Determining a reliable method to detect life on another planet is an essential first step in the pursuit of discovering extraterrestrial life. Polyhydroxyalkanoates (PHAs), bioplastic polymers created by microorganisms, are strong candidates for defining the presence of extraterrestrial life due to their water insolubility, strong ultraviolet resistance, high melting points and high crystallinity, amongst other qualities. PHAs are abundant on Earth, and their chemical properties can easily be distinguished from non-biological matter. Their widespread distribution and conferred resistance to astrobiologically relevant extreme environments render PHAs highly favourable candidates for astrobiological detection. Integrating detection of PHA biosignatures into current and future life-detection instruments would be useful for the planetary search for life. PHAs are analysed and characterized in laboratories by gas chromatography-mass spectrometry, infrared spectroscopy, Raman spectroscopy and immunoassay analysis in addition to other methods. We outline a path forward to integrate PHA detection in astrobiology missions to aid the search for extraterrestrial life.

Recent arguments claim that behavioral science has focused – to its detriment – on the individual over the system when construing behavioral interventions. In this commentary, we argue that tackling economic inequality using both framings in tandem is invaluable. By studying individuals who have overcome inequality, “positive deviants,” and the system limitations they navigate, we offer potentially greater policy solutions.

Approximately 80 million people live with chronic hepatitis B virus (HBV) infection in the WHO Africa Region. The natural history of HBV infection in this population is poorly characterised, and may differ from patterns observed elsewhere due to differences in prevailing genotypes, environmental exposures, co-infections, and host genetics. Existing research is largely drawn from small, single-centre cohorts, with limited follow-up time. The Hepatitis B in Africa Collaborative Network (HEPSANET) was established in 2022 to harmonise the process of ongoing data collection, analysis, and dissemination from 13 collaborating HBV cohorts in eight African countries. Research priorities for the next 5 years were agreed upon through a modified Delphi survey prior to baseline data analysis being conducted. Baseline data on 4,173 participants with chronic HBV mono-infection were collected, of whom 38.3% were women and the median age was 34 years (interquartile range 28–42). In total, 81.3% of cases were identified through testing of asymptomatic individuals. HBeAg-positivity was seen in 9.6% of participants. Follow-up of HEPSANET participants will generate evidence to improve the diagnosis and management of HBV in this region.

Today’s floating-point arithmetic landscape is broader than ever. While scientific computing has traditionally used single precision and double precision floating-point arithmetics, half precision is increasingly available in hardware and quadruple precision is supported in software. Lower precision arithmetic brings increased speed and reduced communication and energy costs, but it produces results of correspondingly low accuracy. Higher precisions are more expensive but can potentially provide great benefits, even if used sparingly. A variety of mixed precision algorithms have been developed that combine the superior performance of lower precisions with the better accuracy of higher precisions. Some of these algorithms aim to provide results of the same quality as algorithms running in a fixed precision but at a much lower cost; others use a little higher precision to improve the accuracy of an algorithm. This survey treats a broad range of mixed precision algorithms in numerical linear algebra, both direct and iterative, for problems including matrix multiplication, matrix factorization, linear systems, least squares, eigenvalue decomposition and singular value decomposition. We identify key algorithmic ideas, such as iterative refinement, adapting the precision to the data, and exploiting mixed precision block fused multiply–add operations. We also describe the possible performance benefits and explain what is known about the numerical stability of the algorithms. This survey should be useful to a wide community of researchers and practitioners who wish to develop or benefit from mixed precision numerical linear algebra algorithms.

Background: Candida auris is an emerging multidrug-resistant yeast that is transmitted in healthcare facilities and is associated with substantial morbidity and mortality. Environmental contamination is suspected to play an important role in transmission but additional information is needed to inform environmental cleaning recommendations to prevent spread. Methods: We conducted a multiregional (Chicago, IL; Irvine, CA) prospective study of environmental contamination associated with C. auris colonization of patients and residents of 4 long-term care facilities and 1 acute-care hospital. Participants were identified by screening or clinical cultures. Samples were collected from participants’ body sites (eg, nares, axillae, inguinal creases, palms and fingertips, and perianal skin) and their environment before room cleaning. Daily room cleaning and disinfection by facility environmental service workers was followed by targeted cleaning of high-touch surfaces by research staff using hydrogen peroxide wipes (see EPA-approved product for C. auris, List P). Samples were collected immediately after cleaning from high-touch surfaces and repeated at 4-hour intervals up to 12 hours. A pilot phase (n = 12 patients) was conducted to identify the value of testing specific high-touch surfaces to assess environmental contamination. High-yield surfaces were included in the full evaluation phase (n = 20 patients) (Fig. 1). Samples were submitted for semiquantitative culture of C. auris and other multidrug-resistant organisms (MDROs) including methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus (VRE), extended-spectrum β-lactamase–producing Enterobacterales (ESBLs), and carbapenem-resistant Enterobacterales (CRE). Times to room surface contamination with C. auris and other MDROs after effective cleaning were analyzed. Results: Candida auris colonization was most frequently detected in the nares (72%) and palms and fingertips (72%). Cocolonization of body sites with other MDROs was common (Fig. 2). Surfaces located close to the patient were commonly recontaminated with C. auris by 4 hours after cleaning, including the overbed table (24%), bed handrail (24%), and TV remote or call button (19%). Environmental cocontamination was more common with resistant gram-positive organisms (MRSA and, VRE) than resistant gram-negative organisms (Fig. 3). C. auris was rarely detected on surfaces located outside a patient’s room (1 of 120 swabs; <1%). Conclusions: Environmental surfaces near C. auris–colonized patients were rapidly recontaminated after cleaning and disinfection. Cocolonization of skin and environment with other MDROs was common, with resistant gram-positive organisms predominating over gram-negative organisms on environmental surfaces. Limitations include lack of organism sequencing or typing to confirm environmental contamination was from the room resident. Rapid recontamination of environmental surfaces after manual cleaning and disinfection suggests that alternate mitigation strategies should be evaluated.

Funding: None

Disclosures: None

Background: Contact tracing alone is often inadequate to determine the source of healthcare personnel (HCP) COVID-19 when SARS-CoV-2 is widespread in the community. We combined whole-genome sequencing (WGS) with traditional epidemiologic analysis to investigate the frequency with which patients or other HCP with symptomatic COVID-19 acted as the source of HCP infection at a large tertiary-care center early in the pandemic. Methods: Cohort samples were selected from patients and HCP with PCR-positive SARS-CoV-2 infection from a period with complete retention of samples (March 14, 2021–April 10, 2020) at Rush University Medical Center, a 664-bed hospital in Chicago, Illinois. During this period, testing was limited to symptomatic patients and HCP. Recommended respiratory equipment for HCP evolved under guidance, including a 19-day period when medical face masks were recommended for COVID-19 care except for aerosol-generating procedures. Viral RNA was extracted and sequenced (NovaSeq, Illumina) from remnant nasopharyngeal swab samples in M4RT viral transport medium. Genomes with >90% coverage underwent cluster detection using a 2 single-nucleotide variant genetic distance cutoff. Genomic clusters were independently evaluated for valid epidemiologic links by 2 infectious diseases physicians (with a third adjudicator) using metadata extracted from the electronic medical record and according to predetermined criteria (Table 1). Results: In total, 1,031 SARS-CoV-2 sequences were analyzed, identifying 49 genomic clusters with HCP (median, 8; range, 2–43 members per cluster; total, 268 patients and 115 HCP) (Fig. 1). Also, 20,190 flowsheet activities were documented for cohort HCP and patient interactions, including 686 instances in which a cohort HCP contributed to a cohort patient’s chart. Most HCP infections were considered not healthcare associated (88 of 115, 76.5%). We did not identify any strong linkages for patient-to-HCP transmission. Moreover, 13 HCP cases (11.3%) were attributed to patient source (weak linkage). Also, 14 HCP cases (12.2%) were attributed to HCP source (11 strong and 3 weak linkages). Weak linkages were due to lack of epidemiologic data for HCP location, particularly nonclinical staff (eg, an environmental service worker who lacked location documentation to rule out patient-specific contact). Agreement for epidemiologic linkage between the 2 evaluators was high (κ, 0.91). Conclusions: Using genomic and epidemiologic data, we found that most HCP COVID-19 infections were not healthcare associated. We found weak evidence to support symptomatic patient-to-HCP transmission of SARS-CoV-2 and stronger evidence for HCP-to-HCP transmission. Large genomic clusters without plausible epidemiologic links were identified, reflecting the limited utility of genomic surveillance alone to characterize chains of transmission of SARS-CoV-2 during extensive community spread.

Funding: None

Disclosures: None

Transition care programmes (TCP) provide older adults with goal-oriented rehabilitation after hospitalisation. However, limited research has focused on understanding older adults' experiences when undertaking TCP. Using a phenomenological approach, we explored the lived experience of older adults undertaking a TCP at a transition care facility in Australia. A purposive sample (N = 33 participants: 16 older adults, four family members and 13 staff) was recruited. Semi-structured interviews were undertaken at three time-points during admission and inductive thematic analysis was utilised. Older adults reflected on their TCP experiences through an emotional lens through which they deliberated, ‘is my destination home?’ Fear of losing independence and uncertainty about their discharge destination strongly influenced older adults' perspectives regarding their TCP experience. Emotional responses, both positive and negative, were influenced by expectations prior to admission, level of family support and staff behaviour. Staff and family concurred that many older adults were confused about their admission to the facility and initially were unprepared to engage in the rehabilitation provided. Older adults experienced TCP as a time of great uncertainty and feared the unknown when discharged from hospital to transition care. They expressed grief at the loss of existing life roles and anxiety about the possibility of being unable to return home. Health professionals need to inform and tailor rehabilitation for older adults to better support this transient time of life.

A widely accepted assumption in both the syntactic and semantic literature is that copulas lack semantic content. A consequent question is how to explain the existence in certain languages of two copular verbs that give rise to different interpretations. Such is the case in numerous languages of the Dene family (formerly known as Athapaskan). We explain this situation with the hypothesis that the copulas realize an underlying three-copula system differing in argument structure. Differences between the interpretations of copular clauses in these languages originate in the compositional semantics of these structures, not in any lexical semantic differences.

This hypothesis successfully predicts the distributional differences between the surface forms of the Dene copulas, such as their compatibility with adjuncts of time and intentionality, interactions with accusative case, and semantic lifetime effects.