A surplus no more? Variation in krill availability impacts reproductive rates of Antarctic baleen whales.

The krill surplus hypothesis of unlimited prey resources available for Antarctic predators due to commercial whaling in the 20th century has remained largely untested since the 1970s. Rapid warming of the Western Antarctic Peninsula (WAP) over the past 50 years has resulted in decreased seasonal ice cover and a reduction of krill. The latter is being exacerbated by a commercial krill fishery in the region. Despite this, humpback whale populations have increased but may be at a threshold for growth based on these human-induced changes. Understanding how climate-mediated variation in prey availability influences humpback whale population dynamics is critical for focused management and conservation actions. Using an 8-year dataset (2013-2020), we show that inter-annual humpback whale pregnancy rates, as determined from skin-blubber biopsy samples (n = 616), are positively correlated with krill availability and fluctuations in ice cover in the previous year. Pregnancy rates showed significant inter-annual variability, between 29% and 86%. Our results indicate that krill availability is in fact limiting and affecting reproductive rates, in contrast to the krill surplus hypothesis. This suggests that this population of humpback whales may be at a threshold for population growth due to prey limitations. As a result, continued warming and increased fishing along the WAP, which continue to reduce krill stocks, will likely impact this humpback whale population and other krill predators in the region. Humpback whales are sentinel species of ecosystem health, and changes in pregnancy rates can provide quantifiable signals of the impact of environmental change at the population level. Our findings must be considered paramount in developing new and more restrictive conservation and management plans for the Antarctic marine ecosystem and minimizing the negative impacts of human activities in the region.

Exploratory qualitative study examining acceptability of strategies to improve access to substance use treatment and HIV prevention services for young adults on probation in Ukraine.

OBJECTIVE: Adults <30 years' of age experience elevated HIV-rates in Ukraine. Young adults (YA) involved in the criminal justice system (CJS) are at an increased HIV-risk given elevated rates of substance use, engagement in high-risk sexual behaviour and insufficient healthcare access. The objective of this exploratory study was to investigate the acceptability of strategies to refer and link CJS-involved YA to HIV-prevention and substance use treatment services from CJS settings. DESIGN: We conducted qualitative individual interviews with CJS-involved YA (18-24 years), and CJS stakeholders. Interviews were guided by the Social Ecological Model. Interviews with YA explored substance use and sexual behaviour, and acceptability of strategies to link YA to HIV-prevention and substance use treatment services from CJS. Stakeholder interviews explored system practices addressing HIV-prevention and substance use and addiction. Data were analysed using Inductive Thematic Analysis. SETTING: Data were collected in three locales, prior to the 2022 Russian-Ukrainian conflict. PARTICIPANTS: Thirty YA and 20 stakeholders. RESULTS: Most YA were men, reported recent injection drug use and were M age=23 years. YA were receptive to linkage to HIV-prevention services from CJS; this was shaped by self-perceived HIV-risk and lack of access to HIV-prevention services. YA were less receptive to being referred to substance use treatment services, citing a lack of self-perceived need and mistrust in treatment efficacy. Stakeholders identified multilevel contextual factors shaping acceptability of HIV-prevention and substance use treatment from CJS (eg, stigma). CONCLUSIONS: Findings should be reviewed as a historical record of the pre-conflict context. In that context, we identified strategies that may have been used to help curtail the transmission of HIV in a population most-at-risk, including CJS-involved YA. This study demonstrates that improving access to substance use treatment and HIV-prevention services via CJS linkage were acceptable if provided in the right conditions (eg, low or no-cost, confidential).

A new radio-frequency acoustic method for remote study of liquids.

In the present work, a novel study method of conductive liquids has been proposed. It is based on a discovered phenomenon of radiofrequency anisotropy of electrolyte solution, which arises in response to mechanical excitation of the solution. The phenomenon was observed during the development of a radiofrequency polarimetric contactless cardiograph. The electric field vector rotates after its transition through the pericardial region due to the acceleration changes of blood. Numerous in vitro experiments with monochromatic and impulse acoustic waves always induced the polarization rotation of the RF wave passing through an electrolyte solution. The response obtained from the solutions on acoustic excitation of the Heaviside function form demonstrates the effect of a solution "memory". The dynamics of this process resembles the spin glasses magnetization. We hypothesized that there was a magnetic moment change within the solution, and the possible reason for it is an appearance of electromagnetic impulse caused by the same acoustic excitation. In a further experiment, we really captured a suspected electrical potential. Given that, we can declare at least three new physical effects never observed before for an electrolyte solution. The study method itself may provide broad options for remote measurement of the electrolyte solution parameters.