66,451 research outputs found

    Optimizations of Autoencoders for Analysis and Classification of Microscopic In Situ Hybridization Images

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    Currently, analysis of microscopic In Situ Hybridization images is done manually by experts. Precise evaluation and classification of such microscopic images can ease experts' work and reveal further insights about the data. In this work, we propose a deep-learning framework to detect and classify areas of microscopic images with similar levels of gene expression. The data we analyze requires an unsupervised learning model for which we employ a type of Artificial Neural Network - Deep Learning Autoencoders. The model's performance is optimized by balancing the latent layers' length and complexity and fine-tuning hyperparameters. The results are validated by adapting the mean-squared error (MSE) metric, and comparison to expert's evaluation.Comment: 9 pages; 9 figure

    Dyadic Greens function for a topological insulator stratified sphere

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    We construct the dyadic Greens functions (DGFs) for a topological insulator (TI) stratified sphere within the framework of axion electrodynamics. For these DGFs, the additional expansion coefficients are included to account for the axion coupling effect. With the application of these DGFs, we derive the formulation of light scattering from a dipole near a TI stratified sphere. In our numerical studies, we give three types of configurations (a metal-coated TI sphere, a metal-TI-metal-coated TI sphere and an alternating metal-TI stratified sphere) to investigate how the topological magneto-electric (TME) response of the TI sphere (shells) influences on the multipolar plasmonic resonance of the metal shells. For these types, the results show that the TME effect causes some modifications of the decay rate spectrum for an emitting dipole near a TI stratified sphere. For the multipolar resonances of the metal shells, it is observed that the TME-induced red-shifts for the bonding and lower order antibonding modes are found but those for the higher order antibonding modes are insignificant. In addition, for a metal-coated TI sphere, we take into account the effects of losses in the TI core of which the dielectric function is chosen to be the form of the bulk or five quintuple layers (5QL) slab and then the some modifications of the TME-induced decay rate spectrum are obviously suppressed. These phenomenological characteristics provide useful guidance to probing the TME effect via molecular fluorescence experiments

    Why and how do farmers’ organizations get involved in the promotion of agroecological techniques? Insights from Burkina Faso

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    Agroecological techniques (AET) have been recognized by many farmers, NGOs, and farmers’ organizations (FOs) as a promising solution for slowing down the persistent soil fertility degradation in West African drylands. In the context of Burkina, the promotion of AET is the result of the interactions between NGOs and farmers’ knowledge through the intermediation of FOs. Although numerous studies have highlighted the instrumental role of FOs in the dissemination of AET in Burkina, there are limited studies focusing on the historical dynamic of FOs’ involvement in the promotion of agroecology. To address this gap, this study aims to answer the following questions: why and how do FOs get involved in the promotion of agroecological techniques, and how do they define the term agroecology or agroecological techniques? A multiple case study approach was used to provide the answer to these questions. The results from the case studies reveal that the FOs’ promotion of AET is largely connected to their aim of fulfilling one of the following three goals: enhancing the productivity of commercial crops; improving the resilience of subsistence farmers; enhancing both the productivity of commercial crops and the resilience of subsistence farmers. The quest to achieve these goals explained their constant interaction with external partners to get the necessary assistance for the provision of agroecological support services to their farmers. Furthermore, the results of the study also reveal that the Farmers’ Organizations’ definitions of agroecology or agroecological terms are mostly associated with the interpretation of agroecology as a collective practice encompassing both economic and ecological aspects of Burkinabù agriculture. A broader insight is that while FOs can fulfill important roles in agroecology transitions this comes with diverse interpretations of agroecology, in which FOs facilitate the hybridization of existing farmers ’practices with those proposed by external actors. The study hence shows the complexity related to the local actors’ definitions of agroecological terms and the broader implication is that in the debate on agroecology transitions, these blended or hybrid forms of agroecology should receive more attention. Areas for future research include drivers of FOs choice making processes in how they approach agroecology, and subsequently the influence of FOs on the drivers of farmers’ decisions toward AET

    Changes in PRC1 activity during interphase modulate lineage transition in pluripotent cells

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    The potential of pluripotent cells to respond to developmental cues and trigger cell differentiation is enhanced during the G1 phase of the cell cycle, but the molecular mechanisms involved are poorly understood. Variations in polycomb activity during interphase progression have been hypothesized to regulate the cell-cycle-phase-dependent transcriptional activation of differentiation genes during lineage transition in pluripotent cells. Here, we show that recruitment of Polycomb Repressive Complex 1 (PRC1) and associated molecular functions, ubiquitination of H2AK119 and three-dimensional chromatin interactions, are enhanced during S and G2 phases compared to the G1 phase. In agreement with the accumulation of PRC1 at target promoters upon G1 phase exit, cells in S and G2 phases show firmer transcriptional repression of developmental regulator genes that is drastically perturbed upon genetic ablation of the PRC1 catalytic subunit RING1B. Importantly, depletion of RING1B during retinoic acid stimulation interferes with the preference of mouse embryonic stem cells (mESCs) to induce the transcriptional activation of differentiation genes in G1 phase. We propose that incremental enrolment of polycomb repressive activity during interphase progression reduces the tendency of cells to respond to developmental cues during S and G2 phases, facilitating activation of cell differentiation in the G1 phase of the pluripotent cell cycle

    Excitation and voltage-gated modulation of single-mode dynamics in a planar nano-gap spin Hall nano-oscillator

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    We experimentally study the dynamical modes excited by current-induced spin-orbit torque and its electrostatic gating effect in a 3-terminal planar nano-gap spin Hall nano-oscillator (SHNO) with a moderate interfacial perpendicular magnetic anisotropy (IPMA). Both quasilinear propagating spin-wave and localized "bullet" modes are achieved and controlled by varying the applied in-plane magnetic field and driving current. The minimum linewidth shows a linear dependence on the actual temperature of the active area, confirming single-mode dynamics based on the nonlinear theory of spin-torque nano-oscillation with a single mode. The observed electrostatic gating tuning oscillation frequency arises from voltage-controlled magnetic anisotropy and threshold current of SHNO via modification of the nonlinear damping and/or the interfacial spin-orbit coupling of the magnetic multilayer. In contrast to previously observed two-mode coexistence degrading the spectral purity in Py/Pt-based SHNOs with a negligible IPMA, a single coherent spin-wave mode with a low driven current can be achieved by selecting the ferromagnet layer with a suitable IPMA because the nonlinear mode coupling can be diminished by bringing in the PMA field to compensate the easy-plane shape anisotropy. Moreover, the simulations demonstrate that the experimentally observed current and gate-voltage modulation of auto-oscillation modes are also closely associated with the nonlinear damping and mode coupling, which are determined by the ellipticity of magnetization precession. The demonstrated nonlinear mode coupling mechanism and electrical control approach of spin-wave modes could provide the clue to facilitate the implementation of the mutual synchronization map for neuromorphic computing applications in SHNO array networks.Comment: 11 pages, 10 figure

    Victims' Access to Justice in Trinidad and Tobago: An exploratory study of experiences and challenges of accessing criminal justice in a post-colonial society

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    This thesis investigates victims' access to justice in Trinidad and Tobago, using their own narratives. It seeks to capture how their experiences affected their identities as victims and citizens, alongside their perceptions of legitimacy regarding the criminal justice system. While there have been some reforms in the administration of criminal justice in Trinidad and Tobago, such reforms have not focused on victims' accessibility to the justice system. Using grounded theory methodology, qualitative data was collected through 31 in-depth interviews with victims and victim advocates. The analysis found that victims experienced interpersonal, structural, and systemic barriers at varying levels throughout the criminal justice system, which manifested as institutionalized secondary victimization, silencing and inequality. This thesis argues that such experiences not only served to appropriate conflict but demonstrates that access is often given in a very narrow sense. Furthermore, it shows a failure to encompass access to justice as appropriated conflicts are left to stagnate in the system as there is often very little resolution. Adopting a postcolonial lens to analyse victims' experiences, the analysis identified othering practices that served to institutionalize the vulnerability and powerlessness associated with victim identities. Here, it is argued that these othering practices also affected the rights consciousness of victims, delegitimating their identities as citizens. Moreover, as a result of their experiences, victims had mixed perceptions of the justice system. It is argued that while the system is a legitimate authority victims' endorsement of the system is questionable, therefore victims' experiences suggest that there is a reinforcement of the system's legal hegemony. The findings suggest that within the legal system of Trinidad and Tobago, legacies of colonialism shape the postcolonial present as the psychology and inequalities of the past are present in the interactions and processes of justice. These findings are relevant for policymakers in Trinidad and Tobago and other regions. From this study it is recognized that, to improve access to justice for victims, there needs to be a move towards victim empowerment that promotes resilience and enhances social capital. Going forward it is noted that there is a need for further research

    Implementing Health Impact Assessment as a Required Component of Government Policymaking: A Multi-Level Exploration of the Determinants of Healthy Public Policy

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    It is widely understood that the public policies of ‘non-health’ government sectors have greater impacts on population health than those of the traditional healthcare realm. Health Impact Assessment (HIA) is a decision support tool that identifies and promotes the health benefits of policies while also mitigating their unintended negative consequences. Despite numerous calls to do so, the Ontario government has yet to implement HIA as a required component of policy development. This dissertation therefore sought to identify the contexts and factors that may both enable and impede HIA use at the sub-national (i.e., provincial, territorial, or state) government level. The three integrated articles of this dissertation provide insights into specific aspects of the policy process as they relate to HIA. Chapter one details a case study of purposive information-seeking among public servants within Ontario’s Ministry of Education (MOE). Situated within Ontario’s Ministry of Health (MOH), chapter two presents a case study of policy collaboration between health and ‘non-health’ ministries. Finally, chapter three details a framework analysis of the political factors supporting health impact tool use in two sub-national jurisdictions – namely, QuĂ©bec and South Australia. MOE respondents (N=9) identified four components of policymaking ‘due diligence’, including evidence retrieval, consultation and collaboration, referencing, and risk analysis. As prospective HIA users, they also confirmed that information is not routinely sought to mitigate the potential negative health impacts of education-based policies. MOH respondents (N=8) identified the bureaucratic hierarchy as the brokering mechanism for inter-ministerial policy development. As prospective HIA stewards, they also confirmed that the ministry does not proactively flag the potential negative health impacts of non-health sector policies. Finally, ‘lessons learned’ from case articles specific to QuĂ©bec (n=12) and South Australia (n=17) identified the political factors supporting tool use at different stages of the policy cycle, including agenda setting (‘policy elites’ and ‘political culture’), implementation (‘jurisdiction’), and sustained implementation (‘institutional power’). This work provides important insights into ‘real life’ policymaking. By highlighting existing facilitators of and barriers to HIA use, the findings offer a useful starting point from which proponents may tailor context-specific strategies to sustainably implement HIA at the sub-national government level

    Formation of ultrapotassic magma via crustal contamination and hybridization of mafic magma: an example from the Stomanovo monzonite, Central Rhodope Massif, Bulgaria

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    Generally all orogenic ultrapotassic rocks are formed after melting of metasomatized sub-continental lithospheric mantle via subducted crustal mica-bearing lithologies. Here we present another possible model, based on the study of the small Stomanovo ultrapotassic monzonite porphyry intrusion in the Central Rhodope Massif, Bulgaria. The monzonite dated at 30.50 ± 0.46 Ma is intruded into the voluminous Oligocene (31.63 ± 0.40 Ma) Bratsigovo–Dospat ignimbrite. The monzonite hosts both normally and reversely zoned clinopyroxene phenocrysts. The normally zoned clinopyroxene is characterized by gradually diminishing core-to-rim Mg no. (89–74), whereas the reversely zoned clinopyroxene has green Fe-rich cores (Mg no. 71–55) mantled by normally zoned clinopyroxene (Mg no. 87–74). Neither the core of the normally zoned clinopyroxene nor the Fe-rich green cores are in equilibrium with the host monzonite. This ultrapotassic monzonite shows more radiogenic Sr isotopes ((87Sr/86Sr)i = 0.71066) and Ï”Nd(t) = −7.8 to −8.0 that are distinct from the host ignimbrites with (87Sr/86Sr)i = 0.70917–0.70927 and Ï”Nd(t) = −4.6 to −6.5. The Sr–Nd isotopic data and the presence of copious zircon xenocrysts from the underlying metamorphic basement suggest extensive crustal assimilation. Our observations indicate that the Stomanovo ultrapotassic monzonite formed after extensive lower or middle crustal fractional crystallization from an evolved magma producing cumulates. The process was followed by hybridization with primitive mantle-derived magma and subsequent continuous crustal contamination. We suggest that instead of inheriting their high K2O and large-ion lithophile element enrichments from slab-derived/metasomatic fluids, the Stomanovo ultrapotassic monzonite may owe some of its unusually high alkalinity to the assimilation of potassium-rich phases from the Rhodope Massif basement rocks
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