6,999 research outputs found
Variations in the occurrence of SuperDARN F region echoes
The occurrence of F region ionospheric echoes observed by a number of
SuperDARN HF radars is analyzed statistically in order to infer solar cycle,
seasonal, and diurnal trends. The major focus is on Saskatoon radar data for
1994–2012. The distribution of the echo occurrence rate is presented in terms of
month of observation and magnetic local time. Clear repetitive patterns are
identified during periods of solar maximum and solar minimum. For years near
solar maximum, echoes are most frequent near midnight during winter. For
years near solar minimum, echoes occur more frequently near noon during
winter, near dusk and dawn during equinoxes and near midnight during summer.
Similar features are identified for the Hankasalmi and Prince George radars
in the northern hemisphere and the Bruny Island TIGER radar in the southern
hemisphere. Echo occurrence for the entire SuperDARN network demonstrates
patterns similar to patterns in the echo occurrence for the Saskatoon radar
and for other radars considered individually. In terms of the solar cycle,
the occurrence rate of nightside echoes is shown to increase by a factor of
at least 3 toward solar maximum while occurrence of the near-noon echoes
does not significantly change with the exception of a clear depression during
the declining phase of the solar cycle
THEORETIC-EXPERIMENTAL EVALUATION OF A CASCADE REFRIGERATION SYSTEM FOR LOW TEMPERATURE APPLICATIONS USING THE PAIR R22/R404A
This paper presents a thermodynamic analysis of a cascade refrigeration system using the refrigerant R22 as the working fluid in the high temperature circuit (HT) and the refrigerant R404a as the working fluid in the low temperature circuit (LT). The present analysis aimed to obtain the condensing temperature of the LT that provides an optimal value for the coefficient of performance (COP) of the cycle. Parameters involved in the analysis included the evaporation temperature, the condensing temperature and the difference between the condensing temperature of the LT (TC_LT) and evaporation temperature of the HT (TE_HT) – ΔTCAS. Simulations were performed using the software EES (Engineering Equation Solver). In addition to the analysis, experimental data obtained from a prototype was compared with the simulated results which showed good agreement. The COP varies with the increase in the intermediate temperature; however this variation does not exceed 1%
Pseudococcus affinis MASK., new vector of grapevine trichoviruses A and B
Research Note
Grapevine trichovirus A (GVA) and grapevine trichovirus B (GVB) were successfully transferred with bulk transmission trials under controlled conditions, from infected grapevines to herbaceous hosts by Pseudococcus affinis MASK., a pseudococcid mealybug that may attack grapevines. P. affinis is the fourth mealybug species capable of vectoring GVA and GVB, confirming that transmission by mealybugs of grapevine trichoviruses may not be species-specific
The Joint Contribution of Activation and Inhibition in Moderating Carryover Effects of Anger on Social Judgment
Carryover effects of emotions that lead to biases in social judgments are commonly
observed. We suggest that such effects may be influenced by the ability to engage
or disengage attention from emotional stimuli. We assessed the ability to activate
and inhibit attention to anger stimuli, experimentally induced anger in a demanding
task, and measured social judgment toward an ambiguous target. Results show that
higher activation and higher inhibition of anger-related information predicted more biased
evaluations of the ambiguous target when individuals were experiencing anger, but not
in an emotionally neutral condition. Interestingly, the effect of activation and inhibition in
the anger condition emerged only when such variables were entered simultaneously
in the regression model, indicating that they had an additive effect in predicting
carryover effects of anger on social judgement. Results are consistent with a cooperative
suppression effect (Conger, 1974) of activation and inhibition and may be explained by
either an increased accessibility of anger-related cues leading to more biased social
judgments, or by an instance in which being good at engaging in and disengaging
attention from emotional cues might have depleted participants’ resources making
carryover effects of anger more likely to occur. Ultimately, the finding highlight that
individual differences in attentional processes are important moderators for carryover
effects of emotions
Endoscopic stenting for left-sided obstructing colorectal cancer
Si sottolinea l'importanza dello stenting endoscopico in pazienti con occlusione da tumore del colon rett
Positive aspects of self-expandable metallic stent endoscopic placement for malignant colorectal obstruction during the COVID-19 pandemic
Lo studio sottolinea l'importanza e l'utilità di stents posizionati per via endoscopica in caso di occlusione acuta-subacuta per tumore del colon retto, nel periodo della pandemia da COVID 1
Bilateral Transcranial Direct Current Stimulation Language Treatment Enhances Functional Connectivity in the Left Hemisphere: Preliminary Data from Aphasia
Several studies have already shown that transcranial direct current stimulation (tDCS) is a useful tool for enhancing recovery in aphasia. However, no reports to date have investigated functional connectivity changes on cortical activity because of tDCS language treatment. Here, nine aphasic persons with articulatory disorders underwent an intensive language therapy in two different conditions: bilateral anodic stimulation over the left Broca's area and cathodic contralesional stimulation over the right homologue of Broca's area and a sham condition. The language treatment lasted 3 weeks (Monday to Friday, 15 sessions). In all patients, language measures were collected before (T0) and at the end of treatment (T15). Before and after each treatment condition (real vs. sham), each participant underwent a resting-state fMRI study. Results showed that, after real stimulation, patients exhibited the greatest recovery not only in terms of better accuracy in articulating the treated stimuli but also for untreated items on different tasks of the language test. Moreover, although after the sham condition connectivity changes were confined to the right brain hemisphere, real stimulation yielded to stronger functional connectivity increase in the left hemisphere. In conclusion, our data provide converging evidence from behavioral and functional imaging data that bilateral tDCS determines functional connectivity changes within the lesioned hemisphere, enhancing the language recovery process in stroke patients
Neurophysiological Markers of Premotor–Motor Network Plasticity Predict Motor Performance in Young and Older Adults
Aging is commonly associated with a decline in motor control and neural plasticity. Tuning cortico–cortical interactions between premotor and motor areas is essential for controlling fine manual movements. However, whether plasticity in premotor–motor circuits predicts hand motor abilities in young and elderly humans remains unclear. Here, we administered transcranial magnetic stimulation (TMS) over the ventral premotor cortex (PMv) and primary motor cortex (M1) using the cortico–cortical paired-associative stimulation (ccPAS) protocol to manipulate the strength of PMv-to-M1 connectivity in 14 young and 14 elderly healthy adults. We assessed changes in motor-evoked potentials (MEPs) during ccPAS as an index of PMv-M1 network plasticity. We tested whether the magnitude of MEP changes might predict interindividual differences in performance in two motor tasks that rely on premotor-motor circuits, i.e., the nine-hole pegboard test and a choice reaction task. Results show lower motor performance and decreased PMv-M1 network plasticity in elderly adults. Critically, the slope of MEP changes during ccPAS accurately predicted performance at the two tasks across age groups, with larger slopes (i.e., MEP increase) predicting better motor performance at baseline in both young and elderly participants. These findings suggest that physiological indices of PMv-M1 plasticity could provide a neurophysiological marker of fine motor control across age-groups
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