Neural Computation via Neural Geometry: A Place Code for Inter-whisker Timing in the Barrel Cortex?

The place theory proposed by Jeffress (1948) is still the dominant model of how the brain represents the movement of sensory stimuli between sensory receptors. According to the place theory, delays in signalling between neurons, dependent on the distances between them, compensate for time differences in the stimulation of sensory receptors. Hence the location of neurons, activated by the coincident arrival of multiple signals, reports the stimulus movement velocity. Despite its generality, most evidence for the place theory has been provided by studies of the auditory system of auditory specialists like the barn owl, but in the study of mammalian auditory systems the evidence is inconclusive. We ask to what extent the somatosensory systems of tactile specialists like rats and mice use distance dependent delays between neurons to compute the motion of tactile stimuli between the facial whiskers (or ‘vibrissae’). We present a model in which synaptic inputs evoked by whisker deflections arrive at neurons in layer 2/3 (L2/3) somatosensory ‘barrel’ cortex at different times. The timing of synaptic inputs to each neuron depends on its location relative to sources of input in layer 4 (L4) that represent stimulation of each whisker. Constrained by the geometry and timing of projections from L4 to L2/3, the model can account for a range of experimentally measured responses to two-whisker stimuli. Consistent with that data, responses of model neurons located between the barrels to paired stimulation of two whiskers are greater than the sum of the responses to either whisker input alone. The model predicts that for neurons located closer to either barrel these supralinear responses are tuned for longer inter-whisker stimulation intervals, yielding a topographic map for the inter-whisker deflection interval across the surface of L2/3. This map constitutes a neural place code for the relative timing of sensory stimuli

Artificial reefs built by 3D printing: Systematisation in the design, material selection and fabrication

The recovery of degraded marine coasts and the improvement of natural habitats are current issues of vital importance for the development of life, both marine and terrestrial. In this sense, the immersion of artificial reefs (ARs) in the marine environment is a way to stimulate the recovery of these damaged ecosystems. But it is necessary to have a multidisciplinary approach that analyses the materials, designs and construction process of artificial reefs in order to understand their true impact on the environment. For this reason, this paper presents the manufacture of artificial reefs by 3D printing, proposing designs with a combination of prismatic and random shapes, with different external overhangs as well as inner holes. For the definition of the artificial reef designs, criteria provided by marine biologists and the results obtained from a numerical simulation with ANSYS were taken into account, with which the stability of the artificial reefs on the seabed was analysed. Three dosages of cement mortars and three dosages of geopolymer mortars were studied as impression materials. The studies included determination of the rheological properties of the mortars, to define the printability, determination of the cost of the materials used, and determination of the mechanical strength and biological receptivity in prismatic specimens that were immersed in the sea for 3 months. To evaluate the environmental impact of the materials used in the production of the mortars, a Life Cycle Assessment (LCA) was carried out. In order to choose the mortars that encompassed the best properties studied, Multi-Criteria Decision Making (MCDM) was applied and the two best mortars were used for the manufacture of the artificial reefs. Finally, the advantages and disadvantages of the 3D printing process used were analysed. The results of the studies carried out in this research show that cement mortars have better characteristics for artificial reef applications using 3D printing, and that the technique applied for the manufacture of the artificial reefs allowed the digital models to be faithfully reproduced

PENGARUH VARIASI BERAT ROLLER TERHADAP DAYA LUARAN

Sepeda motor adalah salah satu jenis kendaraan yang menggunakan mesin pembakaran dalam (internal combustion engine) dengan bensin sebagai bahan bakarnya. Bahan bakar bensin memiliki banyak jenis dari premium, pertalite, pertamax, pertamax plus, pertamax turbo dan pertamax racing. Kinerja variator matic sangat ditentukan oleh roller, dikarenakan roller sangat berpengaruh terhadap perubahan variable dari pulley, tentu akan sangat berpengaruh terhadap kinerja mesin. Roller pada sepeda motor matic memiliki berbagai macam varian ukuran berat roller. Tujuan penelitian ini untuk mengetahui seberapa besar pengaruh roller variasi cvt terhadap motor matic Yamaha Xeon. Metode penelitian ini adalah dyno test, dyno test dilakukan dengan menggunakan jenis chassis dyno test. Dyno test ini dilakukan oleh bengkel motor dengan hasil yang dinamakan power on wheel, hasil dari tes ini biasanya lebih kecil karena energi motor yang dihasilkan dari proses pembakaran akan banyak hilang di transmisi, rantai, v-belt hingga ban saat memakai chassis dyno test tersebut. Setelah melakukan penelitian, hasil dari penelitian ini dapat disimpulkan ialah: RPM 4000 menunjukkan semakin berat roller, semakin tinggi daya luaran motor. RPM 5000 menunjukkan semakin berat roller, semakin tinggi daya luaran motor. RPM 6000 menunjukkan semakin berat roller, semakin rendah daya luaran motor. RPM 7000 menunjukkan semakin berat roller, semakin rendah daya luaran motor

Sooner than you think: a very early affective reaction to the COVID-19 pandemic and quarantine in Argentina

AbstractThe unique circumstances created by the COVID-19 pandemic pose serious challenges to mood stability and emotional regulation at all ages. Although many people tend to react resiliently to stress, others appear to display emotional anxiety and depression-related symptoms. In this study, we carried out a survey (N = 10,053) during the first week of the general lockdown (quarantine) in Argentina to measure early affective reactions in Argentine adults. Respondents showed substantial anxious and depressive symptoms, with 33 % and 23% of participants reporting possible depressive and anxious syndromes, respectively, with the youngest group (18 to 25 y.o.) showing the highest prevalence of symptoms. Even if prior mental health problems predisposed or aggravated the reaction, participants without prior complaints showed signs of psychological impact. Using linear regression, the most important independent variables related to depressive symptoms was the feeling of loneliness followed by daily stress. In the case of anxious states, the strongest variables were negative repetitive thinking and feeling of loneliness. Other psychological, economic, and social factors are discussed.This study is in line with previous literature that highlight the importance of the psychological impact of pandemics, but additionally demonstrates that these reactions are present at a large scale immediately after the start of quarantine with very low infectious rates as an early anticipatory adaptive reaction leading to potential negative outcomes from adjustment disorders to major disorders. In addition, the present results provide potentially relevant information about sudden environmental impacts on affective states and specific pathways for anxiety and depression to be expressed. We end by discussing implications for public policy based on considering the most vulnerable groups.Key FindingsMore than a third of the studied sample (n = 10,053) showed substantial depressive and anxious symptoms between 5 and 7 days after the start of the national quarantine.33.7% of the sample scored above the PHQ-9 cutoff for possible diagnosis of a depressive disorder and 23.2% for an anxiety disorder.28.6% of the participants showed moderate and severe levels of depressive symptoms and 23.2% showed moderate and severe levels of anxiety.The youngest participants were affected the most by the situation.The most important factor related to depressive symptoms was the feeling of loneliness followed by daily stress.The most important factor related to anxious states was negative repetitive thinking followed by feeling of loneliness.The existence of previous mental health difficulties aggravated the reactions, but even people who had not sought out treatment previously showed signs of psychological impact.</jats:sec

Towards reverse design of freeform shapes

The need for more intuitive, faster and more effective tools for freeform product design is still an outstanding research issue in shape modeling. We propose a new methodology in which the designer can define optimal shape modification tools for the situation at hand. The key to this method is a dialogue between the designer and the computer, in which the details of the requested shape modifier are settled. The proposed tool, called user-defined modifier (UDM), is based on recent techniques from freeform shape recognition and parameterized, template-controlled shape modification. The dialogue between user and the system is described, and the basic techniques for the UDM tool are presented as well

Emotional symptoms, mental fatigue and behavioral adherence after 72 continuous days of strict lockdown during the COVID-19 pandemic in Argentina

AbstractBackgroundAn early, total, and prolonged lockdown was adopted in Argentina during the first wave of COVID-19 as the main sanitary strategy to reduce the spread of the virus in the population. The aim of this study was to explore emotional symptoms, mental fatigue, and behavioral adherence associated with the COVID-19 pandemic after an average of 72 days of continuous lockdown in Argentina. Specifically, we intended to know: 1) if the prolongation of the lockdown was associated with elevated emotional symptoms; 2) if the prolonged lockdown affected adherence, a phenomenon called “behavioral fatigue”; and 3) how financial concerns in a developing country affected adherence to the lockdown and emotional status of the population.MethodA survey was designed to evaluate the psychological impact of the pandemic and lockdown. The survey included standardized questionnaires to assess the severity of depressive (PHQ-9) and anxious (GAD-7) symptoms, a questionnaire to evaluate mental fatigue, and several additional instruments to assess other variables of interest: risk perception, lockdown adherence, financial concerns, daily stress, loneliness, intolerance to uncertainty, negative repetitive thinking, and cognitive problems. Three LASSO regression analyses were carried to evaluate the predictive role of the different variables over depression, anxiety, and lockdown adherenceResultsThe survey was responded by 3617 individuals over the age of 18 (85.2% female) from all the provinces of Argentina. Using the Oxford stringency index, Argentina had one of the most stringent and prolonged lockdowns when the sample was collected with 63 to 77 continuous days with a stringency index of more than 85/100. 45.6% of the sample met the cut-off for depression and 27% for anxiety. Previous mental health treatment, low income, being younger, and being female were associated with higher levels of emotional symptoms. Mental fatigue, cognitive failures, and financial concerns were also associated with emotional and subjective complaints, but not with adherence to the lockdown. In the regression models, mental fatigue, cognitive failures, and loneliness were the most important variables to predict depression, meanwhile intolerance to uncertainty and lockdown difficulty were the most important in the case of anxiety. Perceived threat was the most important variable predicting lockdown adherence.ConclusionsEmotional symptoms persisted and even increased during the extended lockdown, but we found no evidence of behavioral fatigue. Instead, mental fatigue, cognitive difficulties, and financial concerns were expressions of the emotional side of the pandemic and the restrictive measures.</jats:sec