Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 113
Filtrar
1.
J Adv Nurs ; 2024 Aug 18.
Artigo em Inglês | MEDLINE | ID: mdl-39154349

RESUMO

AIM: Compare the use and trend of a telemedicine tool for clinical advice among nurses and other Cameroonian healthcare providers and explore its feasibility and accessibility. DESIGN: A comparative observational descriptive study. METHODS: The sample includes all telemedicine users who request advice from volunteer medical specialists in Spain on clinical cases through the telemedicine tool "diagnosis assistance" (DA). It consisted of a total of 296 Cameroonian health professionals (59% women), of whom 77 were nurses. The variables in which the trend was explored (2013-2022) were DAs entered by nurses versus other healthcare professionals, compared by primary specialty, comments and documents attached. Feasibility and accessibility were explored through an anonymous survey. RESULTS: There were 2527 DAs between 2013 and 2022, of which nurses introduced 68%. There is an increasing trend in the nurse/other healthcare providers ratio, with significant differences in the chi-square of the linear trend between 2015 and 2022 (χ2 = 395.05; df = 7; p < .001). The probability that a DA was requested by nurses (PR >1) was observed in all years except for 2014, 2018 and 2019. The most tele-counselling requested by nurses was in the specialties of internal medicine, obstetrics and gynaecology, and dermatology. The exchange of comments and attachments was mainly conducted among nurses (74.9% and 50.4%, respectively). The users surveyed considered the tool valuable for diagnosis, applicable, with limitations due to cost, Internet quality or lack of time and effective at reducing hospital referrals. CONCLUSIONS: Telemedicine for clinical advice has been used mostly and with increasing tendency by nurses, mainly in internal medicine, gynaecology and dermatology, being a useful and feasible resource that can contribute to improving clinical decision-making by African nurses. IMPACT: The study addressed the problem of the shortage of health professionals in Central Africa and the search for alternatives that facilitate decision-making in this context. Tele-counselling tools through digital platforms that put Spanish specialists in contact with health professionals in Central Africa are mostly used by nurses working in rural health centres with a growing trend in their use. The research allows us to determine that tele-counselling tools constitute a well-accepted resource, which has a positive impact in environments with a shortage of human health resources, favouring the safety of both the nursing professional, through support in decision-making, and the populations to whom they provide care, who benefit from a multidisciplinary approach to their processes. REPORTING METHOD: The study has adhered to STROBE guidelines. PATIENT OR PUBLIC CONTRIBUTION: No Patient or Public Contribution.

2.
Prostate ; 83(4): 376-384, 2023 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-36564933

RESUMO

BACKGROUND: There is a considerable need to incorporate biomarkers of resistance to new antiandrogen agents in the management of castration-resistant prostate cancer (CRPC). METHODS: We conducted a phase II trial of enzalutamide in first-line chemo-naïve asymptomatic or minimally symptomatic mCRPC and analyzed the prognostic value of TMPRSS2-ERG and other biomarkers, including circulating tumor cells (CTCs), androgen receptor splice variant (AR-V7) in CTCs and plasma Androgen Receptor copy number gain (AR-gain). These biomarkers were correlated with treatment response and survival outcomes and developed a clinical-molecular prognostic model using penalized cox-proportional hazard model. This model was validated in an independent cohort. RESULTS: Ninety-eight patients were included. TMPRSS2-ERG fusion gene was detected in 32 patients with no differences observed in efficacy outcomes. CTC detection was associated with worse outcome and AR-V7 in CTCs was associated with increased rate of progression as best response. Plasma AR gain was strongly associated with an adverse outcome, with worse median prostate specific antigen (PSA)-PFS (4.2 vs. 14.7 m; p < 0.0001), rad-PFS (4.5 vs. 27.6 m; p < 0.0001), and OS (12.7 vs. 38.1 m; p < 0.0001). The clinical prognostic model developed in PREVAIL was validated (C-Index 0.70) and the addition of plasma AR (C-Index 0.79; p < 0.001) increased its prognostic ability. We generated a parsimonious model including alkaline phosphatase (ALP); PSA and AR gain (C-index 0.78) that was validated in an independent cohort. CONCLUSIONS: TMPRSS2-ERG detection did not correlate with differential activity of enzalutamide in first-line mCRPC. However, we observed that CTCs and plasma AR gain were the most relevant biomarkers.


Assuntos
Células Neoplásicas Circulantes , Neoplasias de Próstata Resistentes à Castração , Humanos , Masculino , Biomarcadores Tumorais/genética , Células Neoplásicas Circulantes/patologia , Nitrilas/uso terapêutico , Prognóstico , Antígeno Prostático Específico , Neoplasias de Próstata Resistentes à Castração/tratamento farmacológico , Neoplasias de Próstata Resistentes à Castração/genética , Neoplasias de Próstata Resistentes à Castração/patologia , Receptores Androgênicos/genética
3.
J Sports Sci ; 40(17): 1919-1930, 2022 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-36074936

RESUMO

This study used principal component analysis (PCA) of waveforms to extract movement patterns from hip and knee angle time-series data; and determined if the extracted movement patterns were predictors of ball velocity during a soccer kick. Twenty-three female and nineteen male professional soccer players performed maximal effort instep kicks while motion capture and post-impact ball velocities data were recorded. Three-dimensional hip and knee joint angle time-series data were calculated from the beginning of the kicking leg's backswing phase until the end of the follow-through phase and entered into separate PCAs for females and males. Three principal components (PC) (i.e., movement patterns) were extracted and PC scores were calculated. Pearson correlation coefficients were calculated to establish correlations between hip and knee PC scores and kicking velocity. Results showed better kicking performance in male players was associated with a greater difference between the hip extension at the end of the backswing/beginning of the leg cocking phases and hip flexion at the end of the follow-through phase (r = -0.519, p = 0.023) and a delayed internal rotation of the hip (r = 0.475, p = 0.040). No significant correlations between ball velocity and hip and knee kinematics were found for female players.


Assuntos
Futebol , Humanos , Masculino , Feminino , Quadril , Análise de Componente Principal , Articulação do Joelho , Fenômenos Biomecânicos
4.
J Sports Sci ; 39(10): 1105-1113, 2021 May.
Artigo em Inglês | MEDLINE | ID: mdl-33337970

RESUMO

In swimming relay races, various start techniques are performed by swimmers, but it remains unclear which technique leads to a better start performance. Therefore, the purpose of the present study was to compare the kinematic characteristics of different relay start techniques with the new starting block Omega OSB11. Eleven international youth swimmers were filmed during 1) no step with parallel feet, 2) no step with separated feet and 3) one-step starts and their centre of mass kinematics calculated with 2D-DLT algorithms. Results indicate that differences between techniques were detected in the spatiotemporal parameters of the block and aerial start phases (e.g., initial and take-off positions, entry height, preparation and changeover times) and in selected parameters of the underwater phase (e.g., emersion time and distance, underwater time and distance). However, no statistical effects were found in 5 m, 10 m and 15 m start times, nor in horizontal take-off velocity, despite an observed trend for the one-step start to be superior to the non-step techniques. These results suggest that differences between relay techniques could rely more on the swimmer's body posture (angular kinematics) on the block, flight and underwater phases than on the centre of mass linear kinematics.


Assuntos
Desempenho Atlético/fisiologia , Comportamento Competitivo/fisiologia , Natação/fisiologia , Adolescente , Fenômenos Biomecânicos , Feminino , Humanos , Masculino , Postura/fisiologia , Estudos de Tempo e Movimento
5.
Sensors (Basel) ; 21(20)2021 Oct 13.
Artigo em Inglês | MEDLINE | ID: mdl-34695999

RESUMO

Mobile robotic platforms have made inroads in the rehabilitation area as gait assistance devices. They have rarely been used for human gait monitoring and analysis. The integration of mobile robots in this field offers the potential to develop multiple medical applications and achieve new discoveries. This study proposes the use of a mobile robotic platform based on depth cameras to perform the analysis of human gait in practical scenarios. The aim is to prove the validity of this robot and its applicability in clinical settings. The mechanical and software design of the system is presented, as well as the design of the controllers of the lane-keeping, person-following, and servoing systems. The accuracy of the system for the evaluation of joint kinematics and the main gait descriptors was validated by comparison with a Vicon-certified system. Some tests were performed in practical scenarios, where the effectiveness of the lane-keeping algorithm was evaluated. Clinical tests with patients with multiple sclerosis gave an initial impression of the applicability of the instrument in patients with abnormal walking patterns. The results demonstrate that the system can perform gait analysis with high accuracy. In the curved sections of the paths, the knee joint is affected by occlusion and the deviation of the person in the camera reference system. This issue was greatly improved by adjusting the servoing system and the following distance. The control strategy of this robot was specifically designed for the analysis of human gait from the frontal part of the participant, which allows one to capture the gait properly and represents one of the major contributions of this study in clinical practice.


Assuntos
Transtornos Neurológicos da Marcha , Procedimentos Cirúrgicos Robóticos , Robótica , Fenômenos Biomecânicos , Marcha , Análise da Marcha , Humanos , Caminhada
6.
J Strength Cond Res ; 34(9): 2449-2455, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-30335717

RESUMO

Collazo García, CL, Rueda, J, Suárez Luginick, B, Navarro, E. Differences in the electromyographic activity of lower-body muscles in hip thrust variations. J Strength Cond Res 34(9): 2449-2455, 2020-Coaches often use variations of an exercise to train a specific muscle. The purpose of this study was to analyze motor patterns in 4 variations of one of the most popular strength training exercises for the lower body: the barbell hip thrust. Seven experienced personal trainers performed a series of 8 repetitions of each variation with a load of 40% one repetition maximum. Subjects rested 3' between series. Electromyographic (EMG) muscle activity was measured in the rectus femoris, vastus medialis; vastus lateralis; gluteus maximus; gluteus medius; biceps femoris; and semitendinosus. Variations of the hip thrust exercise were performed by changing the position of the feet (feet were moving away from the body) and the direction of force exerted by subjects (intentional force aimed at hip's external rotation and knee's flexion). Repeated-measures analysis of variance revealed significant differences in EMG in all muscles except for the gluteus medius, where no differences were observed among variations. The results obtained suggest that hip thrust variations have different motor patterns, which can be exploited to adapt an exercise to the individual needs of each athlete.


Assuntos
Extremidade Inferior/fisiologia , Força Muscular/fisiologia , Músculo Esquelético/fisiologia , Treinamento Resistido/métodos , Adulto , Fenômenos Biomecânicos , Nádegas/fisiologia , Eletromiografia , Músculos Isquiossurais/fisiologia , Humanos , Masculino , Adulto Jovem
7.
Environ Monit Assess ; 192(9): 611, 2020 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-32870472

RESUMO

Indicators of ecosystem health are effective tools to assess freshwater ecosystem impairment. However, they are scarcely used as a monitoring tool by local environmental agencies in Argentina. Here, we review the literature to analyze the use of ecosystem health indicators in freshwaters from Argentina. We found 91 scientific articles relating to the use of ecological indices to assess the impact of different environmental stressors in aquatic environments published between 1996 and 2019. We generated Google Earth map where we deployed the sampling sites and type of indices reported by each article. As biological indices were the most used, we also surveyed bioindication experts to gather information on their application. We found that most studies were concentrated mainly in Pampas (34%), Dry Chaco (20%), Espinal (12%), and Patagonian Steppe (10%) ecoregions. Biological indices (mainly with invertebrates) were more used than geomorphological or physico-chemical indices. Indices resulted useful to evaluate the impact of stressors in 63% of cases, being land use the most studied stressor. However, sampling design varied greatly among studies, making their comparison difficult. The information compiled here could help to the design of monitoring protocols, the adoption of regional indices, and the creation of a national inventory of ecosystem health status, which are mandatory to propose well-grounded conservation and management policies for freshwaters in Argentina.


Assuntos
Ecossistema , Monitoramento Ambiental , Animais , Argentina , Água Doce , Invertebrados
8.
Ecotoxicol Environ Saf ; 180: 565-574, 2019 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-31129435

RESUMO

Natural pesticides are considered a good alternative to synthetic pesticides to reduce environmental impacts. However, biopesticides may have unknown effects on the environment, and can affect non-target organisms. In this study, the ecotoxicological effects of an aqueous extract (hydrolate) from Spanish populations of Artemisia absinthium (var. Candial) showing a promising biopesticide activity, were evaluated on non-target soil organisms from different trophic levels (natural microbial communities characterized through 16S rRNA gene sequencing, the earthworm Eisenia fetida and the plant Allium cepa). The hydrolate usually was considered as a by-product of the distillation to obtain essential oils. However, recently has been found to have nematicide properties. The hydrolate caused acute toxicity at values of LC50 of 3.87% v/v for A. cepa and 0.07 mL/g for E. fetida. All the concentrations except for the most diluted (1% v/v) reduced the bacterial physiological activity compared to controls (LC50 = 25.72% v/v after 24 h of exposure). The hydrolate also slightly altered the ability of the microbial community to degrade carbon substrates. These results indicate that the hydrolate from A. absinthium may affect the survival and metabolic abilities of key soil organisms.


Assuntos
Artemisia absinthium , Agentes de Controle Biológico/toxicidade , Praguicidas/toxicidade , Solo , Allium/efeitos dos fármacos , Animais , Bactérias/efeitos dos fármacos , Cadeia Alimentar , Nematoides , Oligoquetos/efeitos dos fármacos , Extratos Vegetais/toxicidade , RNA Ribossômico 16S/genética , Solo/química , Microbiologia do Solo
9.
Sensors (Basel) ; 19(11)2019 May 28.
Artigo em Inglês | MEDLINE | ID: mdl-31141882

RESUMO

This paper presents an approach to exploit the superimposed training (ST)-based primary users' (PUs) transmissions in the context of spectrum sensing for cognitive radio. In the low signal-to-noise ratio (SNR), the proposed scheme splits the spectrum sensing phase into two sample processing periods, allowing a secondary user (SU) to carry out a training sequence synchronization (with a small probability of error) before the implementation of a robust spectrum sensing algorithm that enhances the detection, based on the deterministic signal components embedded in the ST PU's signals along with the unknown data signal. The overall sensing performance is improved using a reasonable number of samples to achieve a high probability of detection, resulting in a reduced spectrum sensing duration. Furthermore, a low computational complexity version of the proposed ST combined approach for a reduced phase (SCAR-Phase) of spectrum sensing is presented, which attains the same detection performance with a smaller number of real operations in the low SNR. In the practical consideration of imperfect training sequence synchronizations, the results show the advantages of exploiting the ST sequence to perform spectrum sensing, thus quantifying the significant improvement in detection performance and the maximum SU's achievable throughput.

10.
Environ Microbiol ; 20(7): 2422-2437, 2018 07.
Artigo em Inglês | MEDLINE | ID: mdl-29687572

RESUMO

Using the 16S rRNA and mcrA genes, we investigated the composition, abundance and activity of sediment archaeal communities within 18 high-mountain lakes under contrasted metal levels from different origins (bedrock erosion, past-mining activities and atmospheric depositions). Bathyarchaeota, Euryarchaeota and Woesearchaeota were the major phyla found at the meta-community scale, representing 48%, 18.3% and 15.2% of the archaeal community respectively. Metals were equally important as physicochemical variables in explaining the assemblage of archaeal communities and their abundance. Methanogenesis appeared as a process of central importance in the carbon cycle within sediments of alpine lakes as indicated by the absolute abundance of methanogen 16S rRNA and mcrA gene transcripts (105 to 109 copies g-1 ). We showed that methanogen abundance and activity were significantly reduced with increasing concentrations of Pb and Cd, two indicators of airborne metal contaminations. Considering the ecological importance of methanogenesis in sediment habitats, these metal contaminations may have system wide implications even in remote area such as alpine lakes. Overall, this work was pioneer in integrating the effect of long-range atmospheric depositions on archaeal communities and indicated that metal contamination might significantly compromise the contribution of Archaea to the carbon cycling of the mountain lake sediments.


Assuntos
Archaea/efeitos dos fármacos , Lagos/microbiologia , Metais/toxicidade , Microbiologia da Água , Poluentes Químicos da Água/toxicidade , Archaea/genética , Ciclo do Carbono , DNA Arqueal , Ecossistema , Sedimentos Geológicos/microbiologia , Filogenia , RNA Ribossômico 16S
11.
Oecologia ; 183(4): 1167-1181, 2017 04.
Artigo em Inglês | MEDLINE | ID: mdl-28190093

RESUMO

Climate warming can lead to changes in alpine plant species interactions through modifications in environmental conditions, which may ultimately cause drastic changes in plant communities. We explored the effects of 4 years of experimental warming with open-top chambers (OTC) on Vaccinium myrtillus performance and its interaction with neighbouring shrubs at the Pyrenean treeline ecotone. We examined the effects of warming on height, above-ground (AG) and below-ground (BG) biomass and the C and N concentration and isotope composition of V. myrtillus growing in pure stands or in stands mixed with Vaccinium uliginosum or Rhododendron ferrugineum. We also analysed variations in soil N concentrations, rhizosphere C/N ratios and the functional diversity of the microbial community, and evaluated whether warming altered the biomass, C and N concentration and isotope composition of V. uliginosum in mixed plots. Our results showed that warming induced positive changes in the AG growth of V. myrtillus but not BG, while V. uliginosum did not respond to warming. Vaccinium myrtillus performance did not differ between stand types under increased temperatures, suggesting that warming did not induce shifts in the interaction between V. myrtillus and its neighbouring species. These findings contrast with previous studies in which species interactions changed when temperature was modified. Our results show that species interactions can be less responsive to warming in natural plant communities than in removal experiments, highlighting the need for studies involving the natural assembly of plant species and communities when exploring the effect of environmental changes on plant-plant interactions.


Assuntos
Biomassa , Solo , Clima , Ecossistema , Plantas , Temperatura
12.
Ecotoxicol Environ Saf ; 145: 539-548, 2017 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-28787615

RESUMO

An ecotoxicological survey of soils that were polluted with wastes from lindane (γ-HCH) production assessed the effects of organochlorine compounds on the metabolism of microbial communities and the toxicity of these compounds to a native earthworm (Allolobophora chlorotica). Furthermore, the bioremediation role of earthworms as facilitators of soil washing and the microbial degradation of these organic pollutants were also studied. Soil samples that presented the highest concentrations of ε-HCH, 2,4,6-trichlorophenol, pentachlorobenzene and γ-HCH were extremely toxic to earthworms in the short term, causing the death of almost half of the population. In addition, these soils inhibited the heterotrophic metabolic activity of the microbial community. These highly polluted samples also presented substances that were able to activate cellular detoxification mechanisms (measured as EROD and BFCOD activities), as well as compounds that were able to cause endocrine disruption. A few days of earthworm activity increased the extractability of HCH isomers (e.g., γ-HCH), facilitating the biodegradation of organochlorine compounds and reducing the intensity of endocrine disruption in soils that had low or medium contamination levels.


Assuntos
Ecotoxicologia/métodos , Hexaclorocicloexano/toxicidade , Resíduos Industriais/análise , Oligoquetos/efeitos dos fármacos , Microbiologia do Solo , Poluentes do Solo/toxicidade , Animais , Biodegradação Ambiental , Hexaclorocicloexano/análise , Hexaclorocicloexano/química , Isomerismo , Oligoquetos/enzimologia , Solo/química , Poluentes do Solo/análise , Poluentes do Solo/química
13.
Sensors (Basel) ; 17(2)2017 Jan 26.
Artigo em Inglês | MEDLINE | ID: mdl-28134753

RESUMO

Wireless Sensor Networks (WSNs) are composed of spatially distributed autonomous sensor devices, named motes. These motes have their own power supply, processing unit, sensors and wireless communications However with many constraints, such as limited energy, bandwidth and computational capabilities. In these networks, at least one mote called a sink, acts as a gateway to connect with other networks. These sensor networks run monitoring applications and then the data gathered by these motes needs to be retrieved by the sink. When this sink is located in the far field, there have been many proposals in the literature based on Collaborative Beamforming (CB), also known as Distributed or Cooperative Beamforming, for these long range communications to reach the sink. In this paper, we conduct a thorough study of the related work and analyze the requirements to do CB. In order to implement these communications in real scenarios, we will consider if these requirements and the assumptions made are feasible from the point of view of commercial motes and their constraints. In addition, we will go a step further and will consider different alternatives, by relaxing these requirements, trying to find feasible assumptions to carry out these types of communications with commercial motes. This research considers the nonavailability of a central clock that synchronizes all motes in the WSN, and all motes have identical hardware. This is a feasibility study to do CB on WSN, using a simulated scenario with randomized delays obtained from experimental data from commercial motes.

14.
Bioelectromagnetics ; 37(1): 37-48, 2016 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-26661640

RESUMO

This study analyzes if an external magnetic stimulus (2 kHz and approximately 0.1 µT applied near frontal cortex) influences working memory, perception, binary decision, motor execution, and sustained attention in humans. A magnetic stimulus and a sham stimulus were applied to both sides of the head (frontal cortex close to temporal-parietal area) in young and healthy male test subjects (n = 65) while performing Sternberg's memory scanning task. There was a significant change in reaction time. Times recorded for perception, sustained attention, and motor execution were lower in exposed subjects (P < 0.01). However, time employed in binary decision increased for subjects exposed to magnetic fields. From results, it seems that a low intensity 2 kHz exposure modifies short-term working memory, as well as perception, binary decision, motor execution, and sustained attention.


Assuntos
Voluntários Saudáveis , Campos Magnéticos/efeitos adversos , Memória de Curto Prazo , Estudantes , Equipamentos e Provisões Elétricas , Exposição Ambiental/efeitos adversos , Exposição Ambiental/análise , Humanos , Masculino , Modelos Estatísticos , Tempo de Reação , Adulto Jovem
15.
J Appl Biomech ; 32(6): 548-552, 2016 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-27400434

RESUMO

The two-fold purpose of this study was to analyze the time required by a fencer to initiate a defensive action in response to a direct attack, which involves identifying when the defending fencer detects the just-noticeable difference, and, secondly, to assess the effect that an attacker's rapid armed hand movement (feint attack) has on the time required to initiate a defensive move. Twenty-four elite fencers and a fencing master were included in the study. Four adapted force plates were installed on a scaffold used as a fencing piste. A 3D video analysis system recorded the location of 2 markers installed on the fencing master's shoulder and sword. The results confirm that the defending fencer has a mean movement time of 0.353 ± 0.028 s to perform the defensive action, which provides an advantage over the attacking fencer. The velocity of movement in the peripheral visual field has no influence on the time required by elite fencers to initiate a defensive action. This confirms the crucial role that response inhibition processes play when nonrelevant actions are perceived. Kinematic analysis of markers suggests that the eye movements of elite fencers are not the only source of information used while observing an attack.


Assuntos
Tempo de Reação/fisiologia , Esportes/fisiologia , Extremidade Superior/fisiologia , Fenômenos Biomecânicos , Humanos , Movimento/fisiologia , Desempenho Psicomotor/fisiologia , Espanha , Fatores de Tempo , Gravação em Vídeo , Adulto Jovem
16.
Environ Sci Technol ; 49(13): 8041-7, 2015 Jul 07.
Artigo em Inglês | MEDLINE | ID: mdl-26018638

RESUMO

Various factors have been invoked to explain the toxicity of silver nanoparticles (AgNP) to microorganisms including particle size and the nature of stabilizing coatings as well as the amount of dissolved silver occurring in AgNP suspensions. In this study we have assessed the effects of nine differently coated AgNP (chitosan, lactate, polyvinylpyrrolidone, polyethelene glycol, gelatin, sodium dodecylbenzenesulfonate, citrate, dexpanthenol, and carbonate) and AgNO3 on the photosynthesis of the freshwater algae Chlamydomonas reinhardtii. We have thus examined how AgNP effects on algae relate to particle size, measured dissolved silver (Agd), and bioavailable silver (Agbioav). Agbioav was indirectly estimated in toxicity experiments by cysteine-silver complexation at the EC50. The EC50 calculated as a function of measured Agd concentrations showed for some coatings values similar to that of dissolved Ag, whereas other coated AgNP displayed lower EC50 values. In all cases, excess cysteine completely prevented effects on photosynthetic yield, confirming the role of Agd as a cause of the observed effect on the photosynthesis. Toxicity was related neither to particle size nor to the coatings. For all differently coated AgNP suspensions, the EC50 values calculated as a function of Agbioav were comparable to the value of AgNO3. Depending on the coatings Agbioav was comparable to or higher than measured Agd.


Assuntos
Chlamydomonas reinhardtii/efeitos dos fármacos , Nanopartículas Metálicas/química , Nanopartículas Metálicas/toxicidade , Fotossíntese/efeitos dos fármacos , Prata/toxicidade , Benzenossulfonatos/química , Benzenossulfonatos/toxicidade , Carbonatos/química , Carbonatos/toxicidade , Quitosana/química , Quitosana/toxicidade , Chlamydomonas reinhardtii/fisiologia , Citratos/química , Citratos/toxicidade , Cisteína/farmacologia , Cisteína/toxicidade , Gelatina/química , Gelatina/toxicidade , Lactatos/química , Lactatos/toxicidade , Ácido Pantotênico/análogos & derivados , Ácido Pantotênico/química , Ácido Pantotênico/toxicidade , Tamanho da Partícula , Polietilenoglicóis/química , Polietilenoglicóis/toxicidade , Povidona/toxicidade , Prata/farmacocinética , Nitrato de Prata/farmacocinética , Testes de Toxicidade/métodos
17.
Ecotoxicology ; 23(8): 1484-93, 2014 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-25081381

RESUMO

The increasing interest in the development of novel green solvents has led to the synthesis of benign alternative products with minimized environmental impacts. However, most of published studies on green solvents focus primarily on their physicochemical properties, with limited emphasis on absence of ecotoxicological assessment. In this study, we evaluated the acute ecotoxicity of four levulinates (levulinic acid, methyl levulinate, ethyl levulinate and butyl levulinate) on freshwater algae (Chlamydomonas reinhardtii), bacteria (Vibrio fischeri), daphnids (Daphnia magna) and earthworms (Eisenia foetida) using various dose-response tests. As a general trend, the toxicity of levulinate esters in aquatic exposure (assessed as the EC50) increased as a function of increasing alkyl chain length; accordingly, the most toxic compound for the aquatic organisms was butyl levulinate, followed by ethyl levulinate and methyl levulinate. The most toxic compound for E. foetida (terrestrial exposure) was methyl levulinate, followed by ethyl levulinate, butyl levulinate and levulinic acid; in this case, we observed an inverse relationship between toxicity and alkyl chain length. Based on both the lowest EC50 found in the aquatic media and the ratio between predicted environmental concentration and the predicted no-effect concentration, we have estimated the maximum allowable values in the environment for these chemicals to be 1.093 mg L(-1) for levulinic acid, 2.761 mg L(-1) for methyl levulinate, 0.982 mg L(-1) for ethyl levulinate and 0.151 mg L(-1) for butyl levulinate.


Assuntos
Ésteres/toxicidade , Ácidos Levulínicos/toxicidade , Poluentes Químicos da Água/toxicidade , Aliivibrio fischeri/efeitos dos fármacos , Animais , Chlamydomonas/efeitos dos fármacos , Daphnia/efeitos dos fármacos , Ecotoxicologia , Oligoquetos/efeitos dos fármacos , Testes de Toxicidade Aguda
18.
Sports Biomech ; 13(3): 285-95, 2014 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-25325772

RESUMO

The aim of this study was to compare the race characteristics of the start and turn segments of national and regional level swimmers. In the study, 100 and 200-m events were analysed during the finals session of the Open Comunidad de Madrid (Spain) tournament. The "individualized-distance" method with two-dimensional direct linear transformation algorithm was used to perform race analyses. National level swimmers obtained faster velocities in all race segments and stroke comparisons, although significant inter-level differences in start velocity were only obtained in half (8 out of 16) of the analysed events. Higher level swimmers also travelled for longer start and turn distances but only in the race segments where the gain of speed was high. This was observed in the turn segments, in the backstroke and butterfly strokes and during the 200-m breaststroke event, but not in any of the freestyle events. Time improvements due to the appropriate extension of the underwater subsections appeared to be critical for the end race result and should be carefully evaluated by the "individualized-distance" method.


Assuntos
Desempenho Atlético/fisiologia , Comportamento Competitivo/fisiologia , Natação/fisiologia , Fenômenos Biomecânicos , Humanos , Estudos de Tempo e Movimento
19.
Rev Biol Trop ; 62(2): 603-10, 2014 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-25102643

RESUMO

Gobiidae is the most specious fish family in the world with almost 2 000 species, however only 11% of them have been described for their larval stages. The entire life cycle information is essential to understand the biology and ecology of this important fish group. Previous studies on zooplankton samples from Ensenada de La Paz, México, have shown the presence of several Gobiidae larvae and juveniles which were identified as Evermania zosterura. The main objective of this work was to describe the larval stages of this species, widely distributed in the Eastern tropical Pacific. The development of E. zosterura larvae was described based on 66 specimens. A total of 53 specimens were used to describe morphometrics and pigmentation patterns, while 13 specimens were cleared and stained, to obtain meristic characteristics. Cleared specimens had 30 to 31 total vertebrae; dorsal-fin elements: IV; 1, 13-14, anal-fin elements: 1, 13-14, and most had pterygiophore formula 4-111100. The combination of these characteristics confirmed these specimens as E. zosterura. The pigment pattern is similar throughout ontogeny. Larvae are characterized by having three to five dendritic melanophores along the post-anal ventral margin, four to nine smaller melanophores along the ventral margin between the isthmus and anus, and one on the midpoint of the dorsal margin of the tail. There is one small pigment spot on the angle of the jaw, and other on the tip of lower lip. There is an elongated internal pigment under the notochord, between the head and gas bladder. Notochord flexion starts near 3.5mm BL and ends at 4.6mm BL; transformalion to the juvenile stage is at about 13.6mm BL. Our conclusion is that the most useful characters to distinguish this species early-larval stages from those of similar species in the area, are the number of myomeres, the large melanophores (approximately uniformly in size) on the post anal ventral margin, and the elongate internal pigment under the notochord, anterior to the gas bladder.


Assuntos
Perciformes/crescimento & desenvolvimento , Animais , Feminino , Larva/crescimento & desenvolvimento , Masculino , México , Perciformes/anatomia & histologia , Perciformes/classificação , Pigmentação
20.
Phys Rev E ; 109(5-1): 054901, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38907456

RESUMO

We report on the construction of a granular network of particles to study the formation, evolution, and statistical properties of clusters of particles developing at the vicinity of a liquid-solid-like phase transition within a vertically vibrated quasi-two-dimensional granular system. Using the data of particle positions and local order from Castillo et al. [G. Castillo, N. Mujica, and R. Soto, Phys. Rev. Lett. 109, 095701 (2012)0031-900710.1103/PhysRevLett.109.095701], we extract granular clusters taken as communities of the granular network via modularity optimization. Each one of these communities is a patch of particles with a very well defined local orientational order embedded within an array of other patches forming a complex cluster network. The distributions of cluster sizes and lifespans for the cluster network depend on the distance to the liquid-solid-like phase transition of the quasi-two-dimensional granular system. Specifically, the cluster size distribution displays a scale-invariant behavior for at least a decade in cluster sizes, while cluster lifespans grow monotonically with each cluster size. We believe this systematic community analysis for clustering in granular systems can help to study and understand the spatiotemporal evolution of mesoscale structures in systems displaying out-of-equilibrium phase transitions.

SELEÇÃO DE REFERÊNCIAS
Detalhe da pesquisa