JURNAL AGROTEKNOLOGI
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Backpropagation through nonlinear units for the all-optical training of neural networks
No full textWe propose a practical scheme for end-to-end optical backpropagation in neural networks. Using saturable absorption for the nonlinear units, we find that the backward-propagating gradients required to train the network can be approximated in a surprisingly simple pump-probe scheme that requires only simple passive optical elements. Simulations show that, with readily obtainable optical depths, our approach can achieve equivalent performance to state-of-the-art computational networks on image classification benchmarks, even in deep networks with multiple sequential gradient approximation. With backpropagation through nonlinear units being an outstanding challenge to the field, this work provides a feasible path toward truly all-optical neural networks
Cigarette smoke induces miR-132 in Th17 cells that enhance osteoclastogenesis in inflammatory arthritis
No full textRheumatoid arthritis (RA) is a chronic inflammatory disease characterized by joint destruction and severe morbidity. Cigarette smoking (CS) can exacerbate the incidence and severity of RA. Although Th17 cells and the Aryl hydrocarbon receptor (AhR) have been implicated, the mechanism by which CS induces RA development remains unclear. Here, using transcriptomic analysis, we show that microRNA-132 is specifically induced in Th17 cells in the presence of either AhR agonist or CS-enriched medium. miRNA-132 thus induced is packaged into extracellular vesicles produced by Th17 and acts as a proinflammatory mediator increasing osteoclastogenesis through the down-regulation of COX2. In vivo, articular knockdown of miR-132 in murine arthritis models reduces the number of osteoclasts in the joints. Clinically, RA patients express higher levels of miR-132 than do healthy individuals. This increase is further elevated by cigarette smoking. Together, these results reveal a hitherto unrecognized mechanism by which CS could exacerbate RA and further advance understanding of the impact of environmental factors on the pathogenesis of chronic inflammatory diseases
Prominent health problems, socioeconomic deprivation, and higher brain age in lonely and isolated individuals: A population-based study
No full textLoneliness is linked to increased risk for Alzheimer's disease, but little is known about factors potentially contributing to adverse brain health in lonely individuals. In this study, we used data from 24,867 UK Biobank participants to investigate risk factors related to loneliness and estimated brain age based on neuroimaging data. The results showed that on average, individuals who self-reported loneliness on a single yes/no item scored higher on neuroticism, depression, social isolation, and socioeconomic deprivation, performed less physical activity, and had higher BMI compared to individuals who did not report loneliness. In line with studies pointing to a genetic overlap of loneliness with neuroticism and depression, permutation feature importance ranked these factors as the most important for classifying lonely vs. not lonely individuals (ROC AUC = 0.83). While strongly linked to loneliness, neuroticism and depression were not associated with brain age estimates. Conversely, objective social isolation showed a main effect on brain age, and individuals reporting both loneliness and social isolation showed higher brain age relative to controls – as part of a prominent risk profile with elevated scores on socioeconomic deprivation and unhealthy lifestyle behaviours, in addition to neuroticism and depression. While longitudinal studies are required to determine causality, this finding may indicate that the combination of social isolation and a genetic predisposition for loneliness involves a risk for adverse brain health. Importantly, the results underline the complexity in associations between loneliness and adverse health outcomes, where observed risks likely depend on a combination of interlinked variables including genetic as well as social, behavioural, physical, and socioeconomic factors
Competition between triplet pair formation and excimer-like recombination controls singlet fission yield
No full textThe ultimate goal for singlet fission is that each photo-excited singlet exciton, S1, will result in two triplet excitons with unity yield. However, the singlet fission is now recognized to be complicated, involving bright/dark excited states of different spin multiplicity. Identifying the role of such states is vital to optimize singlet fission yield but difficult due to their elusive spectral signature. Here, we develop an experimental protocol based on a refined magneto-optical probe to access the fast time evolution of various excited states. In diphenylhexatriene crystal, the S1 is found to undergo two competing processes—to form one of the two dark triplet pair intermediates having different exchange energies or to form a bright state, Sx, exhibiting excimer-like delayed photoluminescence. Our result provides a clear picture of a competition event in singlet fission, which is beneficial for the development and tailoring of singlet fission materials with high yield
Operationalisation of the Randomized Embedded Multifactorial Adaptive Platform for COVID-19 trials in a low and lower-middle income critical care learning health system
No full textThe Randomized Embedded Multifactorial Adaptive Platform (REMAP-CAP) adapted for COVID-19) trial is a global adaptive platform trial of hospitalised patients with COVID-19. We describe implementation in three countries under the umbrella of the Wellcome supported Low and Middle Income Country (LMIC) critical care network: Collaboration for Research, Implementation and Training in Asia (CCA). The collaboration sought to overcome known barriers to multi centre-clinical trials in resource-limited settings. Methods described focused on six aspects of implementation: i, Strengthening an existing community of practice; ii, Remote study site recruitment, training and support; iii, Harmonising the REMAP CAP- COVID trial with existing care processes; iv, Embedding REMAP CAP- COVID case report form into the existing CCA registry platform, v, Context specific adaptation and data management; vi, Alignment with existing pandemic and critical care research in the CCA. Methods described here may enable other LMIC sites to participate as equal partners in international critical care trials of urgent public health importance, both during this pandemic and beyond
Reducing intrusive memories after trauma via a brief cognitive task intervention in the hospital emergency department: an exploratory pilot randomised controlled trial
No full textIntrusive memories are common after trauma, and can cause significant distress. Interventions to prevent/reduce the occurrence of this core clinical feature of posttraumatic stress disorder are needed; they should be easy to deliver, readily disseminated and scalable. A novel one-session intervention by Iyadurai et al. 2018, Molecular Psychiatry, resulted in intrusion reduction over the subsequent week. Its feasibility in a different setting and longer-term effects (>1 month) need investigation. We conducted an exploratory open-label pilot randomised controlled trial (RCT) to investigate the feasibility and effects of a brief behavioural intervention to reduce intrusive memories in trauma-exposed patients in a Swedish hospital emergency department (ED). Participants (final N = 41) were randomly allocated to either intervention (including memory reminder cue then visuospatial cognitive task “Tetris” with mental rotation instructions) or active control (podcast) condition within 72 h of presenting to the ED (both conditions using their smartphone). Findings were examined descriptively. We estimated between-group effect sizes for the number of intrusive memories post-intervention at week 1 (primary outcome) and week 5 (secondary outcome). Compared to the control condition, participants in the intervention condition reported fewer intrusive memories of trauma, both at week 1 and week 5. Findings extend the previous evaluation in the UK. The intervention was readily implemented in a different international context, with a mixed trauma sample, with treatment gains maintained at 1 month and associated with some functional improvements. Findings inform future trials to evaluate the capacity of the cognitive task intervention to reduce the occurrence of intrusive memories after traumatic events
Microscopic processes during ultra-fast laser generation of Frenkel defects in diamond
No full textEngineering single atomic defects into wide bandgap materials has become an attractive field
in recent years due to emerging applications such as solid-state quantum bits and sensors. The
simplest atomic-scale defect is the lattice vacancy which is often a constituent part of more complex
defects such as the nitrogen-vacancy (NV) centre in diamond, therefore an understanding of the
formation mechanisms and precision engineering of vacancies is desirable. We present a theoretical
and experimental study into the ultra-fast laser generation of vacancy-interstitial pairs (Frenkel
defects) in diamond. In a range of other materials, Frenkel defect formation has previously been
linked to the recombination of laser generated excitonic states, however the mechanism in diamond
is currently unknown and to date no quantitative agreement has been found between experiment
and theory. Here, we find that a model for Frenkel defect generation via the recombination of
a bound biexciton as the electron plasma cools provides good agreement with experimental data.
The process is described by a set of coupled rate equations of the pulsed laser interaction with the
material and of the non-equilibrium dynamics of charge carriers during and in the wake of the pulse
The recent contribution of scientific techniques to the study of Nokalakevi in Samegrelo, Georgia
No full textThe site of Nokalakevi, in western Georgia, has seen significant excavation since 1973, including, since 2001, a collaborative Anglo-Georgian project. However, the interpretation of the site has largely rested on architectural analysis of standing remains and the relative dating of deposits based on the study of ceramics. Since 2013, the Anglo-Georgian Expedition to Nokalakevi has collected a diverse dataset derived from multiple scientific techniques including optically stimulated luminescence (OSL) dating of ceramics, radiocarbon dating, δ13C and δ15N analysis and 87Sr/86Sr analysis. The full results of these analyses are reported here for the first time along with implications for the interpretation of the archaeology, which include greater detail in the site chronology but also indicators of diet and migration.
Batı Gürcistan’daki Nokalakevi yerleşim yerinde, 2001’de başlamiş olan bir İngiliz-Gürcü ortak projesi de dahil olmak üzere, 1973’ten beri önemli kazılar yapılmıştır. Bununla birlikte, yerleşimin yorumlanması büyük ölçüde ayakta kalmış olan kalıntıların mimari analizine ve seramik çalışmalarına dayanarak yapılmış olan, tabakaların göreceli tarihlendirmesine dayanmaktadir. Nokalakevi’de yapılan İngiliz-Gürcü ortak kazıları 2013’ten bu yana seramikleri, optik uyarmalı lüminesans (OSL) tarihlemesi, radyokarbon tarihlemesi, δ13C ve δ15N analizi ve 87Sr/86Sr analizleri dahil olmak üzere birçok bilimsel teknikten yararlanarak incelemiş ve çeşitli verilere ulaşmıştir. Bu analizlerin tam sonuçları, arkeolojinin yorumlanmasına yönelik çıkarımlarla birlikte ilk kez burada rapor edilmektedir. Bu rapor, yerleşimin kronolojisiyle ilgili daha fazla ayrıntıya ve aynı zamanda beslenme ve göç göstergelerini de içeren bazı çıkarımlara sahiptir
Changes in presynaptic gene expression during homeostatic compensation at a central synapse
No full textHomeostatic matching of pre- and postsynaptic function has been observed in many species and neural structures, but whether transcriptional changes contribute to this form of trans-synaptic coordination remains unknown. To identify genes whose expression is altered in presynaptic neurons as a result of perturbing postsynaptic excitability, we applied a transcriptomics-friendly, temperature-inducible Kir2.1-based activity clamp at the first synaptic relay of the Drosophila olfactory system, a central synapse known to exhibit trans-synaptic homeostatic matching. Twelve hours after adult-onset suppression of activity in postsynaptic antennal lobe projection neurons of males and females, we detected changes in the expression of many genes in the third antennal segment, which houses the somata of presynaptic olfactory receptor neurons. These changes affected genes with roles in synaptic vesicle release and synaptic remodeling, including several implicated in homeostatic plasticity at the neuromuscular junction. At 48 h and beyond, the transcriptional landscape tilted toward protein synthesis, folding, and degradation; energy metabolism; and cellular stress defenses, indicating that the system had been pushed to its homeostatic limits. Our analysis suggests that similar homeostatic machinery operates at peripheral and central synapses and identifies many of its components. The presynaptic transcriptional response to genetically targeted postsynaptic perturbations could be exploited for the construction of novel connectivity tracing tools.
SIGNIFICANCE STATEMENT Homeostatic feedback mechanisms adjust intrinsic and synaptic properties of neurons to keep their average activity levels constant. We show that, at a central synapse in the fruit fly brain, these mechanisms include changes in presynaptic gene expression that are instructed by an abrupt loss of postsynaptic excitability. The trans-synaptically regulated genes have roles in synaptic vesicle release and synapse remodeling; protein synthesis, folding, and degradation; and energy metabolism. Our study establishes a role for transcriptional changes in homeostatic synaptic plasticity, points to mechanistic commonalities between peripheral and central synapses, and potentially opens new opportunities for the development of connectivity-based gene expression systems
