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1.
Nature ; 617(7959): 111-117, 2023 05.
Artigo em Inglês | MEDLINE | ID: mdl-37100901

RESUMO

Tropical forests face increasing climate risk1,2, yet our ability to predict their response to climate change is limited by poor understanding of their resistance to water stress. Although xylem embolism resistance thresholds (for example, [Formula: see text]50) and hydraulic safety margins (for example, HSM50) are important predictors of drought-induced mortality risk3-5, little is known about how these vary across Earth's largest tropical forest. Here, we present a pan-Amazon, fully standardized hydraulic traits dataset and use it to assess regional variation in drought sensitivity and hydraulic trait ability to predict species distributions and long-term forest biomass accumulation. Parameters [Formula: see text]50 and HSM50 vary markedly across the Amazon and are related to average long-term rainfall characteristics. Both [Formula: see text]50 and HSM50 influence the biogeographical distribution of Amazon tree species. However, HSM50 was the only significant predictor of observed decadal-scale changes in forest biomass. Old-growth forests with wide HSM50 are gaining more biomass than are low HSM50 forests. We propose that this may be associated with a growth-mortality trade-off whereby trees in forests consisting of fast-growing species take greater hydraulic risks and face greater mortality risk. Moreover, in regions of more pronounced climatic change, we find evidence that forests are losing biomass, suggesting that species in these regions may be operating beyond their hydraulic limits. Continued climate change is likely to further reduce HSM50 in the Amazon6,7, with strong implications for the Amazon carbon sink.


Assuntos
Carbono , Florestas , Árvores , Clima Tropical , Biomassa , Carbono/metabolismo , Secas , Árvores/crescimento & desenvolvimento , Árvores/metabolismo , Xilema/metabolismo , Chuva , Mudança Climática , Sequestro de Carbono , Estresse Fisiológico , Desidratação
2.
Materials (Basel) ; 17(8)2024 Apr 18.
Artigo em Inglês | MEDLINE | ID: mdl-38673234

RESUMO

Thermal energy storage (TES) plays an important role in industrial applications with intermittent generation of thermal energy. In particular, the implementation of latent heat thermal energy storage (LHTES) technology in industrial thermal processes has shown promising results, significantly reducing sensible heat losses. However, in order to implement this technology, a proper selection of materials is important. In this study, a new multi-criteria phase change material (PCM) selection methodology is presented, which considers relevant factors from an application and material handling point of view, such as hygroscopicity, metal compatibility (corrosion), level hazard, cost, and thermal and atmospheric stability. The methodology starts after setting up the system requirements where the PCM will be used, then a material screening is able to find all possible candidates that are listed with all available properties as listed before. Then, a color map is produced, with a qualitative assessment of material properties drawbacks, hazard level, melting enthalpy, and price. The experimentation starts with a preliminary set of tests on hygroscopicity and one-week corrosion test, which allows disregarding PCMs and selecting a short list of potential PCMs that would need further characterization before the final selection.

3.
Science ; 384(6701): 1155, 2024 Jun 14.
Artigo em Inglês | MEDLINE | ID: mdl-38870292

RESUMO

Since 2001, the United Nations has designated 20 June as World Refugee Day. It seeks to raise awareness of refugees-currently estimated to be more than 114 million persons internally displaced, exiled, or on the move-and the often-harsh conditions they confront around the world. Among them are scientists, giving the scientific community a special responsibility to protect and support these colleagues. It is not just scientists and their families whose lives are disrupted, but science as an enterprise as well.

4.
Sci Adv ; 9(8): eade5839, 2023 Feb 22.
Artigo em Inglês | MEDLINE | ID: mdl-36812315

RESUMO

The structure and dynamics of isolated nanosamples in free flight can be directly visualized via single-shot coherent diffractive imaging using the intense and short pulses of x-ray free-electron lasers. Wide-angle scattering images encode three-dimensional (3D) morphological information of the samples, but its retrieval remains a challenge. Up to now, effective 3D morphology reconstructions from single shots were only achieved via fitting with highly constrained models, requiring a priori knowledge about possible geometries. Here, we present a much more generic imaging approach. Relying on a model that allows for any sample morphology described by a convex polyhedron, we reconstruct wide-angle diffraction patterns from individual silver nanoparticles. In addition to known structural motives with high symmetries, we retrieve imperfect shapes and agglomerates that were not previously accessible. Our results open unexplored routes toward true 3D structure determination of single nanoparticles and, ultimately, 3D movies of ultrafast nanoscale dynamics.

5.
Cureus ; 14(8): e28373, 2022 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-36171847

RESUMO

An effective healthcare system should embrace practices that enhance overall quality and productivity. Training primary care physicians in Point-of-Care Ultrasound (POCUS) has become part of the processes that improve the quality of patient care and serve to guide the diagnostic impression quickly and effectively. With the purpose of highlighting the applications and challenges of POCUS use in US primary health care, we conducted a narrative review based on PubMed-indexed and Cochrane Library English text publications searched in May-July 2022 using a combination of key terms including point of care ultrasound, primary care, and US healthcare. Many studies have shown that POCUS has a positive impact on fostering medical attention and reducing morbidity, mortality, and healthcare costs. Besides assisting in procedures, POCUS has a head-to-toe application in evaluating inflammatory and infectious conditions, acute abdomen, cardiopulmonary function, musculoskeletal and vascular pathologies. However, its uniform implementation is limited across the US healthcare system due to multitudes of barriers such as lack of training, resource scarcity, and low reimbursement. Training primary care physicians in general and emergency care providers, in particular, is key to scaleup POCUS use. Large size studies are paramount to further explore the effectiveness of POCUS and identify key challenges to its implementation.

6.
Nat Commun ; 12(1): 2310, 2021 04 19.
Artigo em Inglês | MEDLINE | ID: mdl-33875648

RESUMO

Non-structural carbohydrates (NSC) are major substrates for plant metabolism and have been implicated in mediating drought-induced tree mortality. Despite their significance, NSC dynamics in tropical forests remain little studied. We present leaf and branch NSC data for 82 Amazon canopy tree species in six sites spanning a broad precipitation gradient. During the wet season, total NSC (NSCT) concentrations in both organs were remarkably similar across communities. However, NSCT and its soluble sugar (SS) and starch components varied much more across sites during the dry season. Notably, the proportion of leaf NSCT in the form of SS (SS:NSCT) increased greatly in the dry season in almost all species in the driest sites, implying an important role of SS in mediating water stress in these sites. This adjustment of leaf NSC balance was not observed in tree species less-adapted to water deficit, even under exceptionally dry conditions. Thus, leaf carbon metabolism may help to explain floristic sorting across water availability gradients in Amazonia and enable better prediction of forest responses to future climate change.


Assuntos
Carboidratos/análise , Secas , Florestas , Estações do Ano , Árvores/metabolismo , Água/metabolismo , Bolívia , Brasil , Metabolismo dos Carboidratos , Mudança Climática , Geografia , Peru , Folhas de Planta/metabolismo , Açúcares/metabolismo , Árvores/classificação , Clima Tropical
7.
Ear Hear ; 31(5): 714-21, 2010 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-20539233

RESUMO

OBJECTIVE: Human mutations in the DNA repair genes, Xeroderma pigmentosum (XP)-C and XPA result in hearing loss, which has fueled the hypothesis that there is a significant demand for these genes in protecting cochlear genetic material. Therefore, we quantified the level of XPC and XPA mRNA in the mammalian cochlea. DESIGN: XPC and XPA mRNAs were purified from the cochlea of 15 Fischer344 rats and quantified using SYBR Green chemistry. Another 15 Fischer344 rats were sacrificed for immunolocalization of XPC and XPA polypeptides in the cochlea and kidney (control organ). RESULTS: XP mRNA levels were up to 95% (XPA) and 69% (XPC) of the respective maximum expression capacity of each gene. In addition, these cochlear levels were up to sixfold (XPC) and threefold (XPA) greater than that of the kidney, which is known to exhibit XP-DNA repair activity that is greater than most organs of the body. Immunohistochemistry revealed that most kidney and cochlear cells were immunopositive. CONCLUSION: These data suggest that under normal conditions the cochlea is experiencing persistent genomic stress that helps to explain the hypersensitivity of the cochlea to exogenous stressors (ototoxic xenobiotics and/or acoustic-overexposure) as well as provide a basis to interpret hearing loss among patients with XP.


Assuntos
Proteínas de Transporte/genética , Cóclea/fisiologia , Reparo do DNA/fisiologia , Proteínas de Ligação a DNA/genética , Animais , Proteínas de Transporte/metabolismo , Proteínas de Ligação a DNA/metabolismo , Expressão Gênica/fisiologia , Humanos , Imuno-Histoquímica , Rim/fisiologia , Mamíferos , RNA Mensageiro/metabolismo , Ratos , Ratos Endogâmicos F344
8.
Science ; 370(6517): 701-704, 2020 11 06.
Artigo em Inglês | MEDLINE | ID: mdl-33154138

RESUMO

A hallmark feature of topological insulators is robust edge transport that is impervious to scattering at defects and lattice disorder. We demonstrate a topological system, using a photonic platform, in which the existence of the topological phase is brought about by optical nonlinearity. The lattice structure remains topologically trivial in the linear regime, but as the optical power is increased above a certain power threshold, the system is driven into the topologically nontrivial regime. This transition is marked by the transient emergence of a protected unidirectional transport channel along the edge of the structure. Our work studies topological properties of matter in the nonlinear regime, providing a possible route for the development of compact devices that harness topological features in an on-demand fashion.

9.
Artigo em Inglês | MEDLINE | ID: mdl-32313596

RESUMO

Promoting diversity and inclusiveness in the STEM academic workforce remains a key challenge and national priority. Scientific societies can play a significant role in this process through the creation and implementation of programs to foster STEM academic workforce diversification, and by providing mentoring and skills development training that empower scientists from under-represented minority (URM) backgrounds to succeed in their communities of practice. In this article, we provide examples of challenges met by scientific societies in these areas and present data from the American Society for Cell Biology, highlighting the benefits received by trainees through long-term engagement with its programs. The success of these initiatives illustrates the impact of discipline-specific programming by scientific societies in supporting the development of URM scientists and an increasingly diverse and inclusive academic STEM community.

10.
Eur J Mass Spectrom (Chichester) ; 15(2): 283-91, 2009.
Artigo em Inglês | MEDLINE | ID: mdl-19423913

RESUMO

Azimuthal quadrupolar excitation is a commonly used technique in the field of ion cyclotron resonance mass spectrometry, in particular in combination with buffer-gas collisions to achieve axialization of the stored ions. If the quadrupolar excitation is applied with only one phase to a set of two opposing ring segments (rather than the "regular" method where two sets of electrodes are addressed with opposite polarities), parametric resonance effects at the frequencies 2nu(z) and nu(p) = nu(+) - nu(-) can lead to unintended ejection of ions from the trap. These parametric resonances have been revisited both theoretically and experimentally: multipole components of different azimuthal excitation schemes are derived by a simple vector representation of the excitation signal applied to the ring segments. Thus, parametric contributions can be easily identified, as demonstrated for the two-electrode and the four-electrode quadrupolar excitation schemes as well as further examples. In addition, the effect of the single-phase two-electrode quadrupolar excitation is demonstrated for storage and axialization of cluster ions.

11.
CBE Life Sci Educ ; 16(2)2017.
Artigo em Inglês | MEDLINE | ID: mdl-28389427

RESUMO

As part of its mission, the American Society for Cell Biology (ASCB) works to increase diversity in the scientific workforce, in part through the work of its Minorities Affairs Committee. It is for this reason that the ASCB was happy to welcome the special September 2016 issue of CBE-Life Sciences Education (LSE) focused on broadening participation. As a response to this special issue, we update our ASCB community and LSE readership on the society's efforts to broaden participation of underrepresented minorities in the biological sciences.


Assuntos
Disciplinas das Ciências Biológicas/educação , Grupos Minoritários/educação , Sociedades Científicas , Desenvolvimento de Pessoal , Diversidade Cultural , Mentores , Estados Unidos , Recursos Humanos
12.
Crit Rev Ther Drug Carrier Syst ; 34(1): 35-61, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28322140

RESUMO

Recent advances in nanotechnology have transformed the biomedicine field, in which the use of engineered nanomaterials (ENMs) has provided the foundation for novel applications. For this reason, the number of ENMs has increased rapidly, and here we provide a classification of ENMs based on chemical composition and biomedical applications, which include regenerative medicine, delivery systems, theranostics, and therapy. These have been identified as the most advanced and promising areas for further studies with humans. In addition, we discuss possible side effects related to ENM uses. We identify carbon, metal, and metal oxides as the most versatile ENM material groups, used in bone and neuronal regenerative medicine, thermal therapy, theranostics, drug delivery, gene therapy, and biosensors. However, the majority of drugs approved by the U.S. Food and Drug Administration (FDA) are lipid-based ENMs. We conclude that biomedical applications of ENMs offer potential benefits while side effects are mainly associated with occupational exposure. Finally, we suggest that in the future, nanocomposites, subnanometric structures, and biodegradable and biocorona formation could be used to improve the biomedical field by focusing on infectious diseases, early detection, and precision medicine.


Assuntos
Sistemas de Liberação de Medicamentos/métodos , Nanoestruturas/efeitos adversos , Nanoestruturas/uso terapêutico , Medicina Regenerativa/métodos , Nanomedicina Teranóstica/métodos , Animais , Sistemas de Liberação de Medicamentos/efeitos adversos , Humanos
13.
Int J Nanomedicine ; 9: 2031-41, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-24790441

RESUMO

Nanomaterials are the subject of intense research, focused on their synthesis, modification, and biomedical applications. Increased nanomaterial production and their wide range of applications imply a higher risk of human and environmental exposure. Unfortunately, neither environmental effects nor toxicity of nanomaterials to organisms are fully understood. Cost-effective, rapid toxicity assays requiring minimal amounts of materials are needed to establish both their biomedical potential and environmental safety standards. Drosophila exemplifies an efficient and cost-effective model organism with a vast repertoire of in vivo tools and techniques, all with high-throughput scalability and screening feasibility throughout its life cycle. Here we report tissue specific nanomaterial assessment through direct microtransfer into target tissues. We tested several nanomaterials with potential biomedical applications such as single-wall carbon nanotubes, multiwall carbon nanotubes, silver, gold, titanium dioxide, and iron oxide nanoparticles. Assessment of nanomaterial toxicity was conducted by evaluating progression through developmental morphological milestones in Drosophila. This cost-effective assessment method is amenable to high-throughput screening.


Assuntos
Bioensaio/instrumentação , Drosophila melanogaster/efeitos dos fármacos , Drosophila melanogaster/embriologia , Microinjeções/instrumentação , Micromanipulação/instrumentação , Nanopartículas/toxicidade , Testes de Toxicidade/instrumentação , Animais , Drosophila melanogaster/fisiologia , Desenvolvimento Embrionário/efeitos dos fármacos , Desenvolvimento Embrionário/fisiologia , Desenho de Equipamento , Análise de Falha de Equipamento , Nanopartículas/administração & dosagem
14.
CBE Life Sci Educ ; 12(3): 394-402, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-24006388

RESUMO

Scientific workforce diversity is critical to ensuring the realization of our national research goals and minority-serving institutions play a vital role in preparing undergraduate students for science careers. This paper summarizes the outcomes of supporting career training and research practices by faculty from teaching-intensive, minority-serving institutions. Support of these faculty members is predicted to lead to: 1) increases in the numbers of refereed publications, 2) increases in federal grant funding, and 3) a positive impact on professional activities and curricular practices at their home institutions that support student training. The results presented show increased productivity is evident as early as 1 yr following completion of the program, with participants being more independently productive than their matched peers in key areas that serve as measures of academic success. These outcomes are consistent with the goals of the Visiting Professorship Program to enhance scientific practices impacting undergraduate student training. Furthermore, the outcomes demonstrate the benefits of training support for research activities at minority-serving institutions that can lead to increased engagement of students from diverse backgrounds. The practices and results presented demonstrate a successful generalizable approach for stimulating junior faculty development and can serve as a basis for long-term faculty career development strategies that support scientific workforce diversity.


Assuntos
Academias e Institutos , Comportamento Cooperativo , Docentes , Grupos Minoritários/educação , Competência Profissional , Pesquisa/educação , Academias e Institutos/economia , Etnicidade/educação , Etnicidade/estatística & dados numéricos , Humanos , Grupos Minoritários/estatística & dados numéricos , Modelos Educacionais , Publicações , Pesquisa/economia , Apoio à Pesquisa como Assunto/economia , Estudantes
15.
CBE Life Sci Educ ; 10(3): 287-97, 2011.
Artigo em Inglês | MEDLINE | ID: mdl-21885825

RESUMO

Today, more minority students are entering undergraduate programs than ever before, but they earn only 6% of all science or engineering PhDs awarded in the United States. Many studies suggest that hands-on research activities enhance students' interest in pursuing a research career. In this paper, we present a model for the implementation of laboratory research in the undergraduate teaching laboratory using a culturally relevant approach to engage students. Laboratory modules were implemented in upper-division genetics and cell biology courses using cassava as the central theme. Students were asked to bring cassava samples from their respective towns, which allowed them to compare their field-collected samples against known lineages from agricultural stations at the end of the implementation. Assessment of content and learning perceptions revealed that our novel approach allowed students to learn while engaged in characterizing Puerto Rican cassava. In two semesters, based on the percentage of students who answered correctly in the premodule assessment for content knowledge, there was an overall improvement of 66% and 55% at the end in the genetics course and 24% and 15% in the cell biology course. Our proposed pedagogical model enhances students' professional competitiveness by providing students with valuable research skills as they work on a problem to which they can relate.


Assuntos
Biologia Celular/educação , Cultura , Currículo , Genética/educação , Laboratórios , Ensino , DNA de Plantas/isolamento & purificação , Eletroforese em Gel de Ágar , Marcadores Genéticos , Conhecimento , Aprendizagem , Manihot/genética , Repetições de Microssatélites/genética , Raízes de Plantas/metabolismo , Estômatos de Plantas/metabolismo , Porto Rico , Amido/análise , Estudantes
16.
San Salvador; s.n; 2020. 30 p.
Tese em Espanhol | LILACS, BISSAL | ID: biblio-1123360

RESUMO

Las poblaciones a nivel mundial envejecen a un ritmo acelerado, en El Salvador las personas mayores de 65 años en los últimos 70 años han representado un aumento del 2.9% al 6.8% según el último censo de población y vivienda 2007. Según la Dirección general de estadísticas y censos en estimaciones y proyecciones para el 2050 el envejecimiento poblacional aumenta hasta un 15.6%. La importancia de una población envejecida data en la existencia de fragilidad, existe evidencia de que la fragilidad puede convertirse en uno de los problemas de salud más graves del mundo. Con el número de personas mayores expandiéndose dramáticamente en todos los países, se espera que la prevalencia de fragilidad aumente. En nuestros centros de atención primaria del sistema público no se realiza ningún cribado de identificación pese a su importancia. Por esta razón se planteó el estudio en atención primaria, que abarca cuatro comunidades de la ciudad de San Salvador y que mediante la herramienta Test de cribado de fragilidad de Gerontopole (GFST) se obtiene 34.4% de adultos mayores con fragilidad que requiere una evaluación y tratamiento integral en centros de atención de jerarquía mayor.


Assuntos
Idoso Fragilizado , Medicina de Família e Comunidade
17.
18.
J Biol Chem ; 280(8): 6496-503, 2005 Feb 25.
Artigo em Inglês | MEDLINE | ID: mdl-15596439

RESUMO

Receptor-triggered control of local postsynaptic protein synthesis plays a crucial role for enabling long lasting changes in synaptic functions, but signaling pathways that link receptor stimulation with translational control remain poorly known. Among the putative regulatory factors are mRNA-binding proteins (messenger ribonucleoprotein, mRNP), which control the fate of cytosolic localized mRNAs. Based on the assumption that a subset of mRNA is maintained in an inactive state, mRNP-mRNA complexes were separated into polysome-bound (translated) and polysome-free (nontranslated) fractions by sucrose density centrifugation. Poly(A) mRNA-mRNP complexes were purified from a postmitochondrial extract of rat cerebral cortex by oligo(dT)-cellulose affinity chromatography. The mRNA processing proteins were characterized, from solution, by a nanoflow reverse phase-high pressure liquid chromatography-mu-electrospray ionization mass spectrometry. The majority of detected mRNA-binding proteins was found in both fractions. However, a small number of proteins appeared to be fraction-specific. This subset of proteins is by far the most interesting because the proteins are potentially involved in controlling an activity-dependent onset of translation. They include transducer proteins, kinases, and anchor proteins. This study of the mRNP proteome is the first step in allowing future experimentation to characterize individual proteins responsible for mRNA processing and translation in dendrites.


Assuntos
RNA Mensageiro/metabolismo , Ribonucleoproteínas/isolamento & purificação , Animais , Fracionamento Celular , Centrifugação com Gradiente de Concentração , Córtex Cerebral , Cromatografia de Afinidade , Cromatografia Líquida de Alta Pressão , Substâncias Macromoleculares , Polirribossomos/metabolismo , Ligação Proteica , Biossíntese de Proteínas , Proteômica , RNA Mensageiro/isolamento & purificação , Ratos , Ratos Long-Evans , Ribonucleoproteínas/análise , Ribonucleoproteínas/metabolismo , Ribossomos/metabolismo , Espectrometria de Massas por Ionização por Electrospray
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