488 research outputs found
Solubility of three natural compounds with insecticidal activity in supercritical carbon dioxide: Experimental measurements and predictive modeling with the GC-EoS
In this work, the solubility of thymoquinone, R-(+)-pulegone and 1-octen-3-ol in supercritical CO2 is determined in a range of conditions typical of supercritical fluid processes such as extraction, fractionation and impregnation. These compounds were selected based in their insecticidal activity which may enable to apply them as biopesticides. Solubility was measured using a semicontinuos method in the temperature range of 45–65 °C and pressure of 8–12 MPa, at a CO2 flowrate of 0.05–0.10 g/min, which was verified to be low enough to ensure saturation. Solubilities were predicted using the Group Contribution Equation of State (GC-EoS) and compared to the experimental results, with a good agreement. Consistency of the data was tested using the density-based Chrastil equation
Extracting flowering phenology from grassland species mixtures using time-lapse cameras
Understanding the impacts of climate change on plant phenology is crucial for predicting ecosystem responses. However, accurately tracking the flowering phenology of individual plant species in grassland species mixtures is challenging, hindering our ability to study the impacts of biotic and abiotic factors on plant reproduction and plant-pollinator interactions. Here, we present a workflow for extracting flowering phenology from grassland species mixtures using near-surface time-lapse cameras. We used 89 image series acquired in plots with known species composition at the Jena trait-based experiment (Germany) to develop random forest classifiers, which were used to classify images and compute time series of flower cover for each species. The high temporal resolution of time-lapse cameras allowed to select images in proper light conditions, and to extract vegetation indices and texture metrics to improve discrimination among flowering species. The random forest classifiers showed a high accuracy in predicting the cover of Leucanthemum vulgare, Ranunculus acris, and Knautia arvensis flowers, whereas graminoid flowers were harder to predict due to their green-to-brownish colours. The proposed workflow can be applied in climate change studies, ecosystem functioning, plant community ecology, and biodiversity change research, including the investigation of effects of species richness on individual species' flowering phenology. Our method could be a valuable tool for understanding the impacts of climate change on plant reproduction and ecosystem dynamic
Reinstatement of contextual conditioned anxiety in virtual reality and the effects of transcutaneous vagus nerve stimulation in humans
Since exposure therapy for anxiety disorders incorporates extinction of contextual anxiety, relapses
may be due to reinstatement processes. Animal research demonstrated more stable extinction memory
and less anxiety relapse due to vagus nerve stimulation (VNS). We report a valid human three-day
context conditioning, extinction and return of anxiety protocol, which we used to examine efects of
transcutaneous VNS (tVNS). Seventy-fve healthy participants received electric stimuli (unconditioned
stimuli, US) during acquisition (Day1) when guided through one virtual ofce (anxiety context, CTX+)
but never in another (safety context, CTX−). During extinction (Day2), participants received tVNS,
sham, or no stimulation and revisited both contexts without US delivery. On Day3, participants
received three USs for reinstatement followed by a test phase. Successful acquisition, i.e. startle
potentiation, lower valence, higher arousal, anxiety and contingency ratings in CTX+ versus CTX−,
the disappearance of these efects during extinction, and successful reinstatement indicate validity of
this paradigm. Interestingly, we found generalized reinstatement in startle responses and diferential
reinstatement in valence ratings. Altogether, our protocol serves as valid conditioning paradigm.
Reinstatement efects indicate diferent anxiety networks underlying physiological versus verbal
responses. However, tVNS did neither afect extinction nor reinstatement, which asks for validation
and improvement of the stimulation protocol
Perceived Exercise Habits of Individuals with Parkinson’s Disease Living in the Community
Context
Exercise has been shown to improve gait in individuals with Parkinson’s disease (PD). Stepping practice at higher intensity levels has been suggested as a beneficial treatment option to improve gait in the neurological population. Unfortunately, this mode is poorly understood and underutilized within the PD population. Information on what individuals with PD are doing for exercise would be beneficial to help tailor exercise programs to improve gait and provide exercise options in the community for intensity-based exercise.
Objective
To investigate the current exercise habits of individuals living with PD in the community aimed at improving walking and to understand the impact of perceived intensity on daily exercise practices.
Design, setting, participants
One hundred thirty-eight individuals with PD living in the community were surveyed online regarding their current exercise habits.
Main outcome measure
A total of 22 questions aimed to understand exercise selection, focus, and perceived intensity. Questions asked basic demographic, symptom presentation and management of disease related symptoms that were present while living with PD. Exercise questions focused understanding participants current function level, practice exercise habits and perceived levels of exercise intensity during daily routines.
Results
Of the 138 individuals surveyed for this preliminary study, eighty-seven percent of individuals with PD participated in exercise with seventy-five percent choosing walking as a mode for exercise. Sixty-five percent of the respondents noted that despite exercise, their walking speed and endurance has worsened since diagnosis. Eighty-one percent perceived exercising at moderate intensity levels, however little provocation of intensity symptoms was noted.
Conclusion
Our preliminary study survey results suggest that individuals with PD are exercising but not at high enough intensity levels to promote improvements in gait performance. Individuals with PD may need to be pushed at higher intensity levels, beyond their voluntary limits, to induce gait performance changes. These findings can provide a foundation for future fitness interventions within this population to target improving gait
On a Conjecture of Rapoport and Zink
In their book Rapoport and Zink constructed rigid analytic period spaces
for Fontaine's filtered isocrystals, and period morphisms from PEL
moduli spaces of -divisible groups to some of these period spaces. They
conjectured the existence of an \'etale bijective morphism of
rigid analytic spaces and of a universal local system of -vector spaces on
. For Hodge-Tate weights and we construct in this article an
intrinsic Berkovich open subspace of and the universal local
system on . We conjecture that the rigid-analytic space associated with
is the maximal possible , and that is connected. We give
evidence for these conjectures and we show that for those period spaces
possessing PEL period morphisms, equals the image of the period morphism.
Then our local system is the rational Tate module of the universal
-divisible group and enjoys additional functoriality properties. We show
that only in exceptional cases equals all of and when the
Shimura group is we determine all these cases.Comment: v2: 48 pages; many new results added, v3: final version that will
appear in Inventiones Mathematica
Cohomological characterizations of projective spaces and hyperquadrics
We confirm Beauville's conjecture that claims that if the p-th exterior power
of the tangent bundle of a smooth projective variety contains the p-th power of
an ample line bundle, then the variety is either the projective space or the
p-dimensional quadric hypersurface.Comment: Added Lemma 2.8 and slightly changed proof of Lemma 6.2 to make them
apply for torsion-free sheaves and not only to vector bundle
The Particle Spectrum of Heterotic Compactifications
Techniques are presented for computing the cohomology of stable, holomorphic
vector bundles over elliptically fibered Calabi-Yau threefolds. These
cohomology groups explicitly determine the spectrum of the low energy,
four-dimensional theory. Generic points in vector bundle moduli space manifest
an identical spectrum. However, it is shown that on subsets of moduli space of
co-dimension one or higher, the spectrum can abruptly jump to many different
values. Both analytic and numerical data illustrating this phenomenon are
presented. This result opens the possibility of tunneling or phase transitions
between different particle spectra in the same heterotic compactification. In
the course of this discussion, a classification of SU(5) GUT theories within a
specific context is presented.Comment: 77 pages, 3 figure
Generalization of Conditioned Contextual Anxiety and the Modulatory Effects of Anxiety Sensitivity
Anxiety patients overgeneralize fear responses, possibly because they cannot distinguish between cues never been associated with a threat (i.e., safe) and threat-associated cues. However, as contexts and not cues are discussed as the relevant triggers for prolonged anxiety responses characterizing many anxiety disorders, we speculated that it is rather overgeneralization of contextual anxiety, which constitutes a risk factor for anxiety disorders. To this end, we investigated generalization of conditioned contextual anxiety and explored modulatory effects of anxiety sensitivity, a risk factor for anxiety disorders. Fifty-five participants underwent context conditioning in a virtual reality paradigm. On Day 1 (acquisition), participants received unpredictable mildly painful electric stimuli (unconditioned stimulus, US) in one virtual office (anxiety context, CTX+), but never in a
Week 48 outcomes from the BRAAVE 2020 study: a randomised switch to bictegravir/emtricitabine/tenofovir alafenamide (B/F/TAF) in African American adults with HIV
Background: Black Americans are disproportionately impacted by HIV. The BRAAVE 2020 study, evaluated the safety and efficacy of switching to the guidelines- recommended single- tablet regimen bictegravir, emtricitabine, tenofovir alafenamide (B/F/TAF) in Black adults through week (W) 48.
Method: Adults with HIV self- identifying as Black or African American and virologically suppressed on 2 NRTIs plus a 3rd agent were randomised (2:1) to switch to open- label B/F/TAF once daily or stay on their baseline regimen (SBR). Prior virologic failure was allowed except failure on an INSTI. Prior resistance to NNRTIs, PIs and/or NRTIs was permitted except K65R/E/N, ≥3 thymidine analog mutations or T69- insertions. Primary INSTI- resistance was excluded. SBR participants switched to B/F/TAF at W24. Efficacy was assessed at W24 (Primary endpoint, noninferiority margin 6%) and at W48 as the proportion with HIV- 1 RNA ≥50 c/mL by FDA Snapshot and by changes in CD4 count. Safety was assessed by adverse events (AE) and lab results.
Results: 495 were randomised and treated (B/F/TAF n = 330, SBR n = 165): 32% cis women, 2% transgender women, median age 49 years (range 18– 79) and 10% had pre- existing M184V/I mutation. At W24, 1% (2/328) on B/F/TAF vs 2% (3/165) on SBR had HIV- 1 RNA ≥50 c/mL (difference - 1.2%; 95% CI - 4.8% to 0.9%) demonstrating non-inferiority of B/F/TAF; 2 with pre- existing primary INSTI resistance were excluded from analysis. 163 assigned to SBR completed W24 and switched to B/F/TAF (SBR to B/F/TAF). At W48 1% (3/328) originally randomised to B/F/TAF and 0 SBR to B/F/TAF had HIV- 1 RNA ≥50 c/mL. Baseline NRTI resistance did not affect the efficacy of B/F/TAF. No treatment emergent resistance was detected. Median (IQR) weight increased 0.9 kg (- 1.5, 4.1) and 0.6 kg (- 1.0, 3.1) for B/F/TAF and SBR to B/F/TAF groups, respectively. Study drug- related AEs occurred in 10% of participants while on B/F/TAF; most were grade 1.
Conclusion: Switching to B/F/TAF was highly effective for Black adults regardless of baseline regimen or pre- existing NRTI resistance and was associated with few treatment re-lated AEs or discontinuations
Adults and Children in Low-Income Households That Participate in Cost-Offset Community Supported Agriculture Have High Fruit and Vegetable Consumption
This paper examines fruit and vegetable intake (FVI) in low-income households that participated in a cost-offset (CO), or 50% subsidized, community-supported agriculture (CSA) program. CSA customers paid farms upfront for a share of the harvest, and received produce weekly throughout the growing season. A cohort of adults and children 2–12 y in a summer CO-CSA were surveyed online twice: August 2015 (n = 41) and February 2016 (n = 23). FVI was measured by the National Cancer Institute’s (NCI) Fruit and Vegetable Screener (FVS) and an inventory of locally grown fruits and vegetables. FVI relative to United States (US) recommendations and averages, and across seasons, were tested with non-parametric tests and paired t-tests (p < 0.05). Both adults and children in the CO-CSA had higher FVI than the US averages, and more often met recommendations for vegetables. Some summer fruits and vegetables were more often eaten when locally in-season. The CO-CSA model warrants further examination as an avenue for improving vegetable consumption among adults and children in low-income households. However, causality between CO-CSA participation and FVI cannot be inferred, as CO-CSA participants may be positive deviants with respect to FVI. A multi-state randomized controlled trial is currently underway to evaluate impacts of CO-CSAs on FVI and related outcomes
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