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Planktonic foraminifera regulate calcification according to ocean density
Get PDFFunding: S.D.Z. would like to acknowledge the UK Research and Innovation Grant (SODIOM) EP/Y004221/1. B.R.S. is funded by the NSF EAR Postdoc Fellowship 2305234. J.W.B.R. was supported by European Research Council Horizon 2020 research and innovation programme grant agreement No. 805246.Planktonic foraminifera are key contributors to the oceanic carbon cycle. In pelagic environments, carbonate production by planktonic biomineralizers regulates ocean-atmosphere carbon dioxide exchange and exports surface carbon to the deep ocean. Here we compare shell traits of three planktonic foraminifera species from the central Atlantic with a suite of environmental parameters to discern the factors underlying their variations. Our analysis revealed that calcification in foraminifera is associated with seawater density and depends on species habitat depth, whereas foraminifera bulk shell densities may serve as a seawater density proxy, regardless of species. We observe that their shell weights increased with habitat depth, enabling the living cells to adjust their overall density to match that of the surrounding liquid. This suggests that calcification in nonmotile organisms has a buoyancy regulatory function and will respond to the anthropogenically driven reductions in ocean density (oceanic rarefication), with potential consequences for the carbon cycle.Peer reviewe
Zebra stripes : the questions raised by the answers
Get PDFMultiple hypotheses have been suggested to explain why the three zebra species (Equus quagga, E. grevyi and E. zebra) are striped. We review how well these theories explain the nature (rather than simply the existence) of the stripes. Specifically, we explore how well different theories explain (i) the form of zebra stripes (especially on different body parts), (ii) stripe variation between zebra populations and among species, and (iii) the lack of striping in other equids or other large mammalian herbivores. The main hypotheses discussed during the last decade are the deterrence of biting flies, thermoregulation through stripe‐generated air movement, and three anti‐predation hypotheses: crypsis to avoid detection; dazzle colouration to confuse pursuers; and interspecies signalling to encourage protective mixed‐species herding. Our evaluation suggests that these theories struggle to explain all aspects of variation in striping. For each theory we identify where through logical reasoning or empirical data, the theory is unable to account for an aspect of variation, or whether information is currently lacking. In the latter case we offer concrete suggestions for the types of empirical study that would be most useful. Deterrence of biting flies is the theory that currently has strongest empirical support, but this theory alone struggles to explain why striping occurs so strongly in zebra but not in other African mammals, and the distribution of stripes across the body. These aspects can be explained by the interspecies signalling theory, but this theory has not been empirically evaluated. We suggest how future studies could best utilise our framework to close the most pressing knowledge gaps in our understanding of this iconic example of animal colouration.Peer reviewe
Investigating intentionality in elephant gestural communication
Get PDFFunding: This research was funded by an Austrian Science Fund (FWF) ‘DK Cognition and Communication 2’: W1262-B29 [10.55776/W1262] (V.E. and A.S.) and the European Union's 8th Framework Programme, Horizon 2020 [802719] (C.H.).A crucial feature of language is the ability to communicate cognitive goals to a specific audience, i.e. goal-directed intentionality. Core criteria for this ability include (i) audience directedness: signalling in the presence of an attentive audience, (ii) persistence: continuing signalling until goals are met, and (iii) elaboration: using new signals following communicative failure. While intentional use has been demonstrated in individual gestures in some non-primates, primates—in particular apes—show this ability across many gestures. But is goal-directed intentionality across many gestures restricted to primates? We explored whether savannah elephants use many gestures with goal-directed intentionality. We presented semi-captive elephants with desired and non-desired items, recording their communicative attempts when an experimenter met, partially met or failed to meet their goal of getting the desired item. Elephants used 38 gesture types almost exclusively when a visually attentive experimenter was present, demonstrating audience directedness. They persisted in gesturing more when their goal was partially as compared with fully met but showed no difference in persistence when the goal was met or not met. Elephants elaborated their gesturing when their goal was not met. We find goal-directed intentionality across many elephant gestures and reveal that elephants, like apes, assess the communicative effectiveness of their gesturing.Peer reviewe
The Hα sky in three dimensions
Get PDFFunding: LM acknowledges financial support from a UK-STFC PhD studentship. DK acknowledges support from HST-AR-17060 provided by NASA through a grant from the Space Telescope Science Institute, which is operated by the Association of 389 Universities for Research in Astronomy, Inc., under NASA 390 contract NAS5-26555. WHAM and LMH are supported by U.S. National Science Foundation award AST 2009276.We combine parallax distances to nearby O stars with parsec-scale resolution three-dimensional dust maps of the local region of the Milky Way (within 1.25 kpc of the Sun) to simulate the transfer of Lyman continuum photons through the interstellar medium (ISM). Assuming a fixed gas-to-dust ratio, we determine the density of ionized gas, electron temperature, and Hα emissivity throughout the local Milky Way. There is good morphological agreement between the predicted and observed Hα all-sky map of the Wisconsin Hα Mapper. We find that our simulation underproduces the observed Hα emission while overestimating the sizes of H II regions, and we discuss ways in which agreement between simulations and observations may be improved. Of the total ionizing luminosity of 5.84 × 1050 photons s−1, 15 per cent is absorbed by dust, 64 per cent ionizes ‘classical’ H II regions, 11 per cent ionizes the diffuse warm ionized medium, and 10 per cent escapes the simulation volume. We find that 18 per cent of the high-altitude (|b| > 30◦) Hα arises from dust scattered rather than direct emission. These initial results provide an impressive validation of the three-dimensional dust maps and O-star parallaxes, opening a new frontier for studying the ionized ISM’s structure and energetics in three dimensions.Peer reviewe
The effect of depth on the composition and saturation of total fatty acids present within the tissues and skeletons of two reef-building corals
Get PDFFunding: This work was supported by a University of St. Andrews’ St. Leonard’s Scholarship and received funding from the MASTS (Marine Alliance for Science and Technology for Scotland) pooling initiative and their support is gratefully appreciated. MASTS is funded by the Scottish Funding Council (grant reference HR09011) and contributing institutions.Coral lipids and their fatty acid (FA) constituents fulfil a variety of biological functions. Here we report the FA compositions of the total lipids in the tissues and skeletons of Acropora retusa and Pocillopora meandrina at two water depths (5 and 25 m) in Mo’orea, French Polynesia. Saturated FAs C16:0 and C18:0, commonly associated with storage lipids and cell membrane phospholipids, are the dominant FAs within both the tissues and skeletons of both coral species. Polyunsaturated FAs in this study are usually only detected in coral tissues at 5 m depth. Unsaturated FAs contribute significantly more to the total FA pool at 5 m than at 25 m in the tissues of both coral species and in A. retusa compared to P. meandrina at 5 m depth. Unsaturated FAs are involved in regulating membrane structure fluidity and stress resistance. Their increased presence in shallow corals may be a response to the more variable seawater temperatures recorded at this depth, and/or may be attributed to different feeding strategies, possibly due to varying light intensities between depths. Previous research indicates that shallow water corals at the study site are more prone to bleaching, and that Acropora spp. may be more sensitive than Pocillopora spp. Variations in tissue FA composition may relate to this bleaching sensitivity, as unsaturated FAs are susceptible to lipid peroxidation caused by the presence of reactive oxygen species (ROS). Overall, the contributions of FAs to the total FA pool are similar between the tissues and skeletons suggesting a lack of active regulation of FAs within the coral skeleton.Peer reviewe
Exploring reasons for popular support of spontaneous vigilantism
No full textThis thesis examines the reasons why people engage in spontaneous vigilantism, where it often takes place, why the act itself appears spontaneous, and whether there are individual differences in predicting support for it. Prior research, reviewed in chapters 2 and 3, has demonstrated that people mostly engage and/or support spontaneous vigilantism when law enforcement is not established or, even if established, are inadequate, ineffective and/or unfair. Some researchers like Brown (1975) see vigilantism as a positive act where citizens cooperate for self-protection under conditions of disorder (p.130). However, Sederberg & Rosenberg (1976) argue otherwise, maintaining that vigilantism is a form of politics with three purposes: crime control, social group control and regime change. Johnston (1996) thinks it is too broad a conceptualisation of vigilantism if actions of state authorities against its citizens are considered vigilantism. This thesis investigated vigilantism done with or on behalf of the state in the form of neighbourhood watches and informal vigilante groups (with a focus on the latter due to the spontaneous nature of their activities).
Ethnographic research conducted in Ghana (chapter 4) finds that rather than mere police effectiveness (which was a factor), the existence of legal orders in one social field (termed legal pluralism) meant that residents chose who to resolve their cases for them. Claims of ineffective police, though true, were mainly a rhetorical strategy to legitimise community leaders. Surveys conducted in Ghana, Nigeria and the U.K. (chapter 5) find that pro-vigilantism norms, rather than police effectiveness or unfairness, predict participants’ support for vigilantism in all three countries. Survey evidence from the U.K. (chapter 6) finds that authoritarianism and having a dangerous worldview were the individual differences predicting support for spontaneous vigilantism and suggests that vigilantism thrives in frontiers by creating a dangerous worldview and predicting support for spontaneous vigilantism
Resolutions of toric subvarieties by line bundles and applications
Get PDFFunding: AH was supported by NSF RTG grant DMS-1547145 and by the Simons Foundation (Grant Number 814268 via the Mathematical Sciences Research Institute, MSRI). JH was supported by EPSRC Grant EP/V049097/1.Given any toric subvariety Y of a smooth toric variety X of codimension k, we construct a length k resolution of O by line bundles on X. Furthermore, these line bundles can all be chosen to be direct summands of the pushforward of O under the map of toric Frobenius. The resolutions are built from a stratification of a real torus that was introduced by Bondal and plays a role in homological mirror symmetry. As a corollary, we obtain a virtual analogue of Hilbert’s syzygy theorem for smooth projective toric varieties conjectured by Berkesch, Erman and Smith. Additionally, we prove that the Rouquier dimension of the bounded derived category of coherent sheaves on a toric variety is equal to the dimension of the variety, settling a conjecture of Orlov for these examples. We also prove Bondal’s claim that the pushforward of the structure sheaf under toric Frobenius generates the derived category of a smooth toric variety and formulate a refinement of Uehara’s conjecture that this remains true for arbitrary line bundles.Peer reviewe
Low-dose sulfonylurea plus DPP4 inhibitor lower blood glucose and enhance beta-cell function without hypoglycemia
Get PDFFunding: This research was funded by a Wellcome Trust New Investigator Award to E.R.P. (102820/Z/13/Z).Context: Low-dose sulfonylureas (SUs) have been found to augment the classical incretin effect, increase glucose sensitivity and late phase incretin potentiation. Objective: To evaluate potential synergy between low-dose SU plus a dipeptidyl peptidase 4 (DPP4) inhibitor. Methods: Unblinded randomized crossover study at the Clinical Research Centre, University of Dundee. Thirty participants with T2DM (HbA1c < 64 mmol/mol) were treated with diet or metformin. Participants completed 4, 14-day blocks in a random order: control, gliclazide 20 mg (SU), sitagliptin 100 mg (DPP4 inhibitor [DPP4i]), or combination (SUDPP4i). A mixed meal test was conducted after each intervention. The primary outcome was the effect of treatment on beta-cell glucose sensitivity. Secondary outcomes included frequency of glucose <3 mmol/L on continuous glucose monitoring, subanalyses by genotype (KNCJ11 E23K), gender, and body mass index. Results: SU combination with DPP4i showed additive effect on glucose lowering: mean glucose area under the curve (mean 95% CI) (mmol/L) was control 11.5 (10.7-12.3), DPP4i 10.2 (9.4-11.1), SU 9.7 (8.9-10.5), SUDPP4i 8.7 (7.9-9.5) (P < .001). Glucose sensitivity mirrored the additive effect (pmol min-1 m-2 mM-1): control 71.5 (51.1-91.9), DPP4i 75.9 (55.7-96.0), SU 86.3 (66.1-106.4), SUDPP4i 94.1 (73.9-114.3) (P = .04). The additive effect was seen in men but not women. Glucose time in range <3 mmol/L on continuous glucose monitoring (%) was unaffected: control 1 (2-4), DPP4i 2 (3-6), SU 1 (0-4), SUDPP4i 3 (2-7) (P = .65). Conclusion: Low-dose sulfonylurea plus DPP4i has a potent glucose-lowering effect through augmentation of beta-cell function. A double-blind randomized controlled trial would formalize efficacy and safety of this combination, which may avoid negative aspects of SU.Peer reviewe
Socioecological drivers of injuries and aggression in female and male rhesus macaques (Macaca mulatta)
Get PDFFunding: This work was supported by ANID-Chilean scholarship [number 72190290], the National Institutes of Health [grant R01AG060931 to NS-M, LJNB, and JPH, R00AG051764 to NS-M], a European Research Council Consolidator Grant to LJNB [Friend Origins 864461], a MacCracken Fellowship to CMK, and a National Science Foundation Doctoral Dissertation Research Improvement Grant to CMK [1919784]. The CPRC is supported by the National Institutes of Health. An Animal and Biological Material Resource Center Grant [P40OD012217] was awarded to the UPR from the Office of Research Infrastructure Programs, National Institutes of Health (ORIP).Competition over access to resources, such as food and mates, is one of the major costs associated with group living. Two socioecological factors believed to drive the intensity of competition are group size and sex ratio. However, empirical evidence linking these factors to physical aggression and injuries is scarce. Here, we leveraged 10 years of data from free-ranging female and male rhesus macaques to test whether group size and adult sex ratio predicted the risk of inter and intrasexual aggression, as well as injury risk. We found evidence for an optimal group size at which the risk of intragroup aggression was minimized for both sexes. Despite male-male aggression being lowest in mid-sized groups, males in smaller groups experienced higher injury risk, suggesting within-group aggression might not be the main cause of male injury. Additionally, we found that sex ratio influenced aggression, but not injury risk. Specifically, female aggression toward other females was heightened during the birth season when groups had fewer available males, suggesting either female competition for male friends or exacerbated female-female competition due to the energetic costs of lactation. Male aggression towards females was higher in female-biased groups during the birth season and in male-biased groups during the mating season, which could reflect male competition with females over feeding opportunities and male coercion of females, respectively. Together, these findings provide insights into fitness costs (i.e., injury risk) of inter and intrasexual competition in primates in relation to key aspects of social organization.Peer reviewe
Assessment of decision-making with locally run and web-based large language models versus human board recommendations in otorhinolaryngology, head and neck surgery
Get PDFIntroduction Tumor boards are a cornerstone of modern cancer treatment. Given their advanced capabilities, the role of Large Language Models (LLMs) in generating tumor board decisions for otorhinolaryngology (ORL) head and neck surgery is gaining increasing attention. However, concerns over data protection and the use of confidential patient information in web-based LLMs have restricted their widespread adoption and hindered the exploration of their full potential. In this first study of its kind we compared standard human multidisciplinary tumor board recommendations (MDT) against a web-based LLM (ChatGPT-4o) and a locally run LLM (Llama 3) addressing data protection concerns. Material and methods Twenty-five simulated tumor board cases were presented to an MDT composed of specialists from otorhinolaryngology, craniomaxillofacial surgery, medical oncology, radiology, radiation oncology, and pathology. This multidisciplinary team provided a comprehensive analysis of the cases. The same cases were input into ChatGPT-4o and Llama 3 using structured prompts, and the concordance between the LLMs' and MDT’s recommendations was assessed. Four MDT members evaluated the LLMs' recommendations in terms of medical adequacy (using a six-point Likert scale) and whether the information provided could have influenced the MDT's original recommendations. Results ChatGPT-4o showed 84% concordance (21 out of 25 cases) and Llama 3 demonstrated 92% concordance (23 out of 25 cases) with the MDT in distinguishing between curative and palliative treatment strategies. In 64% of cases (16/25) ChatGPT-4o and in 60% of cases (15/25) Llama, identified all first-line therapy options considered by the MDT, though with varying priority. ChatGPT-4o presented all the MDT’s first-line therapies in 52% of cases (13/25), while Llama 3 offered a homologous treatment strategy in 48% of cases (12/25). Additionally, both models proposed at least one of the MDT's first-line therapies as their top recommendation in 28% of cases (7/25). The ratings for medical adequacy yielded a mean score of 4.7 (IQR: 4–6) for ChatGPT-4o and 4.3 (IQR: 3–5) for Llama 3. In 17% of the assessments (33/200), MDT members indicated that the LLM recommendations could potentially enhance the MDT's decisions. Discussion This study demonstrates the capability of both LLMs to provide viable therapeutic recommendations in ORL head and neck surgery. Llama 3, operating locally, bypasses many data protection issues and shows promise as a clinical tool to support MDT decisions. However at present, LLMs should augment rather than replace human decision-making.Peer reviewe
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