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The article offers information on the use of virtual reality (VR) for pain therapy and the challenges associated with VR-induced cybersickness. Topics include the growing interest in VR for pain management, highlighting its potential to immerse patients in a computer-generated world to distract them from pain.

This article explores the use of artificial intelligence (AI) language models in conducting a post hoc analysis of studies comparing different surgical techniques for parastomal hernia. The researchers utilized an AI-powered chatbot to identify additional studies that may have been missed during a traditional review. However, the analysis revealed that the AI-generated citations were not legitimate and were irrelevant to the original search. This highlights the limitations of relying solely on AI for systematic reviews and emphasizes the importance of human validation. The authors caution against the dissemination of fraudulent information and stress the need for caution and external validation when using AI language models for scientific research. [Extracted from the article]

Data regarding oncologic outcomes of segmental bile duct resection (SBDR) versus pancreatoduodenectomy (PD) for bile duct cancers (BDC) are conflicting. We compared SBDR and PD for BDC utilizing pooled data analysis. A comprehensive PRISMA 2020 systematic review was performed. Studies comparing SBDR with PD for BDC were included. Pooled mean differences (MD), odds ratios (OR), and risk ratios (RR) with 95% confidence intervals (CI) were calculated. Subgroup analyses were performed. Study quality, bias, heterogeneity, and certainty were analyzed. Twelve studies from 2004 to 2021 were included, comprising 533 SBDR and 1,313 PD. SBDR was associated with positive proximal duct margins (OR 1.56; CI 1.11–2.18; P =.01), and distal duct margins (OR 43.25; CI 10.38–180.16; P <.01). SBDR yielded fewer lymph nodes (MD -6.93 nodes; CI -9.72–4.15; P <.01) and detected fewer nodal metastases (OR 0.72; CI 0.55–0.94; P =.01). SBDR portended less perioperative morbidity (OR 0.31; CI 0.21–0.46; P <.01), but not mortality (OR 0.52; CI 0.20–1.32; P =.17). SBDR was associated with locoregional recurrences (OR 1.88; CI 1.01–3.53; P =.02), and lymph node recurrences (OR 2.13; CI 1.42–3.2; P =.04). SBDR yielded decreased 5-year OS (OR 0.75; CI 0.65–0.85; P <.01). Despite decreased perioperative morbidity, SBDR appears to provide inferior oncologic control for BDC. [Display omitted] [ABSTRACT FROM AUTHOR]

Background: Same day discharge (SDD) may be considered in some patients undergoing minimally invasive adrenalectomy (MIA). Recent studies have demonstrated similar outcomes between SDD and admitted patients; however, most excluded pheochromocytoma and adrenal metastases. This study evaluates 30-day complications and hospital readmission in a large cohort of patients undergoing MIA. Methods: Adult patients undergoing MIA (2010–2020) for benign adrenal disorders, pheochromocytoma, and adrenal metastases were identified within the ACS-NSQIP database. Comparisons between patients having SDD versus admission were performed. Factors associated with 30-day complications and unplanned readmission were evaluated by multivariable regression modeling. Results: Of 7316 patients who underwent MIA, 254 had SDD. Baseline characteristics were similar between groups, although SDD patients had lower ASA class (p < 0.001) and were more likely to undergo MIA for nonfunctioning adenoma or primary aldosteronism (p = 0.001). After adjusting for covariates, higher ASA class and presence of medical comorbidities were associated with increased complications (p < 0.001; p < 0.05) and unplanned readmission (p < 0.001; p < 0.05). Additionally, prolonged operative time was associated with 30-day complications (p < 0.001). Notably, SDD was not associated with increased complications (OR 0.78, 95% CI 0.38–1.61, p = 0.502) or unplanned readmission (OR 0.76, 95% CI 0.35–1.64, p = 0.490). The rate of SDD for MIA increased from 1.48% in 2017 to 10.81% in 2020. Conclusions: Not all patients undergoing MIA should have SDD; however, the current analysis demonstrates a trend toward SDD and supports its safety in select patients with adrenal metastases and benign adrenal disorders including pheochromocytoma. [ABSTRACT FROM AUTHOR]

Background: Patients with unstable cervical spine (C-spine) fractures are at a significant risk of respiratory failure. There is no consensus on the optimal timing of tracheostomy in the setting of recent operative cervical fixation (OCF). This study evaluated the impact of tracheostomy timing on surgical site infections (SSIs) in patients undergoing OCF and tracheostomy. Methods: Trauma Quality Improvement Program (TQIP) was used to identify patients with isolated cervical spine injuries who underwent OCF and tracheostomy between 2017 and 2019. Early tracheostomy (<7 days from OCF) was compared with delayed tracheostomy (≥7 days from OCF). Logistic regressions identified variables associated with SSI, morbidity, and mortality. Pearson correlations evaluated time to tracheostomy and length of stay (LOS). Results: Of 1438 patients included, 20 had SSI (1.4%). There was no difference in SSI between early vs delayed tracheostomy (1.6% vs 1.2%, P =.5077). Delayed tracheostomy was associated with increased ICU LOS (23.0 vs 17.0 days, P <.0001), ventilator days (19.0 vs 15.0, P <.0001), and hospital LOS (29.0 vs 22.0 days, P <.0001). Increased ICU LOS was associated with SSI (OR 1.017; CI 0.999-1.032; P =.0273). Increased time to tracheostomy was associated with increased morbidity (OR 1.003; CI 1.002-1.004; P <.0001) on multivariable analysis. Time from OCF to tracheostomy correlated with ICU LOS (r (1354) =.35, P <.0001), ventilator days (r (1312) =.25, P <.0001), and hospital LOS (r (1355) =.25, P <.0001). Conclusion: In this TQIP study, delayed tracheostomy after OCF was associated with longer ICU LOS and increased morbidity without increased SSI. This supports the TQIP best practice guidelines recommending that tracheostomy should not be delayed for concern of increased SSI risk. [ABSTRACT FROM AUTHOR]

Introduction: Parastomal hernia is a debilitating complication of stoma creation. Parastomal hernia repair with mesh reduces recurrence rates in open and laparoscopic settings. Recent comparative studies conflict with previously pooled data on optimal mesh repair technique. The objective of this study is to examine parastomal hernia recurrence rates after Sugarbaker and keyhole repairs by performing an updated systematic review and meta-analysis of comparative studies. Methods: A systematic review of PubMed, MEDLINE, EMBASE, the Cochrane database, SCOPUS, and the PROSPERO registry was performed according to PRISMA 2020 guidelines (PROSPERO ID: CRD42021290483). Studies comparing parastomal hernia recurrences after Sugarbaker and keyhole repairs were included. Studies with overlapping patient cohorts (duplicate data), non-comparative studies, studies that did not report the primary outcome of interest, and studies not in the English language were excluded. Study bias was assessed using the Newcastle–Ottawa scale. Pooled mean differences (MD), odds ratios (OR), and risk ratios (RR) with 95% confidence intervals (CI) were calculated. Heterogeneity was assessed using the I2 statistic. Forest plots and funnel plots were generated. Study quality was analyzed using MINORS. Additional subgroup analysis of modern studies was performed. Results: Ten comparative studies published between 2005 and 2021 from 5 countries were included for analysis comprising 347 Sugarbaker repairs and 246 keyhole repairs. There were no differences in patient age, sex, or BMI between the groups. There was no difference between the groups regarding surgical site infection (OR 0.78; CI 0.31–1.98; P = 0.61) or post-operative bowel obstruction (OR 0.76; CI 0.23–2.56; P = 0.66). Sugarbaker repairs were significantly less often associated with parastomal hernia recurrence when compared to keyhole repairs (OR 0.38; CI 0.18–0.78; P = 0.008). There was no significant heterogeneity among the studies comparing parastomal hernia recurrence (I2 = 32%; P = 0.15). Quality analysis revealed a median MINORS score of 11 (range 6–16). Subgroup analysis of studies performed after the previously published pooled analysis (2015–2021) revealed no significant difference in parastomal hernia recurrence between the two groups (OR 0.58; CI 0.24–1.38; P = 0.22) with a significant subgroup effect (P = 0.05). Conclusions: Though there were lower rates of parastomal hernia recurrence with Sugarbaker repairs on overall analysis, this phenomenon disappeared on subgroup analysis of modern studies. Randomized controlled trials with contemporary cohorts would help further evaluate these repairs and minimize potential bias. [ABSTRACT FROM AUTHOR]

Giant paraesophageal hernias contain greater than fifty percent of the stomach above the diaphragm. Over fifty percent of large bowel obstructions are due to colorectal adenocarcinoma. Here, we present a rare case of a 69-year-old female patient who developed a closed loop colonic obstruction caused by a colonic mass in the distal transverse colon within a giant paraesophageal hernia. We successfully performed emergent paraesophageal hernia reduction and mesh repair with extended right hemicolectomy and ileocolonic anastomosis. Emergent hernia repair via an abdominal approach can be used in this setting. [ABSTRACT FROM AUTHOR]

Background: Chemotherapy (CTX) is associated with improved survival for patients undergoing resection for pancreatic ductal adenocarcinoma (PDAC). The current study evaluated the influence of tumor location on receipt of CTX.Methods: The NCDB (2006-2017) was queried to identify patients with clinical stage I-III PDAC. Predictors of receipt of CTX, sequencing of CTX, and overall survival (OS) were analyzed.Results: Among 14,557 patients who underwent resection for PDAC 3,453 (24%) did not receive CTX. On multivariable analysis, patients with tail tumors were 15% less likely to receive CTX (OR 0.85, 95% CI 0.747-0.968) and 58% less likely to receive neoadjuvant CTX (OR 0.42, 95% CI 0.351-0.509) relative to patients with head/neck tumors. For patients with body tumors, there was no difference in rates of administration or sequence of CTX. For patients with resected tail tumors, median OS was 29.9 vs 18.9 months (p < 0.001) between those who did and did not receive CTX. For patients with tail tumors, independent predictors of not receiving CTX, regardless of sequence, were increasing age (OR 0.95, 95% CI 0.935-0.965), increasing post-op length of stay (OR 0.95, 95% CI 0.932-0.968), and 30-day post-op readmission (OR 0.46, 95% CI 0.315-0.670).Conclusions: In patients with clinical stage I-III PDAC, tumor location within the tail was independently associated with not receiving CTX. Given the marked improvement in OS when CTX is administered, strategies aimed at increasing the number of these patients who receive CTX are necessary. [ABSTRACT FROM AUTHOR]

Introduction: Cryoprecipitate is frequently administered as an adjunct to balanced transfusion in the setting of traumatic hemorrhage. However, civilian studies have not demonstrated a clear survival advantage, and prior observational studies noted selection bias when analyzing cryoprecipitate use. Additionally, due to the logistics involved in cryoprecipitate administration, it is inconsistently implemented alongside standardized massive transfusion protocols. This study aims to evaluate the effects of early cryoprecipitate administration on inpatient mortality in the setting of massive transfusion for exsanguinating trauma and to use propensity score analysis to minimize selection bias.Methods: The registry of an urban level 1 trauma center was queried for adult patients who received at least 6 units of packed red blood cells within 4 h of presentation. Univariate analysis, multiple logistic regression, and propensity score matching were performed.Results: 562 patients were identified. Patients with lower median RTS (6.86 (IQR 4.09-7.84) vs 7.6 (IQR 5.97-7.84), P<0.01), decreased Glasgow coma scale (12 (IQR 4-15) vs 15 (IQR 10-15), P<0.01), and increased lactate (7.5 (IQR 4.3-10.2) vs 4.9 (IQR 3.1-7.2), P<0.01) were more commonly administered cryoprecipitate. Mortality was greater among those who received cryoprecipitate (40.2% vs 23.7%, p<0.01) on univariate analysis. Neither multiple logistic regression (OR 0.917; 95% confidence interval 0.462-1.822; p = 0.805) nor propensity score matching (average treatment effect on the treated 2.3%, p = 0.77) revealed that cryoprecipitate administration was associated with a difference in inpatient mortality.Conclusions: Patients receiving cryoprecipitate within 4 h of presentation were more severely injured at presentation and had increased inpatient mortality. Multivariable logistic regression and propensity score analysis failed to show that early administration of cryoprecipitate was associated with survival benefit for exsanguinating trauma patients. The prospect of definitively assessing the utility of cryoprecipitate in exsanguinating hemorrhage warrants prospective investigation. [ABSTRACT FROM AUTHOR]

The primitive race of Soay sheep from the St Kilda archipelago in northwest Scotland has played an important role in narratives of the history of domestic sheep. The Soays, apparently a 'Bronze Age' race of sheep, were probably confined to the precipitous isle of Soay as soon as 'Iron Age' sheep were introduced to Hirta, St Kilda's main island, owing to the competitive edge of the ferocious Soay rams over the new arrivals. In the 1880s, Pitt-Rivers, following his archaeozoological interests, was the first to keep Soays in his park, their epic journey from the edge of the Atlantic to southern England enabled by his acquaintance with their owner. In the early twentieth century, Soays featured in animal bone reports for archaeological sites, were kept in parks and involved in breeding experiments, particularly around Horsham, Sussex (where their owner lived), and in Edinburgh. The transfer of 107 Soays to Hirta in 1934 and 1935, after humans had evacuated St Kilda, was a remarkable feat, enabling the important long-running Soay Sheep Project. The historical exploitation of 'feral' Soay sheep by the islanders of St Kilda has significant cultural ramifications. [ABSTRACT FROM AUTHOR]

Giant focal nodular hyperplasia (GFNH) is rarely seen in children, presenting complex diagnostic and management considerations. Pathognomonic radiographic findings can be absent in this population, and the nuances of pathologic examination are critical. We present a child with a GFNH involving the right side of the liver arising in the background of hepatic steatosis. The details of the diagnosis and therapeutic decisions involved in his treatment are discussed. [ABSTRACT FROM AUTHOR]

We tracked adult emperor penguins from Rothschild Island, west Antarctic Peninsula in 2015/2016 during a summer with extensive sea ice of long duration, contrasting with past years of reduced sea ice extent associated with the recent, rapid, warming trend across the region. We fitted ARGOS PTT devices to penguins of unknown breeding status. Of 33 penguins tracked, nine returned to the colony, presumably to provision offspring. Their foraging trips lasted 9.6 ± 3.7 days, with maximum distances of 75 ± 45 km from the colony within coastal waters. Also, 18 instruments transmitted until the initiation of the annual moult. Penguins travelled at ~ 2.3 km h−1 before slowing for moult. Post-moult, some devices continued to transmit, with speeds of ~ 0.8 km h−1, plausibly due to ice drift, which is rapid in this region. Penguins remained within the seasonal sea ice throughout, staying within 100 km of land, and generally within 5 to 10 km of features (open water, polynyas, leads, icebergs) that offered potential access to the ocean. Penguins were unlikely to have been constrained by the extensive sea ice habitat in 2015/2016. Similar habitats would also have been available in most years of the satellite record (since 1979); however, the moult locations in 2015/2016 would not have been available in many years, and penguins would have needed to find alternative moult locations during some years. Despite uncertainties, the moult period is a critical time for emperor penguins, particularly as sea ice declines, potentially affecting adult survival. [ABSTRACT FROM AUTHOR]

Summary: After entering the leaf, CO2 faces an intricate pathway to the site of photosynthetic fixation embedded within the chloroplasts. The efficiency of CO2 flux is hindered by a number of structural and biochemical barriers which, together, define the ease of flow of the gas within the leaf, termed mesophyll conductance. Previous authors have identified the key elements of this pathway, raising the prospect of engineering the system to improve CO2 flux and, thus, to increase leaf photosynthetic efficiency. In this review, we provide a perspective on the potential for improving the individual elements that contribute to this complex parameter. We lay particular emphasis on generation of the cellular architecture of the leaf which sets the initial boundaries of a number of mesophyll conductance parameters, incorporating an overview of the molecular transport processes which have been proposed as major facilitators of CO2 flux across structural boundaries along the pathway. The review highlights the research areas where future effort might be invested to increase our fundamental understanding of mesophyll conductance and leaf function and, consequently, to enable translation of these findings to improve the efficiency of crop photosynthesis. Significance Statement: Increasing CO2 flux has been identified as an element of leaf structure/function which could significantly improve photosynthetic efficiency and, thus, crop yield. This review highlights the challenges and opportunities of achieving this aim, bringing into focus our ignorance of some fundamental aspects of leaf developmental physiology, and identifying areas where future research investment could yield improved knowledge, understanding, and impact. [ABSTRACT FROM AUTHOR]

Summary: The quantitative and spatial coordination of stomatal pores in the epidermis and airspaces in the underlying mesophyll tissue is vital for efficient gas exchange in the leaf. The mechanisms that determine the distribution of stomata in the epidermis have been studied extensively, but how this relates to the regulation of mesophyll airspace configuration is poorly understood. Recent studies have investigated how development is coordinated between these tissue layers. The evidence suggests that multiple mechanisms are likely to work concurrently to coordinate stomatal and mesophyll development for optimal leaf gas exchange, and that both genetic and physiological factors contribute to this regulation. Such advances in our understanding of leaf development have important implications for potential improvement of crop water use efficiency. [ABSTRACT FROM AUTHOR]

Individuals with sickle cell disease (SCD) are at high risk of developing life-threatening complications, particularly acute chest syndrome (ACS) postoperatively. The perioperative factors associated with the development of ACS in children with SCD after splenectomy have not been clearly identified. We retrospectively reviewed medical records of all children who underwent splenectomy at our institution between 1997 and 2017 with the goal of identifying perioperative factors associated with postoperative ACS. Categorical and noncategorical variables were compared using Fisher's exact test and Student's two-tailed t -test, respectively. Sixty-five patients with SCD underwent splenectomy at a median of 4.0 (interquartile range [IQR] 2.0-8.0) years of age. A laparoscopic approach was used for 64 (98.5%) patients. Fifty-six (86.2%) underwent laparoscopic total splenectomy, and eight (12.3%) underwent laparoscopic partial splenectomy, of which two were converted to open. One had an open partial splenectomy (1.5%). Of the 65 patients, 10 (15.4%) developed ACS with a mean time to diagnosis of 49.0 ± 34.5 h. Children who developed ACS had a higher postoperative median pain score of 6.8 (IQR 5.1-9.1) versus 2.7 (IQR 1.6-4.2), P < 0.001, higher median pain score area under the curve 111.5 (IQR 76.9-169.1) versus 47.3 (IQR 30.5-78.3), P = 0.01, and received more total morphine equivalents (median 1.4 [IQR 0.4-2.7] versus 0.5 [IQR 0.3-0.9] mg/kg, respectively; P = 0.003), compared with children who did not develop ACS. Significant postoperative pain may be an early sign of ACS that could be worsened by opioid use, supporting the investigation of nonopioid pain control options in this patient population. [ABSTRACT FROM AUTHOR]

A 12-month-old Asian female underwent syndactyly release surgery with advancement flap closure of the first web space of the right hand. The procedure was complicated by enlarging keloids over the surgical site and dactylitis, a rare complication with only a few previously reported cases [Muzaffar AR, Rafols F, Masson J et al. Keloid formation after syndactyly reconstruction: associated conditions, prevalence, and preliminary report of a treatment method. J Hand Surg Am 2004; 29 : 201–8. https://doi.org/10.1016/j.jhsa.2003.10.017 ]. Initial treatment of the keloid scarring with intralesional triamcinolone under general anaesthetic was unsuccessful. Subsequently, we elected to surgically excise the keloids closing with a full-thickness skin graft from the groin, with adjunct oral methotrexate (0.4 mg kg–1 weekly) for 9 months post-surgery. The use of oral methotrexate for this indication is rarely reported: one series included two cases of successful keloid suppression with 4 years of follow-up [Muzaffar et al.] and another series of four patients with successful keloid suppression after surgery for syndactyly with dactylitis [Tolerton SK, Tonkin MA. Keloid formation after syndactyly release in patients with associated macrodactyly: management with methotrexate therapy. J Hand Surg Eur 2011; 36 : 490–7]. Low-dose methotrexate exerts anti-inflammatory effects by stimulating adenosine A2 receptors and increasing adenosine release at sites of inflammation, such as surgical sites [Muzaffar et al.]. In our patient, methotrexate was well-tolerated, keloid recurrence and dactylitis were avoided, and range of movement and functioning of the digits was maintained. Keloid formation after syndactyly release poses a complex management challenge and we propose methotrexate should be considered as an adjunct to reduce recurrence risk. [ABSTRACT FROM AUTHOR]

Structured observations of parent-child interactions are commonly used in research and clinical settings, but require additional empirical support. The current study examined the capacity of child-directed play, parent-directed play, and parent-directed chore interaction analogs to uniquely predict the development of conduct problems across a 6-year follow-up period. Parent-child observations were collected from 338 families from high-risk neighborhoods during the summer following the child's first-grade year. Participating children were 49.2 % female, 54.4 % white, and 45.6 % black, and had an average age of 7.52 years at the first assessment. Conduct problems were assessed via parent report and teacher report at five assessment points between first grade and seventh grade. Latent growth curve modeling was used to analyze predictors of conduct problem trajectory across this 6-year follow-up period. When race, sex, socioeconomic status, and maternal depressive symptoms were controlled, parental negative attention during child-directed play predicted higher levels of parent-reported conduct problems concurrently and after a 6-year follow-up period. Parental negative attention during child-directed play also predicted higher teacher-reported conduct problems 6 years later. Findings support the use of child-directed play and parent-directed chore analogs in predicting longitudinal development of conduct problems. The presence of parental negative attention during child-directed play appears to be an especially important predictor of greater conduct problems over time and across multiple domains. Additionally, the potential importance of task-incongruent behavior is proposed for further study. [ABSTRACT FROM AUTHOR]

Sea ice, including icebergs, has a complex relationship with the carbon held within animals (blue carbon) in the polar regions. Sea-ice losses around West Antarctica's continental shelf generate longer phytoplankton blooms but also make it a hotspot for coastal iceberg disturbance. This matters because in polar regions ice scour limits blue carbon storage ecosystem services, which work as a powerful negative feedback on climate change (less sea ice increases phytoplankton blooms, benthic growth, seabed carbon and sequestration). This resets benthic biota succession (maintaining regional biodiversity) and also fertilizes the ocean with nutrients, generating phytoplankton blooms, which cascade carbon capture into seabed storage and burial by benthos. Small icebergs scour coastal shallows, whereas giant icebergs ground deeper, offshore. Significant benthic communities establish where ice shelves have disintegrated (giant icebergs calving), and rapidly grow to accumulate blue carbon storage. When 5000km² giant icebergs calve, we estimate that they generate approximately 106 tonnes of immobilized zoobenthic carbon per year (tCyr-1). However, their collisions with the seabed crush and recycle vast benthic communities, costing an estimated 4x104 tCyr-1. We calculate that giant iceberg formation (ice shelf disintegration) has a net potential of approximately 106 tCyr-1 sequestration benefits as well as more widely known negative impacts. This article is part of the theme issue 'The marine system of the West Antarctic Peninsula: status and strategy for progress in a region of rapid change'. [ABSTRACT FROM AUTHOR]

This paper investigates the use of resonance-enhanced coupling to increase the received signal level in a six-degree-of-freedom electromagnetic tracking system. Resonant coupling is found to increase the efficiency of the transmitter and increase the gain of the sensing coil, resulting in improved range. However, the measurement update rate is reduced due to the settling time of the transmitter circuit and the limited bandwidth of the sensing circuit. A resistive tuning approach is proposed to balance the tradeoff between a decreased measurement bandwidth and an improved signal level. [ABSTRACT FROM AUTHOR]

The performance of digital-to-analog converters is principally limited by errors in the output voltage levels. Such errors are known as element mismatch and are quantified by the integral non-linearity. Element mismatch limits the achievable accuracy and resolution in high-precision applications as it causes gain and offset errors, as well as harmonic distortion. In this article, five existing methods for mitigating the effects of element mismatch are compared: physical level calibration, dynamic element matching, noise-shaping with digital calibration, large periodic high-frequency dithering, and large stochastic high-pass dithering. These methods are suitable for improving accuracy when using digital-to-analog converters that use multiple discrete output levels to reconstruct time-varying signals. The methods improve linearity and therefore reduce harmonic distortion and can be retrofitted to existing systems with minor hardware variations. The performance of each method is compared theoretically and confirmed by simulations and experiments. Experimental results demonstrate that three of the five methods provide significant improvements in the resolution and accuracy when applied to a general-purpose digital-to-analog converter. As such, these methods can directly improve performance in a wide range of applications including nanopositioning, metrology, and optics. [ABSTRACT FROM AUTHOR]

Electromagnetic tracking systems are used extensively in biomedical devices, gaming consoles, and animation because they are inexpensive and do not require line of sight. However, the measurement range is limited by the amplitude of the induced voltage in the sensing coil. The induced voltage is a function of the transmitter parameters such as the coil dimensions, signal power, and frequency. The transmitted power is typically restricted by the physical constraints in the application. This paper develops an algorithm to optimize the dimensions of the transmitting coil for maximum induced voltage. The proposed method is suitable for a transmitter consisting of three concentric orthogonal transmitting coils of the type commonly used in six-degree-of-freedom localization. The simulation and experimental results are presented, which demonstrate the efficacy of the proposed method. [ABSTRACT FROM PUBLISHER]

This article presents a novel vertical positioning stage with a dual-sensor arrangement suitable for scanning probe microscopy. The stage has a travel range of 8.4 μm and a first resonance frequency of 24 kHz in the direction of travel. The sensor arrangement consists of an integrated piezoelectric force sensor and laminated piezoresistive strain sensor. The piezoelectric force sensor exhibits extremely low noise and introduces a zero into the dynamics which allows the use of integral force feedback. This control method provides excellent damping performance and guaranteed stability. The piezoresistive sensor is used for tracking control with an analog PI controller which is shown to be an approximate inverse of the damped system. The resulting closed-loop system has a bandwidth is 11.4 kHz and 6 σ -resolution of 3.6 nm, which is ideal for nanopositioning and atomic force microscopy (AFM) applications. The proposed vertical stage is used to replace the vertical axis of a commercial AFM. Scans are performed in constant-force contact mode with a tip velocity of 0.2 mm/s, 1 mm/s and 2 mm/s. The recorded images contain negligible artefacts due to insufficient vertical bandwidth. [ABSTRACT FROM AUTHOR]

Repetitive control (RC) achieves tracking and rejection of periodic exogenous signals by incorporating a model of a periodic signal in the feedback path. To improve the performance, an in verse plant response filter (IPRF) is used. To improve robustness, the periodic signal model is bandwidth-limited. This limitation is largely dependent on the accuracy of the IPRF. A new method is presented for synthesizing the IPRF for discrete-time RC. The method produces filters in a simpler and more consistent manner than existing bestpractice methods available in the literature, as the only variable involved is the selection of a windowing function. It is also more efficient in terms of memory and computational complexity than existing methods. Experimental results for a nanopositioning stage show that the proposed method yields the same or better tracking performance compared to existing methods. [ABSTRACT FROM AUTHOR]

The article reports the decision of the U.S. Supreme court in the case 'Burwell v. Hobby Lobby Stores Inc.' in which the Court held that for-profit corporations are "persons" under the Religious Freedom Restoration Act (RFRA). Topics discussed include the U.S. Supreme Court's decision in the case 'Citizens United v. FEC; ' expansion of First Amendment political speech rights to corporations; and adoption of the Fourteenth Amendment to the U.S. Constitution.

This paper proposes an improvement to Integral Force Feedback (IFF), which is a popular method for active vibration control of structures and mechanical systems. Benefits of IFF include robustness, guaranteed stability and simplicity. However, the maximum damping performance is dependent on the stiffness of the system; hence, some systems cannot be adequately controlled. In this paper, an improvement to the classical force feedback control scheme is proposed. The improved method achieves arbitrary damping for any mechanical system by introducing a feed-through term. The proposed improvement is experimentally demonstrated by actively damping an objective lens assembly for a high-speed confocal microscope. [ABSTRACT FROM AUTHOR]

This article describes a position sensitive interferometer with closed-loop control of the reference mirror. A calibrated nanopositioner is used to lock the interferometer phase to the most sensitive point in the interferogram. In this configuration, large low-frequency movements of the sensor mirror can be detected from the control signal applied to the nanopositioner and high-frequency short-range signals can be measured directly from the photodiode. It is demonstrated that these two signals are complementary and can be summed to find the total displacement. The resulting interferometer has a number of desirable characteristics: it is optically simple, does not require polarization or modulation to detect the direction of motion, does not require fringe-counting or interpolation electronics, and has a bandwidth equal to that of the photodiode. Experimental results demonstrate the frequency response analysis of a high-speed positioning stage. The proposed instrument is ideal for measuring the frequency response of nanopositioners, electro-optical components, MEMs devices, ultrasonic devices, and sensors such as surface acoustic wave detectors. [ABSTRACT FROM AUTHOR]

Positive velocity and position feedback (PVPF) is a widely used control scheme in lightly damped resonant systems with collocated sensor actuator pairs. The popularity of PVPF is due to the ability to achieve a chosen damping ratio by repositioning the poles of the system. The addition of a tracking controller, to reduce the effects of inherent nonlinearities, causes the poles to deviate from the intended location and can be a detriment to the damping achieved. By designing the PVPF and tracking controllers simultaneously, the optimal damping and tracking can be achieved. Simulations show full damping of the first resonance mode and significantly higher bandwidth than that achieved using the traditional PVPF design method, allowing for high-speed scanning with accurate tracking. Experimental results are also provided to verify performance in implementation. [ABSTRACT FROM AUTHOR]

• Denver and Expanded Denver BCVI CTA scanning criteria miss over 30% of confirmed BCVI cases, leaving patients undiagnosed and untreated. • We advise liberal CTA scanning for any patient undergoing head and neck CT to identify BCVI cases early. • Ground level falls accounts for nearly 68% of BCVI in those ≥ 65 years of age and CTA should be obtained in this population. • Liberalized CTA scanning is safe, and immediate CTA scans at initial evaluation saves time to treatment and prevents missed BCVI diagnosis. Diagnostic Criteria Study The morbidity and mortality associated with ischemic stroke attributable to blunt cerebrovascular injury (BCVI) warrant aggressive screening. The Denver Criteria (DC) and Expanded Denver Criteria (eDC) have imprecise elements that can be difficult and subjective in application and can delay or prevent screening. We hypothesize these screening criteria lack adequate ability to consistently identify BCVI and that the use of a liberalized screening approach with CT angiography (CTA) is superior without increasing risk of acute kidney injury (AKI). This was a multi-institutional retrospective cohort study of trauma patients who presented between 2015-2020 with radiographically confirmed BCVI diagnosed using each institutions' liberalized screening protocol, defined as automatic CTA of the head and neck for all patients undergoing head and neck CT. Outcomes of interest included AKI, stroke, and death due to BCVI. Outcomes were reported as frequency, percent, and 95% confidence interval as calculated by the Clopper-Pearson method. Incidence of medical follow-up within 1 year of first medical visit was quantified as the median and inter-quartile range of days to follow-up visit. We identified 433 BCVI patients with a mean age of 45.2 (standard deviation 18.9) years, 256 men and 177 women, 1.73 m (0.10) tall, and weighed 80.3 kg (20.3). Forty-one patients had strokes (9.5% [95% confidence interval 6.9, 12.6] and 12 patients (2.8% [1.4, 4.5]) had mortality attributable to BCVI. Of 433 total cases, 132 (30.5% [26.2, 35.1]) would have been missed by DC and 150 (34.6% [30.2, 39.3]) by eDC. Incidence of AKI in our BCVI population was 6 (1.4% [0.01, 3.0]). BCVI would be missed over 30% of the time using the DC and eDC compared to liberalized use of screening CTA. Risk of AKI due to CTA did not occur at a clinically meaningful level, supporting liberal CTA screening. [ABSTRACT FROM AUTHOR]

The image quality of an atomic force microscope highly depends on the tracking performance of the lateral X–Y axis scanner. To reduce the requirement for accurate system models, this article describes a method based on Model-free Repetitive Control (MFRC) for high performance control of fast triangular trajectories in the X-axis while simultaneously achieving coupling compensation from the X-axis to Y-axis. The design and stability analysis of the MFRC scheme are presented in detail. The tracking results are experimentally evaluated with a range of different load conditions, showing the efficacy of the method with large variations in plant dynamics. To address the coupling from the X-axis to the Y-axis while tracking the non-periodic staircase trajectories, a pre-learning step is used to generate the compensation signals, which are combined with the baseline Proportional–Integral (PI) control in a feedforward manner in real-time implementations. This approach is also applied to address the problem of longer convergence if needed. Experimental tracking control and coupling compensation are demonstrated on a commercially available piezo-actuated scanner. The proposed method reduces the root-mean-square coupled tracking errors in Y-axis from 191.4 nm in open-loop control or 194.6 nm with PI control, to 2.8 nm with PI+MFRC control at 100 Hz tracking frequency, which demonstrates the significant improvement achieved by the proposed method. • The Model-free Repetitive Control is proposed for rejecting periodic tracking errors. • This method handles the problem of model uncertainties met in practical applications. • The design and stability analysis of the proposed method are presented in detail. • Experimental tracking and coupling compensation of an AFM scanner are validated. [ABSTRACT FROM AUTHOR]

This article describes a new electrical configuration for driving piezoelectric benders. The ‘Biased Bipolar’ configuration is compatible with parallel-polled, bimorph and multimorph benders. The new configuration is similar to the standard three-wire drive method where the top electrode is biased with a DC voltage and the bottom electrode is grounded. However, the new configuration uses an alternate DC bias voltage and adjusted range for the central electrode which allows the full range of positive and negative electric fields to be utilized. Using this technique, the predicted deflection and force can be increased by a factor of 2.2 compared to the standard two wire configuration and 1.3 times for the standard three wire configuration. These predictions were verified experimentally where the measured factor of improvement in displacement and force was of 2.4 and 1.3 compared to the standard two-wire and three-wire configurations. [ABSTRACT FROM AUTHOR]

Accurate spatial estimation of forest carbon stocks and their spatial uncertainties at local, regional, national, and global scales is a critical step in global carbon cycle modeling and management. This study aimed at enhancing the methods that are currently used in this area by combining plot data from the forest inventory and analysis program of the U.S. Forest Service and free landsat thematic mapper image data. Three mapping methods including linear regression, sequential Gaussian co-simulation, and block co-simulation algorithm were compared with respect to the accuracy of forest carbon stock estimates obtained for a study area in Southern Illinois, USA. The results indicated that although the linear regression resulted in smaller prediction errors than the sequential Gaussian co-simulation and the block co-simulation approaches, it also produced both negative and unreasonably large estimates, which is a serious drawback. Moreover, the sequential Gaussian co-simulation and the block co-simulation produced not only accurate carbon predictions, but also uncertainties for the local estimates. In addition, the block co-simulation approach scaled up both forest carbon stocks and the input uncertainties from finer to coarser spatial resolutions as is required for mapping forest carbon at national and global scales. Thus, the co-simulation and block co-simulation algorithms resolved an important current methodological challenge. [ABSTRACT FROM AUTHOR]

The first airborne hyperspectral campaign in the Antarctic Peninsula region was carried out by the British Antarctic Survey and partners in February 2011. This paper presents an insight into the applicability of currently available radiative transfer modelling and atmospheric correction techniques for processing airborne hyperspectral data in this unique coastal Antarctic environment. Results from the Atmospheric and Topographic Correction version 4 (ATCOR-4) package reveal absolute reflectance values somewhat in line with laboratory measured spectra, with Root Mean Square Error (RMSE) values of 5% in the visible near infrared (0.4-1 µm) and 8% in the shortwave infrared (1-2.5 µm). Residual noise remains present due to the absorption by atmospheric gases and aerosols, but certain parts of the spectrum match laboratory measured features very well. This study demonstrates that commercially available packages for carrying out atmospheric correction are capable of correcting airborne hyperspectral data in the challenging environment present in Antarctica. However, it is anticipated that future results from atmospheric correction could be improved by measuring in situ atmospheric data to generate atmospheric profiles and aerosol models, or with the use of multiple ground targets for calibration and validation. [ABSTRACT FROM AUTHOR]

The resolution is a critical performance metric of precision mechatronic systems such as nanopositioners and atomic force microscopes. However, there is not presently a strict definition for the measurement or reporting of this parameter. This article defines resolution as the smallest distance between two non-overlapping position commands. Methods are presented for simulating and predicting resolution in both the time and frequency domains. In order to simplify resolution measurement, a new technique is proposed which allows the resolution to be estimated from a measurement of the closed-loop actuator voltage. Simulation and experimental results demonstrate the proposed techniques. The paper concludes by comparing the resolution benefits of new control schemes over standard output feedback techniques. [ABSTRACT FROM AUTHOR]

Trauma systems continue to evolve to create the best outcomes possible for patients who have undergone traumatic injury. This review aims to evaluate the existing research on outcomes based on field triage to a Level 1 trauma center (L1TC) compared to other levels of hospitals and nontrauma centers. A structured literature search was conducted using PubMed, CINAHL, Embase, and the Cochrane Database. Studies analyzing measures of morbidity, mortality, and cost after receiving care at L1TCs compared to lower-level trauma centers and nontrauma centers in the United States and Canada were included. Three independent reviewers reviewed abstracts, and two independent reviewers conducted full-text review and quality assessment of the included articles. Twelve thousand five hundred fourteen unique articles were identified using the literature search. 61 relevant studies were included in this scoping review. 95.2% of included studies were national or regional studies, and 96.8% were registry-based studies. 72.6% of included studies adjusted their results to account for injury severity. The findings from receiving trauma care at L1TCs vary depending on severity of injury, type of injury sustained, and patient characteristics. Existing literature suffers from limitations inherent to large de-identified databases, making record linkage between hospitals impossible. This scoping review shows that the survival benefit of L1TC care is largest for patients with the most severe injuries. This scoping review demonstrates that further research using high-quality data is needed to elucidate more about how to structure trauma systems to improve outcomes for patients with different severities of injuries and in different types of facilities. [ABSTRACT FROM AUTHOR]

Piezoelectric force and position sensors provide high sensitivity but are limited at low frequencies due to their high-pass response which complicates the direct application of integral control. To overcome this issue, an additional sensor or low-frequency correction method is typically employed. However, these approaches introduce an additional first-order response that must be higher than the high-pass response of the piezo and interface electronics. This article describes a simplified method for lowfrequency correction that uses the piezoelectric sensor as an electrical component in a filter circuit. The resulting response is first-order, rather than second-order, with a cut-off frequency equal to that of a buffer circuit with the same input resistance. The proposed method is demonstrated to allow simultaneous damping and tracking control of a high-speed vertical nanopositioning stage. [ABSTRACT FROM AUTHOR]

The first airborne hyperspectral campaign in the Antarctic Peninsula region was carried out by the British Antarctic Survey and partners in February 2011. This paper presents an insight into the applicability of currently available radiative transfer modelling and atmospheric correction techniques for processing airborne hyperspectral data in this unique coastal Antarctic environment. Results from the Atmospheric and Topographic Correction version 4 (ATCOR-4) package reveal absolute reflectance values somewhat in line with laboratory measured spectra, with Root Mean Square Error (RMSE) values of 5% in the visible near infrared (0.4-1 μm) and 8% in the shortwave infrared (1-2.5 μm). Residual noise remains present due to the absorption by atmospheric gases and aerosols, but certain parts of the spectrum match laboratory measured features very well. This study demonstrates that commercially available packages for carrying out atmospheric correction are capable of correcting airborne hyperspectral data in the challenging environment present in Antarctica. However, it is anticipated that future results from atmospheric correction could be improved by measuring in situ atmospheric data to generate atmospheric profiles and aerosol models, or with the use of multiple ground targets for calibration and validation. [ABSTRACT FROM AUTHOR]

The article describes a method for estimating the spectrum or RMS value of a low-level signal corrupted by noise. If two identical sensors can be employed simultaneously and the additive noise sources are uncorrelated, the cross power spectrum can recover the power spectrum of the underlying signal. When using the Welch method to estimate the cross power spectrum, the estimation process is shown to be biased but consistent, with a variance that is inversely proportional to the number of data sets. The proposed technique is demonstrated experimentally to recover the vibration spectrum of a piezoelectric cantilever. The dual sensor method reduces the effective noise floor by three orders of magnitude and recovers spectral features that were otherwise lost in noise. [ABSTRACT FROM AUTHOR]

Abstract: Position sensors with nanometer resolution are a key component of many precision imaging and fabrication machines. Since the sensor characteristics can define the linearity, resolution and speed of the machine, the sensor performance is a foremost consideration. The first goal of this article is to define concise performance metrics and to provide exact and approximate expressions for error sources including non-linearity, drift and noise. The second goal is to review current position sensor technologies and to compare their performance. The sensors considered include: resistive, piezoelectric and piezoresistive strain sensors; capacitive sensors; electrothermal sensors; eddy current sensors; linear variable displacement transformers; interferometers; and linear encoders. [Copyright &y& Elsevier]

Attention-deficit/hyperactivity disorder (ADHD) affects between 2 and 8 % of college students. ADHD is associated with impaired academic, psychological, and social functioning, and with a wide array of negative outcomes including lower GPAs, graduation rates, and self-reported quality of life. The college environment often brings decreased external structure and increased availability of immediate rewards, presenting added demands for behavioral self-regulation-an area in which students with ADHD are already vulnerable. Despite the significant impact of ADHD in college and the unique challenges presented by the college context, virtually no treatment development research has been conducted with this population. In order to provide a framework to guide intervention development, this comprehensive review integrates research from three key domains that inform treatment for college students with ADHD: (1) functional impairment associated with ADHD among college students, (2) etiology of ADHD and the developmental context for ADHD among emerging adults (age 18-24), and (3) treatment outcome research for ADHD among adolescents and adults. A detailed set of proposed treatment targets and intervention principles are identified, and key challenges associated with treatment development in this population are discussed. [ABSTRACT FROM AUTHOR]

Abstract: Organosolv lignin was chemically modified with boron-containing reagents using a novel “graft-to” approach. The newly synthesized graft copolymers were prepared by covalently linking boron end-functionalized polycaprolactone (PCL) macromolecular reagents with organosolv lignin via reversible covalent bonds. Using a combination of 1H, 13C, 19F, and 11B NMR, it has been shown that arylboronate ester bonds are involved in the key linkages between the polyester grafts and the lignin core. Using a straightforward synthetic procedure and altering both the PCL graft density and the PCL molecular weight, a selection of compositions were studied. The newly prepared lignin-g-PCL copolymers were analyzed by differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). The Lignin-PCL5200 series shows an increase in PCL crystallinity with an increase PCL graft density. However, the crystallinity of the PCL in the lignin-g-PCL9100 set of materials remained constant throughout the series. TGA analysis for all lignin-g-PCL copolymers prepared herein show thermal decomposition near 300 °C. [Copyright &y& Elsevier]

The mechanical design of a high-bandwidth, short-range vertical positioning stage is described for integration with a commercial scanning probe microscope (SPM) for dual-stage actuation to significantly improve scanning performance. The vertical motion of the sample platform is driven by a stiff and compact piezo-stack actuator and guided by a novel circular flexure to minimize undesirable mechanical resonances that can limit the performance of the vertical feedback control loop. Finite element analysis is performed to study the key issues that affect performance. To relax the need for properly securing the stage to a working surface, such as a laboratory workbench, an inertial cancellation scheme is utilized. The measured dominant unloaded mechanical resonance of a prototype stage is above 150 kHz and the travel range is approximately 1.56 μm. The high-bandwidth stage is experimentally evaluated with a basic commercial SPM, and results show over 25-times improvement in the scanning performance. [ABSTRACT FROM AUTHOR]

Many forms of scanning probe microscopy require a piezoelectric actuator to vary the probe-sample distance. Examples include constant-force atomic force microscopy and constant-current scanning tunneling microscopy. In such modes, the topography of the sample is reconstructed from the voltage applied to the vertical piezoelectric actuator. However, piezoelectric actuators exhibit significant hysteresis which can produce up to 14% uncertainty in the reproduced topography. In this work, a charge drive is used to linearize the vertical piezoelectric actuator which reduces the error from 14% to 0.65%. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents a new sensor arrangement and feedback controller for hysteresis, creep and vibration in piezoelectric actuators. A piezoelectric force sensor is combined with a resistive strain gage to provide both extremely low noise and high stability. The use of a force sensor also results in a system transfer function that exhibits zero-pole ordering. Such systems allow a simple integral controller to provide excellent tracking and damping performance with guaranteed stability. The proposed technique is demonstrated on a nanopositioning platform with a range of 10 m and a resonance frequency of 2.4kHz. In closed-loop, the controller damps the resonance by 33dB and provides a tracking bandwidth of 1.8kHz. Excellent tracking of a 130Hz triangular reference and reduction of hysteresis to 0.46% at 10Hz is also demonstrated. The closed-loop positioning noise, predicted from the sensor noise density, was approximately 0.67nm peak-to-peak, or 0.0067% of the 10 m range. [Copyright &y& Elsevier]

Due to their high stiffness, small dimensions, and low mass, piezoelectric stack actuators are capable of developing large displacements over bandwidths of greater than 100 kHz. However, due to their large electrical capacitance, the associated driving amplifier is usually limited in bandwidth to a few kilohertz or less. In this paper the limiting characteristics of piezoelectric drives are identified as the small-signal bandwidth, output impedance, cable inductance, and power dissipation. A new dual amplifier is introduced that exhibits a small-signal bandwidth of 2 MHz with a 100 nF capacitive load. The dual amplifier is comprised of a standard high-voltage amplifier combined with a fast low-voltage amplifier to improve performance at higher frequencies. Experiments demonstrate a 300 kHz sine wave of 20 Vp-p amplitude being applied to a 100 nF load with negligible phase delay and a peak-to-peak current of 3.8 A. With a voltage range of 200 V and peak current of 1.9 A a standard amplifier would require a worst-case power dissipation of 380 W. However, the dual-amplifier arrangement has a worst-case power dissipation of only 30 W. The penalty is reduced range at high frequencies and slower operation from the high-voltage stage. [ABSTRACT FROM AUTHOR]

In a zone of improved upland pasture some 2 km east of the Cistercian monastery of Strata Florida (Ystrad Fflur), Ceredigion, are the earthwork remains of a 'sheepcote' and four abandoned medieval farms, one probably originating as a monastic sheep-handling station. Documentary evidence and field observation suggest that these farms have preserved their late-medieval forms in a relatively unmodified state. Three were apparently situated along a contemporary ffridd boundary (head dyke) that separated a zone of pasture and perhaps arable land from mountain pasture. We cannot establish the relationship between the 'sheepcote' and the 'farms' through field observation alone, nor do we know the absolute age of the ffridd boundary. Our paper describes and briefly discusses the character and local context of the area defined by the latter. The pattern of land-use is comparable to that in Swaledale (North Yorkshire), an area that has been discussed on the one hand in terms of patterns of townships (hamlets) and their land-use zones, and on the other in terms of monastic enterprise and the identification of 'vaccaries'. In the study of 'monastic landscapes', we risk becoming preoccupied with estate economies and the identification of 'tool-kits', at the expense of dealing with the complexity of relationships between monasteries and local communities. [ABSTRACT FROM AUTHOR]

Piezoelectric tube scanners are widely used in scanning probe microscopes to position the sample or the probe. Fast and accurate scanning requires the suppression of dominant low-frequency resonances as well as the compensation of dynamics-coupling effects. The present article gives a detailed description of the fully coupled tube scanner dynamics over a wide frequency range modeled by finite element (FE) analysis using the commercially available software package ANSYS. The effect of a sample mass attached to the top of the tube is investigated by considering its added mass and local stiffening. A model order reduction scheme is applied to obtain a low order model that describes the lateral and vertical deflections as well as the voltage induced on quadrant electrodes. Comparison to experimental data demonstrates a good agreement for both the full FE model and reduced order model. [ABSTRACT FROM AUTHOR]

Megaphyll leaf evolution was a critical event in Earth history that had major consequences for the biotic regulation of the global environment. Zimmermann''s telome theory has been widely accepted for over seventy years as the leading explanation for this evolutionary innovation. According to the telome theory, megaphylls evolved from the three-dimensional lateral branches of early vascular land plants in a hypothetical series of three transformations; first, the formation of determinate lateral branches (overtopping); second, the development of ‘flattened’ branch systems (planation); and third, the fusion of planated branches with lateral outgrowths of photosynthetic mesophyll tissue to form the leaf blade (webbing). A critical review of the molecular and cellular evidence identifies plausible genetic, cellular and physiological mechanisms in extant higher plants for overtopping and planation but more limited evidence for the process of webbing (lateral outgrowth fusion). We highlight key outstanding questions concerning the telome theory that are likely to be resolved when gene identification and functional analysis techniques are applied to photosynthetic organisms that have different evolutionary histories. [Copyright &y& Elsevier]