13,759 research outputs found

    What is the importance of sperm subpopulations?

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    .The study of sperm subpopulations spans three decades. The origin, meaning, and practical significance, however, are less clear. Current technology for assessing sperm morphology (CASA-Morph) and motility (CASA-Mot) has enabled the accurate evaluation of these features, and there are many options for data classification. Subpopulations could occur as a result of the stage of development of each spermatozoon in the subpopulation. Spermatogenesis might contribute to the production of these subpopulations. Insights from evolutionary biology and recent molecular research are indicative of the diversity among male gametes that could occur from unequal sharing of transcripts and other elements through cytoplasmic bridges between spermatids. Sperm cohorts exiting the gonads would contain different RNA and protein contents, affecting the spermatozoon physiology and associations with the surrounding environmental milieu. Subsequently, these differences could affect how spermatozoa interact with the environmental milieu (maturation, mixing with seminal plasma, and interacting with the environmental milieu, or female genital tract and female gamete). The emergence of sperm subpopulations as an outcome of evolution, related to the reproductive strategies of the species, genital tract structures, and copulatory and fertilization processes. This kind of approach in determining the importance of sperm subpopulations in fertilization capacity should have a practical impact for conducting reproductive technologies, inspiring and enabling new ways for the more efficient use of spermatozoa in the medical, animal breeding, and conservation fields. This manuscript is a contribution to the Special Issue in memory of Dr. Duane GarnerS

    Exploring the effects of spinal cord stimulation for freezing of gait in parkinsonian patients

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    Dopaminergic replacement therapies (e.g. levodopa) provide limited to no response for axial motor symptoms including gait dysfunction and freezing of gait (FOG) in Parkinson’s disease (PD) and Richardson’s syndrome progressive supranuclear palsy (PSP-RS) patients. Dopaminergic-resistant FOG may be a sensorimotor processing issue that does not involve basal ganglia (nigrostriatal) impairment. Recent studies suggest that spinal cord stimulation (SCS) has positive yet variable effects for dopaminergic-resistant gait and FOG in parkinsonian patients. Further studies investigating the mechanism of SCS, optimal stimulation parameters, and longevity of effects for alleviating FOG are warranted. The hypothesis of the research described in this thesis is that mid-thoracic, dorsal SCS effectively reduces FOG by modulating the sensory processing system in gait and may have a dopaminergic effect in individuals with FOG. The primary objective was to understand the relationship between FOG reduction, improvements in upper limb visual-motor performance, modulation of cortical activity and striatal dopaminergic innervation in 7 PD participants. FOG reduction was associated with changes in upper limb reaction time, speed and accuracy measured using robotic target reaching choice tasks. Modulation of resting-state, sensorimotor cortical activity, recorded using electroencephalography, was significantly associated with FOG reduction while participants were OFF-levodopa. Thus, SCS may alleviate FOG by modulating cortical activity associated with motor planning and sensory perception. Changes to striatal dopaminergic innervation, measured using a dopamine transporter marker, were associated with visual-motor performance improvements. Axial and appendicular motor features may be mediated by non-dopaminergic and dopaminergic pathways, respectively. The secondary objective was to demonstrate the short- and long-term effects of SCS for alleviating dopaminergic-resistant FOG and gait dysfunction in 5 PD and 3 PSP-RS participants without back/leg pain. SCS programming was individualized based on which setting best improved gait and/or FOG responses per participant using objective gait analysis. Significant improvements in stride velocity, step length and reduced FOG frequency were observed in all PD participants with up to 3-years of SCS. Similar gait and FOG improvements were observed in all PSP-RS participants up to 6-months. SCS is a promising therapeutic option for parkinsonian patients with FOG by possibly influencing cortical and subcortical structures involved in locomotion physiology

    A Microfluidic Device as a Drug Carrier

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    The development of nanomedicine or medical nanotechnology, has brought important new ways to the development of medicines and biotechnology products. As a result of groundbreaking discoveries in the use of nanoscale materials significant commercialization initiatives have been launched and are at the forefront of the rapidly expanding field of nanotechnology by using smart particles. Microfluidic technologies use nano-and micro-scale manufacturing technologies to develop controlled and reproducible liquid microenvironments. Lead compounds with controlled physicochemical properties can be obtained using microfluidics, characterized by high productivity, and evaluated by biomimetic methods. Microfluidics, for example, can not only produce nanoparticles in a well-controlled, reproducible, and high-throughput manner, but it can also continuously create three-dimensional environments to mimic physiological and/or pathological processes. Materials with smart properties can be manipulated to respond in a controllable and reversible way, modifying some of their properties as a result of external stimuli such as mechanical stress or a certain temperature. All in all, microfluidic technology offers a potential platform for the rapid synthesis of various novel drug delivery systems. Therefore, these smart particles are equally necessary as the drug in drug delivery

    BECOMEBECOME - A TRANSDISCIPLINARY METHODOLOGY BASED ON INFORMATION ABOUT THE OBSERVER

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    ABSTRACT Andrea T. R. Traldi BECOMEBECOME A Transdisciplinary Methodology Based on Information about the Observer The present research dissertation has been developed with the intention to provide practical strategies and discover new intellectual operations which can be used to generate Transdisciplinary insight. For this reason, this thesis creates access to new knowledge at different scales. Firstly, as it pertains to the scale of new knowledge generated by those who attend Becomebecome events. The open-source nature of the Becomebecome methodology makes it possible for participants in Becomebecome workshops, training programmes and residencies to generate new insight about the specific project they are working on, which then reinforce and expand the foundational principles of the theoretical background. Secondly, as it pertains to the scale of the Becomebecome framework, which remains independent of location and moment in time. The method proposed to access Transdisciplinary knowledge constitutes new knowledge in itself because the sequence of activities, described as physical and mental procedures and listed as essential criteria, have never been found organised 6 in such a specific order before. It is indeed the order in time, i.e. the sequence of the ideas and activities proposed, which allows one to transform Disciplinary knowledge via a new Transdisciplinary frame of reference. Lastly, new knowledge about Transdisciplinarity as a field of study is created as a consequence of the heretofore listed two processes. The first part of the thesis is designated ‘Becomebecome Theory’ and focuses on the theoretical background and the intellectual operations necessary to support the creation of new Transdisciplinary knowledge. The second part of the thesis is designated ‘Becomebecome Practice’ and provides practical examples of the application of such operations. Crucially, the theoretical model described as the foundation for the Becomebecome methodology (Becomebecome Theory) is process-based and constantly checked against the insight generated through Becomebecome Practice. To this effect, ‘information about the observer’ is proposed as a key notion which binds together Transdisciplinary resources from several studies in the hard sciences and humanities. It is a concept that enables understanding about why and how information that is generated through Becomebecome Practice is considered of paramount importance for establishing the reference parameters necessary to access Transdisciplinary insight which is meaningful to a specific project, a specific person, or a specific moment in time

    In search of 'The people of La Manche': A comparative study of funerary practices in the Transmanche region during the late Neolithic and Early Bronze Age (250BC-1500BC)

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    This research project sets out to discover whether archaeological evidence dating between 2500 BC - 1500 BC from supposed funerary contexts in Kent, flanders and north-eastern Transmanche France is sufficient to make valid comparisons between social and cultural structures on either side of the short-sea Channel region. Evidence from the beginning of the period primarily comes in the form of the widespread Beaker phenomenon. Chapter 5 shows that this class of data is abundant in Kent but quite sparse in the Continental zones - most probably because it has not survived well. This problem also affects the human depositional evidence catalogued in Chapter 6, particularly in Fanders but also in north-eastern Transmanche France. This constricts comparative analysis, however, the abundant data from Kent means that general trends are still discernible. The quality and volume of data relating to the distribution, location, morphology and use of circular monuments in all three zones is far better - as demonstrated in Chapter 7 -mostly due to extensive aerial surveying over several decades. When the datasets are taken as a whole, it becomes possible to successfully apply various forms of comparative analyses. Most remarkably, this has revealed that some monuments apparently have encoded within them a sophisticated and potentially symbolically charged geometric shape. This, along with other less contentious evidence, demonstrates a level of conformity that strongly suggests a stratum of cultural homogeneity existed throughout the Transmanche region during the period 2500 BC - 1500 BC. The fact that such changes as are apparent seem to have developed simultaneously in each of the zones adds additional weight to the theory that contact throughout the Transmanche region was endemic. Even so, it may not have been continuous; there may actually have been times of relative isolation - the data is simply too course to eliminate such a possibility

    A comparison of LED panels for use in Virtual Production: Findings and recommendations

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    We evaluate four LED panels from three vendors for use in Virtual Production using experimental conditions. Tests were designed to assess Moire and scan-line artefacts, light reflectivity and grazing angle. We discuss LED manufacturing processes and the implications of these on visual artefacts, power consumption and colour fidelity, and conclude with results and recommendations for LED vendors, practitioners and procurement teams in Virtual Production

    Elasticidad de membrana plasmática de levaduras mediante estudios de retracción de Nanotubo

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    27 h. figuras; tabls.; ilus. Abstract en español e inglés. Contiene Referencia Bibliográfica.Las membranas biológicas constituyen la estructura celular más común en la materia viva, pudiendo ser consideradas como un ejemplo de alta tecnología natural de microencapsulación. Las membranas se comportan como barreras mecánicas semipermeables, regulando el tránsito y la señalización de los compartimentos celulares con el exterior. A su vez, son extremadamente dinámicas tanto de manera global como a pequeña escala espacial. Las interacciones de los lípidos entre sí y con otras moléculas presentes en las membranas (principalmente proteínas) son determinantes para muchas funciones, como la señalización, los procesos de fusión y fisión o la adhesión celular. La forma física de una estructura membranosa está determinada básicamente por su grado de curvatura intrínseca. De igual manera, esta propiedad evidencia la tendencia que tienen los lípidos a formar fases no lamelares. La disposición de los lípidos en la bicapa está directamente relacionada con su forma intrínseca o geométrica, que también condiciona el modo en que estas moléculas se empaquetan e interaccionan entre sí. En este trabajo de tesina se puso foco en la capacidad que tiene la membrana plasmática de cambiar localmente su curvatura. Para realizar estos estudios, deformamos la membrana plasmática localmente, generando tubos de membrana de diámetro nanométrico mediante el empleo de pinzas ópticas. El trabajo se realizó sobre membranas de levaduras Saccharomyces cerevisiae de la cepa BY4741. Estudios previos han demostrado que cuando una bicapa lipídica es sometida a un cambio local de curvatura presenta un comportamiento elástico, mientras que las membranas celulares de mamíferos son marcadamente viscoelásticas. Por otro lado, no se han reportado estudios de deformaciones locales de curvatura en membranas de organismos de otros reinos, que no contienen colesterol sino otros esteroles u hopanoides. Mediante estos experimentos se pretendió poner a punto la metodología a fin de estudiar cómo es la energética de deformación fuera del plano de membrana plasmática de levaduras S. cerevisiae cepa BY4741, la cual contiene un alto porcentaje del esterol ergosterol, en comparación con el comportamiento ya conocido de membrana plasmática de células de mamífero. En este trabajo se encontró que la relajación de nanotubos de membranas plasmáticas de levaduras S. cerevisiae cepa BY4741 ocurre con tiempos característicos en el intervalo 0,02-0,5 s, y si promediamos todos los valores encontrados, obtenemos un valor promedio de 0,2 s ± 0,1 s. Este valor es similar a lo informado para eritrocitos, así como para células tumorales cerebrales en humanos y células de ovario de hámster chino. Hasta donde sabemos, no hay estudios de este tipo reportados en microorganismos eucariotas.Fil: Bischof, Andrea Alejandra. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales; Argentina.Fil: Bischof, Andrea Alejandra. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Departamento de Química Biológica; Argentina.Fil: Bischof, Andrea Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro de Investigaciones en Química Biológica de Córdoba; Argentina
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