Aerodynamic response of a red-tailed hawk to discrete transverse gusts

A limiting factor in the design of smaller size uncrewed aerial vehicles is their inability to navigate through gust-laden environments. As a result, engineers have turned towards bio-inspired engineering approaches for gust mitigation techniques. In this study, the aerodynamics of a red-tailed hawk's response to variable-magnitude discrete transverse gusts was investigated. The hawk was flown in an indoor flight arena instrumented by multiple high-speed cameras to quantify the 3D motion of the bird as it navigated through the gust. The hawk maintained its flapping motion across the gust in all runs; however, it encountered the gust at different points in the flapping pattern depending on the run and gust magnitude. The hawk responded with a downwards pitching motion of the wing, decreasing the wing pitch angle to between -20∘and -5∘, and remained in this configuration until gust exit. The wing pitch data was then applied to a lower-order aerodynamic model that estimated lift coefficients across the wing. In gusts slower than the forward flight velocity (low gust ratio), the lift coefficient increases at a low-rate, to a maximum of around 2-2.5. In gusts faster than the forward flight velocity (high gust ratio), the lift coefficient initially increased rapidly, before increasing at a low-rate to a value around 4-5. In both regimes, the hawk's observed height change due to gust interaction was similar (and small), despite larger estimated lift coefficients over the high gust regime. This suggests another mitigation factor apart from the wing response is present. One potential factor is the tail pitching response observed here, which prior work has shown serves to mitigate pitch disturbances from gusts.

Introduction of an assessment toolkit associated with increased rate of DLB diagnosis

Background

Dementia with Lewy bodies (DLB) and dementia in Parkinson’s disease (PDD) are recognised to be under-recognised in clinical practice in the UK, with only one third to a half of expected cases diagnosed. We aimed to assess whether clinical diagnostic rates could be increased by the introduction of a structured assessment toolkit for clinicians.

Methods

We established baseline diagnostic rates for DLB and PDD in four memory clinics and three movement disorder/Parkinson’s disease (PD) clinics in two separate geographical regions in the UK. An assessment toolkit specifically developed to assist with the recognition and diagnosis of DLB and PDD was then introduced to the same clinical teams and diagnostic rates for DLB and PDD were reassessed.

For assessing DLB diagnosis, a total of 3820 case notes were reviewed before the introduction of the toolkit, and 2061 case notes reviewed after its introduction. For PDD diagnosis, a total of 1797 case notes were reviewed before the introduction of the toolkit and 3405 case notes after it. Mean values and proportions were analysed using Student’s t test for independent samples and χ² test, respectively.

Results

DLB was diagnosed in 4.6% of dementia cases prior to the introduction of the toolkit, and 6.2% of dementia cases afterwards, an absolute rise of 1.6%, equal to a 35% increase in the number of DLB cases diagnosed when using the toolkit (χ² = 4.2, P = 0.041).

The number of PD patients diagnosed with PDD was not found overall to be significantly different when using the toolkit: 9.6% of PD cases before and 8.2% of cases after its introduction (χ² = 1.8, P = 0.18), though the ages of PD patients assessed after the toolkit’s introduction were lower (73.9 years vs 80.0 years, t = 19.2, p < 0.001).

Conclusion

Introduction of the assessment toolkit was associated with a significant increase in the rate of DLB diagnosis, suggesting that a structured means of assessing symptoms and clinical features associated with DLB can assist clinicians in recognising cases. The assessment toolkit did not alter the overall rate of PDD diagnosis, suggesting that alternate means may be required to improve the rate of diagnosis of dementia in Parkinson’s disease.

Prospective study of change in liver function and fat in patients with colorectal liver metastases undergoing preoperative chemotherapy: protocol for the CLiFF Study

INTRODUCTION

Preoperative chemotherapy in patients undergoing resection for colorectal liver metastases (CLM) improves oncological outcomes. However, chemotherapy-associated liver injury (occurring in two patterns: vascular and fat deposition) is a real clinical concern prior to hepatic resection. After major liver resection, regeneration of the residual liver is a prerequisite for recovery and avoidance of liver failure, but this regenerative capacity may be hindered by chemotherapy. Thus, there is a need to predict for this serious complication. Over the past two decades, several tests and derived indices have been developed, which have failed to achieve clinical utility, mainly as they were indirect measurements of liver function. Here, we will use a novel test of liver function (the liver maximum capacity (LiMAx) test), and measure liver fat using MRI.

METHODS AND ANALYSIS

This prospective study will assess changes in liver function longitudinally, measured by the LiMAx test, and liver fat, measured by advanced MRI using both MR spectroscopy and the modified Dixon method, in up to 35 patients undergoing preoperative chemotherapy for CLM. The primary outcomes will be the changes in liver function and fat compared with baseline prechemotherapy measurements. Secondary outcome measures include: routinely measured liver function blood tests, anthropometric measurements, postoperative histology and digital quantification of fat, postoperative complications and mortality and quality of life.

ETHICS AND DISSEMINATION

The study was approved by a National Health Service Research Ethics Committee and registered with the Health Research Authority. Dissemination will be via international and national conferences and the National Institute for Health Research network. Manuscripts will be published.

TRIAL REGISTRATION NUMBER

This study is registered online at www.clinicaltrials.gov (registration number NCT03562234).

Carbapenem-resistant Enterobacteriaceae in patients with bacteraemia at tertiary hospitals in South Africa, 2015 to 2018

Enhanced surveillance for CREs was established at national sentinel sites in South Africa. We aimed to apply an epidemiological and microbiological approach to characterise CREs and to assess trends in antimicrobial resistance from patients admitted to tertiary academic hospitals. A retrospective analysis was conducted on patients of all ages with CRE bacteraemia admitted at any one of 12 tertiary academic hospitals in four provinces (Gauteng, KwaZulu-Natal, Western Cape and Free State) in South Africa. The study period was from July 2015 to December 2018. A case of CRE bacteraemia was defined as a patient admitted to one of the selected tertiary hospitals where any of the Enterobacteriaceae was isolated from a blood culture, and was resistant to the carbapenems (ertapenem, meropenem, imipenem and/or doripenem) or had a positive result for the Modified Hodge Test (MHT) according to the Clinical and Laboratory Standards Institute (CLSI) guidelines. A positive blood culture result obtained after 21 days of the last blood culture result was regarded as a new case. To distinguish hospital-acquired (HA) from the community-acquired (CA) bacteraemia, the following definitions were applied: the HA CRE bacteraemia was defined as a patient with CRE isolated from blood culture ≥ 72 h of hospital admission or with any prior healthcare contact, within 1 year prior to the current episode or referral from a healthcare facility where the patient was admitted before the current hospital. A case of the CA CRE bacteraemia was defined as a patient with CRE isolated from blood culture < 72 h of hospital admission and with no prior healthcare contact. The majority of carbapenem-resistant Enterobacteriaceae (CRE) (70%) were hospital-acquired (HA) with Klebsiella pneumoniae being the predominant species (78%). In-hospital mortality rate was 38%. The commonest carbapenemase genes were bla-_OXA-48 (52%) and bla-_NDM (34%). The high mortality rate related to bacteraemia with CRE and the fact that most were hospital-acquired infections highlights the need to control the spread of these drug-resistant bacteria. Replacement with OXA-48 is the striking finding from this surveillance analysis. Infection control and antibiotic stewardship play important roles in decreasing the spread of resistance.

Modafinil and cognitive enhancement in schizophrenia and healthy volunteers: the effects of test battery in a randomised controlled trial

BACKGROUND

Cognitive deficits in schizophrenia have major functional impacts. Modafinil is a cognitive enhancer whose effect in healthy volunteers is well-described, but whose effects on the cognitive deficits of schizophrenia appear to be inconsistent. Two possible reasons for this are that cognitive test batteries vary in their sensitivity, or that the phase of illness may be important, with patients early in their illness responding better.

METHODS

A double-blind, randomised, placebo-controlled single-dose crossover study of modafinil 200 mg examined this with two cognitive batteries [MATRICS Consensus Cognitive Battery (MCCB) and Cambridge Neuropsychological Test Automated Battery (CANTAB)] in 46 participants with under 3 years' duration of DSM-IV schizophrenia, on stable antipsychotic medication. In parallel, the same design was used in 28 age-, sex-, and education-matched healthy volunteers. Uncorrected p values were calculated using mixed effects models.

RESULTS

In patients, modafinil significantly improved CANTAB Paired Associate Learning, non-significantly improved efficiency and significantly slowed performance of the CANTAB Stockings of Cambridge spatial planning task. There was no significant effect on any MCCB domain. In healthy volunteers, modafinil significantly increased CANTAB Rapid Visual Processing, Intra-Extra Dimensional Set Shifting and verbal recall accuracy, and MCCB social cognition performance. The only significant differences between groups were in MCCB visual learning.

CONCLUSIONS

As in earlier chronic schizophrenia studies, modafinil failed to produce changes in cognition in early psychosis as measured by MCCB. CANTAB proved more sensitive to the effects of modafinil in participants with early schizophrenia and in healthy volunteers. This confirms the importance of selecting the appropriate test battery in treatment studies of cognition in schizophrenia.

Systematic review of the evidence for rational dosing of colistin

BACKGROUND

There is an alarming global increase in the incidence of nosocomial infections with multidrug-resistant Gram-negative bacteria, which are often only susceptible to colistin. Colistin was developed prior to current methods of establishing dosing using pharmacokinetic-pharmacodynamic relationships. Dosing regimens differ in package inserts from different manufacturers and in different guidelines. It is imperative to avoid under-dosing with colistin in order to limit the development of resistance, as it is the last line of defence.

METHODS

We conducted a systematic review of the literature to develop guidelines for rational dosing of intravenous colistin, with a particular focus on critically ill patients.

RESULTS

Colistin is administered as the inactive pro-drug colistimethate sodium. Colistin demonstrates concentration-dependent bacterial killing, suggesting that higher doses should be administered less frequently to achieve higher peak concentrations. Dose-related nephrotoxicity occurs, making it impossible to safely achieve concentrations that prevent the selection of resistant mutants or the effective eradication of bacteria with higher minimum inhibitory concentrations. Theoretically, combination therapy should be used to reduce the risk of selection of resistant bacteria. In critically ill patients, a loading dose should be given to rapidly achieve therapeutic concentrations, followed by maintenance doses of 4.5 MU 12-hourly. Maintenance dose adjustment is necessary with renal impairment.

CONCLUSION

Easier access to colistin is needed in South Africa, where it is not a registered medicine. Further research is needed to better characterise colistin's pharmacokinetic-pharmacodynamic relationships in humans and to establish whether combinations of colistin with other antimicrobials result in improved clinical outcomes or a reduction in selection of resistant bacteria.

Mycobacterial transport medium for routine culture of fine needle aspiration biopsies

Fine needle aspiration biopsy (FNAB) offers a simple outpatient technique for specimen collection in child tuberculosis suspects with peripheral lymphadenopathy. To perform FNAB with mycobacterial culture on an outpatient basis requires use of a sterile transport medium to facilitate bedside inoculation, maintain organism viability and reduce contamination risk en route to the laboratory. The mycobacterial yield and time to positive culture following bedside inoculation into standard mycobacterial growth indicator tubes were compared with initial inoculation into an inexpensive "in-house" liquid growth medium. Of 150 FNAB performed, 57 (38%) cultured Mycobacterium tuberculosis complex. There was one case each with non-tuberculous mycobacteria and Mycobacterium bovis BCG; the remaining 55 being M tuberculosis. Results were concordant in 142 (94.7%) bedside and laboratory inoculation pairs. There was no significant difference in time to positive culture between bedside and laboratory inoculation (16.2 days (SD 0.87) vs 17.1 days (SD 0.85)). Provision of inexpensive specimen transport bottles and practical tuition in FNAB should improve cost-effective diagnosis of tuberculosis at the primary healthcare level.

Fine-needle aspiration biopsy: a first-line diagnostic procedure in paediatric tuberculosis suspects with peripheral lymphadenopathy?

OBJECTIVE

To evaluate the diagnostic yield and time to diagnosis of fine-needle aspiration biopsy (FNAB) vs. routine respiratory specimens collected from children with a palpable peripheral lymph node mass and symptoms suspicious of tuberculosis (TB).

DESIGN

We performed a retrospective review of laboratory records at Tygerberg Hospital over a 4-year period from January 2003 to December 2006. All children (aged <13 years) in whom an FNAB and other mycobacterial specimens were collected as part of their diagnostic workup were included.

RESULTS

In 95 children, the following specimens were collected: FNAB (n = 95), gastric aspirates (n = 142), other respiratory specimens (n = 36), non-respiratory specimens (n = 26). Mycobacterial disease was diagnosed in 70 (73.7%) patients. Children without respiratory specimens (n = 6) and/or with Mycobacterium bovis bacille Calmette-Guérin disease (n = 15) were excluded from comparative analysis. In the remainder, FNAB was positive in 45/74 (60.8%) vs. any respiratory specimen in 29/74 (39.2%, P < 0.001). The mean time to bacteriological diagnosis with FNAB was 7.1 days (95%CI 4.2-10.1) compared to 22.5 days (95%CI 15.8-29.1) for any respiratory specimen.

CONCLUSION

FNAB is a simple, rapid and effective modality for achieving confirmation of mycobacterial disease in paediatric TB suspects with a palpable peripheral lymph node mass.

Effects of haemopoietic growth factors in combination with etoposide on sister chromatid exchange frequencies in peripheral blood mononuclear cells

Prior to work on the influence of dosing and scheduling of the drug etoposide in bone marrow cells, the DNA-damaging effects of three haemopoietic growth factors, either alone or in combination with etoposide, were investigated. Sister chromatid exchange (SCE) frequencies in phytohaemagglutinin-stimulated mononuclear cells of six normal volunteers were used as an indicator of DNA damage. The effects of three growth factors on SCEs were investigated at concentrations ranging between 0 and 100 ng/ml and those of etoposide alone, at concentrations varying between 0 and 2 microM. The effect of combinations of growth factor (GF) and etoposide were assessed at a 40-ng/ml concentration of each cytokine and at 0.4 microM etoposide. Results showed not only a dose-dependent rise in SCE frequency in cells treated with etoposide but also a cytokine effect. Stem-cell factor did not cause a significant change in SCE numbers. However, cytokines with activity at the progenitor cell level induced small but significant increases in SCE numbers at concentrations of 50 and 100 ng/ml (P < 0.001). Results of combination studies indicated a significant 60% increase in SCE numbers in cells treated with GF and etoposide as compared with etoposide alone (P < 0.00001). This finding suggests a sensitivity of peripheral blood mononuclear cells to SCE induction by GFs given either as single agents or in combination with etoposide.

Case mix and content of trainee consultations: findings from the north of England study of standards and performance in general practice

BACKGROUND

Previous studies have examined the differences in the work of trainees and trainers. However, they have not investigated how many of these differences are due to differences in the case mix seen by trainees.

AIM

A study was undertaken to investigate the effect of case mix on the content of consultations with trainee general practitioners.

METHOD

Details of surgery consultations with 207 trainee general practitioners and 255 principals in 62 training practices in the north of England were prospectively recorded during one week in each of four consecutive years.

RESULTS

Trainee general practitioners saw a higher proportion of younger patients and those categorized as suffering from an acute minor condition compared with principals. They saw a lower proportion of patients categorized as suffering from chronic intermediate, chronic major and female conditions. The reported content of trainee and principal consultations differed over all four years in that trainees examined more patients, issued more new prescriptions, issued fewer repeat prescriptions, arranged fewer return appointments and referred fewer patients. However, adjusting for case mix reduced the number of significant differences between trainees and principals to two: trainees issued fewer repeat prescriptions and had more consultations lasting longer than nine minutes.

CONCLUSION

The case mix and content of consultations differ between trainees and principals and some of the differences in content are due to the differences in case mix; trainees generally behave more like principals than has been previously suggested. Thus, case mix is an important factor in understanding the content of trainee consultations.

Development of patient satisfaction questionnaires: I. Methodological issues

OBJECTIVES

To develop a method for conducting postal surveys of patients' views and experiences of general practitioner care and to produce an off the shelf tool for general practice audit.

DESIGN

Prospective study of performance of two patient questionnaires assessing accessibility to services (questionnaire 1) and interpersonal aspects of care (questionnaire 2) in comparing general practices.

SETTING

Five general practices in Newcastle upon Tyne.

PATIENTS

3800 patients aged 16 and over, 1900 randomly drawn from family health services authority lists for each practice (questionnaire 1) and 1900 drawn from practice records (questionnaire 2).

MAIN MEASURES

Response rates and technical evaluation of performance of the questionnaires (reliability, item nonresponse, ineligible response, sensitivity, and validity).

RESULTS

Response rate for questionnaire 1 was 77% (range 69% to 83%) and to questionnaire 2, 82% (77% to 86%). Analysis of respondents and nonrespondents showed that significantly more women, people aged 65 or more, and those consulting in the past six months returned the questionnaires. Technical evaluation indicated good face validity and content validity and good internal consistency.

CONCLUSIONS

A standardised off the shelf tool for audit was developed, and it will be a valuable model for future audits in general practice.

Neurochemical perspectives of the narcoleptic syndrome

Narcolepsy has been defined as a disorder of excessive sleep often associated with cataplexy, sleep paralysis and hypnagogic hallucinations. Although the pathophysiology of the narcoleptic syndrome is not well understood, derangement in the functions of CNS catecholamines and serotonin (5-HT) have been implicated. In the present paper we summarize evidence to suggest a role for the endogenous opioids in the regulation of normal sleep and in the pathophysiology of the narcoleptic syndrome.

Cerebral cysticercosis presenting as progressive dementia

Cysticercosis is a parasitic infestation that commonly affects the central nervous system. This is a report of an elderly man who presented with progressive dementia, labelled as Alzheimer's in whom diffuse cerebral cysticercosis was subsequently demonstrated. The dementia responded favorably to treatment with steroids and mebendazole. This report demonstrates the importance of excluding cerebral cysticercosis as a treatable cause of progressive dementia.

Anesthesia in multiple sclerosis

The effect of general anesthesia on 42 multiple sclerosis (MS) patients who underwent 88 episodes of general anesthesia was analyzed. One patient experienced a relapse after a procedure under general anesthesia, which is compatible with the natural history of the disease. A literature review revealed little information on this subject or on the use of particular anesthetic agents in MS. Our experience with spinal and local anesthesia is reported. In the evaluation of the former our limited data suggested that spinal anesthesia is less preferable than other alternatives in MS. Local anesthetics had a benign effect on the course of MS.