Climate constrains the evolutionary history and biodiversity of crocodylians

The fossil record of crocodylians and their relatives (pseudosuchians) reveals a rich evolutionary history, prompting questions about causes of long-term decline to their present-day low biodiversity. We analyse climatic drivers of subsampled pseudosuchian biodiversity over their 250 million year history, using a comprehensive new data set. Biodiversity and environmental changes correlate strongly, with long-term decline of terrestrial taxa driven by decreasing temperatures in northern temperate regions, and biodiversity decreases at lower latitudes matching patterns of increasing aridification. However, there is no relationship between temperature and biodiversity for marine pseudosuchians, with sea-level change and post-extinction opportunism demonstrated to be more important drivers. A ‘modern-type' latitudinal biodiversity gradient might have existed throughout pseudosuchian history, and range expansion towards the poles occurred during warm intervals. Although their fossil record suggests that current global warming might promote long-term increases in crocodylian biodiversity and geographic range, the 'balancing forces' of anthropogenic environmental degradation complicate future predictions

Supraspinal fatigue in human inspiratory muscles with repeated sustained maximal efforts

To investigate the involvement of supraspinal fatigue in the loss of maximal inspiratory pressure (PImax), we fatigued the inspiratory muscles. Six participants performed 5 sustained maximal isometric inspiratory efforts (15-s contractions, duty cycle ~75%) which reduced PImax, as measured from esophageal and mouth pressure, to around half of their initial maximums. Transcranial magnetic stimulation (TMS) delivered over the motor cortex near the beginning and end of each maximal effort evoked superimposed twitch-like increments in the ongoing PImax, increasing from ~1.0% of PImax in the unfatigued contractions to ≥40% of ongoing PImax for esophageal and mouth pressures. The rate of increase in the superimposed twitch as PImax decreased with fatigue was not significantly different between the esophageal and mouth pressure measures. The inverse relationship between superimposed twitch pressure and PImax indicates a progressive decline in the ability of motor cortical output to drive the inspiratory muscles maximally, leading to the development of supraspinal fatigue. TMS also evoked silent periods in the electromyographic recordings of diaphragm, scalenes, and parasternal intercostal. The duration of the silent period increased with fatigue in all three muscles, which suggests greater intracortical inhibition, with the largest change observed in the diaphragm. The peak rate of relaxation in pressure during the silent period slowed as fatigue developed, indicating peripheral contractile changes in the active inspiratory muscles. These changes in the markers of fatigue show that both central and peripheral fatigue contribute to the loss in PImax when inspiratory muscles are fatigued with repeated sustained maximal efforts. NEW & NOTEWORTHY When the inspiratory muscles are fatigued with repeated sustained maximal efforts, supraspinal fatigue, a component of central fatigue, contributes to the loss in maximal inspiratory pressure. The presence of supraspinal fatigue was confirmed by the increase in amplitude of twitch-like increments in pressure evoked by motor cortical stimulation during maximal efforts, indicating that motor cortical output was not maximal as extra muscle force could be generated to increase inspiratory pressure

Parasitic dinoflagellate Hematodinium perezi prevalence in larval and juvenile blue crabs Callinectes sapidus from coastal bays of Virginia

The parasitic dinoflagellate Hematodinium perezi infects the American blue crab Callinectes sapidus and other decapods along the Eastern seaboard and Gulf of Mexico coast of the USA. Large juvenile and adult blue crabs experience high mortality during seasonal outbreaks of H. perezi, but less is known about its presence in the early life history stages of this host. We determined the prevalence of H. perezi in megalopae and early benthic juvenile crabs from multiple locations along the Virginia portion of the Delmarva Peninsula. The DNA of H. perezi was not detected in any megalopae collected from several locations within the oceanic coastal bay complex in which H. perezi is found at high prevalence levels. However, prevalence levels were high in early benthic juveniles from 2 oceanic coastal embayments: South Bay and Cobb Bay. Prevalence levels were lower at locations within Chesapeake Bay, including Cherrystone Creek, Hungars Creek, and Pungoteague Creek. Sampling over different seasons and several consecutive years indicates that disease transmission occurs rapidly after megalopae settle in high-salinity bays along the Delmarva Peninsula during the late summer and fall. Infected juvenile crabs can overwinter with the parasite and, when subjected to increasing water temperatures in spring, infections progress rapidly, culminating in transmission to other crabs in late spring and early summer. In high-salinity embayments, H. perezi can reach high prevalence levels and may significantly affect recruitment of juvenile blue crabs into the adult fisher

Exploring shear alignment of concentrated wormlike micelles using rheology coupled with small-angle neutron scattering

Wormlike micelles (WLMs) are vital components of many consumer products and industrial fluids, adding a shear-dependent viscous texture through their entanglement in solutions. It is now well accepted from experiments such as coupling rheology and scattering that, similar to many polymer solutions and dispersions of highly anisotropic particles, WLM behavior during shear arises from the alignment of the "worms"with the shear field, resulting in ordering that is rapidly lost in the cessation of shear. Most studies of such systems have been limited to dilute systems that are far below concentrations used industrially and commercially, due to the complexity of analyzing shear-induced many-body effects in high volume fraction dispersions. Here, we explore the shear alignment of concentrated WLM solutions comprising sodium laureth sulfate and cocamidopropyl betaine in 0.38 M aqueous sodium chloride. By analyzing only scattering data at high values of the scattering vector (i.e., correlations at short length scales that are dominant in such concentrated systems), we explore whether useful information can be obtained by naïvely approximating the WLMs as an ensemble of unconnected short rods representing sections of the worms. By taking this reductionist approach to analyzing the obtained two-dimensional scattering patterns from these systems under shear, we find that in this regime, such concentrated worms can be approximated as cylinders that become more aligned with the direction of shear as volume fraction and shear rate increase

Impact of a hospice rapid response service on preferred place of death, and costs

Background: Many people with a terminal illness would prefer to die at home. A new palliative rapid response service (RRS) provided by a large hospice provider in South East England was evaluated (2010) to provide evidence of impact on achieving preferred place of death and costs. The RRS was delivered by a team of trained health care assistants and available 24/7. The purpose of this study was to (i) compare the characteristics of RRS users and non-users, (ii) explore differences in the proportions of users and non-users dying in the place of their choice, (iii) monitor the whole system service utilisation of users and non-users, and compare costs. Methods: All hospice patients who died with a preferred place of death recorded during an 18 month period were included. Data (demographic, preferences for place of death) were obtained from hospice records. Dying in preferred place was modelled using stepwise logistic regression analysis. Service use data (period between referral to hospice and death) were obtained from general practitioners, community providers, hospitals, social services, hospice, and costs calculated using validated national tariffs. Results: Of 688 patients referred to the hospice when the RRS was operational, 247 (35.9 %) used it. Higher proportions of RRS users than non-users lived in their own homes with a co-resident carer (40.3 % vs. 23.7 %); more non-users lived alone or in residential care (58.8 % vs. 76.3 %). Chances of dying in the preferred place were enhanced 2.1 times by being a RRS user, compared to a non-user, and 1.5 times by having a co-resident carer, compared to living at home alone or in a care home. Total service costs did not differ between users and non-users, except when referred to hospice very close to death (users had higher costs). Conclusions: Use of the RRS was associated with increased likelihood of dying in the preferred place. The RRS is cost neutral

Cellular Contraction and Polarization Drive Collective Cellular Motion

Coordinated motions of close-packed multicellular systems typically generate cooperative packs, swirls, and clusters. These cooperative motions are driven by active cellular forces, but the physical nature of these forces and how they generate collective cellular motion remain poorly understood. Here, we study forces and motions in a confined epithelial monolayer and make two experimental observations: 1) the direction of local cellular motion deviates systematically from the direction of the local traction exerted by each cell upon its substrate; and 2) oscillating waves of cellular motion arise spontaneously. Based on these observations, we propose a theory that connects forces and motions using two internal state variables, one of which generates an effective cellular polarization, and the other, through contractile forces, an effective cellular inertia. In agreement with theoretical predictions, drugs that inhibit contractility reduce both the cellular effective elastic modulus and the frequency of oscillations. Together, theory and experiment provide evidence suggesting that collective cellular motion is driven by at least two internal variables that serve to sustain waves and to polarize local cellular traction in a direction that deviates systematically from local cellular velocity

A case of PTSD presenting with psychotic symptomatology: a case report

A male patient aged 43 presented with psychotic symptomatology after a traumatic event involving accidental mutilation of the fingers. Initial presentation was uncommon although the patient responded well to pharmacotherapy. The theoretical framework, management plan and details of the treatment are presented

Resonance as the Mechanism of Daytime Periodic Breathing in Patients with Heart Failure

Rationale: In patients with chronic heart failure, daytime oscillatory breathing at rest is associated with a high risk of mortality. Experimental evidence, including exaggerated ventilatory responses to CO2 and prolonged circulation time, implicates the ventilatory control system and suggests feedback instability (loop gain > 1) is responsible. However, daytime oscillatory patterns often appear remarkably irregular versus classic instability (Cheyne-Stokes respiration), suggesting our mechanistic understanding is limited. Objectives: We propose that daytime ventilatory oscillations generally result from a chemoreflex resonance, in which spontaneous biological variations in ventilatory drive repeatedly induce temporary and irregular ringing effects. Importantly, the ease with which spontaneous biological variations induce irregular oscillations (resonance “strength”) rises profoundly as loop gain rises toward 1. We tested this hypothesis through a comparison of mathematical predictions against actual measurements in patients with heart failure and healthy control subjects. Methods: In 25 patients with chronic heart failure and 25 control subjects, we examined spontaneous oscillations in ventilation and separately quantified loop gain using dynamic inspired CO2 stimulation. Measurements and Main Results: Resonance was detected in 24 of 25 patients with heart failure and 18 of 25 control subjects. With increased loop gain—consequent to increased chemosensitivity and delay—the strength of spontaneous oscillations increased precipitously as predicted (r = 0.88), yielding larger (r = 0.78) and more regular (interpeak interval SD, r = −0.68) oscillations (P < 0.001 for all, both groups combined). Conclusions: Our study elucidates the mechanism underlying daytime ventilatory oscillations in heart failure and provides a means to measure and interpret these oscillations to reveal the underlying chemoreflex hypersensitivity and reduced stability that foretells mortality in this population

Inflammatory and blood gas markers of COVID-19 delirium compared to non-COVID-19 delirium: a cross-sectional study

OBJECTIVES: We aimed to find the association of inflammation and respiratory failure with delirium in COVID-19 patients. We compare the inflammatory and arterial blood gas markers between patients with COVID-19 delirium and delirium in other medical disorders. METHODS: This cross-sectional study used the CHART-DEL, a validated research tool, to screen patients for delirium retrospectively from clinical notes. Inflammatory markers C-reactive protein (CRP) and white cell count (WBC), and the partial pressures of oxygen (PO2) and carbon dioxide (PCO2) were compared between patients with COVID-19 delirium and delirium in other medical disorders. RESULTS: In bivariate analysis, CRP (mg/L) was significantly higher in the COVID-19 group, (81.7 ± 80.0 vs. 58.8 ± 87.7, p = 0.04), and WBC (109/L) was significantly lower (7.44 ± 3.42 vs. 9.71 ± 5.45, p = 0.04). The geometric mean of CRP in the COVID-19 group was 140% higher in multiple linear regression (95% CI = 7-439%, p = 0.03) with age and sex as covariates. There were no significant differences in pO2 or pCO2 across groups. CONCLUSION: The association between higher CRP and COVID-19 in patients with delirium may suggest an inflammatory basis for delirium in COVID-19. Our findings may assist clinicians in establishing whether delirium is due to COVID-19, which may improve management and outcomes of infected patients