The effect of environment on the formation and evolution of galaxies in the distant universe

In this thesis I primarily use the UKIDSS Ultra-Deep Survey (UDS) to investigate the effect environment has on galaxies across the redshift range 0.25 1). The combination of a large contiguous area (0.77 deg2) and depth (KAB ∼24) allows us to study a range of environments up to a redshift of z ∼3. Due to the multiwavelength coverage we are able to obtain reliable photometric redshifts which are necessary for studies of environment. I utilise progressive releases of the UDS data to study the effect environment has on the rest frame (U-B) colour of galaxies. Using the U-B colour and absolute K-band magnitude I was able to divide our galaxies into red and blue and study their average environments. In this thesis I also employ data from the spaced based, GOODS NICMOS Survey (GNS) to help study the environments out to high redshift (z ∼3), in which I also study the colour-density relation. The UDS project was recently enhanced by the addition of ∼3500 spectra of highredshift galaxies, obtained using the VIMOS and FORS2 instruments on the VLT. The data reduction and redshift determination for the VIMOS data is discussed and is exploited to improve the photometric redshifts for the study of environments in the DR8. The ∼1600 reliable spectra are utilised directly to investigate the effect that environment has on the spectral properties of galaxies. We find that red galaxies are on average in denser environments than blue galaxies up to a redshift of z ∼2. The colour-density relation is strongest at the lowest redshifts studied (0.25 < z < 0.75) and gradually weakens out to redshift z ∼2 where it becomes almost flat. We also observe a distinct positive correlation between K-band luminosity and local density for galaxies between 1.25 < z < 2.75. This relation becomes strongest for the blue galaxies on the smallest scale studied (125kpc radius). Through studying the effect of environment on spectral features we have found evidence that galaxies between a redshift of 1.25 < z < 2.2 have significantly larger values of the C(29-33) index, in denser environments, indicating that older/more passive galaxies, even at this high redshift, reside in denser environments. The other indices similarly tend to indicate that older galaxies inhabit denser environments, whilst the environment has little effect on the properties of the blue galaxies. The spectra also indicate that one age determining index, C(29-33) is a very good indicator of colour for samples of galaxies at high redshift where the traditional measures such as the 4000°A break strength are difficult to obtain. This study of environments leads us to the final conclusion that although the stellar mass of a galaxy is clearly important in determining its evolution, its environment is also an important driver in a galaxy’s evolution. Disentangling the relative importance of these drivers (nature vs nurture) will be a major goal in the coming years

Evidence for a correlation between the sizes of quiescent galaxies and local environment to z ~ 2

We present evidence for a strong relationship between galaxy size and environment for the quiescent population in the redshift range 1 < z < 2. Environments were measured using projected galaxy overdensities on a scale of 400 kpc, as determined from ~ 96,000 K-band selected galaxies from the UKIDSS Ultra Deep Survey (UDS). Sizes were determined from ground-based K-band imaging, calibrated using space-based CANDELS HST observations in the centre of the UDS field, with photometric redshifts and stellar masses derived from 11-band photometric fitting. From the resulting size-mass relation, we confirm that quiescent galaxies at a given stellar mass were typically ~ 50 % smaller at z ~ 1.4 compared to the present day. At a given epoch, however, we find that passive galaxies in denser environments are on average significantly larger at a given stellar mass. The most massive quiescent galaxies (M_stellar > 2 x 10^11 M_sun) at z > 1 are typically 50 % larger in the highest density environments compared to those in the lowest density environments. Using Monte Carlo simulations, we reject the null hypothesis that the size-mass relation is independent of environment at a significance > 4.8 sigma for the redshift range 1 < z < 2. In contrast, the evidence for a relationship between size and environment is much weaker for star-forming galaxies.Comment: Accepted for publication in MNRAS. 16 pages, 11 figures, 6 table

Abdominal aortic aneurysm repair with the Zenith stent graft: Short to midterm results

AbstractPurpose: The purpose of this study was to assess the short-term and mid-term results of endovascular aneurysm repair with the Zenith stent graft in a single-center prospective study. Method: Between October 1998 and July 2001, we used the Zenith stent graft for elective endovascular aneurysm repair in 116 patients, six of whom were women. The mean age was 75 years, and the mean aneurysm diameter was 60.3 ± 8.8 mm. Stent grafts were oversized 10% to 20% relative to computed tomographic (CT) scan-based diameter measurements. All repairs were performed in the operating room through surgically exposed femoral arteries. The results were assessed before discharge with three-phase, contrast-enhanced CT scan and plain abdominal radiograph. These studies were repeated at 1, 6, 12, and 24 months after operation. Follow-up periods ranged from 1 to 34 months. Results: No failed insertions and no conversions to open surgery occurred. The diameter of the main body of the stent graft was 28 mm or more in 73 patients (63%). Additional stents were inserted during surgery to treat kinking in eight patients (6.9%) and renal artery encroachment in two patients (1.7%). Mean fluoroscopy time was 35.1 ± 18.3 minutes, contrast load was 146 ± 53 mL (350 mg/mL), and estimated blood loss was 249 ± 407 mL. The major complication rate was 9.5%, and the minor complication rate was 10.3%. The perioperative complications were myocardial infarction in four patients, arrythmia in four patients, and pulmonary embolism, renal failure, stroke, small bowel obstruction, femoral stenosis, digital embolism, and graft limb thrombosis in one patient each. All 116 patients went home from the hospital, but one patient died 2 weeks later of a combination of pulmonary embolism and myocardial infarction. Endoleak was seen on the first CT scan in 16 patients (15%); 15 were type II, and one was type III. No endoleaks of type I or IV were seen. Additional interventions were performed for each of the following conditions: type II endoleak (n = 4), type III endoleak (n = 1), femoral clamp injury (n = 1), renal artery stenosis (n = 1), and graft limb occlusion (n = 1). One patient had acute aneurysm dilatation and rupture caused by a type II endoleak through the inferior mesenteric artery 6 months after stent graft implantation. No cases were seen of late graft occlusion, stent graft migration, stent fracture, barb fracture, or secondary endoleak. Conclusion: The Zenith device is safe, versatile, and effective in the short to medium term. Most patients need wide stent grafts (≥28 mm proximally and ≥16 mm distally) to achieve 10% to 20% oversizing to prevent type I endoleak. (J Vasc Surg 2002;36:217-25.

The intersocietal IWGDF, ESVS, SVS guidelines on peripheral artery disease in people with diabetes and a foot ulcer.

Diabetes related foot complications have become a major cause of morbidity and are implicated in most major and minor amputations globally. Approximately 50% of people with diabetes and a foot ulcer have peripheral artery disease (PAD) and the presence of PAD significantly increases the risk of adverse limb and cardiovascular events. The International Working Group on the Diabetic Foot (IWGDF) has published evidence based guidelines on the management and prevention of diabetes related foot complications since 1999. This guideline is an update of the 2019 IWGDF guideline on the diagnosis, prognosis and management of peripheral artery disease in people with diabetes mellitus and a foot ulcer. For this guideline the IWGDF, the European Society for Vascular Surgery and the Society for Vascular Surgery decided to collaborate to develop a consistent suite of recommendations relevant to clinicians in all countries. This guideline is based on three new systematic reviews. Using the Grading of Recommendations, Assessment, Development, and Evaluation framework clinically relevant questions were formulated, and the literature was systematically reviewed. After assessing the certainty of the evidence, recommendations were formulated which were weighed against the balance of benefits and harms, patient values, feasibility, acceptability, equity, resources required, and when available, costs. Through this process five recommendations were developed for diagnosing PAD in a person with diabetes, with and without a foot ulcer or gangrene. Five recommendations were developed for prognosis relating to estimating likelihood of healing and amputation outcomes in a person with diabetes and a foot ulcer or gangrene. Fifteen recommendations were developed related to PAD treatment encompassing prioritisation of people for revascularisation, the choice of a procedure and post-surgical care. In addition, the Writing Committee has highlighted key research questions where current evidence is lacking. The Writing Committee believes that following these recommendations will help healthcare professionals to provide better care and will reduce the burden of diabetes related foot complications

Effectiveness of bedside investigations to diagnose peripheral artery disease among people with diabetes mellitus: A systematic review.

As a progressive disease process, early diagnosis and ongoing monitoring and treatment of lower limb peripheral artery disease (PAD) is critical to reduce the risk of diabetes-related foot ulcer (DFU) development, non-healing of wounds, infection and amputation, in addition to cardiovascular complications. There are a variety of non-invasive tests available to diagnose PAD at the bedside, but there is no consensus as to the most diagnostically accurate of these bedside investigations or their reliability for use as a method of ongoing monitoring. Therefore, the aim of this systematic review was to first determine the diagnostic accuracy of non-invasive bedside tests for identifying PAD compared to an imaging reference test and second to determine the intra- and inter-rater reliability of non-invasive bedside tests in adults with diabetes. A database search of Medline and Embase was conducted from 1980 to 30 November 2022. Prospective and retrospective investigations of the diagnostic accuracy of bedside testing in people with diabetes using an imaging reference standard and reliability studies of bedside testing techniques conducted in people with diabetes were eligible. Included studies of diagnostic accuracy were required to report adequate data to calculate the positive likelihood ratio (PLR) and negative likelihood ratio (NLR) which were the primary endpoints. The quality appraisal was conducted using the Quality Assessment of Diagnostic Accuracy Studies and Quality Appraisal of Reliability quality appraisal tools. From a total of 8517 abstracts retrieved, 40 studies met the inclusion criteria for the diagnostic accuracy component of the review and seven studies met the inclusion criteria for the reliability component of the review. Most studies investigated the diagnostic accuracy of ankle -brachial index (ABI) (N = 38). In people with and without DFU, PLRs ranged from 1.69 to 19.9 and NLRs from 0.29 to 0.84 indicating an ABI 1.3, TBI of <0.70, and absent or monophasic pedal Doppler waveforms are useful to identify the presence of disease. The ability of the tests to exclude disease is variable and although reliability may be acceptable, evidence of error in the measurements means test results that are within normal limits should be considered with caution and in the context of other vascular assessment findings (e.g., pedal pulse palpation and clinical signs) and progress of DFU healing

Performance of non-invasive bedside vascular testing in the prediction of wound healing or amputation among people with foot ulcers in diabetes: A systematic review.

INTRODUCTION The presence of peripheral artery disease (PAD) confers a significantly increased risk of failure to heal and major lower limb amputation for people with diabetes-related foot ulcer (DFU). Determining performance of non-invasive bedside tests for predicting likely DFU outcomes is therefore key to effective risk stratification of patients with DFU and PAD to guide management decisions. The aim of this systematic review was to determine the performance of non-invasive bedside tests for PAD to predict DFU healing, healing post-minor amputation, or need for minor or major amputation in people with diabetes and DFU or gangrene. METHODS A database search of Medline and Embase was conducted from 1980 to 30 November 2022. Prospective studies that evaluated non-invasive bedside tests in patients with diabetes, with and without PAD and foot ulceration or gangrene to predict the outcomes of DFU healing, minor amputation, and major amputation with or without revascularisation, were eligible. Included studies were required to have a minimum 6-month follow-up period and report adequate data to calculate the positive likelihood ratio (PLR) and negative likelihood ratio for the outcomes of DFU healing, and minor and major amputation. Methodological quality was assessed using the Quality in Prognosis Studies tool. RESULTS From 14,820 abstracts screened 28 prognostic studies met the inclusion criteria. The prognostic tests evaluated by the studies included: ankle-brachial index (ABI) in 9 studies; ankle pressures in 10 studies, toe-brachial index in 4 studies, toe pressure in 9 studies, transcutaneous oxygen pressure (TcPO2 ) in 7 studies, skin perfusion pressure in 5 studies, continuous wave Doppler (pedal waveforms) in 2 studies, pedal pulses in 3 studies, and ankle peak systolic velocity in 1 study. Study quality was variable. Common reasons for studies having a moderate or high risk of bias were poorly described study participation, attrition rates, and inadequate adjustment for confounders. In people with DFU, toe pressure ≥30 mmHg, TcPO2 ≥25 mmHg, and skin perfusion pressure of ≥40 mmHg were associated with a moderate to large increase in pretest probability of healing in people with DFU. Toe pressure ≥30 mmHg was associated with a moderate increase in healing post-minor amputation. An ABI using a threshold of ≥0.9 did not increase the pretest probability of DFU healing, whereas an ABI <0.5 was associated with a moderate increase in pretest probability of non-healing. Few studies investigated amputation outcomes. An ABI <0.4 demonstrated the largest increase in pretest probability of a major amputation (PLR ≥10). CONCLUSIONS Prognostic capacity of bedside testing for DFU healing and amputation is variable. A toe pressure ≥30 mmHg, TcPO2 ≥25 mmHg, and skin perfusion pressure of ≥40 mmHg are associated with a moderate to large increase in pretest probability of healing in people with DFU. There are little data available evaluating the prognostic capacity of bedside testing for healing after minor amputation or for major amputation in people with DFU. Current evidence suggests that an ABI <0.4 may be associated with a large increase in risk of major amputation. The findings of this systematic review need to be interpreted in the context of limitations of available evidence, including varying rates of revascularisation, lack of post-revascularisation bedside testing, and heterogenous subpopulations

Effectiveness of revascularisation for the ulcerated foot in patients with diabetes and peripheral artery disease: A systematic review.

INTRODUCTION Peripheral artery disease (PAD) is associated with an increased likelihood of delayed or non-healing of a diabetes-related foot ulcer, gangrene, and amputation. The selection of the most effective surgical technique for revascularisation of the lower limb in this population is challenging and there is a lack of conclusive evidence to support the choice of intervention. This systematic review aimed to determine, in people with diabetes and tissue loss, if direct revascularisation is superior to indirect revascularisation and if endovascular revascularisation is superior to open revascularisation for the outcomes of wound healing, minor or major amputation, and adverse events including mortality. METHODS Title and abstract searches of Medline, Embase, PubMed, and EBSCO were conducted from 1980 to 30th November 2022. Cohort and case-control studies and randomised controlled trials reporting comparative outcomes of direct (angiosome) revascularisation (DR) and indirect revascularisation (IR) or the comparative outcomes of endovascular revascularisation and open or hybrid revascularisation for the outcomes of healing, minor amputation, and major amputation in people with diabetes, PAD and tissue loss (including foot ulcer and/or gangrene) were eligible. Methodological quality was assessed using the Cochrane risk-of-bias tool for randomised trials, the ROBINS-I tool for non-randomised studies, and Newcastle-Ottawa Scale for observational and cohort studies where details regarding the allocation to intervention groups were not provided. RESULTS From a total 7086 abstracts retrieved, 26 studies met the inclusion criteria for the comparison of direct angiosome revascularisation (DR) and indirect revascularisation (IR), and 11 studies met the inclusion criteria for the comparison of endovascular and open revascularisation. One study was included in both comparisons. Of the included studies, 35 were observational (31 retrospective and 4 prospective cohorts) and 1 was a randomised controlled trial. Cohort study quality was variable and generally low, with common sources of bias related to heterogeneous participant populations and interventions and lack of reporting of or adjusting for confounding factors. The randomised controlled trial had a low risk of bias. For studies of DR and IR, results were variable, and it is uncertain if one technique is superior to the other for healing, prevention of minor or major amputation, or mortality. However, the majority of studies reported that a greater proportion of participants receiving DR healed compared with IR, and that IR with collaterals may have similar outcomes to DR for wound healing. For patients with diabetes, infrainguinal PAD, and an adequate great saphenous vein available for use as a bypass conduit who were deemed suitable for either surgical procedure, an open revascularisation first approach was superior to endovascular therapy to prevent a major adverse limb event or death (Hazard Ratio: 0.72; 95% CI 0.61-0.86). For other studies of open and endovascular approaches, there was generally no difference in outcomes between the interventions. CONCLUSIONS The majority of available evidence for the effectiveness of DR and IR and open and endovascular revascularisation for wound healing and prevention of minor and major amputation and adverse events including mortality in people with diabetes, PAD and tissue loss is inconclusive, and the certainty of evidence is very low. Data from one high quality randomised controlled trial supports the use of open over endovascular revascularisation to prevent a major limb event and death in people with diabetes, infrainguinal disease and tissue loss who have an adequate great saphenous vein available and who are deemed suitable for either approach

Perioperative exercise programmes to promote physical activity in the medium to long term: systematic review and qualitative research

Background: In England, more than 4 million hospital admissions lead to surgery each year. The perioperative encounter (from initial presentation in primary care to postoperative return to function) offers potential for substantial health gains in the wider sense and over the longer term. Objectives: The aim was to identify, examine and set in context a range of interventions applied perioperatively to facilitate physical activity in the medium to long term. Data sources: The following databases were searched – Cochrane Central Register of Controlled Trials, MEDLINE, the Cumulative Index to Nursing and Allied Health Literature, EMBASE, PsycINFO and SPORTDiscus in October 2020. Clinical trials databases were also searched, and backward and forward citation searches were conducted. Review methods: We undertook a systematic review; ran database searches in October 2020; extracted data; conducted risk-of-bias assessments of studies; and used Grading of Recommendations Assessment, Development and Evaluation assessments. We conducted focus groups and interviews with people running services designed to promote physical activity, to understand the practical and contextual factors that make such interventions ‘work’. Although the two streams of work were conducted independently, we considered overlapping themes from their findings. Results: In the review, we found 51 randomised controlled trials and two quasi-randomised trials; nine non-randomised studies formed a supplementary data set. Studies included 8604 adults who had undergone (or were undergoing) surgery, and compared 67 interventions facilitating physical activity. Most interventions were started postoperatively and included multiple components, grouped as follows: education and advice, behavioural mechanisms and physical activity instruction. Outcomes were often measured using different tools; pooling of data was not always feasible. Compared with usual care, interventions may have slightly increased the amount of physical activity, engagement in physical activity and health-related quality of life at the study’s end (moderate-certainty evidence). We found low-certainty evidence of an increase in physical fitness and a reduction in pain, although effects generally favoured interventions. Few studies reported adherence and adverse events; certainty of these findings was very low. Although infrequently reported, participants generally provided positive feedback. For the case studies, we conducted two online focus groups and two individual interviews between November 2020 and January 2021, with nine participants from eight services of physical activity programmes. Conceptual and practical aspects included how the promotion of physical activity can be framed around the individual to recruit and retain patients; how services benefit from committed and compassionate staff; how enthusiasts, data collection and evidence play key roles; and how digital delivery could work as part of a blended approach, but inequalities in access must be considered. Limitations: Outcome measures in the review varied and, despite a large data set, not all studies could be pooled. This also limited the exploration of differences between interventions; components of interventions often overlapped between studies, and we could not always determine what ‘usual care’ involved. The case study exploration was limited by COVID-19 restrictions; we were unable to visit sites and observe practice, and the range of services in the focus groups was also limited. Conclusions: Evidence from the review indicates that interventions delivered in the perioperative setting, aimed at enhancing physical activity in the longer term, may have overall benefit. The qualitative analysis complemented these findings and indicated that interventions should be focused around the individual, delivered locally and compassionately, and promoted by a patient’s full clinical team. There is a need to develop a core outcome set for similar studies to allow quantitative synthesis. Future work should also investigate the experiences of patients in different contexts, such as different communities, and with different surgical indications

Effectiveness of the perioperative encounter in promoting regular exercise and physical activity: a systematic review and meta-analysis

Background Low levels of physical activity (PA) are associated with poorer health outcomes. The perioperative encounter (extending from initial contact in primary care to beyond discharge from hospital) is potentially a good time to intervene, but data regarding the effectiveness of interventions are scarce. To address this, we systematically reviewed existing literature to evaluate the effectiveness of interventions applied perioperatively to facilitate PA in the medium to long-term (at least six months after the intervention). Methods In this systematic review and meta-analysis, we searched Central Register of Controlled Trials (CENTRAL, Cochrane Library), MEDLINE, CINAHL, Embase, PsycInfo, and SPORTDiscus from database inception to October 22nd 2020, with an updated search done on August 4th 2022. We searched clinical trials registers, and conducted forward- and backward-citation searches. We included randomised controlled trials and quasi-randomised trials comparing PA interventions with usual care, or another PA intervention, in adults who were scheduled for, or had recently undergone, surgery. We included trials which reported our primary outcomes: amount of PA or whether participants were engaged in PA at least six months after the intervention. A random effects meta-analysis was used to pool data across studies as risk ratios (RR), or standardised mean differences (SMDs), which we interpreted using Cohen. We used the Cochrane risk of bias tool and used GRADE to assess the certainty of the evidence. This study is registered with PROSPERO, CRD42019139008. Findings We found 57 trials including 8548 adults and compared 71 interventions facilitating PA. Most interventions were started postoperatively and included multiple components. Compared with usual care, interventions may slightly increase the number of minutes of PA per day or week (SMD 0.17, 95% CI 0.09–0.26; 14 studies, 2172 participants; I2 = 0%), and people's engagement in PA at the study's end (RR 1.19, 95% CI 0.96–1.47; 9 studies, 882 participants; I2 = 25%); this was moderate-certainty evidence. Some studies compared two different types of interventions but it was often not feasible to combine data in analysis. The effect estimates generally indicated little difference between intervention designs and we judged all the evidence for these comparisons to be very low certainty. Thirty-six studies (63%) had low risk of selection bias for sequence generation, 27 studies (47%) had low risk of bias for allocation concealment, and 56 studies (98%) had a high risk of performance bias. For detection bias for PA outcomes, we judged 30 studies (53%) that used subjective measurement tools to have a high risk of detection bias. Interpretation Interventions delivered in the perioperative setting, aimed at enhancing PA in the medium to long-term, may have overall benefit. However, because of imprecision in some of the findings, we could not rule out the possibility of no change in PA

Effectiveness of the perioperative encounter in promoting regular exercise and physical activity: a systematic review and meta-analysis

Background: Low levels of physical activity (PA) are associated with poorer health outcomes. The perioperative encounter (extending from initial contact in primary care to beyond discharge from hospital) is potentially a good time to intervene, but data regarding the effectiveness of interventions are scarce. To address this, we systematically reviewed existing literature to evaluate the effectiveness of interventions applied perioperatively to facilitate PA in the medium to long-term (at least six months after the intervention). Methods: In this systematic review and meta-analysis, we searched Central Register of Controlled Trials (CENTRAL, Cochrane Library), MEDLINE, CINAHL, Embase, PsycInfo, and SPORTDiscus from database inception to October 22nd 2020, with an updated search done on August 4th 2022. We searched clinical trials registers, and conducted forward- and backward-citation searches. We included randomised controlled trials and quasi-randomised trials comparing PA interventions with usual care, or another PA intervention, in adults who were scheduled for, or had recently undergone, surgery. We included trials which reported our primary outcomes: amount of PA or whether participants were engaged in PA at least six months after the intervention. A random effects meta-analysis was used to pool data across studies as risk ratios (RR), or standardised mean differences (SMDs), which we interpreted using Cohen. We used the Cochrane risk of bias tool and used GRADE to assess the certainty of the evidence. This study is registered with PROSPERO, CRD42019139008. Findings: We found 57 trials including 8548 adults and compared 71 interventions facilitating PA. Most interventions were started postoperatively and included multiple components. Compared with usual care, interventions may slightly increase the number of minutes of PA per day or week (SMD 0.17, 95% CI 0.09–0.26; 14 studies, 2172 participants; I2 = 0%), and people's engagement in PA at the study's end (RR 1.19, 95% CI 0.96–1.47; 9 studies, 882 participants; I2 = 25%); this was moderate-certainty evidence. Some studies compared two different types of interventions but it was often not feasible to combine data in analysis. The effect estimates generally indicated little difference between intervention designs and we judged all the evidence for these comparisons to be very low certainty. Thirty-six studies (63%) had low risk of selection bias for sequence generation, 27 studies (47%) had low risk of bias for allocation concealment, and 56 studies (98%) had a high risk of performance bias. For detection bias for PA outcomes, we judged 30 studies (53%) that used subjective measurement tools to have a high risk of detection bias. Interpretation: Interventions delivered in the perioperative setting, aimed at enhancing PA in the medium to long-term, may have overall benefit. However, because of imprecision in some of the findings, we could not rule out the possibility of no change in PA. Funding: National Institute for Health Research Health Services and Delivery Research programme (NIHR127879)