Effects of official and unofficial environmental regulations on environmental quality: Evidence from the Yangtze River Economic Belt, China.

Due to the increasing impact of climate change, there is a need to examine the effect of environmental regulation on environmental quality. Consequently, we examine the nonlinear and mediation effects of environmental regulation on environmental quality using panel data of 45 major cities in the Yangtze River Economic Belt, China, from 2013 to 2020. Environmental regulation is divided into official and unofficial environmental regulations according to its formality. The results indicate that an increase of official and unofficial environmental regulations can promote the improvement of environmental quality. In fact, the positive effect of environmental regulation on cities with better environmental quality is greater than that of cities with poorer environmental quality. The implementation of both official and unofficial environmental regulations can improve environmental quality better than the single implementation of either official environmental regulation or unofficial environmental regulation. There are full mediation effects of Gross Domestic Product per capita and technological progress in the positive effects of official environmental regulation on environmental quality. There are also partial mediation effects of technological progress and industrial structure in the positive effects of unofficial environmental regulation on environmental quality. This study assesses the policy effectiveness of environmental regulation and determines the underlying mechanism between environmental regulation and environmental quality to provide a reference for other countries regarding environmental improvement.

Comparison of manual and semi-automatic registration in augmented reality image-guided liver surgery: a clinical feasibility study.

BACKGROUND: The laparoscopic approach to liver resection may reduce morbidity and hospital stay. However, uptake has been slow due to concerns about patient safety and oncological radicality. Image guidance systems may improve patient safety by enabling 3D visualisation of critical intra- and extrahepatic structures. Current systems suffer from non-intuitive visualisation and a complicated setup process. A novel image guidance system (SmartLiver), offering augmented reality visualisation and semi-automatic registration has been developed to address these issues. A clinical feasibility study evaluated the performance and usability of SmartLiver with either manual or semi-automatic registration. METHODS: Intraoperative image guidance data were recorded and analysed in patients undergoing laparoscopic liver resection or cancer staging. Stereoscopic surface reconstruction and iterative closest point matching facilitated semi-automatic registration. The primary endpoint was defined as successful registration as determined by the operating surgeon. Secondary endpoints were system usability as assessed by a surgeon questionnaire and comparison of manual vs. semi-automatic registration accuracy. Since SmartLiver is still in development no attempt was made to evaluate its impact on perioperative outcomes. RESULTS: The primary endpoint was achieved in 16 out of 18 patients. Initially semi-automatic registration failed because the IGS could not distinguish the liver surface from surrounding structures. Implementation of a deep learning algorithm enabled the IGS to overcome this issue and facilitate semi-automatic registration. Mean registration accuracy was 10.9 ± 4.2 mm (manual) vs. 13.9 ± 4.4 mm (semi-automatic) (Mean difference - 3 mm; p = 0.158). Surgeon feedback was positive about IGS handling and improved intraoperative orientation but also highlighted the need for a simpler setup process and better integration with laparoscopic ultrasound. CONCLUSION: The technical feasibility of using SmartLiver intraoperatively has been demonstrated. With further improvements semi-automatic registration may enhance user friendliness and workflow of SmartLiver. Manual and semi-automatic registration accuracy were comparable but evaluation on a larger patient cohort is required to confirm these findings.

A fluorescence toolbox: A review of investigation of electrophoretic separations, process, and interfaces.

This review focuses on fluorescence spectroscopy techniques for the investigation of electrophoretic separations. Fluorescence has been used as a sensitive detector for capillary, gel, and microchip electrophoresis for decades. However, advanced fluorescence methods can be used to study transport, interfacial phenomena, intermolecular and affinity interactions, and other processes that occur during separation. This so-called spectroscopic toolkit can be implemented to understand fundamental behavior in electrophoresis and electrokinetic chromatography. Techniques such as fluorescence recovery after photobleaching, fluorescence correlation spectroscopy, and fluorescence anisotropy are discussed in relation to electrophoretic separations. Newer methods such as super-resolution microscope are also introduced.

Modulation and study of photoblinking behavior in dye doped silver-silica core-shell nanoparticles for localization super-resolution microscopy.

Blinking of fluorescent nanoparticles is a compelling phenomenon with widely debated mechanisms. The ability to inhibit or control blinking is important for applications in the field of optical, semiconductor and fluorescent imaging. Self-blinking nanomaterials are also attractive labels for localization-based super-resolution microscopy. In this work, we have synthesized silver core silica nanoparticles (Ag@SiO2) doped with Rhodamine 110 and studied the parameters that affect blinking. We found that under nitrogen rich conditions the nanoparticles shifted towards higher duty cycles. Also, it was found that hydrated nanoparticles showed a less drastic response to nitrogen rich conditions as compared to dried nanoparticles, indicating that surrounding matrix played a role in the response of nanoparticles to molecular oxygen. Further, the blinking is not a multi-body phenomena, super-resolution localization combined with intensity histogram analysis confirmed that single particles are emitting.

Flatulence After Anti-reflux Treatment (FAART) Study.

BACKGROUND: Flatulence is known to be a common side effect of laparoscopic fundoplication, yet the true incidence is unclear and its impact on patients' quality of life not well understood. This study aimed to assess the long-term incidence of flatulence, and its effect on quality of life, following fundoplication. METHODS: All patients who underwent primary laparoscopic fundoplication between 1999 and 2009 were identified from a prospectively maintained institutional database. A cross-sectional analysis of post-operative gastrointestinal symptoms and quality of life was performed using a symptom-specific questionnaire. Statistical analysis of outcomes stratified by sex and type of fundoplication was performed. RESULTS: 462 eligible patients were identified from the database, with follow-up obtained in 265 (57%). Median age at surgery was 53 (22-78) years. 137 patients (52%) were female. 138 (52%) underwent a 360° fundoplication, the remainder a partial fundoplication. At median follow-up of 11 (8-15) years, excessive flatulence was reported by 85%. Only 12% reported an adverse impact on social life, and 11% an adverse impact on quality of life. Flatulence was worse following a total than partial fundoplication, women reported more gas-related symptoms than men, yet neither sex nor wrap type had a significant impact on social life or quality of life. CONCLUSIONS: The majority of patients report excessive flatulence at long-term follow-up after anti-reflux surgery, yet the impact on social life and quality life was small. There was no evidence to support tailoring of wrap type by sex to avoid gas-related symptoms. The authors advocate that all patients understand the inevitable side effects of fundoplication to help manage expectations from surgery.

Lessons learned about prevalence and growth rates of abdominal aortic aneurysms from a 25-year ultrasound population screening programme.

BACKGROUND: This study aimed to assess how the prevalence and growth rates of small and medium abdominal aortic aneurysms (AAAs) (3·0-5·4 cm) have changed over time in men aged 65 years, and to evaluate long-term outcomes in men whose aortic diameter is 2·6-2·9 cm (subaneurysmal), and below the standard threshold for most surveillance programmes. METHODS: The Gloucestershire Aneurysm Screening Programme (GASP) started in 1990. Men aged 65 years with an aortic diameter of 2·6-5·4 cm, measured by ultrasonography using the inner to inner wall method, were included in surveillance. Aortic diameter growth rates were estimated separately for men who initially had a subaneurysmal aorta, and those who had a small or medium AAA, using mixed-effects models. RESULTS: Since 1990, 81 150 men had ultrasound screening for AAA (uptake 80·7 per cent), of whom 2795 had an aortic diameter of 2·6-5·4 cm. The prevalence of screen-detected AAA of 3·0 cm or larger decreased from 5·0 per cent in 1991 to 1·3 per cent in 2015. There was no evidence of a change in AAA growth rates during this time. Of men who initially had a subaneurysmal aorta, 57·6 (95 per cent c.i. 54·4 to 60·7) per cent were estimated to develop an AAA of 3·0 cm or larger within 5 years of the initial scan, and 28·0 (24·2 to 31·8) per cent to develop a large AAA (at least 5·5 cm) within 15 years. CONCLUSION: The prevalence of screen-detected small and medium AAAs has decreased over the past 25 years, but growth rates have remained similar. Men with a subaneurysmal aorta at age 65 years have a substantial risk of developing a large AAA by the age of 80 years.

Value of risk scores in the decision to palliate patients with ruptured abdominal aortic aneurysm.

BACKGROUND: The aim of this study was to develop a 48-h mortality risk score, which included morphology data, for patients with ruptured abdominal aortic aneurysm presenting to an emergency department, and to assess its predictive accuracy and clinical effectiveness in triaging patients to immediate aneurysm repair, transfer or palliative care. METHODS: Data from patients in the IMPROVE (Immediate Management of the Patient With Ruptured Aneurysm: Open Versus Endovascular Repair) randomized trial were used to develop the risk score. Variables considered included age, sex, haemodynamic markers and aortic morphology. Backwards selection was used to identify relevant predictors. Predictive performance was assessed using calibration plots and the C-statistic. Validation of the newly developed and other previously published scores was conducted in four external populations. The net benefit of treating patients based on a risk threshold compared with treating none was quantified. RESULTS: Data from 536 patients in the IMPROVE trial were included. The final variables retained were age, sex, haemoglobin level, serum creatinine level, systolic BP, aortic neck length and angle, and acute myocardial ischaemia. The discrimination of the score for 48-h mortality in the IMPROVE data was reasonable (C-statistic 0·710, 95 per cent c.i. 0·659 to 0·760), but varied in external populations (from 0·652 to 0·761). The new score outperformed other published risk scores in some, but not all, populations. An 8 (95 per cent c.i. 5 to 11) per cent improvement in the C-statistic was estimated compared with using age alone. CONCLUSION: The assessed risk scores did not have sufficient accuracy to enable potentially life-saving decisions to be made regarding intervention. Focus should therefore shift to offering repair to more patients and reducing non-intervention rates, while respecting the wishes of the patient and family.

Intracranial pressure in patients with papilloedema.

OBJECTIVES: Papilloedema is a clinical manifestation of chronically raised intracranial pressure (ICP), often seen in idiopathic intracranial hypertension (IIH). However, the extent of intracranial hypertension required to produce papilloedema is not known. We compare ICP values in IIH patients who developed papilloedema and those who did not. We aim to identify a pathological ICP threshold predictive of the development of papilloedema in IIH patients. MATERIALS AND METHODS: Single-centre cohort of IIH patients (2006-2016) who underwent 24-hour ICP monitoring (ICPM) and ophthalmology assessments, prior to intervention. Papilloedema was graded according to the Frisén scale. An unpaired t-test compared 24-hour ICPM between papilloedema and no-papilloedema groups. Fisher's exact test was used to determine predictive value of ICP. RESULTS: Thirty-six patients with IIH (35 F: 1M), mean age 32.5 ± 9.49 years (mean ± SD) were included. Patients with papilloedema had a mean median 24-hour ICP of 10.4 ± 5.32 mm Hg (n = 25), significantly higher than the group without papilloedema 6.31 ± 3.30 mm Hg (n = 11) (P < .05). The papilloedema group were exposed to higher pressures (10 mm Hg) for 30 minutes or more. Using 24-hour median ICP of 10 mm Hg as a minimum cut-off predictive value gives a specificity = 91%, sensitivity = 48%, PPV = 92% and NPV = 44% of detecting papilloedema. CONCLUSIONS: A 24-hour ICP of 10 mmHg or more is a good predictor for papilloedema and reflects a pathological threshold. The range varied widely suggesting papilloedema can occur at even lower pressures. These results are consistent with emerging evidence suggest that pathologically "high" 24 hours ICP is lower than previously quoted.

The intersystem crossing of a cyclic (alkyl)(amino) carbene gold (i) complex.

The intersystem crossing (ISC) mechanism of a cyclic (alkyl)(amino) carbene gold (I) complex (CMA1) is studied using quantum dynamics. A model spin-vibronic Hamiltonian is developed, which includes 10 excited states and two important nuclear degrees of freedom. The quantum dynamics reveals that ISC from S1 → T1 occurs on the tens of picosecond time scale, consistent with recent experiments. It is driven by motion along the torsional degree of freedom of the carbazole (Cz) ligand, which causes orthogonality between the donor and acceptor groups closing the gap between the initial (S1) and final (T1) states. The role of higher triplet states through spin-vibronic interactions is also discussed. Although previous calculations, evaluated in the Condon approximation, yield large ISC rates, our present dynamical treatment, taking into account the large amplitude torsional motion, increases the calculated rate by an order of magnitude improving the agreement with experiments. The model spin-vibronic Hamiltonian developed can also be used to understand the properties of related linear metal carbene compounds, facilitating molecular design.

Relationship between residual feed intake and radiated heat loss using infrared thermography in young beef bulls.

Residual feed intake (RFI) has been used to select metabolically efficient cattle in beef breeding programs, particularly for sire selection. Adoption of genetic selection using RFI has been limited due to the cost and difficulty of measuring individual feed intake. An alternative method of predicting RFI is to measure radiated heat loss using infrared thermography (IRT) as previous studies have shown promise using this technique to predict metabolic efficiency in mature cows, heifers, and growing bulls. The objective of this study was to explore use of IRT to predict RFI in growing beef bulls. Sixty bulls in each of two years were fed either a forage-based or a grain-based ration. Eye (Ey) and cheek (Ck) surface temperatures were measured using infrared images of the head collected on 16 and 14 sample days in Years 1 and 2, respectively, using a FLIR S60 camera. In Year 2, infrared images were collected continuously using a within-pen FLIR A310 camera system. Bulls were grouped into low, medium and high classes based on ±â€¯0.5 standard deviations of backfat adjusted residual feed intake (RFIFat); RFIFat values ranged from - 2.27 to + 2.61 kg DM day-1 (mean=0.0; SD=0.61). Sample day Ey and Ck temperatures were pooled and an average temperature was calculated for individual bulls. Average Ey and Ck temperatures measured using the FLIR S60 and the within-pen camera did not differ significantly across low, medium and high RFI groups (P > 0.05). Temperature deviations associated with extremes in ambient temperature (placing animals outside their thermoneutral zone) or underlying subclinical health problems could bias results in IRT measurements and RFI ranking. Standardization of IRT data and the conditions during measurement is necessary to more accurately assess its potential use to predict RFI.

Fine-mapping the MHC locus in juvenile idiopathic arthritis (JIA) reveals genetic heterogeneity corresponding to distinct adult inflammatory arthritic diseases.

OBJECTIVES: Juvenile idiopathic arthritis (JIA) is a heterogeneous group of diseases, comprising seven categories. Genetic data could potentially be used to help redefine JIA categories and improve the current classification system. The human leucocyte antigen (HLA) region is strongly associated with JIA. Fine-mapping of the region was performed to look for similarities and differences in HLA associations between the JIA categories and define correspondences with adult inflammatory arthritides. METHODS: Dense genotype data from the HLA region, from the Immunochip array for 5043 JIA cases and 14 390 controls, were used to impute single-nucleotide polymorphisms, HLA classical alleles and amino acids. Bivariate analysis was performed to investigate genetic correlation between the JIA categories. Conditional analysis was used to identify additional effects within the region. Comparison of the findings with those in adult inflammatory arthritic diseases was performed. RESULTS: We identified category-specific associations and have demonstrated for the first time that rheumatoid factor (RF)-negative polyarticular JIA and oligoarticular JIA are genetically similar in their HLA associations. We also observe that each JIA category potentially has an adult counterpart. The RF-positive polyarthritis association at HLA-DRB1 amino acid at position 13 mirrors the association in adult seropositive rheumatoid arthritis (RA). Interestingly, the combined oligoarthritis and RF-negative polyarthritis dataset shares the same association with adult seronegative RA. CONCLUSIONS: The findings suggest the value of using genetic data in helping to classify the categories of this heterogeneous disease. Mapping JIA categories to adult counterparts could enable shared knowledge of disease pathogenesis and aetiology and facilitate transition from paediatric to adult services.

Sex differences in mortality after abdominal aortic aneurysm repair in the UK.

BACKGROUND: The UK abdominal aortic aneurysm (AAA) screening programmes currently invite only men for screening because the benefit in women is uncertain. Perioperative risk is critical in determining the effectiveness of screening, and contemporary estimates of these risks in women are lacking. The aim of this study was to compare mortality following AAA repair between women and men in the UK. METHODS: Anonymized data from the UK National Vascular Registry (NVR) for patients undergoing AAA repair (January 2010 to December 2014) were analysed. Co-variables were extracted for analysis by sex. The primary outcome measure was in-hospital mortality. Secondary outcome measures included mortality by 5-year age groups and duration of hospital stay. Logistic regression was performed to adjust for age, calendar time, AAA diameter and smoking status. NVR-based outcomes were checked against Hospital Episode Statistics (HES) data. RESULTS: A total of 23 245 patients were included (13·0 per cent women). Proportionally, more women than men underwent open repair. For elective open AAA repair, the in-hospital mortality rate was 6·9 per cent in women and 4·0 per cent in men (odds ratio (OR) 1·48, 95 per cent c.i. 1·08 to 2·02; P = 0·014), whereas for elective endovascular AAA repair it was 1·8 per cent in women and 0·7 per cent in men (OR 2·86, 1·72 to 4·74; P < 0·001); the results in HES were similar. For ruptured AAA, there was no sex difference in mortality within the NVR; however, in HES, for ruptured open AAA repair, the in-hospital mortality rate was higher in women (33·6 versus 27·1 per cent; OR 1·36, 1·16 to 1·59; P < 0·001). CONCLUSION: Women have a higher in-hospital mortality rate than men after elective AAA repair even after adjustment. This higher mortality may have an impact on the benefit offered by any screening programme offered to women.

History rather than hybridization determines population structure and adaptation in Populus balsamifera.

Hybridization between species is known to greatly affect their genetic diversity and, therefore, their evolution. Also, within species, there may be genetic clusters between which gene flow is limited, which may impact natural selection. However, few studies have looked simultaneously at the influence of among-species and within-species gene flow. Here, we study the influence of hybridization between Populus balsamifera and Populus trichocarpa on population structure and adaptation in P. balsamifera. We did this by sampling a total of 1517 individuals from across the ranges of these two species, and by genotyping them using a combination of 93 nuclear and 17 cpDNA SNPs. We found that hybridization is mostly limited to the contact zone where the species' distributions overlap. Within P. balsamifera, we found multiple levels of population structure. Interestingly, the border between the Eastern and Central clusters is very sharp, whereas the border between the Central and Western clusters is diffuse. Outlier analysis revealed that three loci associated with the sharp border were also associated with climate. We hypothesize that the observed clusters derive from three refugia during the Pleistocene ice ages. Between the Central and Western clusters, post-glacial long-distance gene flow has led to the diffusion of their border. In the Eastern cluster, we hypothesize that endogenous genomic barriers have developed, leading to the sharp border and a spurious climate association. We conclude that the large-scale genetic structure of P. balsamifera is mostly shaped by historical factors and the influence of interspecific hybridization is limited.

Sensory trait variation contributes to biased dispersal of threespine stickleback in flowing water.

Gene flow is widely thought to homogenize spatially separate populations, eroding effects of divergent selection. The resulting theory of 'migration-selection balance' is predicated on a common assumption that all genotypes are equally prone to dispersal. If instead certain genotypes are disproportionately likely to disperse, then migration can actually promote population divergence. For example, previous work has shown that threespine stickleback (Gasterosteus aculeatus) differ in their propensity to move up- or downstream ('rheotactic response'), which may facilitate genetic divergence between adjoining lake and stream populations of stickleback. Here, we demonstrate that intraspecific variation in a sensory system (superficial neuromast lines) contributes to this variation in swimming behaviour in stickleback. First, we show that intact neuromasts are necessary for a typical rheotactic response. Next, we showed that there is heritable variation in the number of neuromasts and that stickleback with more neuromasts are more likely to move downstream. Variation in pectoral fin shape contributes to additional variation in rheotactic response. These results illustrate how within-population quantitative variation in sensory and locomotor traits can influence dispersal behaviour, thereby biasing dispersal between habitats and favouring population divergence.

Venous thromboembolism in patients with esophageal or gastric cancer undergoing neoadjuvant chemotherapy.

There is a well-established link between cancer and venous thromboembolism (VTE), and patients receiving chemotherapy for esophageal or gastric cancer appear at high risk of developing VTE. The incidence of VTE in the neoadjuvant setting in these patients is poorly understood, as is the role for thromboprophylaxis during neoadjuvant chemotherapy. A PubMed search was conducted using a combination of terms including; esophageal & gastric cancer, deep venous thrombosis (DVT), VTE, neoadjuvant, chemotherapy and chemoradiotherapy. One hundred and fifty-four articles were retrieved and a narrative review was conducted. For patients with esophageal and gastric cancer the incidence of VTE ranged from 4 to 19%. Gastric cancer (Odds Ratio [OR] 6.38, [95% CI: 1.96-20.80]) and Stage III/IV disease, (OR 5.16 [95% CI: 1.29-20.73]) were identified as risk factors for developing VTE. Neoadjuvant chemotherapy was identified as an independent risk factor for developing VTE. Symptomatic and asymptomatic VTE have a similar effect on mortality. Median overall survival for asymptomatic VTE was 13.9 months (95% CI: 5.0-∞) versus 12.8 months (95% CI: 4.7-30.3) if the VTE was symptomatic. Neoadjuvant chemotherapy is a significant risk factor for VTE in patients with esophageal and gastric cancer. Intervention to minimize the risk using pharmacological and mechanical thromboprophylaxis should be considered, and this should start in the neoadjuvant period.

Development of a risk prediction model for Barrett's esophagus in an Australian population.

Esophageal adenocarcinoma has poor 5-year survival rates. Increased survival might be achieved with earlier treatment, but requires earlier identification of the precursor, Barrett's esophagus. Population screening is not cost effective, this may be improved by targeted screening directed at individuals more likely to have Barrett's esophagus. To develop a risk prediction tool for Barrett's esophagus, this study compared individuals with Barrett's esophagus against population controls. Participants completed a questionnaire comprising 35 questions addressing medical history, symptom history, lifestyle factors, anthropomorphic measures, and demographic details. Statistical analysis addressed differences between cases and controls, and entailed initial variable selection, checking of model assumptions, and establishing calibration and discrimination. The area under the curve (AUC) was used to assess overall accuracy. One hundred and twenty individuals with Barrett's esophagus and 235 population controls completed the questionnaire. Significant differences were identified for age, gender, reflux history, family reflux history, history of hypertension, alcoholic drinks per week, and body mass index. These were used to develop a risk prediction model. The AUC was 0.82 (95% CI 0.78-0.87). Good calibration between predicted and observed risk was noted (Hosmer-Lemeshow test P = 0.67). At the point minimizing false positives and false negatives, the model achieved a sensitivity of 84.96% and a specificity of 66%. A well-calibrated risk prediction model with good discrimination has been developed to identify patients with Barrett's esophagus. The model needs to be externally validated before consideration for clinical practice.

Elective ICP monitoring: how long is long enough?

BACKGROUND: Intracranial pressure monitoring is commonly undertaken to assess and manage acute patients following head injury. However, ICP monitoring can also be a useful diagnostic tool in the management of CSF dynamics in elective patients. To date, there is little published research to suggest how long these elective patients require ICP monitoring in order to gain an accurate picture of a patient's ICP dynamics. At the author's institution, a minimum of 48-h data collection is currently undertaken in patients with a suspected ICP abnormality. METHODS: A retrospective audit was undertaken comparing overall median ICP and overall median pulse amplitude data at three time points, 24 h, 48 h and total time analysed (if longer than 48 h). Paired T-test was used to assess if there were statistically significant differences between 24-h versus 48-h monitoring and total duration of monitoring. All patients admitted over a 6-month period for ICPM who met the inclusion/exclusion criteria were included. RESULTS: Eighteen patients met the criteria. Median age was 45.8 years, range 22-83 years, 12 female and 6 male. No complications were experienced as a result of ICPM. Diagnosis included NPH, IIH, suspected shunt malfunction and Chiari malformation. The results demonstrated that there is no statistical difference between 24 h and 48 h or longer for both overall median ICP and pulse amplitude. CONCLUSION: The results of this study demonstrate that ICP monitoring of elective adult patients using a Spiegelberg intraparenchymal bolt for 24 h gives an accurate picture of a patient's ICP dynamics compared with longer periods of monitoring.

Arbuscular mycorrhizas are present on Spitsbergen.

A previous study of 76 plant species on Spitsbergen in the High Arctic concluded that structures resembling arbuscular mycorrhizas were absent from roots. Here, we report a survey examining the roots of 13 grass and forb species collected from 12 sites on the island for arbuscular mycorrhizal (AM) colonisation. Of the 102 individuals collected, we recorded AM endophytes in the roots of 41 plants of 11 species (Alopecurus ovatus, Deschampsia alpina, Festuca rubra ssp. richardsonii, putative viviparous hybrids of Poa arctica and Poa pratensis, Poa arctica ssp. arctica, Trisetum spicatum, Coptidium spitsbergense, Ranunculus nivalis, Ranunculus pygmaeus, Ranunculus sulphureus and Taraxacum arcticum) sampled from 10 sites. Both coarse AM endophyte, with hyphae of 5-10 µm width, vesicles and occasional arbuscules, and fine endophyte, consisting of hyphae of 1-3 µm width and sparse arbuscules, were recorded in roots. Coarse AM hyphae, vesicles, arbuscules and fine endophyte hyphae occupied 1.0-30.7, 0.8-18.3, 0.7-11.9 and 0.7-12.8% of the root lengths of colonised plants, respectively. Principal component analysis indicated no associations between the abundances of AM structures in roots and edaphic factors. We conclude that the AM symbiosis is present in grass and forb roots on Spitsbergen.

The prevalence of proximal hamstring pathology on MRI in the asymptomatic population.

PURPOSE: Injury to the proximal hamstring complex (PHC) is becoming more frequently diagnosed. Patients attending our tertiary referral centre demonstrated 'pathological changes' in the unaffected normal contralateral PHC on MRI. The prevalence of PHC pathology, however, has not been previously documented in the literature in asymptomatic subjects. It is the hypothesis of this study that the natural history of asymptomatic pathological change on MRI in the PHC is not clear. The aim is to quantify the natural history of PHC degeneration. METHOD: Two hundred and fifty-three consecutive patients with an asymptomatic PHC were reviewed retrospectively between 2009 and 2010. The PHC was assessed in multiple MRI planes by a specialist musculoskeletal consultant radiologist. RESULTS: Five hundred and six proximal hamstrings complexes were reviewed. Eighty-nine patients (35 %) were radiological normal both sides, median age 51 years (range 13-88). Thirty-four patients (13 %) had unilateral pathology, median age 55 years (range 25-89). Of these, 3 patients (1 %) had presence of a complete tear, median age 81 years (range 72-87). Sixteen patients (7 %) had tendinosis, median age 60 years (range 37-78). Fifteen patients (6 %) had a unilateral partial tear, median age 57 years (range 35-78). One hundred and thirty patients (52 %) had bilateral pathology, median age 65 years (range 25-89). Fifty-three patients (21 %) had the presence of bilateral tendinopathy alone, median age 56 years (range 25-89). Twenty-seven patients (11 %) had a partial tear on one side and tendinosis on the other, median age 68 years (range 38-89). Thirty-nine patients (15 %) had evidence of bilateral partial tears, median age 63 years (range 36-89), with 52 % demonstrating a torn conjoined and semi-membranosus tendon. The remaining 48 % had either an isolated tear of the conjoined or the semi-membranosus (the more commonly injured tendon 74 % of the time). Four patients (2 %) had bilateral complete ruptures with a median age of 68 years (range 59-78). Six patients (2 %) had a complete tear on one side and a partial tear on the other, median age 68 years (range 34-83). One patient had a complete tear on one side and tendinosis on the other, age 81 years. CONCLUSION: There is a higher prevalence of pathology in the asymptomatic population, 15 % have bilateral partial tears, and 2 % have bilateral complete tears. The semi-membranosus being the most affected, this may help clinically stratify the need for surgical intervention. LEVEL OF EVIDENCE: I.