On optimal solution error covariances in variational data assimilation problems

The problem of variational data assimilation for a nonlinear evolution model is formulated as an optimal control problem to find unknown parameters such as distributed model coefficients or boundary conditions. The equation for the optimal solution error is derived through the errors of the input data (background and observation errors), and the optimal solution error covariance operator through the input data error covariance operators, respectively. The quasi-Newton BFGS algorithm is adapted to construct the covariance matrix of the optimal solution error using the inverse Hessian of an auxiliary data assimilation problem based on the tangent linear model constraints. Preconditioning is applied to reduce the number of iterations required by the BFGS algorithm to build a quasi-Newton approximation of the inverse Hessian. Numerical examples are presented for the one-dimensional convection-diffusion model

A posteriori error covariances in variational data assimilation

The problem of variational data assimilation for a nonlinear evolution model is formulated as an optimal control problem to find some unknown parameters of the model. The equation for the error of the optimal solution is derived through the statistical errors of the input data (background, observation, and model errors). A numerical algorithm is developed to construct an a posteriori covariance operator of the analysis error using the Hessian of an auxiliary control problem based on tangent linear model constraints

Fungos cavern?colas da Gruta Velha Nova na Serra do Espinha?o em Monjolos, Minas Gerais - Brasil

Ag?ncia financiadora: Funda??o de Amparo ? Pesquisa do Estado de Minas Gerais (FAPEMIG) - Apoio financeiro do projeto (Pesquisa na ?rea de Espeleologia ? Parceria FAPEMIG-VALE ? RDP 00017-18).As cavernas s?o ambientes pobres em carbono org?nico e alguns nutrientes que possuem caracter?sticas ?nicas onde ocorrem organismos desconhecidos ou adaptados. Os fungos que ocorrem nas cavernas podem ser end?micos ou adaptados a esse ambiente e podem apresentar metabolismo espec?fico com produ??o de compostos desconhecidos e de interesse ? humanidade. Assim, esses ambientes s?o frequentemente explorados na busca de novos compostos bioativos produzidos por fungos. O presente trabalho teve como objetivo revisar a import?ncia da identifica??o dos fungos que ocorrem em cavernas e seus potenciais biotecnol?gicos, preserva??o desses ambientes, e o isolamento de fungos que ocorrem na Caverna Velha Nova, Monjolos, localizada na Serra do Espinha?o Meridional de Minas Gerais. Na revis?o s?o abordados principalmente a import?ncia dos fungos, o impacto do turismo sobre a ecologia cavern?cola, medidas de preserva??o e a import?ncia dos estudos nestes ambientes. Para o isolamento de fungos da caverna Velha Nova, foram utilizadas amostras do ar, solo, rochas, espeleotemas e serrapilheira. Ap?s o isolamento, os microfungos foram identificados por m?todos morfol?gicos e sequenciamento do DNA gen?mico. Cento e setenta e oito isolados foram obtidos e entre estes foram identificados os g?neros Aspergillus, Amphichorda, Chaetomium, Penicillium, Humicola, Mucor, Gliomastix, Clonostachys, Myrothecium, Cladosporium, Scedosporium, Meyerozyma e Rhizopus. Devido a poss?vel identifica??o de uma nova esp?cie de Amphichorda, seu posicionamento filogen?tico foi descrito.Funda??o de Amparo ? Pesquisa do Estado de Minas Gerais (FAPEMIG)Disserta??o (Mestrado) ? Programa de P?s-Gradua??o em Produ??o Vegetal, Universidade Federal dos Vales do Jequitinhonha e Mucuri, 2021.Caves are environments poor in organic carbon and some nutrients that have unique characteristics where unknown or adapted organisms occur. Fungi that occur in caves can be endemic or adapted to this environment and can present specific metabolism with the production of unknown compounds of interest to humanity. Thus, these environments are frequently explored in the search for new bioactive compounds produced by fungi. The present work aimed to review the importance of the identification of fungi that occur in caves and their biotechnological potentials, preservation of these environments, and the isolation of fungi that occur in the Velha Nova cave, Monjolos, located in the Serra do Espinha?o Meridional of Minas Gerais. The review deals mainly with the importance of fungi, the impact of tourism on cave ecology, preservation measures and the importance of studies in these environments. Samples from the air, soil, rocks, speleothems and litter were used to isolate fungi from Velha Nova cave. After isolation, some fungi were identified with morphological methods and DNA sequencing. One hundred and seventy-eight isolated fungi were obtained and among these, Aspergillus, Amphichorda, Chaetomium, Penicillium, Humicola, Mucor, Gliomastix, Clonostachys, Myrothecium, Cladosporium, Scedosporium, Meyerozyma and Rhizopus were identified. Due to the isolation of a new species of Amphichorda, its phylogenetic position has been described

Plasticity of the Mycobacterium tuberculosis respiratory chain and its impact on tuberculosis drug development.

The viability of Mycobacterium tuberculosis (Mtb) depends on energy generated by its respiratory chain. Cytochrome bc1-aa3 oxidase and type-2 NADH dehydrogenase (NDH-2) are respiratory chain components predicted to be essential, and are currently targeted for drug development. Here we demonstrate that an Mtb cytochrome bc1-aa3 oxidase deletion mutant is viable and only partially attenuated in mice. Moreover, treatment of Mtb-infected marmosets with a cytochrome bc1-aa3 oxidase inhibitor controls disease progression and reduces lesion-associated inflammation, but most lesions become cavitary. Deletion of both NDH-2 encoding genes (Δndh-2 mutant) reveals that the essentiality of NDH-2 as shown in standard growth media is due to the presence of fatty acids. The Δndh-2 mutant is only mildly attenuated in mice and not differently susceptible to clofazimine, a drug in clinical use proposed to engage NDH-2. These results demonstrate the intrinsic plasticity of Mtb's respiratory chain, and highlight the challenges associated with targeting the pathogen's respiratory enzymes for tuberculosis drug development

Using biomarkers to predict TB treatment duration (Predict TB): a prospective, randomized, noninferiority, treatment shortening clinical trial

Background : By the early 1980s, tuberculosis treatment was shortened from 24 to 6 months, maintaining relapse rates of 1-2%. Subsequent trials attempting shorter durations have failed, with 4-month arms consistently having relapse rates of 15-20%. One trial shortened treatment only among those without baseline cavity on chest x-ray and whose month 2 sputum culture converted to negative. The 4-month arm relapse rate decreased to 7% but was still significantly worse than the 6-month arm (1.6%, P<0.01).  We hypothesize that PET/CT characteristics at baseline, PET/CT changes at one month, and markers of residual bacterial load will identify patients with tuberculosis who can be cured with 4 months (16 weeks) of standard treatment.Methods: This is a prospective, multicenter, randomized, phase 2b, noninferiority clinical trial of pulmonary tuberculosis participants. Those eligible start standard of care treatment. PET/CT scans are done at weeks 0, 4, and 16 or 24. Participants who do not meet early treatment completion criteria (baseline radiologic severity, radiologic response at one month, and GeneXpert-detectable bacilli at four months) are placed in Arm A (24 weeks of standard therapy). Those who meet the early treatment completion criteria are randomized at week 16 to continue treatment to week 24 (Arm B) or complete treatment at week 16 (Arm C). The primary endpoint compares the treatment success rate at 18 months between Arms B and C.Discussion: Multiple biomarkers have been assessed to predict TB treatment outcomes. This study uses PET/CT scans and GeneXpert (Xpert) cycle threshold to risk stratify participants. PET/CT scans are not applicable to global public health but could be used in clinical trials to stratify participants and possibly become a surrogate endpoint. If the Predict TB trial is successful, other immunological biomarkers or transcriptional signatures that correlate with treatment outcome may be identified. TRIAL REGISTRATION: NCT02821832

Technological characterization of an exaurid zeolite for removal of Mn2 + ions

As ze?litas apresentam importante propriedades fisico-qu?micas que aliadas a sua disponibilidade e seu baixo custo viabilizam sua aplica??o em v?rios processos industriais. Atualmente tem-se dado enfoque para utiliza??o de ze?litas na adsor??o de metais no tratamento de ?gua e de efluentes industriais. Assim, o presente trabalho teve como objetivo a caracteriza??o tecnol?gica de uma ze?lita, visando atestar a viabilidade de sua utiliza??o na remo??o de ?ons Mn2+(aq) em diferentes condi??es experimentais. O material utilizado neste trabalho era uma ze?lita sint?tica exaurida utilizada como catalisador no craqueamento de petr?leo. Inicialmente, realizou-se a ativa??o da ze?lita com solu??o de NaOH, 1 mol.L-1. Em seguida, foi feita a caracteriza??o da mesma e sua aplica??o nos ensaios de adsor??o com solu??o sint?tica de Mn2+ a 50 mg.L-1, realizados em batelada. Foram investigados valores de pH entre 4 e 8, e temperatura entre 25?C e 70?C. Observou-se que a ze?lita foi identificada, por difra??o de raios-X, como Faujasita. O pH ?timo de adsor??o sem risco de remo??o por precipita??o foi de 6,5 e a melhor temperatura, 25?C. O tempo de equil?brio da adsor??o do Mn2+(aq) por adsor??o foi de 4 horas. Nessas condi??es, obteve-se um carregamento de 10,8 mg Mn2+-g ze?lita. Os resultados mostraram o potencial de aplica??o deste material para processos de remo??o de ?ons mangan?s presentes em solu??es aquosas.Zeolites have important chemical properties which combined with their availability and low-cost support their application in various industrial processes. Currently, much attention has been given to their use for metal sorption from wastewaters and industrial effluents. Therefore, the present study carried out a technological characterization of a waste zeolite sample followed by assessing its application in the removal of Mn2+ ions in different experimental conditions. The material used in this work was a spent synthetic zeolite used as a petroleum cracking catalyst. The zeolite was firstly washed in a 1 mol.L-1 NaOH solution. After characterization, batch sorption experiments were carried out with 50 mg.L-1 Mn2+ synthetic solutions. The pH values were set between 4 and 8 and temperature in the 25-70?C range. The zeolite phase was identified by X-ray diffraction as faujasite. The optimum pH for manganese sorption was 6.5 and the optimum temperature value was 25?C. The time required for equilibrium to be achieved was 4 hours, which enabled to attain a loading of 10.8 mg Mn2+/g zeolite. The results herein presented confirmed the potential application of this material for manganese ions sorption.Zeolites have important chemical properties which combined with their availability and low-cost support their application in various industrial processes. Currently, much attention has been given to their use for metal sorption from wastewaters and industrial effluents. Therefore, the present study carried out a technological characterization of a waste zeolite sample followed by assessing its application in the removal of Mn2+ ions in different experimental conditions. The material used in this work was a spent synthetic zeolite used as a petroleum cracking catalyst. The zeolite was firstly washed in a 1 mol.L-1 NaOH solution. After characterization, batch sorption experiments were carried out with 50 mg.L-1 Mn2+ synthetic solutions. The pH values were set between 4 and 8 and temperature in the 25-70?C range. The zeolite phase was identified by X-ray diffraction as faujasite. The optimum pH for manganese sorption was 6.5 and the optimum temperature value was 25?C. The time required for equilibrium to be achieved was 4 hours, which enabled to attain a loading of 10.8 mg Mn2+/g zeolite. The results herein presented confirmed the potential application of this material for manganese ions sorption

Mycobacterium tuberculosis Responds to Chloride and pH as Synergistic Cues to the Immune Status of its Host Cell

PubMed ID: 23592993This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited

Antarctic climate, Southern Ocean circulation patterns, and deep water formation during the Eocene

We assess early-to-middle Eocene seawater neodymium (Nd) isotope records from seven Southern Ocean deep-sea drill sites to evaluate the role of Southern Ocean circulation in long-term Cenozoic climate change. Our study sites are strategically located on either side of the Tasman Gateway and are positioned at a range of shallow (Nd(t) = −9.3 ± 1.5). IODP Site U1356 off the coast of Adélie Land, a locus of modern-day Antarctic Bottom Water production, is identified as a site of persistent deep water formation from the early Eocene to the Oligocene. East of the Tasman Gateway an additional local source of intermediate/deep water formation is inferred at ODP Site 277 in the SW Pacific Ocean (εNd(t) = −8.7 ± 1.5). Antarctic-proximal shelf sites (ODP Site 1171 and Site U1356) reveal a pronounced erosional event between 49 and 48 Ma, manifested by ~2 εNd unit negative excursions in seawater chemistry toward the composition of bulk sediments at these sites. This erosional event coincides with the termination of peak global warmth following the Early Eocene Climatic Optimum and is associated with documented cooling across the study region and increased export of Antarctic deep waters, highlighting the complexity and importance of Southern Ocean circulation in the greenhouse climate of the Eocene

Effect of C-2 substitution on the stability of non-traditional cephalosporins in mouse plasma

This work is licensed under a Creative Commons Attribution 4.0 International License.A systematic study of the stability of a set of cephalosporins in mouse plasma reveals that cephalosporins lacking an acidic moiety at C-2 may be vulnerable to β-lactam cleavage in mouse plasma