ABSTRACT
We describe herein a simple procedure for quantifying endospore abundances in ancient and organic-rich permafrost. We repeatedly (10x) extracted and fractionated permafrost using a tandem filter assembly composed of 3 and 0.2 µm filters. Then, the 0.2 µm filter was washed (7x), autoclaved, and the contents eluted, including dipicolinic acid (DPA). Time-resolved luminescence using Tb(EDTA) yielded a LOD of 1.46 nM DPA (6.55 × 103 endospores/mL). In review, DPA/endospore abundances were ~2.2-fold greater in older 33 ky permafrost (258 ± 36 pmol DPA gdw-1; 1.15 × 106 ± 0.16 × 106 spores gdw-1) versus younger 19 ky permafrost (p = 0.007297). This suggests that dormancy increases with permafrost age.
Subject(s)
Permafrost/chemistry , Spectrometry, Fluorescence/methods , Spores, Bacterial/chemistry , Spores, Bacterial/isolation & purification , Chelating Agents/analysis , Chelating Agents/chemistry , Chelating Agents/isolation & purification , Picolinic Acids/analysis , Picolinic Acids/chemistry , Picolinic Acids/isolation & purification , Terbium/chemistryABSTRACT
On November 5-8, 2019, the "Mars Extant Life: What's Next?" conference was convened in Carlsbad, New Mexico. The conference gathered a community of actively publishing experts in disciplines related to habitability and astrobiology. Primary conclusions are as follows: A significant subset of conference attendees concluded that there is a realistic possibility that Mars hosts indigenous microbial life. A powerful theme that permeated the conference is that the key to the search for martian extant life lies in identifying and exploring refugia ("oases"), where conditions are either permanently or episodically significantly more hospitable than average. Based on our existing knowledge of Mars, conference participants highlighted four potential martian refugium (not listed in priority order): Caves, Deep Subsurface, Ices, and Salts. The conference group did not attempt to reach a consensus prioritization of these candidate environments, but instead felt that a defensible prioritization would require a future competitive process. Within the context of these candidate environments, we identified a variety of geological search strategies that could narrow the search space. Additionally, we summarized a number of measurement techniques that could be used to detect evidence of extant life (if present). Again, it was not within the scope of the conference to prioritize these measurement techniques-that is best left for the competitive process. We specifically note that the number and sensitivity of detection methods that could be implemented if samples were returned to Earth greatly exceed the methodologies that could be used at Mars. Finally, important lessons to guide extant life search processes can be derived both from experiments carried out in terrestrial laboratories and analog field sites and from theoretical modeling.
Subject(s)
Exobiology , Extraterrestrial Environment , Mars , Caves , Computer Simulation , Ice , Space FlightSubject(s)
Orthohantavirus/isolation & purification , Peromyscus/virology , Sigmodontinae/virology , Animals , Female , Humans , Male , PrevalenceABSTRACT
From the earliest recorded history, people with disabilities have been ostracized, rejected, and discriminated against in society. Although social work has a history rich in advocacy for oppressed people, the profession has been hesitant to become involved with people with disabilities. This article addresses historical and contemporary issues concerning disability. Recent developments in the disability movement, including independent living, are discussed and compared to social work's approaches to disability. Finally, a plea is made to the social work profession and the disability movement to combine efforts to enhance the lives of people with disabilities.
Subject(s)
Disabled Persons , Social Work/trends , Activities of Daily Living , Attitude to Health , History, 17th Century , History, 18th Century , History, 20th Century , History, Ancient , History, Medieval , Humans , Minority Groups , Patient Advocacy , Religion and Medicine , Social Values , Social Work/history , Social Work/organization & administrationABSTRACT
The psychological perspective of disability views the extent of disability as substantially determined by the availability of essential resources in the physical and social environments of people with disabilities. This article reports the findings of a study of the post-hospital adjustment of individuals treated for injuries that produced paraplegia or quadriplegia. Comparisons of emotional and social adjustments were made between groups of respondents contrasted by size of community, independent living vs. physical dependence, employment status, and degree of social interaction. Resultant data documented the critical importance of these ecological variables. Practice implications of the findings are discussed.
