136986 research outputs found
Sort by
Central nervous system stimulants in recreational and medical use
No full textStimulants that act on the central nervous system have been used since antiquity for ritual and other uses. Organic chemistry techniques, especially those developed in Germany in the late 1800s, resulted in the isolation and structural determination of several important stimulants. Synthetic pathways for amphetamine and related stimulants were developed in the first half of the 19th century, and these new drugs were widely marketed. Awareness of abuse potential emerged soon after but was contested. Stimulants have been used to counteract fatigue and promote wakefulness during military operations, as well as to treat sleep disorders, since the 1930s. Methylphenidate was approved to treat children with behavioral problems in 1962, predating the recognition of attention deficit hyperactivity disorder (ADHD). Stimulant abuse became a political concern in the post-war period, initially with the use of pep-pills by long-haul truck drivers and later as drug dealing became common in night clubs, with new laws limiting availability passed in the early 1960s. They have also been used to increase athletic and cognitive performance. Stimulants are still first-line therapies for ADHD and some sleep disorders; however, newer-generation drugs have been developed with better safety profiles and lower abuse potential. Illicit stimulant use continues to be common in many countries
Evaluation of deformable image registration accuracy for liver re-irradiation patients using contrast and non-contrast computed tomography images
No full textBACKGROUND: Re-irradiation of liver tumors is increasing in frequency, requiring clinicians to account for previous radiation dose to prevent unacceptable toxicity. Given the heterogeneity of liver morphological changes between treatments, deformable image registration (DIR) is required to accumulate dose from previous treatments onto the latest planning images for radiotherapy. PURPOSE: The increase in re-irradiation of patients with liver cancer has led to the need to account for previous radiotherapy treatments. This feasibility study used contemporaneous intravenous contrast computed tomography images (CTs) to evaluate the accuracy of DIR dose accumulation in the re-irradiation of liver patients, via the use of structural landmarks. METHODS: We used nine liver patients who received repeat stereotactic body radiation therapy (SBRT) liver radiotherapy, with contrast and non-contrast planning CTs, to evaluate the accuracy of dose accumulation in the liver. The initial planning CT was deformed to the second planning CT, and the deformation vector field was used to deform the initial dose map. The dose could then be accumulated by adding the deformed initial dose map to the second dose map. Three methods of performing DIR were compared, including with and without corresponding anatomical landmarks. Target registration error (TRE), dice similarity coefficient, and Hausdorff distance were used to assess the accuracy of the dose accumulation. RESULTS: The lowest TRE was achieved with the structure guided algorithm using all of the available anatomical landmarks, with a mean + standard deviation of 1.7 mm (SD = 0.9 mm) for non-contrast (p < 0.0005) and 1.6 mm (SD = 0.9 mm) for contrast CTs (p < 0.0005). DIR based on contrast CTs reduced the TREs, the distance between the location of a given landmark on the second image, and the location of where that landmark is deformed to from the first image, with all DIR algorithms (p < 0.0005 for each contrast non-contrast pair). There were also statistically significant differences between dose accumulation errors for Contrast CTs with a mean of 0.92 Gy (SD = 3.08 Gy) and Non-Contrast CTs of 1.07 Gy (SD = 3.36 Gy) (p < 0.05), and the differences between each of the algorithms were also statistically significant, with p-values < 0.05. CONCLUSIONS: DIR improves the dose accumulation accuracy in re-irradiation in liver SBRT. DIR accuracy can be improved using contrast CTs and corresponding anatomical landmarks. Providing additional information into the DIR in the form of corresponding anatomical landmarks dramatically improved image registration accuracy and thus reduced dose accumulation errors. Dose accumulation accuracy was dependent on the TRE, and on the dose-gradient of the mapped dose
Feeling Underqualified and out of My League: Motivational and Affective Paths to Adaptive and Maladaptive Behaviors
No full textThis study explored the motivational and affective implications of perceived underqualification, specifically examining how it leads to increased levels of envy and help-seeking behaviors. We predicted that envy and help seeking behaviors would in turn indirectly relate to interpersonal deviance and task performance. We further hypothesized that two psychological resources, hope and self-efficacy, would moderate the relationships between perceived underqualification, envy, and help seeking. We tested our model with a sample of 149 medical school students who were undergoing a clinical rotation as well as their rotation coordinators at a university hospital located in northwestern Turkey. Data collection spanned four waves, from the first day of their rotation to the end of that one-month rotation. Results supported positive indirect effects between perceived underqualification and task performance via help seeking, and between perceived underqualification and interpersonal deviance via envy. Further, hope moderated the relationship between perceived underqualification and task performance via help seeking, and self-efficacy moderated the relationship between perceived underqualification and envy
Correction: Machine learning-enhanced monitoring of global copper mining areas (Scientific Data, (2025), 12, 1, (1120), 10.1038/s41597-025-05296-y)
No full text10.1038/s41597-025-05594-
Enhancing randomized clinical trials with digital twins
No full textDigital twins (DTs) can transform randomized clinical trials by improving ethical standards, including safety, informed consent, equity, and data privacy. They also enhance trial efficiency by enabling early detection of adverse events and streamlined design. This paper explores the role of DTs in personalized medicine, from pre-clinical research to post-marketing, while addressing technological, legal, and ethical challenges in implementation.10.1038/s41540-025-00592-
Risk and return spillovers among developed and emerging market currencies
No full textWe develop a network model capturing the dynamic interactions among foreign exchange (FX) returns and realized risk measures for 20 developed market (DM) and emerging market (EM) currencies. We show that DM currencies are more integrated within the network than EM currencies on average and tend to become more dependent on external conditions over time. Spillovers between DMs and EMs evolve more rapidly than spillovers within DMs and within EMs and are a major contributor to overall spillover dynamics. Auxiliary regressions reveal that the net DM-to-EM spillover comoves with global factors known to drive EM capital flows
Interdecadal cycles in Australian annual rainfall
No full textAbstract. Extremes of Australian rainfall have profound economic, ecological and societal impacts; however, the current forecast horizon is limited to a few months. This study investigates interdecadal periodicity in annual rainfall records across eastern Australia. Wavelet analysis was conducted on rainfall data from 347 sites covering 130 years (1890–2020). Prominent cycles were extracted from each site and clustered using a Gaussian mixture model. This revealed three principal cycles centred around 12.9, 20.4 and 29.1 years that were highly significant over red noise using a t test (p<0.0001). Overall, the three cycles combined had a mean contribution to the total rainfall variance (R2) of 13 % across all of the sites, but this was up to 29 % at individual sites. Both the 12.9- and 20.4-year cycles were detected at over 95 % of the sites. The strength of each cycle varied over time, and this amplitude modulation of the signal showed a systematic movement across the area investigated. Eighty-six percent of extremely wet years fell within the positive phase of the combined reconstruction, with 80 % of extremely dry years falling in the negative phase. These results indicate underlying periodicity in annual rainfall across eastern Australia, with the potential to build this into long-term forecasts. This concept has been suggested in the past but has not been rigorously tested. These findings open new paths for research into rainfall patterns in Australia and internationally. They also have broad implications for the management of water resources across all sectors
Advancing polymer composites in civil infrastructure through 3D printing
No full textPolymer composites (PCs) are increasingly used in civil infrastructure and construction due to their high strength, lightweight properties, and durability. When combined with automated manufacturing technologies such as 3D printing, they enable the efficient fabrication of complex engineering structures while minimizing material waste. As construction moves toward sustainable, automated, and digitally driven methods, understanding the potential of 3D-printed polymer composites becomes essential. This review addresses this emerging need by offering a civil-infrastructure specific synthesis of polymer composites in additive manufacturing as a pathway to a more sustainable and resilient built environment. The paper presents a comprehensive overview of the use of PCs in automated construction, highlighting key 3D printing techniques and printable polymer-based materials applied in building and infrastructure projects. It also discusses recent developments, current challenges, and emerging opportunities in PC-based 3D printing for civil engineering, supported by case studies, innovative construction methodologies, and future research directions
Flows and Bottlenecks: Understanding Collaboration Between Domestic Violence and Substance Use Sectors Through Metaphor Analysis
No full textAbstract
Purpose
Collaboration between domestic and family violence (DFV) and substance use sectors can enhance client outcomes, however, it also presents challenges. This study identified areas of inquiry, which created collaborative flows and bottlenecks between domestic violence and substance use professionals.
Methods
Adopting a system’s approach to action research, an Australian Policy Stakeholder Group was formed. Over a two-year period, senior policy workers, practitioners, and managers convened to identify ways to reduce sectoral silos. The authors analyzed themes contributing to collaborative flows and bottlenecks. Metaphor analysis was also used to reveal the implicit assumptions participants held about these themes.
Results
Three themes facilitated collaborative flow: increasing consensus that the relationship between substance use and DFV is complex; integrating substance use content into supportive interventions for victim-survivors; and the concept of substance use coercion. These facilitated open negotiations of contested worldviews among participants. Three themes led to collaborative bottlenecks: short-term funding cycles; the (de) gendering of DFV; and disputed notions of accountability for people who use violence. Metaphor analysis revealed that collaborative bottlenecks were conceived as contentious terrain, causing apprehension amongst participants.
Conclusions
Collaborative flows and bottlenecks between DFV and substance use sectors evolve over time. Professionals navigating them must be cognizant of context that influences collaborative dynamics, which can enhance the support provided to families affected by DFV and substance use
Rumen Microbes Associated Potential to Establish Climate Resilience In Ruminants – A Review
No full textAbstract
Ruminants are stated to play a pivotal role of converting feed resources into nutritious outputs suitable for human consumption, which primarily is attributed to the diversified rumen microbiota they harbor. The rumen microbial niche is however not explored to its complete potential due to several limitations, the crucial one being the inability to culture more than 80% of the rumen microbes. Advances in next generation sequencing approaches have made promising inroads to bridge this gap. The adoption of techniques like 16S rRNA sequencing and whole genome shotgun metagenomics has now made it possible to assess the structural and functional dynamics of rumen microbiota. Nevertheless, there is a dearth of information pertaining to the impact of climate change on rumen microbe. This review was therefore an attempt to highlight the potential role of rumen microbiome during heat stress and also to emphasize on the significance of adopting rumen metagenomics to link climate change impact with altered productive potential in ruminants. Changes in ruminal microflora, like alterations in
Firmicutes-Bacteroidetes
ratio (highly correlated with milk fat yield), altered abundance of
Fibrobacteres
group (potentially heat generating microbes),
Actinobacteria
group (acetate producing microbes),
Fusobacteria
,
Cyanobacteria
and so on were observed in ruminants during heat stress. Furthermore, it was also possible to link these alterations with several functional and metabolic pathways, like energy production and conversion, defense mechanism, lipid transport and metabolism, coenzyme transport and metabolism, cell cycle control, cell division and a few more. Employing rumen metagenomics could also aid in understanding the differences in heat stress adaptive strategies between breeds. Therefore, intensifying the application of this methodology with heat stress in ruminants and extending it to assess the effectiveness of nutritional amelioration strategies could start a new journey towards heat stress mitigation in ruminants