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1.
Sci Rep ; 14(1): 20686, 2024 09 05.
Artigo em Inglês | MEDLINE | ID: mdl-39237604

RESUMO

The warming of the Arctic had lead to a diverse range of impacts on local biota, including northward shifts of some species range. Here, we report past and present distribution and abundance of an Arctic zooplanktivorous seabird, the little auk Alle alle in West Greenland south of 74° N, and examine the changes in sea surface temperature (SST) and sea ice concentration (SIC) in the birds foraging areas in 1850-2007. We estimated the little auk population in the studied region to be 5,200 pairs in the 1930s, 6,000-6,500 pairs in the 1940-1970s and 70-80 pairs by the 2000s. We found that periods with increased SST and reduced SIC, especially in the last few decades, coincided with little auk population declines. Besides, years with little auk presence in breeding sites were characterized by either low SST and low to moderate SIC or higher SST but moderate to high SIC. Observed contraction of the breeding range and a decrease in abundance of the little auk may be attributed to more complex climate-driven changes in the marine ecosystem at finer spatial and temporal scales and/or cannot be easily detected given the coarseness of data used. It is possible that the population in this region has never been very numerous being subjected to local impacts such as disease, bycatch, predation, etc. The climate warming that is currently being observed, along with corresponding shifts in zooplankton communities, may lead to extirpation of the studied little auk populations.


Assuntos
Ecossistema , Animais , Groenlândia , Regiões Árticas , Mudança Climática , Camada de Gelo , Dinâmica Populacional , Temperatura , Charadriiformes/fisiologia
2.
J Am Heart Assoc ; 13(15): e034529, 2024 Aug 06.
Artigo em Inglês | MEDLINE | ID: mdl-39056329

RESUMO

BACKGROUND: Ticagrelor is recommended over clopidogrel in acute coronary syndrome based on the results of the PLATO (Study of Platelet Inhibition and Patient Outcomes) trial. We aimed to emulate PLATO in older adults with and without frailty and with acute coronary syndrome treated with percutaneous coronary intervention. METHODS AND RESULTS: We created a new-user cohort of Medicare fee-for-service beneficiaries aged ≥65 years hospitalized for acute coronary syndrome from 2014 to 2018 and initiated ticagrelor or clopidogrel following percutaneous coronary intervention. Frailty was defined using a validated claims-based frailty index ≥0.25. Coprimary outcomes were major adverse cardiovascular events and major bleeding. Follow-up began on the date of first outpatient prescription for ticagrelor or clopidogrel and ended on the earliest date for an outcome event, death, discontinuation of the index drug, or disenrollment from Medicare. The study included 42 843 older adults; 23% were frail. After propensity score matching, the rates of major adverse cardiovascular events per 100 person-years comparing ticagrelor versus clopidogrel groups were 7.8 and 7.3 in the frail cohort (hazard ratio [HR], 1.07 [95% CI, 0.84-1.36]) and 3.7 and 4.2 in the nonfrail cohort (HR, 0.87 [95% CI, 0.75-1.02]). The corresponding rates of major bleeding were 4.3 and 3.8 in the frail cohort (HR, 1.12 95% CI, [0.80-1.56]) and 2.2 and 1.8 in the nonfrail cohort (HR, 1.22 [95% CI, 0.98-1.51]). CONCLUSIONS: There was a trend toward a modest reduction in risk of major adverse cardiovascular events and a trend toward a modest increase in risk of major bleeding with ticagrelor compared with clopidogrel in the nonfrail cohort. There was insufficient evidence for the benefit of ticagrelor in frail older adults.


Assuntos
Clopidogrel , Infarto do Miocárdio , Intervenção Coronária Percutânea , Inibidores da Agregação Plaquetária , Ticagrelor , Humanos , Ticagrelor/uso terapêutico , Ticagrelor/efeitos adversos , Clopidogrel/uso terapêutico , Clopidogrel/efeitos adversos , Idoso , Feminino , Masculino , Inibidores da Agregação Plaquetária/uso terapêutico , Inibidores da Agregação Plaquetária/efeitos adversos , Infarto do Miocárdio/tratamento farmacológico , Infarto do Miocárdio/mortalidade , Estados Unidos/epidemiologia , Idoso de 80 Anos ou mais , Resultado do Tratamento , Fragilidade/complicações , Fragilidade/diagnóstico , Medicare , Idoso Fragilizado , Hemorragia/induzido quimicamente , Medição de Risco , Fatores de Risco , Síndrome Coronariana Aguda/tratamento farmacológico , Síndrome Coronariana Aguda/mortalidade
3.
Appetite ; 201: 107550, 2024 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-38880283

RESUMO

This mixed-methods cross-sectional study examines food consumption patterns, dietary diversity, and factors affecting food intake and malnutrition in the rural Mbale District in Eastern Uganda, during both wet and dry seasons. Participants (n = 100; 66% females) completed a food frequency questionnaire identifying foods and beverages consumed in the preceding 12 months. Individual interviews (n = 8) were conducted with key workers. Analysis of seventeen food items revealed seasonal variations in carbohydrate and protein sources. During the dry season, staples like matooke (mashed boiled plantains) and sweet and Irish potatoes were affected, while protein-rich foods such as beans and groundnuts saw increased consumption in the wet season. Fruit and vegetable intake also rose during the wet season. The main causes of malnutrition that emerged from the interviews were the lack of knowledge about food and nutrition, financial struggles, climate impact, and cultural beliefs. The last theme covered strategies to combat malnutrition. Although carbohydrate intake remains consistent throughout seasons due to reliance on posho (maize flour porridge) and cassava, variations in the number of meals and protein sources, particularly beans and groundnuts, were observed. Both of these, being the primary protein sources in rural households' diets, are highly susceptible to climate fluctuations. This may pose significant implications for food security, as heightened climate instability may impede their production. Solutions to combat malnutrition discussed by the interviewees include education, employment, family planning, and healthcare improvements. Professionals emphasise the need for comprehensive approaches to address these complex issues. In addition, data on food consumption during the dry and wet seasons should be collected as a difference in food consumption during the seasons may become more prominent with the need to implement tailored interventions.


Assuntos
Dieta , Comportamento Alimentar , Desnutrição , População Rural , Estações do Ano , Humanos , Estudos Transversais , Uganda , Feminino , Masculino , População Rural/estatística & dados numéricos , Adulto , Dieta/estatística & dados numéricos , Desnutrição/epidemiologia , Pessoa de Meia-Idade , Adulto Jovem , Adolescente , Inquéritos sobre Dietas
4.
J Prosthet Dent ; 2024 Apr 17.
Artigo em Inglês | MEDLINE | ID: mdl-38637193

RESUMO

Nasal obturation using a removable medical device is a suitable treatment option for patients with velopharyngeal dysfunction. In the United Kingdom in recent years, the use of nasal obturation has increased because of the successful collaborations among the Speech and Language Therapy, Restorative Dentistry, and Maxillofacial departments. However, fabrication of the devices requires specialist skill and considerable time. A digital process which facilitates the rapid, cost effective production of a light, comfortable, unobtrusive nasal obturator is described.

6.
Innov Surg Sci ; 8(3): 159-183, 2023 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-38077487

RESUMO

Objectives: This article describes the many anomalies within and outside the head and neck of hemifacial microsomia (HFM). Methods: The OMENS+ classification system is described with particular reference to the mandibular features classified by Pruzansky and modified by Kaban. The application of virtual surgical planning (VSP) to HFM, largely in children, is described and taken through to aspects indicated in maturity. Results: VSP is demonstrated with clinical cases examples in HFM patients for (1) grafts and flaps replacing missing parts of the zygomatic bone, temporo-mandibular joint and mandible, (2) distraction osteogenesis for lengthening of the mandibular ramus, advancement of the mandibular body, widening of the face and simultaneous mid-face and mandibular rotation, (3) implants and correction of microtia for bone anchored ear prostheses, (4) correction of microtia by autogenous ear construction, and (5) end stage rotational bimaxillary osteotomies. Conclusions: 3D virtual and physical planning is a valuable adjunct to the treatment of this complex condition.

7.
J Am Chem Soc ; 145(41): 22814-22825, 2023 Oct 18.
Artigo em Inglês | MEDLINE | ID: mdl-37797311

RESUMO

Isolated dysprosocenium cations, [Dy(CpR)2]+ (CpR = substituted cyclopentadienyl), have recently been shown to exhibit superior single-molecule magnet (SMM) properties over closely related complexes with equatorially bound ligands. However, gauging the crossover point at which the CpR substituents are large enough to prevent equatorial ligand binding, but small enough to approach the metal closely and generate strong crystal field splitting has required laborious synthetic optimization. We therefore created the computer program AtomAccess to predict the accessibility of a metal binding site and its ability to accommodate additional ligands. Here, we apply AtomAccess to identify the crossover point for equatorial coordination in [Dy(CpR)2]+ cations in silico and hence predict a cation that is at the cusp of stability without equatorial interactions, viz., [Dy(Cpttt)(Cp*)]+ (Cpttt = C5H2tBu3-1,2,4, Cp* = C5Me5). Upon synthesizing this cation, we found that it crystallizes as either a contact ion-pair, [Dy(Cpttt)(Cp*){Al[OC(CF3)3]4-κ-F}], or separated ion-pair polymorph, [Dy(Cpttt)(Cp*)][Al{OC(CF3)3}4]·C6H6. Upon characterizing these complexes, together with their precursors, yttrium and yttrium-doped analogues, we find that the contact ion-pair shows inferior SMM properties to the separated ion-pair, as expected, due to faster Raman and quantum tunneling of magnetization relaxation processes, while the Orbach region is relatively unaffected. The experimental verification of the predicted crossover point for equatorial coordination in this work tests the limitations of the use of AtomAccess as a predictive tool and also indicates that the application of this type of program shows considerable potential to boost efficiency in exploratory synthetic chemistry.

8.
Am J Cardiol ; 205: 425-430, 2023 10 15.
Artigo em Inglês | MEDLINE | ID: mdl-37666014

RESUMO

Endovascular revascularization of the superficial femoral artery (SFA) may lead to recurrent ischemic syndromes, revascularization, or amputation. The impact of these events on mortality is unknown. We followed all patients having SFA endovascular revascularization for claudication or chronic limb-threatening ischemia in 2 cardiovascular (CV) divisions in Boston, Massachusetts. Any recurrent limb event after the initial SFA revascularization included recurrent claudication (67%), limb ulceration or gangrene (13%), repeat endovascular revascularization (61%), surgical revascularization (15%), or major (9%) or minor amputation (8%). We linked data to the National Death Index to ascertain cause of death grouped into CV mortality, or non-CV mortality. Hazard ratios (HRs) and 95% confidence intervals (95% CIs) from Cox proportional hazards and sub-HRs from Fine-Gray competing risks analyses were clustered by patient. Overall, there were 202 patients with 253 index limb endovascular procedures. A recurrent limb event occurred in 123 limbs (49%) and 93 patients (46%). Patients with and without recurrent limb events had similar numbers of deaths over follow-up (76 [62%] vs 71 [55%], respectively). In multivariable models, recurrent limb event was not related to all-cause death (HR 0.92, 95% CI 0.64 to 1.33), CV death (HR 1.29, 95% CI 0.72 to 1.30), or non-CV death (HR 0.65, CI 0.39 to 1.07). Competing risk analyses suggested male gender and chronic limb-threatening ischemia were more strongly related to CV death, and chronic kidney more strongly related to disease to non-CV death. In conclusion, recurrent limb events, which contribute to patient morbidity, do not increase the risk of all-cause or cause-specific mortality, and should not discourage repeat revascularization to relieve symptoms or ischemia.


Assuntos
Procedimentos Endovasculares , Doença Arterial Periférica , Humanos , Masculino , Artéria Femoral , Boston/epidemiologia , Isquemia Crônica Crítica de Membro , Doença Arterial Periférica/cirurgia , Extremidade Inferior
9.
Entropy (Basel) ; 25(8)2023 Aug 10.
Artigo em Inglês | MEDLINE | ID: mdl-37628219

RESUMO

We ground the asymmetry of causal relations in the internal physical states of a special kind of open and irreversible physical system, a causal agent. A causal agent is an autonomous physical system, maintained in a steady state, far from thermal equilibrium, with special subsystems: sensors, actuators, and learning machines. Using feedback, the learning machine, driven purely by thermodynamic constraints, changes its internal states to learn probabilistic functional relations inherent in correlations between sensor and actuator records. We argue that these functional relations just are causal relations learned by the agent, and so such causal relations are simply relations between the internal physical states of a causal agent. We show that learning is driven by a thermodynamic principle: the error rate is minimised when the dissipated power is minimised. While the internal states of a causal agent are necessarily stochastic, the learned causal relations are shared by all machines with the same hardware embedded in the same environment. We argue that this dependence of causal relations on such 'hardware' is a novel demonstration of causal perspectivalism.

10.
Phys Chem Chem Phys ; 25(25): 16735-16744, 2023 Jun 28.
Artigo em Inglês | MEDLINE | ID: mdl-37266931

RESUMO

The use of magnetisation decay measurements to characterise very slow relaxation of the magnetisation in single-molecule magnets is becoming increasingly prevalent as relaxation times move to longer timescales outside of the AC susceptibility range. However, experimental limitations and a poor understanding of the distribution underlying the stretched exponential function, commonly used to model the data, may be leading to misinterpretation of the results. Herein we develop guidelines on the experimental design, data fitting, and analysis required to accurately interpret magnetisation decay measurements. Various measures of the magnetic relaxation rate extracted from magnetisation decay measurements of [Dy(Dtp)2][Al{OC(CF3)3}4] previously characterised by Evans et al., fitted using combinations of fixing or freely fitting different parameters, are compared to those obtained using the innovative square-wave "waveform" technique of Hilgar et al. The waveform technique is comparable to AC susceptometry for measurement of relaxation rates on long timescales. The most reliable measure of the relaxation time for magnetisation decays is found to be the average logarithmic relaxation time, e〈ln[τ]〉, obtained via a fit of the decay trace using a stretched exponential function, where the initial and equilibrium magnetisation are fixed to first measured point and target values respectively. This new definition causes the largest differences to traditional approaches in the presence of large distributions or relaxation rates, with differences up to 50% with ß = 0.45, and hence could have a significant impact on the chemical interpretation of magnetic relaxation rates. A necessary step in progressing towards chemical control of magnetic relaxation is the accurate determination of relaxation times, and such large variations in experimental measures stress the need for consistency in fitting and interpretation of magnetisation decays.

11.
Int J Surg Case Rep ; 105: 108053, 2023 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-37001368

RESUMO

INTRODUCTION AND IMPORTANCE: Transverse colon volvulus is a rare cause of colonic obstruction accounting for 1-3 % of colonic volvuli due to the short mesentery and hepatic and splenic attachments. Previous mobilisation of the flexures and conditions resulting in chronic dilatation of the colon predispose to the condition. The risk of mortality is high, ranging from 11 to 20 % highlighting the need for early diagnosis and intervention. CASE PRESENTATION: We present a case of a 90-year-old male who was referred with a large bowel obstruction with a transition at the splenic flexure and the liver rotated to the left upper quadrant. The patient was taken to the theatre and an emergency laparotomy was performed with findings of a transverse colon volvulus. The liver was initially found in the left upper quadrant and was freely mobile in the upper abdomen consistent with an absence of the hepatic ligament. A subtotal colectomy was performed. Unfortunately, the postoperative course was complicated by a cardiac event and the patient died on postoperative day six. CLINICAL DISCUSSION: Absence of hepatic ligaments is a rare cause of transverse colon volvulus which has only been described in one previous case report. Diagnosis of transverse colon volvulus can be challenging and early operative intervention with colectomy is required to minimise mortality. CONCLUSION: This case illustrates an unusual cause of transverse colon volvulus secondary to the absence of the hepatic ligaments and stresses the need for early diagnosis and intervention due to the high mortality associated with this condition.

12.
Chem Commun (Camb) ; 59(18): 2656-2659, 2023 Feb 28.
Artigo em Inglês | MEDLINE | ID: mdl-36780133

RESUMO

The effects of external pressure on a high-performing dysprosocenium single-molecule magnet are investigated using a combination of X-ray diffraction, magnetometry and theoretical calculations. The effective energy barrier (Ueff) decreases from ca. 1300 cm-1 at ambient pressure to ca. 1125 cm-1 at 3 GPa. Our results indicate that compression < 1.2 GPa has a negligible effect on the Orbach process, but magnetic relaxation > 1 GPa increases via Raman relaxation and/or quantum tunnelling of magnetisation.

13.
Plast Reconstr Surg ; 151(5): 814e-827e, 2023 05 01.
Artigo em Inglês | MEDLINE | ID: mdl-36728885

RESUMO

BACKGROUND: Ideal nerve repair involves tensionless direct repair, which may not be possible after resection. Bridging materials include nerve autograft, allograft, or conduit. This study aimed to perform a systematic literature review and meta-analysis to compare the meaningful recovery (MR) rates and postoperative complications following autograft, allograft, and conduit repairs in nerve gaps greater than 5 mm and less than 70 mm. A secondary aim was to perform a comparison of procedure costs. METHODS: The search was conducted in MEDLINE from January of 1980 to March of 2020, following Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Studies were included whether they reported nerve injury type, repair type, gap length, and outcomes for MR rates. Thirty-five studies with 1559 nerve repairs were identified. RESULTS: Overall MR for sensory and motor function was not significantly different between autograft ( n = 670) and allograft ( n = 711) across both short and long gaps. However, MR rates for autograft (81.6%) and allograft (87.1%) repairs were significantly higher compared with conduits (62.2%) ( P < 0.05) in sensory short gap repairs. Complication rates were comparable for autograft and allograft but higher for conduit with regard to pain. Analysis of costs showed that total costs for allograft repair were less than autograft in the inpatient setting and were comparable in the outpatient setting. CONCLUSIONS: Literature showed comparable rates of MR between autograft and allograft, regardless of gap length or nerve type. Furthermore, the rates of MR were lower in conduit repairs. In addition, the economic analysis performed demonstrates that allograft does not represent an increased economic burden compared with autograft.


Assuntos
Traumatismos dos Nervos Periféricos , Humanos , Autoenxertos , Traumatismos dos Nervos Periféricos/etiologia , Traumatismos dos Nervos Periféricos/cirurgia , Transplante Homólogo , Transplante Autólogo/efeitos adversos , Aloenxertos/transplante
14.
J Phys Chem Lett ; 14(8): 2193-2200, 2023 Mar 02.
Artigo em Inglês | MEDLINE | ID: mdl-36812166

RESUMO

We perform magnetization sweeps on the high-performing single-molecule magnet [Dy(Cpttt)2][B(C6F5)4] (Cpttt = C5H2tBu3-1,2,4; tBu = C(CH3)3) to determine the quantum tunneling gap of the ground-state avoided crossing at zero-field, finding a value on the order of 10-7 cm-1. In addition to the pure crystalline material, we also measure the tunnel splitting of [Dy(Cpttt)2][B(C6F5)4] dissolved in dichloromethane (DCM) and 1,2-difluorobenzene (DFB). We find that concentrations of 200 or 100 mM [Dy(Cpttt)2][B(C6F5)4] in these solvents increases the size of the tunneling gap compared to the pure sample, despite a similarity in the strength of the dipolar fields, indicating that either a structural or vibrational change due to the environment increases quantum tunneling rates.

15.
Innovations (Phila) ; 18(1): 67-72, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-36803147

RESUMO

OBJECTIVE: We describe the use of 3-dimensional (3D) printing technology to plan and reconstruct the sternum, adjoining cartilages, and ribs with a custom-made, anatomically designed, 3D-printed titanium implant for an isolated sternal metastasis complicated with a pathological fracture. METHODS: We imported submillimeter slice computed tomography scan data into Mimics Medical 20.0 software and by manual bone threshold segmentation created a 3D virtual model of the patient's chest wall and tumor. For all-around tumor-free margins, we grew the tumor by 2 cm. The replacement implant was designed in 3D using the anatomical features of the sternum, cartilages, and ribs and manufactured using TiMG 1 powder fusion technology. Physiotherapy was provided prior to and following surgery, and the impact of reconstruction on pulmonary functions was assessed. RESULTS: At surgery, the precise resection, clear margins, and a secure fit were achieved. At follow-up, there was no dislocation, paradoxical movement, change in performance status, or dyspnea. There was a decrease in forced expiratory volume in 1 s (FEV1) from 105% prior to surgery to 82% following surgery and in forced vital capacity (FVC) from 108% to 75%, with no difference in the FEV1/FVC ratio, suggesting a restrictive pattern of impairment. CONCLUSIONS: With 3D printing technology, reconstructing a large anterior chest wall defect with a custom-made, anatomical, 3D-printed titanium alloy implant is feasible and safe, and it preserves the shape, structure, and function of the chest wall, albeit with a restrictive pattern of pulmonary function, which can be addressed with physiotherapy.


Assuntos
Parede Torácica , Humanos , Parede Torácica/cirurgia , Titânio , Desenho de Prótese , Esterno/cirurgia , Esterno/patologia , Impressão Tridimensional , Costelas/cirurgia
16.
Hand (N Y) ; 18(7): 1135-1141, 2023 10.
Artigo em Inglês | MEDLINE | ID: mdl-35321574

RESUMO

BACKGROUND: The Orthopaedic Minimal Data Set (OrthoMiDaS) Episode of care (OME) is a prospectively collected database enabling capture of patient and surgeon-reported data in a more efficient, comprehensive, and dependable manner than electronic medical record (EMR) review. We aimed to assess and validate the OME as a data capture tool for carpometacarpal (CMC) arthroplasty compared to traditional EMR-based review. Specifically, we aimed to: (1) compare the completeness of the OME versus EMR data; and (2) evaluate the extent of agreement between the OME and EMR data-based datasets for carpometacarpal (CMC) arthroplasty. METHODS: The first 100 thumb CMC arthroplasties after OME inception (Febuary, 2015) were included. Blinded EMR-based review of the same cases was performedfor 48 perioperative variables and compared to their OME-sourced counterparts. Outcomes included completion rates and agreement measures in OME versus EMR-based control datasets. RESULTS: The OME demonstrated superior completion rates compared to EMR-based retrospective review. There was high agreement between both datasets where 75.6% (34/45) had an agreement proportion of >0.90% and 82.2% (37/45) had an agreement proportion of >0.80. Over 40% of the variables had almost perfect to substantial agreement (κ > 0.60). Among the 6 variables demonstrating poor agreement, the surgeon-inputted OME values were more accurate than the EMR-based review control. CONCLUSIONS: This study validates the use of the OME for CMC arthroplasty by illustrating that it is reliably able to match or supersede traditional chart review for data collection; thereby offering a high-quality tool for future CMC arthroplasty studies.


Assuntos
Articulações Carpometacarpais , Ortopedia , Humanos , Articulações Carpometacarpais/cirurgia , Polegar/cirurgia , Smartphone , Artroplastia
17.
BMC Musculoskelet Disord ; 23(1): 971, 2022 Nov 09.
Artigo em Inglês | MEDLINE | ID: mdl-36352375

RESUMO

Previous studies have shown radioulnar wrist compression augments carpal arch space. This study investigated the effects of radioulnar wrist compression on patient-reported outcomes associated with carpal tunnel syndrome. Subjects underwent thrice-daily (15 min each time 45 min daily) wrist compression over 4 weeks with an additional four weeks of follow-up without treatment. Primary outcomes included Boston Carpal Tunnel Questionnaire symptom and functional severity scales (SSS and FSS) and symptoms of numbness/tingling based on Visual Analog Scales. Our results showed that radioulnar wrist compression improved SSS by 0.55 points after 2 weeks (p < 0.001) and 0.51 points at 4 weeks (p < 0.006) compared to the baseline scale. At the four-week follow-up, SSS remined improved at 0.47 points (p < 0.05). Symptoms of numbness/tingling improved at two and 4 weeks, as well as the follow-up (p < 0.05). Hand motor impairment such as weakness had a lower frequency across carpal tunnel syndrome sufferers and does not significantly improve (p > 0.05). Radioulnar wrist compression might be an effective alternative treatment in improving sensory related symptoms in patients with mild to moderate carpal tunnel syndrome.


Assuntos
Síndrome do Túnel Carpal , Humanos , Síndrome do Túnel Carpal/complicações , Síndrome do Túnel Carpal/diagnóstico , Síndrome do Túnel Carpal/terapia , Punho , Hipestesia/diagnóstico , Hipestesia/etiologia , Articulação do Punho , Medidas de Resultados Relatados pelo Paciente
18.
J Anim Ecol ; 91(12): 2384-2399, 2022 12.
Artigo em Inglês | MEDLINE | ID: mdl-36177549

RESUMO

Understanding how ecological processes combine to shape population dynamics is crucial in a rapidly changing world. Evidence has been emerging for how fundamental drivers of density dependence in mobile species are related to two differing types of environmental variation-temporal variation in climate, and spatiotemporal variation in food resources. However, to date, tests of these hypotheses have been largely restricted to mid-trophic species in terrestrial environments and thus their general applicability remains unknown. We tested if these same processes can be identified in marine upper trophic level species. We assembled a multi-decadal data set on population abundance of 10 species of colonial seabirds comprising a large component of the UK breeding seabird biomass, and covering diverse phylogenies, life histories and foraging behaviours. We tested for evidence of density dependence in population growth rates using discrete time state-space population models fit to long time-series of observations of abundance at seabird breeding colonies. We then assessed if the strength of density dependence in population growth rates was exacerbated by temporal variation in climate (sea temperature and swell height), and attenuated by spatiotemporal variation in prey resources (productivity and tidal fronts). The majority of species showed patterns consistent with temporal variation in climate acting to strengthen density dependent feedbacks to population growth. However, fewer species showed evidence for a weakening of density dependence with increasing spatiotemporal variation in prey resources. Our findings extend this emerging theory for how different sources of environmental variation may shape the dynamics and regulation of animal populations, demonstrating its role in upper trophic marine species. We show that environmental variation leaves a signal in long-term population dynamics of seabirds with potentially important consequences for their demography and trophic interactions.


Assuntos
Crescimento Demográfico , Animais , Dinâmica Populacional
19.
Angew Chem Int Ed Engl ; 61(39): e202208851, 2022 Sep 26.
Artigo em Inglês | MEDLINE | ID: mdl-35946808

RESUMO

Ditetrelenes R2 E=ER2 (E=Si, Ge, Sn, Pb) substituted by multiple N/P/O/S-donor groups are extremely rare due to their propensity to disaggregate into their tetrylene monomers R2 E. We report the synthesis of the first fully phosphanyl-substituted digermene {(Mes)2 P}2 Ge=Ge{P(Mes)2 }2 (3, Mes=2,4,6-Me3 C6 H2 ), which adopts a highly unusual structure in the solid state, that is both strongly trans-bent and highly twisted. Variable-temperature 31 P{1 H} NMR spectroscopy suggests that 3 persists in solution, but is subject to a dynamic equilibrium between two conformations, which have different geometries about the Ge=Ge bond (twisted/non-twisted) due to a difference in the nature of their π-stacking interactions. Compound 3 undergoes unprecedented, spontaneous decomposition in solution to give a unique GeI cluster {(Mes)2 P}4 Ge4 ⋅5 CyMe (7).

20.
Mar Pollut Bull ; 179: 113681, 2022 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-35569289

RESUMO

Maritime traffic is increasing globally, with a four-fold increase in commercial vessel movements between 1992 and 2012. Vessels contribute to noise and air pollution, provide pathways for non-native species, and collide with marine wildlife. While knowledge of shipping trends and potential environmental impacts exists at both local and global levels, key information on vessel density for regional-scale management is lacking. This study presents the first in-depth spatio-temporal analysis of shipping in the north-east Atlantic region, over three years in a five-year period. Densities increased by 34%, including in 73% of Marine Protected Areas. Western Scotland and the Bay of Biscay experienced the largest increases in vessel density, predominantly from small and slow vessels. Given well-documented impacts that shipping can have on the marine environment, it is crucial that this situation continues to be monitored - particularly in areas designated to protect vulnerable species and ecosystems which may already be under pressure.


Assuntos
Poluição do Ar , Ecossistema , Meio Ambiente , Ruído , Navios
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