1,182 research outputs found

    Can Assisted Reproductive Technologies Help Conserve 300 Million Years of Evolution? A First Attempt at Developing These Technologies for Male Reptiles

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    Biodiversity loss is the most critical environmental problem threatening ecosystem, animal, and human health today. Increases in extinction rates have been observed over the past 50 years, with reptile losses occurring twelve times faster than traditional extinction rates. This demonstrated biodiversity loss is secondary to climate change, habitat destruction, infectious disease, invasive species, poaching, and unsustainable trade. Approximately 20% of all reptiles are threatened with extinction and population declines are approaching rates similar to the current amphibian extinction crisis. Preventing the extinction of reptiles will require humans to acknowledge these losses and develop plans to preserve these evolutionary sentinel species. Assisted reproductive technologies (ART) are well developed in a handful of species, and these technologies have become integral parts of conservation programs for threatened and endangered species. The creation of functional and sustainable reproductive assistance programs for reptiles using ART will strengthen our conservation capacity. Combining ART with an understanding of reproductive physiology will enable scientists to capture genetic material from different animals housed at different institutions, overcoming reproductive barriers. Subsequent gamete transport will reduce the need to transport animals from stressful or dangerous environments for breeding. Additionally, these gametes could be stored indefinitely to preserve genetic diversity. The goal of this research was to systematically apply ART to male reptiles. Semen was safely and successfully collected from veiled (Chamaeleo calyptratus) and panther chameleons (Furcifer pardalis) using electroejaculation. The annual reproductive cycles of these two chameleons were characterized under captive conditions, and both species follow season breeding cycles. Human chorionic gonadotropin can be used to increase circulating plasma testosterone concentrations in veiled chameleons. Short-term cooled semen storage can be done in red-eared sliders (Trachemys scripta elegans) and diamondback water snakes (Nerodia fasciata) using Ham’s F10, INRA 96, and sperm washing buffer; green anole (Anolis carolinensis) semen could not be stored using these same extenders. Red-eared slider turtle spermatozoa motility was lost following cryopreservation, but plasma membrane integrity remained. Reptile survival is dependent on how we plan today. ART will help us develop programs to preserve the genetics of these sentinel animals

    Chameleon radiation by oceanic dispersal

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    Historical biogeography is dominated by vicariance methods that search for a congruent pattern of fragmentation of ancestral distributions produced by shared Earth history(1-3). A focus of vicariant studies has been austral area relationships and the break-up of the supercontinent Gondwana(3-5). Chameleons are one of the few extant terrestrial vertebrates thought to have biogeographic patterns that are congruent with the Gondwanan break-up of Madagascar and Africa(6,7). Here we show, using molecular and morphological evidence for 52 chameleon taxa, support for a phylogeny and area cladogram that does not fit a simple vicariant history. Oceanic dispersal-not Gondwanan breakup-facilitated species radiation, and the most parsimonious biogeographic hypothesis supports a Madagascan origin for chameleons, with multiple 'out-of-Madagascar' dispersal events to Africa, the Seychelles, the Comoros archipelago, and possibly Reunion Island. Although dispersal is evident in other Indian Ocean terrestrial animal groups(8-16), our study finds substantial out-of-Madagascar species radiation, and further highlights the importance of oceanic dispersal as a potential precursor for speciation.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/62614/1/415784a.pd

    Chameleons in the early universe: kicks, rebounds, and particle production

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    Chameleon gravity is a scalar-tensor theory that includes a nonminimal coupling between the scalar field and the matter fields and yet mimics general relativity in the Solar System. The scalar degree of freedom is hidden in high-density environments because the effective mass of the chameleon scalar depends on the trace of the stress-energy tensor. In the early Universe, when the trace of the matter stress-energy tensor is nearly zero, the chameleon is very light, and Hubble friction prevents it from reaching the minimum of its effective potential. Whenever a particle species becomes nonrelativistic, however, the trace of the stress-energy tensor is temporarily nonzero, and the chameleon begins to roll. We show that these “kicks” to the chameleon field have catastrophic consequences for chameleon gravity. The velocity imparted to the chameleon by the kick is sufficiently large that the chameleon’s mass changes rapidly as it slides past its potential minimum. This nonadiabatic evolution shatters the chameleon field by generating extremely high-energy perturbations through quantum particle production. If the chameleon’s coupling to matter is slightly stronger than gravitational, the excited modes have trans-Planckian momenta. The production of modes with momenta exceeding 107 GeV can only be avoided for small couplings and finely tuned initial conditions. These quantum effects also significantly alter the background evolution of the chameleon field, and we develop new analytic and numerical techniques to treat quantum particle production in the regime of strong dissipation. This analysis demonstrates that chameleon gravity cannot be treated as a classical field theory at the time of big bang nucleosynthesis and casts doubt on chameleon gravity’s viability as an alternative to general relativity

    The stability of the iris as a biometric modality

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    In this thesis, the question of the stability of a group of individual subjects\u27 irises is examined and answered. This stability is examined in regards to the time scale of the month range. The covariate for this research was time. Images collected during one month of separation between captures were examined. The genuine and impostor scores for these images were calculated and then interpreted using the stability score index. This index produced a quantifiable value for the stability of iris match scores over the months of the examination. ^ Additionally, a new framework for collecting and analyzing time in biometrics was created called the biometric time model. This model, which examines inputs from the smallest of phases (subject interactions with a sensor) to the life of the system or user provides detail of user and system metrics that were before unascertainable. With this model, a better understanding of how system and user data that was collected in different time intervals relates. Finally, a proposed method of the consistent language of reporting time in future research is produced

    Understanding School Genres Using Systemic Functional Linguistics: A Study of Science and Narrative Texts

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    The purpose of this study is to examine elementary level textbooks (grades 2-4; Houghton Mifflin Harcourt Publishing; The Trophies Collection) using Systemic Functional Linguistics as the theoretical framework to study the different types of lexical choice and grammatical options made in the textbooks. The two genres examined are science and narrative, which are significantly different from each other. Science texts are “information based,” and narrative texts, “story based.” It is very important for teachers to understand how the genres are different so that they can convey those differences to their students. The two school genres, science and narrative, differ from each other in their lexicogrammatical features. These features can be analyzed and evaluated and then taught. An appraisal analysis identifies items that display the author’s attitude in the text, and a grammatical metaphor analysis identifies modes of expression displaying incongruency between the two levels of semantics and lexicogrammar. Evaluating appraisal items and understanding how grammatical metaphors are arranged within these texts can help differentiate some of the discourse semantic features of science or “informational” texts and narratives or “story” texts. The results of this analysis may help teachers during class instruction

    Interactive Training of the Emergency Medical Services Improved Prehospital Stroke Recognition and Transport Time

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    Funding Information: This study received funding from Boehringer Ingelheim GmbH & Co KG Lithuania. The funder was not involved in the study design, collection, analysis, interpretation of data, the writing of this article or the decision to submit for publication. The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. Funding Information: We greatly acknowledge the EMS staff for taking part in the training. LS was supported by the Swiss National Science Foundation postdoctoral scholarship (P2GEP3_191584). This article/publication is based on work from the IRENE COST Action—Implementation Research Network in Stroke Care Quality (CA18118), supported by COST (European Cooperation in Science and Technology; www.cost.eu ). Publisher Copyright: Copyright © 2022 Sveikata, Melaika, Wiśniewski, Vilionskis, Petrikonis, Stankevičius, Jurjans, Ekkert, Jatužis and Masiliūnas.Background and Purpose: Acute stroke treatment outcomes are predicated on reperfusion timeliness which can be improved by better prehospital stroke identification. We aimed to assess the effect of interactive emergency medical services (EMS) training on stroke recognition and prehospital care performance in a very high-risk cardiovascular risk population in Lithuania. Methods: We conducted a single-center interrupted time-series study between March 1, 2019 and March 15, 2020. Two-hour small-group interactive stroke training sessions were organized for 166 paramedics serving our stroke network. We evaluated positive predictive value (PPV) and sensitivity for stroke including transient ischemic attack identification, onset-to-door time, and hospital-based outcomes during 6-months prior and 3.5 months after the training. The study outcomes were compared between EMS providers in urban and suburban areas. Results: In total, 677 suspected stroke cases and 239 stroke chameleons (median age 75 years, 54.8% women) were transported by EMS. After the training, we observed improved PPV for stroke recognition (79.8% vs. 71.8%, p = 0.017) and a trend of decreased in-hospital mortality (7.8% vs. 12.3, p = 0.070). Multivariable logistic regression models adjusted for age, gender, EMS location, and stroke subtype showed an association between EMS stroke training and improved odds of stroke identification (adjusted odds ratio [aOR] 1.6 [1.1–2.3]) and onset-to-door ≤ 90 min (aOR 1.6 [1.1–2.5]). The improvement of PPV was observed in urban EMS (84.9% vs. 71.2%, p = 0.003), but not in the suburban group (75.0% vs. 72.6%, p = 0.621). Conclusions: The interactive EMS training was associated with a robust improvement of stroke recognition, onset to hospital transport time, and a trend of decreased in-hospital mortality. Adapted training strategies may be needed for EMS providers in suburban areas. Future studies should evaluate the long-term effects of the EMS training and identify optimal retraining intervals.publishersversionPeer reviewe

    Beware of chameleons – chameleons beware:the propriety of innovation as a concept for the coordination of novelty and change : insights from the Dutch outbound travel industry

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    Innovation is a taken-for-granted buzzword of modern society that is generally viewed as positive. The concept and its use in organisations have received limited scrutiny in the innovation literatures. This thesis therefore examines the propriety of innovation for the coordination of novelty and change. Using different theories premised on post-structuralist thought, it attempts to open up the concept of innovation. To this end, it examines an industry that has always been particularly prone to innovation and change: the Dutch travel industry. Drawing from three interrelated case studies conducted in this setting from 2016 to 2019, it examines the concept of innovation and its uses from up close. The first case study (The Machine) traces the development of a carbon management calculator for tour operators. This technology failed. Or did it not? The second case study (The Expert) examines how a PhD thesis on aviation-induced climate change impacted the Dutch aviation policy process and contributed to a new narrative on sustainable aviation in which technological innovation plays a prominent role. The third case study (The Firm) investigates the development of an innovation unit in a large, corporate tourism organisation (TUI) and illustrates how this unit ended up strengthening the organisational practices it set out to transform. The case studies present innovation as a collection of emergent, conflicting practices and communications that generate their own support and resistance. The thesis shows that innovation is highly political and sheds light on the paradox of innovation: attempts to create novelty can end up reinforcing the status quo. Promises of novel technologies can play a prominent role in this process.  The thesis draws attention to chameleons: actors that – like their reptilian equivalent – wittingly or unwittingly change colour to suit new dawns but remain their former shape. It concludes with directions that can help researchers and practitioners in better understanding and addressing these tricky creatures and questions if we should abandon the term innovation

    Quartic chameleons: Safely scale-free in the early Universe

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    In chameleon gravity, there exists a light scalar field that couples to the trace of the stress-energy tensor in such a way that its mass depends on the ambient matter density, and the field is screened in local, high-density environments. Recently it was shown that, for the runaway potentials commonly considered in chameleon theories, the field's coupling to matter and the hierarchy of scales between Standard Model particles and the energy scale of such potentials result in catastrophic effects in the early Universe when these particles become nonrelativistic. Perturbations with trans-Planckian energies are excited, and the theory suffers a breakdown in calculability at the relatively low temperatures of Big Bang Nucleosynthesis. We consider a chameleon field in a quartic potential and show that the scale-free nature of this potential allows the chameleon to avoid many of the problems encountered by runaway potentials. Following inflation, the chameleon field oscillates around the minimum of its effective potential, and rapid changes in its effective mass excite perturbations via quantum particle production. The quartic model, however, only generates high-energy perturbations at comparably high temperatures and is able remain a well-behaved effective field theory at nucleosynthesis
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