regurgitation. After multiple antibiotic treatment the patient underwent aortic valve replacement and recovered satisfactorily. Clinical and epidemiological characteristics of this syndrome are discussed.

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Introducción: El objetivo fue evaluar la costo-efectividad del reemplazo valvular aórtico percutáneo (RVAP) contra terapia conservadora (TC) en pacientes con estenosis aórtica (EA) severa de muy alto riesgo, en un centro de derivación. Métodos: Los pacientes derivados entre Enero 2013 y Septiembre 2014, considerados de muy alto riesgo y candidatos a RVAP fueron incluidos. El costo de los recursos usados, de las readmisiones y la sobrevida fueron obtenidos para determinar el tiempo de vida ganado y la relación incremental de costo-efectividad (RICE) del RVAP Resultados: El grupo estudiado quedó compuesto por 39 pacientes, con edad promedio 82±7 años, más frecuentemente mujeres (74.4%), con elevado perfil de riesgo (STS score 11.4±5.6). Diecisiete pacientes (43.6%) fueron sometidos a RVAP y 22 (56.4%) a TC. Durante el seguimiento se registraron 25 rehospitalizaciones en el grupo de TC, a un costo promedio de $4.195.073 por paciente (7,027 dólares). Todos los pacientes sometidos a RAVP recibieron con éxito una prótesis Sapien XT y fueron egresados vivos. El costo promedio estimado del RVAP fue $20.000.000 (33,500 dólares). La sobrevida media fue de 54.5% (10 eventos) en grupo TC contra 94.1% (una muerte) en el grupo RVAP [285±204 días/seguimiento] (p<0.001). Así se pudo estimar que RVAP se asoció a un incremento de vida de al menos un año, lo cual resultó en una RICE de 26,470 dólares/año de vida ganado. Conclusión: El RAVP resultó costo-efectivo comparado con la TC en pacientes portadores de EA severa de muy alto riego tratados en la realidad de un centro de derivación nacional.

Aim: to evaluate cost-effectiveness of Transcatheter Aortic Valve Replacement (TAVR) compared to conservative treatment in patients with very high risk severe aortic stenosis (AS) referred to a tertiary center in Santiago, Chile Methods: Patients with high surgical risk and severe AS referred between January 2013 and September 2014 were included. Cost of resources, readdmissions, life-years gained and incremental cost-effectiveness of TAVI were calculated Results: Thirty-nine patients were finally included. Mean age was 82±7 years old, more commonly women (74%) with a mean STS score of 11.4±5.6 that confirmed their high-risk. Seventeen patients (43.6%) had TAVR and 22 (56.4%) underwent conventional medical therapy. All patients in the TAVR group - treated with Sapien XT® device - survived the procedure and were discharged alive. Mean cost of the procedure was approximately US$ 33,500. After a mean follow-up period of 285±204 days, mean survival rate in the control group was 54.5% (10 deaths) as compared to 94.1% in the TAVR group (1 death, p<0.001). Therefore, a gain of al least one year was obtained with TAVR resulting in an incremental cost effectiveness of US$ 26.470 per year of life gained. Conclusion: TAVR resulted costly-effective compared to conventional therapy in patients with severe AS and high surgical risk in a Chilean referral center.

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INTRODUCTION: Foot amputation wounds in patients with diabetes are complex and treatment is often difficult. At the moment negative pressure wound therapy (NPWT) is widely used for the treatment of several types of wounds. Nevertheless, the clinical evidence to support the application of this dressing in foot amputation wounds in patients with diabetes is scarce. The aim of this study was to evaluate the efficacy of NPWT compared with standard wound dressing to treat diabetic foot amputation wounds. PATIENTS AND METHOD: Randomised controlled trial. Diabetic patients aged 18 years or older with a foot amputation wound were assigned to treatment with NPWT (A group) or standard wound dressing (B group). Primary efficacy end point was time in reaching 90% of wound granulation. A size of sample of 11 patients per group was used. NPWT was prepared with a polyurethane ether foam dressing, a Nelaton catheter, a transparent adhesive drape and continuous negative pressure of 100 mmHg. The wound was treated every 48-72 h and evaluated weekly. Descriptive and analytical statistics were used. RESULTS: There were 24 patients, with a mean age of 61.8 +/- 9 years (79% men), 12 in each group. The average time to reach 90% of granulation was lower in A group (18.8 +/- 6 days versus 32.3 +/- 13.7 days), a statistically significant difference (P = 0.007). CONCLUSION: NPWT reduces the granulation time of diabetic foot amputation wounds by 40%, compared with the standard wound dressing.

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