9,391 research outputs found
The CTLA-4 and PD-1/PD-L1 inhibitory pathways independently regulate host resistance to Plasmodium-induced acute immune pathology.
No full textThe balance between pro-inflammatory and regulatory immune responses in determining optimal T cell activation is vital for the successful resolution of microbial infections. This balance is maintained in part by the negative regulators of T cell activation, CTLA-4 and PD-1/PD-L, which dampen effector responses during chronic infections. However, their role in acute infections, such as malaria, remains less clear. In this study, we determined the contribution of CTLA-4 and PD-1/PD-L to the regulation of T cell responses during Plasmodium berghei ANKA (PbA)-induced experimental cerebral malaria (ECM) in susceptible (C57BL/6) and resistant (BALB/c) mice. We found that the expression of CTLA-4 and PD-1 on T cells correlates with the extent of pro-inflammatory responses induced during PbA infection, being higher in C57BL/6 than in BALB/c mice. Thus, ECM develops despite high levels of expression of these inhibitory receptors. However, antibody-mediated blockade of either the CTLA-4 or PD-1/PD-L1, but not the PD-1/PD-L2, pathways during PbA-infection in ECM-resistant BALB/c mice resulted in higher levels of T cell activation, enhanced IFN-γ production, increased intravascular arrest of both parasitised erythrocytes and CD8(+) T cells to the brain, and augmented incidence of ECM. Thus, in ECM-resistant BALB/c mice, CTLA-4 and PD-1/PD-L1 represent essential, independent and non-redundant pathways for maintaining T cell homeostasis during a virulent malaria infection. Moreover, neutralisation of IFN-γ or depletion of CD8(+) T cells during PbA infection was shown to reverse the pathologic effects of regulatory pathway blockade, highlighting that the aetiology of ECM in the BALB/c mice is similar to that in C57BL/6 mice. In summary, our results underscore the differential and complex regulation that governs immune responses to malaria parasites
Temporal and spatial variability in speakers with Parkinson's Disease and Friedreich's Ataxia
No full textSpeech variability in groups of speakers with Parkinson's disease (PD) and with Friedreich's ataxia was compared with healthy controls. Speakers repeated the same phrase 20 times at one of two rates (fast or habitual). A non-linear analysis of variability was performed which used some of the principles behind the spatio-temporal index (STI). The STI usually employs variation in lip displacement over repetitions of the same utterance and a linear analysis of such signals is conducted to represent the combined variation in spatial and temporal control. When working with patients, audio measures (here we used speech energy) are preferred over kinematics ones as they are minimally disruptive to speech. Non-linear methods allow spatial variability to be estimated separately from temporal variability. The results are tentatively interpreted as showing that PD speakers were distinguished from healthy control speakers in spatial variability and ataxic speakers were distinguished from controls in temporal variability. These findings are consistent with the speech symptoms reported for these disorders. We conclude that the non-linear analysis using the speech energy measure is worth investigating further as it is potentially revealing of the differences underlying these two pathologies
Implications of the Improvement of Teaching Quality for Professional Development (PD) of Academics at the Colleges of Applied Sciences (CASs) in the Sultanate of Oman
No full textThe Oman Accreditation Council (OAC), which is called later the Oman Academic Accreditation Authority (OAAA), designed a higher education institution (HEI) Quality Assurance (QA) framework for Omani public and private Higher Education Institutions (HEIs), starting with a quality audit process in 2008. The Colleges of Applied Sciences (CASs), as a public HEI, are required to ensure the quality of all services and activities to meet particular national standards (specified in the framework) in order to gain a HEI and programme certificate. In line with a quality audit scope, the quality of the fields of PD and related teaching quality should be ensured and enhanced by the promotion and contribution of the former field to the maintenance and improvement of the latter one.
The chief purpose of this study was to identify the uptake and implications of the growing requirement to improve teaching quality and the PD of academics at the CASs in the Sultanate of Oman especially in the context of the application of the QA framework. The study focused on examining the academics’ participation in professional development programmes (PDPs) and current perceptions of PD with respect to the improvement of teaching quality improvement at these colleges. The current study also dealt with a reorganization and prioritization of academics’ PD needs, barriers to effective PD, and factors to enhance PD of academics regarding teaching quality improvement in the colleges.
Based on the purpose and research objectives, the current study adopted both positivist (quantitative) and interpretive (qualitative) research paradigms. Because the study perused quantitative and qualitative data regarding certain variables, it chose a mixed-research design. The researcher designed survey questionnaire to collect quantitative data and a semi-structured interview and a focus group discussion to probe and interpret quantitative findings. After fulfillment of the validity and reliability measurements, a self-completion questionnaire was distributed to a stratified random sample of academics (170) over the six CASs. A total of 150 questionnaires (out of 170) were completed and returned and the response-rate reached 88.2%. The quantitative data was analyzed by appropriate analysis using the Statistical Package for Social sciences (SPSS), while the qualitative data was analyzed by appropriate qualitative analysis.
The findings of the study showed that the level of academics’ participation in PDPs to improve teaching quality in the last two years in the CASs seems to be unsatisfactorily low. The current perceptions of the PD situations in the colleges, relating to teaching quality improvement, signified a shortage in the number of available PDPs and/or a discouragement of academics’ participation in these programmes in the last two years. The study also revealed all the 22 PD needs of academics regarding the improvement of teaching quality are significantly demanded by participants; the higher rated needs focused on a development of ‘student centred’ skills, such as critical thinking and problem-solving skills.
Furthermore, the study illustrated that the highest significant perceived barriers to effective PD in the CASs, as related to teaching quality improvement, focus on a lack of a clear institutional PD policy and a lack of appropriately systematic PD plans. The study also revealed all 10 perceived factors to enhance PD regarding teaching quality improvement are very important. The most significant factors represented and stressed particular problematic issues (the high rated barriers) and a reduction of a heavy workload to enhance academics’ participation in PD regarding the improvement of teaching quality.
Conclusions drawn from the discussion of the findings of study include a lack of a clear PD policy at national and institutional levels and absence of a particular authority/unit concerning PD issues in Omani HEIs. The two problematic issues resulted in a lack of systematic and realistic PD plans in the CASs, involving a lack of academics’ involvement in PD plans, a misconnection of academics’ PD needs to PD, inappropriate facilities and resources allocation, and inappropriate evaluation processes of PD. In addition, the conclusions also include that PD of academics regarding the improvement of teaching quality in the colleges requires more attention and focus to manage particular significant issues perceived by participants as both barriers and potential facilitators relating to PD of academics.
Based on identified conclusions, particular implications for policy and practice to enhance PD to improve teaching quality were set at three levels: governmental, institutional, and individual. Moreover, achievements of the current study according to the research questions were identified and contributions of the study to the fields of PD, teaching quality, and the context of QA and quality audit in HE were addressed. Based on the findings and conclusions, particular directions and recommended issues were suggested to be studied by further research to benefit the enhancement of PD and related teaching quality improvement
"Habermas and theology" by Nicholas Adams
No full textReview of Nicholas Adams, Habermas and theology (Cambridge: Cambridge University Press, 2006)Publisher PD
Obtenção, caracterização e avaliação da atividade de um nanocatalisador de Pd(0) sintetizado in situ sob a superfície de Fe3O4@dextrana para redução do 4-nitrofenol
No full textTese (doutorado) - Universidade Federal de Santa Catarina, Centro de Ciências Físicas e Matemáticas, Programa de Pós-Graduação em Química, Florianópolis, 2015.O objetivo principal deste trabalho é a preparação, caracterização e avaliação da atividade catalítica das nanopartículas (NPs) de Pd impregnadas no suporte magnético magnetita e estabilizada por dextrana. As NPs-Pd foram preparadas por crescimento in situ sob a superfície de nanopartículas superparamagnéticas (NPSMs) (Fe3O4@dextrana/Pd(0)). O controle do crescimento das NPs-Pd foi feito com o auxílio de NaBH4, como agente redutor. O catalisador de Fe3O4@dextrana/Pd foi totalmente caracterizado por diversas técnicas tais como espectroscopia de infravermelho, espalhamento de luz dinâmico, espalhamento de raios-X a baixos ângulos, microscopia eletrônica de transmissão e varredura, e difração de raios-X de pó. A caracterização mostrou que o catalisador é constituído de um suporte feito de Fe3O4@dextrana composto por unidades de nanocristais com tamanho de 9,7 nm, formando nanoclusters de 105,6 nm, contendo as NPs-Pd de 7,8 nm impregnadas em sua superfície. Os estudos cinéticos foram realizados por UV-vis, sendo que a atividade catalítica foi avaliada pela reação modelo de redução do p-nitrofenol (Nip), utilizando NaBH4. Aplicando um modelo de reação de superfície pseudo-molecular, a reação foi investigada pelo modelo teórico de isoterma de adsorção, revelando ser uma reação bimolecular que segue o mecanismo de Langmuir-Hinshelwood. A atividade catalítica do nanocatalisador Fe3O4@ dextrana/Pd com área superficial de 3,33 m2L-1x10-3 (0, 0053 mg L-1 de Pd) pode ser efetivamente analisada, e foi possível obter os parâmetros cinéticos kL, KBH4- e KNip. Os resultados mostraram que as moléculas de Nip possuem afinidade de adsorção muito maior do que BH4- pela superfície das NPs-Pd, resultado da influência do caráter hidrofóbico do Nip sob a constante de adsorção do substrato. Um novo parâmetro de atividade catalítica ??? foi proposto e utilizado com sucesso na comparação com outros catalisadores reportados na literatura. As NPSMs de Fe3O4@dextrana/Pd apresentaram um valor de ? = 3,65 L mg-1 s-1, superior ao citado na literatura. O estudo do reuso de Fe3O4@dextrana/Pd demonstrou que é possível reutilizar as mesmas por até 5 vezes com cerca de 99% de conversão do Nip e valor alto de TOF, 692 h-1.Abstract : The aim of this work was the preparation, characterization and evaluation of catalytic activity of Pd nanoparticles (NPs) impregnated in magnetite and stabilized by dextran. The Pd NPs were prepared by the in situ growth under the surface of superparamagnetic nanoparticles. The growth control of Pd NPs was made with the aid of NaBH4, as reducing agent. The catalyst Fe3O4@dextran/Pd was fully characterized by several techniques such as: infrared spectroscopy, dynamic light scattering, X-ray scattering at small angle, transmission and scanning electron microscopy , and diffraction X-ray powder. The characterization revealed that the catalyst consisted of a support made of Fe3O4@dextran nanocrystals composed of units with 9.7 nm in size, forming nanoclusters of 105.6 nm containing NPs of Pd with 7.8 nm diameter, impregnated in the surface. The kinetic studies were performed by UV-vis spectrocopy, and the catalytic activity was evaluated by the model reaction of the p-nitrophenol (Nip) reduction, using NaBH4 as a reducing agent. Applying a pseudo-molecular surface reaction approach, the reduction reaction could be investigated by means of a theoretical adsorption model, revealing that the reaction is bimolecular and followed the Langmuir-Hinshelwood mechanism.The catalytic activity of nano-catalyst of Fe3O4@dextran/Pd, with a surface area of 3.33m2L-1x103 (0.0053 mg L-1Pd), could be effectively determined, obtaining the kinetic parameters kL, KBH4- and KNip. These kinetics results showed that the Nip molecules have higheraffinity for the catalyst surface than the molecules of BH4-, as a result of the influence of the Nip hydrophobic character. A new catalytic activity parameter "?" was proposed and effectively used for comparison with other recent reported catalysts. The reuse studies showed that could be reused up to 5 times with about 99% conversion of Nip and a high TOF value, 692 h-1
Fullerene-like WS<sub>2</sub> supported Pd catalyst for hydrogen evolution reaction
No full textHydrogen is the most desirable green energy carrier and electrocatalytic hydrogen evolution reaction (HER) from water is a promising route for hydrogen production. The search for efficient, low-cost HER catalysts is a challenging and attracting topic. In this work, we report that inorganic fullerene-like WS2 supported Pd nanoparticles (Pd/WS2), with Pd loading of 0.76 wt%, are active for electrocatalytic HER conducted in 0.5 M H2SO4 solution, with overpotential at 10 mA cm−2 current density of ~130 mV and Tafel slope of 82.4 mV dec−1, which is comparable to that of Pt/WS2 (0.88 wt% Pt loading) with higher costs. Characteristic results indicate that WO3 impurities were in-situ produced on the WS2 surface and the Pd NPs are primarily located inside the WS2 nanocages. Contrasting experiments suggest that the WO3 impurities play a crucial role in generating Hads intermediate and the Pd NPs are active sites of H2 production, and a reaction mechanism is proposed. The Pd/WS2 catalyst also shows good long-term stability owing to the location of Pd NPs inside the WS2 cages. The high HER activity, low costs and good stability make the Pd catalyst a potential alternative to Pt catalyst for HER.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Micro and Nano Engineerin
Enhanced T-Cell Immunity to Osteosarcoma Through Antibody Blockade of PD-1/PD-L1 Interactions
No full textabstract: Osteosarcoma is the most common bone cancer in children and adolescents. Although 70% of patients with localized disease are cured with chemotherapy and surgical resection, patients with metastatic osteosarcoma are typically refractory to treatment. Numerous lines of evidence suggest that cytotoxic T lymphocytes (CTLs) limit the development of metastatic osteosarcoma. We have investigated the role of PD-1, an inhibitory TNFR family protein expressed on CTLs, in limiting the efficacy of immune-mediated control of metastatic osteosarcoma. We show that human metastatic, but not primary, osteosarcoma tumors express a ligand for PD-1 (PD-L1) and that tumor-infiltrating CTLs express PD-1, suggesting this pathway may limit CTLs control of metastatic osteosarcoma in patients. PD-L1 is also expressed on the K7M2 osteosarcoma tumor cell line that establishes metastases in mice, and PD-1 is expressed on tumor-infiltrating CTLs during disease progression. Blockade of PD-1/PD-L1 interactions dramatically improves the function of osteosarcoma-reactive CTLs in vitro and in vivo, and results in decreased tumor burden and increased survival in the K7M2 mouse model of metastatic osteosarcoma. Our results suggest that blockade of PD-1/PD-L1 interactions in patients with metastatic osteosarcoma should be pursued as a therapeutic strategy.This is a non-final version of an article published in final form as Lussier, Danielle M., O'Neill, Lauren, Nieves, Lizbeth M., McAfee, Megan S., Holechek, Susan A., Collins, Andrea W., Dickman, Paul, Jacobsen, Jeffrey, Hingorani, Pooja, & Blattman, Joseph N. (2015). Enhanced T-Cell Immunity to Osteosarcoma Through Antibody Blockade of PD-1/PD-L1 Interactions. JOURNAL OF IMMUNOTHERAPY, 38(3), 96-106. http://dx.doi.org/10.1097/CJI.000000000000006
Modeling of Surface Segregation for Binary Alloys in Vacuum and Gas Environments: Applied to Pd-alloys
No full textComputational modeling offers the possibility to design alloys in a cheaper and faster way. A model for surface segregation for binary alloys in vacuum and by adsorption and absorption of gases was developed and applied. The proposed model was used in conjunction with the Miedema semi-empirical model for the calculation of enthalpies of solution and formation of binary alloys and with the cluster variation method (CVM) for the calculation of the ? and ? phase boundaries in the ternary Pd-M-H systems. The models for segregation were applied in a temperature range from 298K to 600K, considering the surface plane (111) of the FCC crystal structure. The model for segregation in vacuum was applied to Pd-Au, Pd-Ag, Pd-Cu, Pd-Ni and Pd-Pt. For this case Pd is segregated for the Pd-Pt alloys only. By increasing the temperature from 298K to 600K, the surface concentrations of Pd decreased for all of the alloys. By varying the plane from (111) to (100) few changes were observed. The calculated results compared to experiments were found to be in good agreement for Pd-Au and Pd-Ag. For the model of surface segregation by adsorption and chemisorption, H2, CO and O2 gases on Pd-Ag, Pd-Cu, Pd-Ni and Pd-Pt were considered. In the presence of adsorbed or chemisorbed hydrogen, segregation of Pd was found for Pd-Ag, Pd-Cu and Pd-Pt alloys. For adsorbed O2 and CO on Pd-Ag and Pd-Cu alloys gases, segregation of Pd was enhanced. The model for segregation by absorption of hydrogen was applied for Pd-Ag, Pd-Cu, Pd-Ni and Pd-Pt alloys, using a hydrogen (bulk) concentration of 0.50 H/M. No Pd segregation was found for Pd-Ag alloys. For Pd-Pt alloys, Pd segregation was observed. For Pd-Cu alloys with large concentrations of Pd, a surface enrichment of Pd was calculated, while for alloys with low concentration of Pd a slight Cu surface enrichment was observed. Enhanced segregation of Ni was found for Pd-Ni alloys. The H/M fractions at the boundaries of the ? and ? phase obtained with the CVM for the Pd85Ag15H system were used as input values to calculate the surface concentration of Ag. As the hydrogen concentration was increased, the surface segregation of Pd also increased. For the surface segregation by adsorption and absorption combined, segregation of Pd was observed for Pd-Ag, Pd-Cu and Pd-Pt alloys. Surface enrichment of Ni was found for Pd-Ni alloys. The proposed model enables to predict surface segregation under various conditions and the results show that it is affected by many parameters.Master Materials Science and EngineeringDepartment of Materials Science and EngineeringMechanical, Maritime and Materials Engineerin
- …
