Low-Field Portable MR Imaging to Evaluate Ventricular Volumes: A Single-Center Retrospective Study.

This study assesses the efficacy of low-field portable MR imaging in measuring ventricular volumes in the pediatric population in the hospital setting. We compared portable and standard of care MR images from the same patient. The estimated ventricular volumes had excellent agreement with a mean bias of 2.06% by Bland-Altman analysis and a correlation of 0.99. From this initial data set, our results suggest that low-field, portable MR imaging is a promising technique for imaging and quantifying ventricular volumes.

Redox cycling-based signal amplification at alkanethiol modified nanoporous gold interdigitated microelectrodes.

Interdigitated electrodes (IDEs) enable electrochemical signal enhancement through repeated reduction and oxidation of the analyte molecule. Porosity on these electrodes is often used to lower the impedance background. However, their high capacitive current and signal interferences with oxygen reduction limit electrochemical detection ability. We present utilization of alkanethiol modification on nanoporous gold (NPG) electrodes to lower their background capacitance and chemically passivate them from interferences due to oxygen reduction, while maintaining their fast electron transfer rates, as validated by lower separation between anodic and cathodic peaks (ΔE) and lower charge transfer resistance (Rct) values in comparison to planar gold electrodes. Redox amplification based on this modification enables sensitive detection of various small molecules, including pyocyanin, p-aminophenol, and selective detection of dopamine in the presence of ascorbic acid. Alkanethiol NPG arrays are applied as a multiplexed sensor testbed within a well plate to screen binding of various peptide receptors to the SARS COV2 S-protein by using a sandwich assay for conversion of PAPP (4-aminophenyl phosphate) to PAP (p-aminophenol), by the action of AP (alkaline phosphatase), which is validated against optical ELISA screens of the peptides. Such arrays are especially of interest in small volume analytical settings with complex samples, wherein optical methods are unsuitable.

Pulmonary Matrix-derived Hydrogels from Patients with Idiopathic Pulmonary Fibrosis Induce a Proinflammatory State in Lung Fibroblasts In Vitro.

Idiopathic pulmonary fibrosis (IPF), one of the most common forms of interstitial lung disease, is a poorly understood, chronic, and often fatal fibroproliferative condition with only two FDA-approved medications. Understanding the pathobiology of the fibroblast in IPF is critical to evaluating and discovering novel therapeutics. Using a decellularized lung matrix derived from IPF patients, we generate three-dimensional (3D) hydrogels as in vitro models of lung physiology and characterize the phenotype of fibroblasts seeded into the hydrogels. When cultured in IPF ECM hydrogels, IPF fibroblasts display differential contractility compared to their normal counterparts, lose the classical myofibroblast marker α-smooth muscle actin, and increase expression of proinflammatory cytokines compared to fibroblasts seeded two-dimensionally (2D) on tissue culture dishes. We validate this proinflammatory state in fibroblast-conditioned media studies with monocytes and monocyte-derived macrophages. These findings add to a growing understanding of the lung microenvironment effect on fibroblast phenotypes, shed light on the potential role of fibroblasts as immune signaling hubs during lung fibrosis, and suggest intervention in fibroblast-immune cell crosstalk as a possible novel therapeutic avenue.

Specific CD4+ T cell phenotypes associate with bacterial control in people who 'resist' infection with Mycobacterium tuberculosis.

A subset of individuals exposed to Mycobacterium tuberculosis (Mtb) that we refer to as 'resisters' (RSTR) show evidence of IFN-γ- T cell responses to Mtb-specific antigens despite serially negative results on clinical testing. Here we found that Mtb-specific T cells in RSTR were clonally expanded, confirming the priming of adaptive immune responses following Mtb exposure. RSTR CD4+ T cells showed enrichment of TH17 and regulatory T cell-like functional programs compared to Mtb-specific T cells from individuals with latent Mtb infection. Using public datasets, we showed that these TH17 cell-like functional programs were associated with lack of progression to active tuberculosis among South African adolescents with latent Mtb infection and with bacterial control in nonhuman primates. Our findings suggested that RSTR may successfully control Mtb following exposure and immune priming and established a set of T cell biomarkers to facilitate further study of this clinical phenotype.

Olecranon Osteotomy Exposure for Distal Humeral Fracture Treatment.

Background: Olecranon osteotomy (OO) is commonly utilized to improve exposure when treating intra-articular distal humeral fractures. A chevron-shaped osteotomy facilitates reduction and increases surface area for healing1. Following distal humeral fracture reduction and fixation, the OO fragment is fixed with a precontoured plate. The OO technique yields comparable outcomes to alternative techniques1,2. Description: The technique is performed as follows. (1) Imaging is reviewed and preoperative planning is performed. (2) The patient is positioned in the lateral decubitus position with the operative extremity placed over a bolster. (3) A longitudinal posterior skin incision is centered just medial or lateral to the tip of the olecranon. Full-thickness skin flaps are raised medially and laterally. (4) The ulnar nerve is identified and mobilized for later anterior subcutaneous transposition. (5) An OO is performed at the non-articular "bare area" of the trochlear notch with an oscillating saw and completed with an osteotome. (6) Open reduction and internal fixation of the distal humerus is performed. (7) The osteotomy fragment is reduced, and a precontoured plate is applied. (8) A small longitudinal slit in the distal triceps over the proximal edge of the plate decreases plate prominence and is repaired with suture. (9) The subcutaneous tissues and skin are closed in the usual manner. Alternatives: Alterative techniques include extra-articular OO, triceps splitting, triceps reflecting, and lateral para-olecranon combined with a medial approach. Multiple drill holes and a thin osteotome can help mitigate the kerf created by the oscillating saw. Alternative fixation methods include a predrilled 6.5-mm intramedullary screw, a tension band construct, suture fixation, or a one-third tubular plate. Rationale: The OO technique provides improved exposure when compared with alternative techniques, enabling accurate reduction and fixation of distal humeral fractures1-3. Wilkinson and Stanley found that OO exposed the distal humeral articular surface to a greater degree than the triceps-splitting and triceps-reflecting approaches3. OO has not been associated with triceps weakness, unlike some of the alternative techniques2. Expected Outcomes: The incidence of good-to-excellent outcomes is similar when comparing the techniques for exposure of intra-articular distal humeral fractures4. Osteotomies united in all patients in 2 reported series, totaling 84 cases1,2. Removal of symptomatic hardware used in OO fragment fixation can occur in a small subset of patients1,2. Important Tips: Provisionally size a precontoured plate and fix it on the olecranon to aid in later reduction and fracture fixation.The bare area is the desired position for the OO because of its natural lack of cartilage5,6. This non-articular bare area is located just distal to the deepest portion of the trochlear notch, approximately 2 to 2.5 cm distal to the olecranon tip5,6.An (apex-distal) chevron osteotomy angle of ∼130° will help to keep the osteotomy within the non-articular bare area6.Beginning on the dorsal surface of the ulna, directly posterior to the bare area, an oscillating saw is utilized to create a chevron osteotomy to subchondral bone, perpendicular to the long axis of the ulna5,6.The OO is completed by fracturing through the osteochondral surface, which leaves an irregular chondral cancellous surface that can accurately interdigitate. This facilitates later reduction and stability of the osteotomy.Anatomic articular reduction of the OO is not solely judged on the dorsal cortical bone because of the kerf removed by the saw blade. Instead, examination of the articular surface of the trochlear notch is the primary assessment of reduction.Placement of suture through the proximal portion of the plate aids in the repair of the longitudinal split of the distal triceps.Successful treatment of distal humeral fractures requires accurate reduction and rigid fixation aided by adequate exposure achieved through OO. Acronyms and Abbreviations: ORIF = open reduction and internal fixationOT = occupational therapyHWR = hardware removalK-wire = Kirschner wireROM = range of motion.

Intrasaccular Flow Disruption: Examining Global Access and Research Trends.

The Woven EndoBridge (WEB) and other intrasaccular flow disruptors show promise in treating intracranial aneurysms. We performed a bibliometric analysis to provide novel insights into the trends and trajectory of these devices. We systematically assessed bibliometric data such as citations, journals, study designs, open access status, and multi-institutional involvement for the top-cited articles on WEB and other disruptors. The top 100 cited studies on the WEB had citations from 7 to 144 (mean±s.d. 35.6 ± 29.5), while only 33 studies were published for other intrasaccular flow disruptors (4.24 ± 8.45). Of the other devices, the Contour has the most publications (n=21). Retrospective reviews were the most common study design for both WEB and other intrasaccular devices. France published the most studies in top 100 WEB papers (n=35), while Germany led for other flow disruptors (n=10). In all studies analyzed, no senior authors from Africa are present. The top 100 WEB publications had a higher mean citation count (35.6 vs. 4.24, p < 0.001), higher mean citations per year (5.24 vs. 1.03, p < 0.01), and a higher proportion of multi-institutional collaborations (44.0% vs. 12.1%, p < 0.01) than other intrasaccular flow disruptors. In conclusion, countries with the most publications on WEB are not necessarily the ones leading the way with newer intrasaccular devices, while study designs remain similar. There is limited contribution to the literature outside of Europe and North America. Our findings identify notable collaborators and trends, providing a snapshot of the field and a roadmap for future research.

Structural variants contribute to phenotypic variation in maize.

Comprehensively identifying the loci shaping trait variation has been challenging, in part because standard approaches often miss many types of genetic variants. Structural variants, especially transposable elements are likely to affect phenotypic variation but we need better methods in maize for detecting polymorphic structural variants and TEs using short-read sequencing data. Here, we used a whole genome alignment between two maize genotypes to identify polymorphic structural variants and then genotyped a large maize diversity panel for these variants using short-read sequencing data. We characterized variation of SVs within the panel and identified SV polymorphisms that are associated with life history traits and genotype-by-environment interactions. While most of the SVs associated with traits contained TEs, only one of the SV's boundaries clearly matched TE breakpoints indicative of a TE insertion, whereas the other polymorphisms were likely caused by deletions. All of the SVs associated with traits were in linkage disequilibrium with nearby single nucleotide polymorphisms (SNPs), suggesting that this method did not identify variants that would have been missed in a SNP association study.

Evaluating Solid Phase Adsorption Toxin Tracking (SPATT) for passive monitoring of per- and polyfluoroalkyl substances (PFAS) with Ion Mobility Spectrometry-Mass Spectrometry (IMS-MS).

Detection and monitoring of per- and polyfluoroalkyl substances (PFAS) in aquatic environments has become an increasingly higher priority of regulatory agencies as public concern for human intake of these chemicals continues to grow. While many methods utilize active sampling strategies ("grab samples") for precise PFAS quantitation, here we evaluate the efficacy of low-cost passive sampling devices (Solid Phase Adsorption Toxin Tracking, or SPATTs) for spatial and temporal PFAS assessment of aquatic systems. For this study, passive samplers were initially deployed in North Carolina along the Cape Fear River during the summer and fall of 2016 and 2017. These were originally intended for the detection of microcystins and monitoring potentially harmful algal blooms, though this period also coincided with occurrences of PFAS discharge from a local fluorochemical manufacturer into the river. Additional samplers were then deployed in 2022 to evaluate changes in PFAS fingerprint and abundances. Assessment of PFAS showed legacy compounds were observed across almost all sampling sites over all 3 years (PFHxS, PFOS, PFHxA, etc.), while emerging replacement PFAS (e.g., Nafion byproducts) were predominantly localized downstream from the manufacturer. Furthermore, samplers deployed downstream from the manufacturer in 2022 noted sharp decreases in observed signal for replacement PFAS in comparison to samplers deployed in 2016 and 2017, indicating mitigation and remediation efforts in the area were able to reduce localized fluorochemical contamination.

A phylogeny-informed characterisation of global tetrapod traits addresses data gaps and biases.

Tetrapods (amphibians, reptiles, birds, and mammals) are model systems for global biodiversity science, but continuing data gaps, limited data standardisation, and ongoing flux in taxonomic nomenclature constrain integrative research on this group and potentially cause biased inference. We combined and harmonised taxonomic, spatial, phylogenetic, and attribute data with phylogeny-based multiple imputation to provide a comprehensive data resource (TetrapodTraits 1.0.0) that includes values, predictions, and sources for body size, activity time, micro- and macrohabitat, ecosystem, threat status, biogeography, insularity, environmental preferences, and human influence, for all 33,281 tetrapod species covered in recent fully sampled phylogenies. We assess gaps and biases across taxa and space, finding that shared data missing in attribute values increased with taxon-level completeness and richness across clades. Prediction of missing attribute values using multiple imputation revealed substantial changes in estimated macroecological patterns. These results highlight biases incurred by nonrandom missingness and strategies to best address them. While there is an obvious need for further data collection and updates, our phylogeny-informed database of tetrapod traits can support a more comprehensive representation of tetrapod species and their attributes in ecology, evolution, and conservation research.

Deep learning-based image quality assessment: impact on detection accuracy of prostate cancer extraprostatic extension on MRI.

OBJECTIVE: To assess impact of image quality on prostate cancer extraprostatic extension (EPE) detection on MRI using a deep learning-based AI algorithm. MATERIALS AND METHODS: This retrospective, single institution study included patients who were imaged with mpMRI and subsequently underwent radical prostatectomy from June 2007 to August 2022. One genitourinary radiologist prospectively evaluated each patient using the NCI EPE grading system. Each T2WI was classified as low- or high-quality by a previously developed AI algorithm. Fisher's exact tests were performed to compare EPE detection metrics between low- and high-quality images. Univariable and multivariable analyses were conducted to assess the predictive value of image quality for pathological EPE. RESULTS: A total of 773 consecutive patients (median age 61 [IQR 56-67] years) were evaluated. At radical prostatectomy, 23% (180/773) of patients had EPE at pathology, and 41% (131/318) of positive EPE calls on mpMRI were confirmed to have EPE. The AI algorithm classified 36% (280/773) of T2WIs as low-quality and 64% (493/773) as high-quality. For EPE grade ≥ 1, high-quality T2WI significantly improved specificity for EPE detection (72% [95% CI 67-76%] vs. 63% [95% CI 56-69%], P = 0.03), but did not significantly affect sensitivity (72% [95% CI 62-80%] vs. 75% [95% CI 63-85%]), positive predictive value (44% [95% CI 39-49%] vs. 38% [95% CI 32-43%]), or negative predictive value (89% [95% CI 86-92%] vs. 89% [95% CI 85-93%]). Sensitivity, specificity, PPV, and NPV for EPE grades ≥ 2 and ≥ 3 did not show significant differences attributable to imaging quality. For NCI EPE grade 1, high-quality images (OR 3.05, 95% CI 1.54-5.86; P < 0.001) demonstrated a stronger association with pathologic EPE than low-quality images (OR 1.76, 95% CI 0.63-4.24; P = 0.24). CONCLUSION: Our study successfully employed a deep learning-based AI algorithm to classify image quality of prostate MRI and demonstrated that better quality T2WI was associated with more accurate prediction of EPE at final pathology.

The Influence of Regional Geophysical Resource Variability on the Value of Single- and Multistorage Technology Portfolios.

A stylized macro-scale energy model of least-cost electricity systems relying only on wind and solar generation was used to assess the value of different storage technologies, individually and combined, for the contiguous U.S. as well as for four geographically diverse U.S. load-balancing regions. For the contiguous U.S. system, at current costs, when only one storage technology was deployed, hydrogen energy storage produced the lowest system costs, due to its energy-capacity costs being the lowest of all storage technologies modeled. Additional hypothetical storage technologies were more cost-competitive than hydrogen (long-duration storage) only at very low energy-capacity costs, but they were more cost-competitive than Li-ion batteries (short-duration storage) at relatively high energy- and power-capacity costs. In all load-balancing regions investigated, the least-cost systems that included long-duration storage had sufficient energy and power capacity to also meet short-duration energy and power storage needs, so that the addition of short-duration storage as a second storage technology did not markedly reduce total system costs. Thus, in electricity systems that rely on wind and solar generation, contingent on social and geographic constraints, long-duration storage may cost-effectively provide the services that would otherwise be provided by shorter-duration storage technologies.

Comparative Optics of the Surgical Microscope and Rigid Endoscopes in Neurosurgery.

This chapter is intended to provide a brief overview of the optics of surgical microscopes and rigid endoscopes, with the aim of providing the reader with the principles dictating the nature of surgical visualization when either of the visual control systems is used. It is not by any means geared toward elaborating on the detailed optical physics of these systems, which is beyond the scope and objective of this chapter.

Personal electric deterrents can reduce shark bites from the three species responsible for the most fatal interactions.

The frequency of unprovoked shark bites is increasing worldwide, leading to a growing pressure for mitigation measures to reduce shark-bite risk while maintaining conservation objectives. Personal shark deterrents are a promising and non-lethal strategy that can protect ocean users, but few have been independently and scientifically tested. In Australia, bull (Carcharhinus leucas), tiger (Galeocerdo cuvier), and white sharks (Carcharodon carcharias) are responsible for the highest number of bites and fatalities. We tested the effects of two electric deterrents (Ocean Guardian's Freedom+ Surf and Freedom7) on the behaviour of these three species. The surf product reduced the probability of bites by 54% across all three species. The diving product had a similar effect on tiger shark bites (69% reduction) but did not reduce the frequency of bites from white sharks (1% increase), likely because the electrodes were placed further away from the bait. Electric deterrents also increased the time for bites to occur, and frequency of reactions and passes for all species tested. Our findings reveal that both Freedom+ Surf and Freedom7 electric deterrents affect shark behaviour and can reduce shark-bite risk for water users, but neither product eliminated the risk of shark bites entirely. The increasing number of studies showing the ability of personal electric deterrents to reduce shark-bite risk highlights personal protection as an effective and important part of the toolbox of shark-bite mitigation measures.

Cannabis Co-Use Among Black Individuals with Chronic Pain Who Use Opioids: Associations with Other Substance Use and Pain Related Outcomes.

Background Black individuals with chronic musculoskeletal (MSK) pain tend to experience worse pain and opioid use-related outcomes, including other substance co-use, compared with non-Hispanic White individuals. Co-using cannabis with opioids could instigate a cascade of pain-related vulnerabilities and poor outcomes. Here, we test associations between cannabis/opioid co-use and pain-related outcomes among Black individuals with chronic MSK pain. Methods Black adults with chronic MSK pain who use opioids (N=401; 51.62% female, Mage=35.90, SD=11.03) completed online measures of pain intensity/interference, emotional distress, opioid dependence, and risky use of other substances. Results Compared with opioid use alone, opioid and cannabis co-use was associated with elevated anxiety and depression symptoms, opioid dependence, and risky substance use, but not pain. Conclusions Black individuals with chronic MSK pain who co-use opioids and cannabis warrant targeted interventions that address their needs. Tailored interventions could help address disparities in pain-related outcomes and opioid morbidity and mortality rates.

Evaluation of pediatric patients for intestinal transplantation in the modern era.

OBJECTIVES: To review recent evaluations of pediatric patients with intestinal failure (IF) for intestinal transplantation (ITx), waiting list decisions, and outcomes of patients listed and not listed for ITx at our center. METHODS: Retrospective chart review of 97 patients evaluated for ITx from January 2014 to December 2021 including data from referring institutions and protocol laboratory testing, body imaging, endoscopy, and liver biopsy in selected cases. Survival analysis used Kaplan-Meier estimates and Cox proportional hazards regression. RESULTS: Patients were referred almost entirely from outside institutions, one-third because of intestinal failure-associated liver disease (IFALD), two-thirds because of repeated infective and non-IFALD complications under minimally successful intestinal rehabilitation, and a single patient because of lost central vein access. The majority had short bowel syndrome (SBS). Waiting list placement was offered to 67 (69%) patients, 40 of whom for IFALD. The IFALD group was generally younger and more likely to have SBS, have received more parenteral nutrition, have demonstrated more evidence of chronic inflammation and have inferior kidney function compared to those offered ITx for non-IFALD complications and those not listed. ITx was performed in 53 patients. Superior postevaluation survival was independently associated with higher serum creatinine (hazard ratio [HR] 15.410, p = 014), whereas inferior postevaluation survival was associated with ITx (HR 0.515, p = 0.035) and higher serum fibrinogen (HR 0.994, p = 0.005). CONCLUSIONS: Despite recent improvements in IF management, IFALD remains a prominent reason for ITx referral. Complications of IF inherent to ITx candidacy influence postevaluation and post-ITx survival.

Cellular architecture shapes the naïve T cell response.

After antigen stimulation, naïve T cells display reproducible population-level responses, which arise from individual T cells pursuing specific differentiation trajectories. However, cell-intrinsic predeterminants controlling these single-cell decisions remain enigmatic. We found that the subcellular architectures of naïve CD8 T cells, defined by the presence (TØ) or absence (TO) of nuclear envelope invaginations, changed with maturation, activation, and differentiation. Upon T cell receptor (TCR) stimulation, naïve TØ cells displayed increased expression of the early-response gene Nr4a1, dependent upon heightened calcium entry. Subsequently, in vitro differentiation revealed that TØ cells generated effector-like cells more so compared with TO cells, which proliferated less and preferentially adopted a memory-precursor phenotype. These data suggest that cellular architecture may be a predeterminant of naïve CD8 T cell fate.

Utilizing gas flux from automated head chamber systems to estimate dietary energy values for beef cattle fed a finishing diet.

Dietary net energy for maintenance (NEm) and gain (NEg) can be estimated using calculations based on live performance or adjusted-final body weight, which is calculated based on carcass characteristics. These values are commonly referred to as performance-adjusted (pa) NEm (paNEm) and NEg (paNEg). The NEm and NEg of a diet can also be estimated by adding recovered energy (RE) with heat production (HP) derived from an automated head chamber system (AHCS), which we will term gas-adjusted (ga) NEm (gaNEm) and NEg (gaNEg). Furthermore, HP from the Brouwer equation requires an estimate of urinary nitrogen (UN) excretion, which can be calculated based on N intake, blood urea N, UN concentration, and urine creatinine, or it could be zeroed. Alternatively, HP can be calculated using an alternative equation based on the respiratory quotient. Demonstrating agreement between pa and ga derived dietary energy values provides an opportunity to validate using the AHCS for energetic experiments and this comparison has not been conducted previously. Accordingly, the objective of this experiment was to assess the agreement between live and carcass paNEm and paNEg with gaNEm and gaNEg, where HP was calculated using 4 different approaches. Estimates of HP were not different (P = 0.99) between the 4 approaches employed, indicating that all options investigated are appropriate. Live paNEm and paNEg had a higher agreement (Lin's concordance correlation coefficient [CCC] = 0.91) with gaNEm and gaNEg than carcass values (CCC ≤ 0.84). These results suggest that researchers can implement the AHCS to provide good estimates of dietary energy values in finishing beef cattle that are unrestrained.

Automated head chamber systems (AHCS) implemented into beef cattle research allow estimation of gas flux, heat production (HP), and calculated gas-adjusted dietary net energy for maintenance (gaNEm) and gain (gaNEg) values when paired with recovered energy. However, a comparison between AHCS-derived values and performance-adjusted NEm (paNEm) and NEg (paNEg) from either live performance (live paNEm and paNEg) or carcass data (carcass paNEm and paNEg) has not been conducted. Accordingly, the objectives of this experiment were to evaluate the agreement between gaNEm and gaNEg, estimated using different approaches for calculating HP, with live paNEm and paNEg or carcass paNEm and paNEg. Accounting for urinary nitrogen or methane when calculating HP does not appreciably influence HP estimates or subsequent calculations to estimate dietary NEm and NEg. There was excellent agreement between live paNEm and gaNEm, and between paNEg and gaNEg. Measures of precision, accuracy, and agreement were lower for carcass than for live-derived values when compared to gaNEm and gaNEg but were still acceptable. These results suggest that researchers can implement the AHCS to provide estimates of HP, gas flux, and estimates of dietary energy values in unrestrained finishing beef cattle-fed diets ranging in crude protein content (10.8% to 12.5%). Additional research is warranted on the use of the AHCS to conduct energetic studies across varying diets and production systems, particularly grazing systems.

A dual mechanisms of control account of age differences in working memory.

Age-related differences in working memory (WM) can be large, but the exact sources are unclear. We hypothesized that young adults outperform older adults on WM tasks because they use controlled attention processes to prioritize the maintenance of relevant information in WM in a proactive mode, whereas older adults tend to rely on the strength of familiarity signals to make memory decisions in a reactive mode. We used a WM task that cued participants to prioritize one item over others and presented repeated lure probes that cause errors when one is engaged in a reactive mode. Results showed that, relative to young adults with full attention available to use proactive control during the delays, older adults with full attention (and young adults with divided attention) during the delays had exaggerated error rates to repeated lure probes compared to control probes. When the amount of proactive interference was increased (by repeating stimuli across trials), older adults were able to engage in proactive control, and this eliminated their exaggerated error rate (while young adults with divided attention could not). These results provide evidence for a dual mechanisms of control account of age differences in WM. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Sublethal effects of a commercial Bt product and Bt cotton flowers on the bollworm (Helicoverpa zea) with impacts to predation from a lady beetle (Hippodamia convergens).

Insecticidal Bacillus thuringiensis Berliner (Bt) toxins produced by transgenic cotton (Gossypium hirsutum L.) plants have become an essential component of cotton pest management. Bt toxins are the primary management tool in transgenic cotton for lepidopteran pests, the most important of which is the bollworm (Helicoverpa zea Boddie) (Lepidoptera: Noctuidae) in the United States (U.S.). However, bollworm larvae that survive after consuming Bt toxins may experience sublethal effects, which could alter interactions with other organisms, such as natural enemies. Experiments were conducted to evaluate how sublethal effects of a commercial Bt product (Dipel) incorporated into artificial diet and from Bt cotton flowers impact predation from the convergent lady beetle (Hippodamia convergens Guérin-Méneville) (Coleoptera: Coccinellidae), common in cotton fields of the mid-southern U.S. Sublethal effects were detected through reduced weight and slower development in bollworm larvae which fed on Dipel incorporated into artificial diet, Bollgard II, and Bollgard 3 cotton flowers. Sublethal effects from proteins incorporated into artificial diet were found to significantly alter predation from third instar lady beetle larvae. Predation of bollworm larvae also increased significantly after feeding for three days on a diet incorporated with Bt proteins. These results suggest that the changes in larval weight and development induced by Bt can be used to help predict consumption of bollworm larvae by the convergent lady beetle. These findings are essential to understanding the potential level of biological control in Bt cotton where lepidopteran larvae experience sublethal effects.

Knudsen effusion mass spectrometry: Current and future approaches.

RATIONALE: Knudsen effusion mass spectrometry (KEMS) has been a powerful tool in physical chemistry since 1954. There are many excellent reviews of the basic principles of KEMS in the literature. In this review, we focus on the current status and potential growth areas for this instrumental technique. METHODS: We discuss (1) instrumentation, (2) measurement techniques, and (3) selected novel applications of the technique. Improved heating methods and temperature measurement allow for better control of the Knudsen cell effusive source. Accurate computer models of the effusive beam and its introduction to the ionizer allow optimization of such parameters as sensitivity and removal of background signals. Computer models of the ionizer allow for optimized sensitivity and resolution. Additionally, data acquisition systems specifically tailored to a KEMS system permit improved quantity and quality of data. RESULTS: KEMS is traditionally utilized for thermodynamic measurements of pure compounds and solutions. These measurements can now be strengthened using first principles and model-based computational thermochemistry. First principles can be used to calculate accurate Gibbs energy functions (gefs) for improving third law calculations. Calculated enthalpies of formation and dissociation energies from ab initio methods can be compared to those measured using KEMS. For model-based thermochemistry, solution parameters can be derived from measured thermochemical data on metallic and nonmetallic solutions. Beyond thermodynamic measurements, KEMS has been used for many specific applications. We select examples for discussion: measurements of phase changes, measurement/control of low-oxygen potential systems, thermochemistry of ultrahigh-temperature ceramics, geological applications, nuclear applications, applications to organic and organometallic compounds, and thermochemistry of functional room temperature materials, such as lithium ion batteries. CONCLUSIONS: We present an overview of the current status of KEMS and discuss ideas for improving KEMS instrumentation and measurements. We discuss selected KEMS studies to illustrate future directions of KEMS.