Extreme solar storms and the quest for exact dating with radiocarbon.

Radiocarbon (14C) is essential for creating chronologies to study the timings and drivers of pivotal events in human history and the Earth system over the past 55,000 years. It is also a fundamental proxy for investigating solar processes, including the potential of the Sun for extreme activity. Until now, fluctuations in past atmospheric 14C levels have limited the dating precision possible using radiocarbon. However, the discovery of solar super-storms known as extreme solar particle events (ESPEs) has driven a series of advances with the potential to transform the calendar-age precision of radiocarbon dating. Organic materials containing unique 14C ESPE signatures can now be dated to annual precision. In parallel, the search for further storms using high-precision annual 14C measurements has revealed fine-scaled variations that can be used to improve calendar-age precision, even in periods that lack ESPEs. Furthermore, the newly identified 14C fluctuations provide unprecedented insight into solar variability and the carbon cycle. Here, we review the current state of knowledge and share our insights into these rapidly developing, diverse research fields. We identify links between radiocarbon, archaeology, solar physics and Earth science to stimulate transdisciplinary collaboration, and we propose how researchers can take advantage of these recent developments.

Achilles tendon material properties are greater in the jump leg of jumping athletes.

PURPOSE: The Achilles tendon (AT) must adapt to meet changes in demands. This study explored AT adaptation by comparing properties within the jump and non-jump legs of jumping athletes. Non-jumping control athletes were included to control limb dominance effects. METHODS: AT properties were assessed in the preferred (jump) and non-preferred (lead) jumping legs of male collegiate-level long and/or high jump (jumpers; n=10) and cross-country (controls; n=10) athletes. Cross-sectional area (CSA), elongation, and force during isometric contractions were used to estimate the morphological, mechanical and material properties of the ATs bilaterally. RESULTS: Jumpers exposed their ATs to more force and stress than controls (all p≤0.03). AT force and stress were also greater in the jump leg of both jumpers and controls than in the lead leg (all p<0.05). Jumpers had 17.8% greater AT stiffness and 24.4% greater Young's modulus in their jump leg compared to lead leg (all p<0.05). There were no jump versus lead leg differences in AT stiffness or Young's modulus within controls (all p>0.05). CONCLUSION: ATs chronically exposed to elevated mechanical loading were found to exhibit greater mechanical (stiffness) and material (Young's modulus) properties.

Utilization of mechanical diagnosis and therapy (MDT) for the treatment of lumbar pain in the presence of known lumbar transverse process fractures: a case study.

BACKGROUND: Spinal fractures are typically considered a contraindication to mechanical diagnosis and therapy (MDT). OBJECTIVE AND IMPORTANCE: The purpose of this case study is to illustrate how MDT was used safely and effectively to treat lumbar pain in a patient with multiple lumbar transverse process fractures. CLINICAL PRESENTATION: The subject was a 24-year-old female with left L2-5 transverse process fractures, sustained 10 weeks prior in a pedestrian versus motor vehicle accident. INTERVENTION AND TECHNIQUE: After collaboration with her physiatrist, an MDT examination revealed a presentation consistent with the lumbar derangement syndrome. CONCLUSION: After three visits, utilizing patient generated forces with the extension principle of treatment, her pain, Oswestry disability index (ODI) score, and function all improved.

Liver resection morbidity, mortality, and risk factors at the departments of hepatobiliary surgery in Veracruz, Mexico. / Morbilidad, mortalidad y factores de riesgo de la cirugía hepática en los departamentos de cirugía hepatobiliar de Veracruz, México.

INTRODUCTION: Liver resection has been associated with high morbidity and mortality, and the most serious complication is liver failure. Patient evaluation is limited to risk scales. The 50-50 criteria and bilirubin peak>7mg/dl have been used as mortality predictors. AIM: The aim of this study was to determine the risk factors associated with morbidity and mortality for liver resection in our population. MATERIAL AND METHODS: A retrospective study was carried out on 51 patients that underwent liver resection. Sociodemographic variables, pathology, and the surgical act were analyzed, together with morbidity and mortality and their associated factors. RESULTS: Fifty-one patients, 23 men and 28 women, were analyzed. They had a mean age of 51.4±19.13 years, 64.7% had concomitant disease, and their mean MELD score was 7.49±1.79. The mean size of the resected lesions was 7.34±3.47cm, 51% were malignant, and 34 minor resections were performed. The Pringle maneuver was used in 64.7% of the cases and the mean blood loss was 1,090±121.76ml. Morbidity of 25.5% was associated with viral hepatitis infection, greater blood loss, transfusion requirement, the Pringle maneuver, lower hemoglobin and PTT values, and higher MELD, INR, bilirubin, and glucose values. A total 3.9% mortality was associated with hyperbilirubinemia, hyperglycemia, and greater blood loss and transfusions. CONCLUSIONS: The main risk factors associated with the morbidity and mortality of liver resection in our population were those related to the preoperative biochemical parameters of the patient and the factors that occurred during the surgical act.

Independent quality assurance of a helical tomotherapy machine using the dose magnifying glass.

PURPOSE: Helical tomotherapy is a complex delivery technique, integrating CT image guidance and intensity modulated radiotherapy in a single system. The integration of the CT detector ring on the gantry not only allows patient position verification but is also often used to perform various QA procedures. This convenience lacks the rigor of a machine-independent QA process. METHODS: In this article, a Si strip detector, known as the Dose Magnifying Glass (DMG), was used to perform machine-independent QA measurements of the multileaf collimator alignment, leaf open time threshold, and leaf fluence output factor (LFOF). RESULTS: The DMG measurements showed good agreements with EDR2 film for the MLC alignment test while the CT detector agrees well with DMG measurements for leaf open time threshold and LFOF measurements. The leaf open time threshold was found to be approximately 20 ms. The LFOF measured with the DMG agreed within error with the CT detector measured LFOF. CONCLUSIONS: The DMG with its 0.2 mm spatial resolution coupled to TERA ASIC allowed real-time high temporal resolution measurements of the tomotherapy leaf movement. In conclusion, DMG was shown to be a suitable tool for machine-independent QA of a tomotherapy unit.

Attentional bias modification for acute experimental pain: A randomized controlled trial of retraining early versus later attention on pain severity, threshold and tolerance.

BACKGROUND: Noxious attentional bias is thought to confer vulnerability to pain, suggesting that modifying the bias could reduce pain outcomes. Herein is presented a randomized controlled trial to test the effects of retraining the dot probe attentional bias at short versus long stimulus durations towards neutral stimuli, and away from threat stimuli, on acute pain experience, in comparison with a placebo control group. METHODS: Eighty-one pain-free volunteers, blinded to condition, were randomized to complete either one of two neutral bias modification programs in which words were presented for 500 ms (ABM-500; n = 28) or 1250 ms (ABM-1250; n = 26), or to a sham training program that included both stimulus durations (ABM-Placebo; n = 27). Testing took place in a university laboratory. At post-training, participants completed the pain-inducing 'cold pressor task', and measures of pain severity, threshold and tolerance were taken. Attentional bias was also measured at pre- and post-training. RESULTS: Findings indicated that ABM-500 reliably increased pain threshold and tolerance, in comparison with the control group. In contrast, ABM-1250 did not affect any of the pain outcomes. Expected ABM effects on attentional bias were not evident at the group level, but nevertheless ABM-500 bias reduction was significantly associated with increased pain tolerance. CONCLUSIONS: These findings suggest that retraining attention at short stimulus exposure durations is relatively more efficacious in promoting transfer of attentional retraining effects to real-world acute pain stressors, in comparison with both the longer stimulus duration and ABM-Placebo. SIGNIFICANCE: Testing of the impact of modifying maintained attentional bias on vulnerability to an acute pain stressor. Findings suggested that retraining rapid attentional bias using short exposure durations conferred greater analgesic benefit, in comparison with both the slower bias and sham-training.

A Nagumo-type model for competing populations with nonlocal coupling.

We consider a model of two competing species with nonlocal competition for resources. The net birthrate is cubic, so that the model allows simulation of the Allee effect, whereby extinction is stable and intermediate populations promote growth, while saturation occurs via cubic competition terms. The model includes both interspecies and intraspecies nonlocal competition which enters via convolution integrals with a specified asymmetric competition kernel function. We introduce two parameters, δ, describing the extent of the coupling, with δ = 0 corresponding to local coupling, and α, describing the extent of the asymmetry, with α = 0 corresponding to symmetric nonlocal interactions. We consider the case where the local model admits a stable coexistence (populations of both species positive) equilibrium solution. We perform a linear stability analysis and show that this solution can be destabilized by sufficient nonlocality, i.e., when δ increases beyond a critical value. We then consider nonlinear patterns, far from the stability boundary. We show that nonlinear patterns consist of arrays of islands, regions of nonzero population, separated by deadzones, where the populations are essentially extinct, (with the array propagating in the case α ≠ 0). The predominant effect of the cubic model is that the islands for the two species are disjoint, so that each species lives in the deadzone of the other species. In addition, some patterns involve both hospitable and inhospitable deadzones, so that islands form in only some of the deadzones.

Hysterosalpingographic diagnosis of a single cervical ectopic ureter.

Single ectopic ureters terminating in the female genital tract are rare congenital anomalies caused by an abnormally lateral origin of the ureteric bud from the mesonephric duct in the three- to four-week embryo. The ureter remains intimately involved with mesonephric duct remnants, which acquire a communication with müllerian structures. Hysterosalpingography in a continent infertile patient outlined a single cervical ureter from a hypoplastic kidney draining into Gartner's duct remnants. No previous case of single cervical ectopic ureter has been reported without a müllerian anomaly, nor has a single cervical ureter been demonstrated on hysterosalpingography.

Predictive modelling of growth of Yersinia enterocolitica: the effects of temperature, pH and sodium chloride.

The growth responses of Yersinia enterocolitica as affected by NaCl concentration, pH value and storage temperature were studied in laboratory medium. Growth curves at concentrations of NaCl in the range 0.5-6.5% (w/v), pH values in the range 4.0-7.0 and storage temperatures in the range 5-30 degrees C were fitted using the Gompertz routine and the derived parameters modelled. Growth curves could then be regenerated for any set of conditions within the matrix studied and values for growth rate, generation time, lag time and time to 1000-fold increase predicted. The model was validated against data from the literature and was found to give realistic estimates for generation time in media and a range of foods including meat and meat products, milk, eggs, fish and tofu. All predictions were consistently 'fail-safe'.

Predictive modelling of growth of Staphylococcus aureus: the effects of temperature, pH and sodium chloride.

The growth responses of Staphylococcus aureus as affected by NaCl concentration, pH value and storage temperature were studied in laboratory medium. Growth curves at concentrations of NaCl in the range 0.5-13.5% (w/v), pH values in the range 4.0-7.0 and storage temperatures in the range 10-30 degrees C were fitted using the Gompertz routine and the derived parameters modelled. Growth curves could then be regenerated for any set of conditions within the matrix studied and values for growth rate, generation time, lag time and time to 1000-fold increase predicted. The model was validated against data from the literature and was found to give realistic estimates of generation time for media and a range of foods including milk, cheese, starch-based foods and cooked meats but not for mayonnaise or Wiltshire bacon. All predictions were consistently 'fail-safe'.

Predictive modelling of growth of Escherichia coli O157:H7: the effects of temperature, pH and sodium chloride.

The growth responses of Escherichia coli O157:H7 as affected by NaCl concentration, pH value and storage temperature were studied in laboratory medium. Growth curves at concentrations of NaCl in the range 0.5-6.5% (w/v), pH values in the range 4.0-7.0 and storage temperatures in the range 10-30 degrees C were fitted using the Gompertz routine and the derived parameters modelled. Growth curves could then be regenerated for any set of conditions within the matrix studied and values for growth rate, generation time, lag time and time to 1000-fold increase predicted. The model was validated against data from the literature and was found to give realistic estimates for generation time in media and a range of foods including meat and poultry, milk, cheese and tempeh. All predictions were consistently 'fail-safe'.

Predictive modelling of Escherichia coli O157:H7: inclusion of carbon dioxide as a fourth factor in a pre-existing model.

Two models for Escherichia coli O157:H7 are compared, one with growth-controlling factors pH (4.5-7.0), temperature (10-30 degrees C) and NaCl concentration (0.5-6.5% w/v) and the other with the same factors and ranges, but with the addition of carbon dioxide (CO2: 10-80% v/v). Validation of the four-factor model, to include food packed in modified atmospheres containing CO2, was not possible due to lack of published data. However, where CO2 concentration was entered as 0%, only minor differences occurred between the predictions from the two models for the same conditions of pH, NaCl and temperature; consequently reliable, safe predictions using the four-factor model, with CO2 concentration recorded as 0%, can be made for foods packed in air. At temperatures from 10 to 30 degrees C, it was found that lower (10 and 20%) concentrations of CO2 had little effect on lag times and growth rates, and higher concentrations still permitted growth of E. coli O157:H7 under a wide range of conditions of NaCl concentration, pH value and temperature, suggesting that the organism is relatively CO2-tolerant.

Ultrasonic detection of occult testicular neoplasms in patients with gynaecomastia.

Gynaecomastia occurs in up to 10% of patients with malignant testicular tumours. In most cases a testicular mass will be easily palpable but occasionally these tumours are occult. Ultrasound has been shown to be of value in the detection of occult neoplasms in patients presenting with nodal disease. Two patients with gynaecomastia and palpably normal testes are presented in whom testicular tumour was diagnosed by ultrasonic examination of the scrotum.

Implementation of a programme for reduction of radiographic doses and results achieved through increases in tube potential.

Experiences in implementation of a programme to reduce doses to patients from radiographic examinations are described. A preliminary survey of entrance doses for selected examinations, calculated from mean exposure factors, identified equipment and examinations requiring attention. Subsequently more detailed studies were carried out with thermoluminescent dosimeters (TLDs). Results were coordinated with the aid of a database, which was used to monitor the agreement between dose calculations and TLD measurements. Surveys highlighted that doses from lumbar and thoracic spine examinations were high throughout the region. Reductions of 26-36% in entrance dose and 20-25% in effective dose were achieved by raising tube potentials for these examinations. This gave a reduction in annual collective dose of 4 man-Sv with no cost implication. In some departments dose charts were used to support the purchase of new screens. Surveys revealed a wide range in other factors such as transmission of X-ray table tops and results are being used in planning replacement of equipment.

Low-field (0.08 T) magnetic resonance imaging of the pancreas: comparison with computed tomography and ultrasound.

Seventy-four patients referred for computed tomography (CT) and ultrasound examination with a presumptive diagnosis of pancreatic disease have been studied using a low-field (0.08 T) magnetic resonance (MR) imaging instrument. A further 50 patients being examined for non-pancreatic disease were also examined to assess the appearances of the normal pancreas. All the MR examinations were performed using an interleaved saturation-recovery/short inversion time (TI) inversion-recovery sequence. Part or all of the pancreas was seen in 96% of normal cases. In inflammatory disease, MR was more accurate than either CT or ultrasound for diagnosis, whilst for the demonstration of pancreatic tumours, MR was found to be no better or worse than either CT or ultrasound. The use of specific T1 measurement for soft-tissue characterization was not useful because of the large overlap in values between normal, inflamed and malignant pancreatic tissue. T1 measurement was found to be useful in differentiating different pathological fluids.

Deep venous thrombosis of the upper extremity--a case report.

This report describes a case of deep venous thrombosis (DVT) of the upper extremity following a routine blood donation by a regular donor. This cause of an upper limb DVT has not been previously reported. A review of the literature follows.

Homoclinic snaking near a codimension-two Turing-Hopf bifurcation point in the Brusselator model.

Spatiotemporal Turing-Hopf pinning solutions near the codimension-two Turing-Hopf point of the one-dimensional Brusselator model are studied. Both the Turing and Hopf bifurcations are supercritical and stable. The pinning solutions exhibit coexistence of stationary stripes of near critical wavelength and time-periodic oscillations near the characteristic Hopf frequency. Such solutions of this nonvariational problem are in contrast to the stationary pinning solutions found in the subcritical Turing regime for the variational Swift-Hohenberg equations, characterized by a spatially periodic pattern embedded in a spatially homogeneous background state. Numerical continuation was used to solve periodic boundary value problems in time for the Fourier amplitudes of the spatiotemporal Turing-Hopf pinning solutions. The solution branches are organized in a series of saddle-node bifurcations similar to the known snaking structures of stationary pinning solutions. We find two intertwined pairs of such branches, one with a defect in the middle of the striped region, and one without. Solutions on one branch of one pair differ from those on the other branch by a π phase shift in the spatially periodic region, i.e., locations of local minima of solutions on one branch correspond to locations of maxima of solutions on the other branch. These branches are connected to branches exhibiting collapsed snaking behavior, where the snaking region collapses to almost a single value in the bifurcation parameter. Solutions along various parts of the branches are described in detail. Time dependent depinning dynamics outside the saddle nodes are illustrated, and a time scale for the depinning transitions is numerically established. Wavelength variation within the snaking region is discussed, and reasons for the variation are given in the context of amplitude equations. Finally, we compare the pinning region to the Maxwell line found numerically by time evolving the amplitude equations.

Stability and pattern formation for competing populations with asymmetric nonlocal coupling.

We consider a model of two competing species with asymmetric nonlocal coupling in a competition for resources. The nonlocal coupling is via convolution integrals and the asymmetry is via convolution kernel functions which are not even functions of their arguments. The nonlocality is due to species mobility, so that at any fixed point in space the competition for resources depends not just on the populations at that point but on a suitably weighted average of the populations. We introduce two parameters, δ, describing the extent of the coupling, with δ=0 corresponding to local coupling, and α, describing the extent of the asymmetry, with α=0 corresponding to symmetric nonlocal interactions. We consider the case where the model admits a stable coexistence equilibrium solution. We perform a linear stability analysis and show that this solution can be destabilized by sufficient nonlocality, i.e., when δ increases beyond a critical value. We consider two specific kernel functions, (i) an asymmetric Gaussian and (ii) an asymmetric stepfunction. We compute the stability boundary as a function of α, and for δ beyond the stability boundary we determine unstable wavenumber bands. We compute nonlinear patterns for δ significantly beyond the stability boundary. Patterns consist of arrays of islands, regions of nonzero population, separated by either near-deadzones where the populations are small, but nonzero, or by deadzones where populations are exponentially small and essentially extinct. We find solutions consisting of propagating traveling waves of islands, solutions exhibiting colony formation, where a colony is formed just ahead of an island and eventually grows as the parent island decays, and modulated traveling waves, where competition between the two species allows propagation and inhibits colony formation. We explain colony formation and the modulated traveling waves as due to a positive feedback mechanism associated with small variations in the amplitude of the parent island.

A dosimetric analysis of tomotherapy based intensity modulated radiation therapy with and without bone marrow sparing in gynecologic malignancies.

Whole pelvic radiotherapy with concurrent chemotherapy is the standard of care for locally advanced cervical carcinoma. Published literature reports that the pelvic bone marrow (BM) dosimetric parameters of V10 > 90% and V20 > 80% are associated with higher rates of hematologic toxicities using this approach. Here, we investigate the ability of Tomotherapy based intensity modulated radiation therapy (IMRT) to reduce dose to pelvic BM while evaluating dose distribution to critical structures and planning target volume (PTV) coverage. Ten patients were selected for analysis. Normal structures, whole pelvic BM, PTV contours, and IMRT objects were standardized. Two whole pelvis Tomotherapy plans were created for each patient, one standard plan, and one with the addition of a BM sparing (BMS) constraint (V10 <85%, V20 < 80%). Data were calculated from multiple points with regard to BM dose, normal structure dose, and PTV coverage. Differences in dose distributions between the two sets of plans were analyzed using a paired t-test. The addition of a BMS planning constraint resulted in significant decreases in pelvic BM dose at the following dosimetric points: V5, V10, V15, V20, V30, V40, V50, and mean dose (p < 0.05 for all points). There were no significant differences in dose to small bowel, bladder or rectum, with the exception of one data point (small bowel V30, p = 0.004) between the two sets of plans. There was no sacrifice of PTV coverage or loss of homogeneity with the addition of a BMS planning constraint. BMS-IMRT significantly reduces radiation dose to the pelvic BM while maintaining the ability to spare dose to the small bowel, bladder and rectum. The planning constraints were met without violation of study criteria, and without sacrifice of PTV coverage. Further investigation is warranted to determine if rates of hematologic toxicity improve with utilization of Tomotherapy based BMS-IMRT.