The emergence of life from nonlife, or abiogenesis, remains a fundamental question in scientific inquiry. In this article, we investigate the probability of the origin of life (per conducive site) by leveraging insights from Earth's environments. If life originated endogenously on Earth, its existence is indeed endowed with informative value, although the interpretation of the attendant significance hinges critically upon prior assumptions.
View Article and Find Full Text PDFAstrobiology
January 2024
The ubiquity of information transmission via molecular communication between cells is comprehensively documented on Earth; this phenomenon might even have played a vital role in the origin(s) and early evolution of life. Motivated by these considerations, a simple model for molecular communication entailing the diffusion of signaling molecules from transmitter to receiver is elucidated. The channel capacity (maximal rate of information transmission) and an optimistic heuristic estimate of the actual information transmission rate are derived for this communication system; the two quantities, especially the latter, are demonstrated to be broadly consistent with laboratory experiments and more sophisticated theoretical models.
View Article and Find Full Text PDFInformation transmission via communication between agents is ubiquitous on Earth, and is a vital facet of living systems. In this paper, we aim to quantify this rate of information transmission associated with Earth's biosphere and technosphere (i.e.
View Article and Find Full Text PDFFront Psychol
February 2022
Many models have posited that the concomitant evolution of large brains and body sizes in hominins was constrained by metabolic costs. In such studies, the impact of body temperature has arguably not been sufficiently addressed despite the well-established fact that the rates of most physiological processes are manifestly temperature-dependent. Hence, the potential role of body temperature in regulating the number of neurons and body size is investigated by means of a heuristic quantitative model.
View Article and Find Full Text PDFThe capacity to sense gradients efficiently and acquire information about the ambient environment confers many advantages such as facilitating movement toward nutrient sources or away from toxic chemicals. The amplified dispersal evinced by organisms endowed with motility is possibly beneficial in related contexts. Hence, the connections between information acquisition, motility, and microbial size are explored from an explicitly astrobiological standpoint.
View Article and Find Full Text PDFBackground: Randomized trials of complex interventions are increasingly including qualitative components to further understand factors that contribute to their success. In this paper, we explore the experiences of health care practitioners in a province wide smoking cessation program (the Smoking Treatment for Ontario Patients program) who participated in the COMBAT trial. This trial examined if the addition of an electronic prompt embedded in a Clinical Decision Support System (CDSS)-designed to prompt practitioners to Screen, provide a Brief intervention and Referral to Treatment (SBIRT) to patients who drank alcohol above the amounts recommended by the Canadian Cancer Society guidelines-influenced the proportion of practitioners delivering a brief intervention to their eligible patients.
View Article and Find Full Text PDFBackground: Modifiable risk factors such as tobacco use, physical inactivity, and poor diet account for a significant proportion of the preventable deaths in Canada. These factors are also known to cluster together, thereby compounding the risks of morbidity and mortality. Given this association, smoking cessation programs appear to be well-suited for integration of health promotion activities for other modifiable risk factors.
View Article and Find Full Text PDFWe estimate the relative likelihood of success in the searches for primitive versus intelligent life on other planets. Taking into account the larger search volume for detectable artificial electromagnetic signals, we conclude that both searches should be performed concurrently, albeit with significantly more funding dedicated to primitive life. Based on the current federal funding allocated to the search for biosignatures, our analysis suggests that the search for extraterrestrial intelligence (SETI) may merit a federal funding level of at least $10 million per year, assuming that the average lifetime of technological species exceeds a millennium.
View Article and Find Full Text PDFAs evident from the nearby examples of Proxima Centauri and TRAPPIST-1, Earth-sized planets in the habitable zone of low-mass stars are common. Here, we focus on such planetary systems and argue that their (oceanic) tides could be more prominent due to stronger tidal forces. We identify the conditions under which tides may exert a significant positive influence on biotic processes including abiogenesis, biological rhythms, nutrient upwelling, and stimulating photosynthesis.
View Article and Find Full Text PDFProc Natl Acad Sci U S A
January 2018
The presence of an atmosphere over sufficiently long timescales is widely perceived as one of the most prominent criteria associated with planetary surface habitability. We address the crucial question of whether the seven Earth-sized planets transiting the recently discovered ultracool dwarf star TRAPPIST-1 are capable of retaining their atmospheres. To this effect, we carry out numerical simulations to characterize the stellar wind of TRAPPIST-1 and the atmospheric ion escape rates for all of the seven planets.
View Article and Find Full Text PDFWe present a simple model for estimating the probability of interplanetary panspermia in the recently discovered system of seven planets orbiting the ultracool dwarf star TRAPPIST-1 and find that panspermia is potentially orders of magnitude more likely to occur in the TRAPPIST-1 system compared with the Earth-to-Mars case. As a consequence, we argue that the probability of abiogenesis is enhanced on the TRAPPIST-1 planets compared with the solar system. By adopting models from theoretical ecology, we show that the number of species transferred and the number of life-bearing planets are also likely to be higher because of the increased rates of immigration.
View Article and Find Full Text PDFUnlabelled: In this paper, percolation theory is employed to place tentative bounds on the probability p of interstellar travel and the emergence of a civilization (or panspermia) that colonizes the entire Galaxy. The ensuing ramifications with regard to the Fermi paradox are also explored. In particular, it is suggested that the correlation function of inhabited exoplanets can be used to observationally constrain p in the near future.
View Article and Find Full Text PDFA biphasic gastroretentive floating drug delivery system with multiple-unit mini-tablets based on gas formation technique was developed to maintain constant plasma level of a drug concentration within the therapeutic window. The system consists of loading dose as uncoated core units, and prolonged-release core units are prepared by direct compression process; the latter were coated with three successive layers, one of which is seal coat, an effervescent (sodium bicarbonate) layer, and an outer polymeric layer of polymethacrylates. The formulations were evaluated for quality control tests, and all the parameters evaluated were within the acceptable limits.
View Article and Find Full Text PDFThe purpose of this research was to investigate novel particulate carrier systems such as solid lipid nanoparticles (SLN) and nanostructured lipid carrier (NLC) for transdermal delivery of nitrendipine (NDP). For this investigation, four different gel-forming agents were selected for hydrogel preparation. Aqueous dispersions of lipid nanoparticles made from trimyristin (TM) were prepared by hot homogenization technique followed by sonication and then incorporated into the freshly prepared hydrogels.
View Article and Find Full Text PDFThe aim of the investigation is to develop solid lipid nanoparticles (SLN) and nano-structured lipid carrier (NLC) as carriers for topical delivery of nitrendipine (NDP). NDP-loaded SLN and NLC were prepared by hot homogenization technique followed by sonication, and they were characterized for particle size, zeta potential, entrapment efficiency, stability, and in vitro release profiles. Also the percutaneous permeation of NDPSLN A, NDPSLN B, and NDPNLC were investigated in abdominal rat skin using modified Franz diffusion cells.
View Article and Find Full Text PDFObjectives: the tissue renin-angiotensin system (RAS), which plays an important role in vascular structure and function, is regulated in part by an insertion-deletion polymorphism of the angiotensin converting enzyme (ACE) gene. We hypothesised that ACE genotype might affect rate of AAA expansion via modulating long-term structural changes associated with RAS activation.
Methods: fifty-eight patients (50 M, mean age 70 years, mean initial aneurysm size 4.
J Am Coll Surg
September 1999
Background: Acquired abnormalities of the biliary tract from chronic gallstone disease are rare. The aim of this study was to examine the frequency with which these abnormalities occur and to assess the probability of encountering such an abnormality at laparoscopic cholecystectomy.
Study Design: We conducted a prospective study of all patients undergoing elective and emergency cholecystectomy under the care of one surgeon between January 1991 and December 1997.
We report our experience with the technique of lymphatic mapping using patent blue V dye in patients with limb malignant melanoma. The technique is based on the hypothesis that embolic metastases occur along lymphatic channels to a 'sentinel' lymph node: the draining lymph node nearest the site of the primary malignant melanoma. Patent blue V dye (0.
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