Anharmonicity in Thermal Insulators: An Analysis from First Principles.

The anharmonicity of atomic motion limits the thermal conductivity in crystalline solids. However, a microscopic understanding of the mechanisms active in strong thermal insulators is lacking. In this Letter, we classify 465 experimentally known materials with respect to their anharmonicity and perform fully anharmonic ab initio Green-Kubo calculations for 58 of them, finding 28 thermal insulators with κ<10 W/mK including 6 with ultralow κ≲1 W/mK. Our analysis reveals that the underlying strong anharmonic dynamics is driven by the exploration of metastable intrinsic defect geometries. This is at variance with the frequently applied perturbative approach, in which the dynamics is assumed to evolve around a single stable geometry.

Recent advances in the SISSO method and their implementation in the SISSO++ code.

Accurate and explainable artificial-intelligence (AI) models are promising tools for accelerating the discovery of new materials. Recently, symbolic regression has become an increasingly popular tool for explainable AI because it yields models that are relatively simple analytical descriptions of target properties. Due to its deterministic nature, the sure-independence screening and sparsifying operator (SISSO) method is a particularly promising approach for this application. Here, we describe the new advancements of the SISSO algorithm, as implemented into SISSO++, a C++ code with Python bindings. We introduce a new representation of the mathematical expressions found by SISSO. This is a first step toward introducing "grammar" rules into the feature creation step. Importantly, by introducing a controlled nonlinear optimization to the feature creation step, we expand the range of possible descriptors found by the methodology. Finally, we introduce refinements to the solver algorithms for both regression and classification, which drastically increase the reliability and efficiency of SISSO. For all these improvements to the basic SISSO algorithm, we not only illustrate their potential impact but also fully detail how they operate both mathematically and computationally.

Hierarchical Symbolic Regression for Identifying Key Physical Parameters Correlated with Bulk Properties of Perovskites.

Symbolic regression identifies nonlinear, analytical expressions relating materials properties and key physical parameters. However, the pool of expressions grows rapidly with complexity, compromising its efficiency. We tackle this challenge hierarchically: identified expressions are used as inputs for further obtaining more complex expressions. Crucially, this framework can transfer knowledge among properties, as demonstrated using the sure-independence-screening-and-sparsifying-operator approach to identify expressions for lattice constant and cohesive energy, which are then used to model the bulk modulus of ABO_{3} perovskites.

Cyclic Ether Triggers for Polymeric Frustrated Lewis Pair Gels.

Sterically hindered Lewis acid and base centers are unable to form Lewis adducts, instead forming frustrated Lewis pairs (FLPs), where latent reactivity can be utilized for the activation of small molecules. Applying FLP chemistry into polymeric frameworks transforms this chemistry into responsive and functional materials. Here, we report a versatile synthesis strategy for the preparation of macromolecular FLPs and explore its potential with the ring-opening reactions of cyclic ethers. Addition of the cyclic substrates triggered polymer network formation, where the extent of cross-linking, strength of network, and reactivity are tuned by the steric and electronic properties of the ethers. The resultant networks behave like covalently cross-linked polymers, demonstrating the versatility of FLPs to simultaneously tune both small-molecule capture and mechanical properties of materials.

Synovial neutrophilic gelatinase-associated lipocalin in the diagnosis of periprosthetic joint infection after total knee arthroplasty.

BACKGROUND: Periprosthetic joint infection (PJI) is one of the most serious complications following total knee arthroplasty (TKA). However, the diagnosis remains a challenge for clinicians. In 2011, the muscoskeletal infection society (MSIS) criteria provided a consensus which has been updated in 2013, but these criteria are complex and contain tests that are time-consuming. The same is applicable to the pro-Implant guidelines. Therefore, a simpler diagnostic test is desirable. OBJECTIVES: The value of neutrophil gelatinase-associated lipocalin (NGAL), leucocyte esterase (LE) levels, and the white blood cell (WBC) count in synovial fluid to diagnose PJI after TKA was evaluated. METHODS: In a retrospective cohort study, we analyzed 89 synovial fluid samples from 86 patients with suspected PJI after TKA. Thirteen and 23 of those samples were classified as PJI according to the MSIS and pro-Implant criteria, respectively. Subsequently, NGAL, LE levels, and the WBC count were determined, the former one using an immunoassay. Using either the MSIS or pro-Implant criteria as the golden standard for PJI, sensitivity and specificity of those markers were determined with ROC curves, and medians were compared with Mann-Whitney U and Pearson Chi-square tests. RESULTS: When applying the MSIS criteria, NGAL revealed 92% sensitivity and 83% specificity. WBC count showed similar sensitivity (92%) and specificity (84%), whereas sensitivity and specificity for LE were 39% and 88% respectively. When applying the pro-Implant criteria, sensitivity was 95% and specificity was 95% for NGAL. Sensitivity and specificity for WBC count were 100% and 97% and for LE 39% and 92% respectively. CONCLUSION: NGAL and WBC count in synovial fluid has high accuracy in the diagnosis of PJI after TKA and should seriously be considered as part of PJI diagnostics. Leucocyte esterase can serve as rule-in criterion peroperatively. These conclusions are independent of which criteria set was used as golden standard.

No selection for change in polyandry under experimental evolution.

What drives mating system variation is a major question in evolutionary biology. Female multiple mating (polyandry) has diverse evolutionary consequences, and there are many potential benefits and costs of polyandry. However, our understanding of its evolution is biased towards studies enforcing monandry in polyandrous species. What drives and maintains variation in polyandry between individuals, genotypes, populations and species remains poorly understood. Genetic variation in polyandry may be actively maintained by selection, or arise by chance if polyandry is selectively neutral. In Drosophila pseudoobscura, there is genetic variation in polyandry between and within populations. We used isofemale lines to found replicate populations with high or low initial levels of polyandry and tracked polyandry under experimental evolution over seven generations. Polyandry remained relatively stable, reflecting the starting frequencies of the experimental populations. There were no clear fitness differences between high versus low polyandry genotypes, and there was no signature of balancing selection. We confirmed these patterns in direct comparisons between evolved and ancestral females and found no consequences of polyandry for female fecundity. The absence of differential selection even when initiating populations with major differences in polyandry casts some doubt on the importance of polyandry for female fitness.

Modeling optical coupling of plasmons and inhomogeneously broadened emitters.

Optically coupling quantum emitters to nanoparticles provides the foundation for many plasmonic applications. Including quantum mechanical effects within the calculations can be crucial for designing new devices, but classical approximations are sometimes sufficient. Comprehending how the classical and quantum mechanical descriptions of quantum emitters alter their calculated optical response will lead to a better understanding of how to design devices. Here, we describe how the semiclassical Maxwell-Liouville method can be used to calculate the optical response from inhomogeneously broadened states. After describing the Maxwell-Liouville algorithm, we use the method to study the photon echoes from quantum dots and compare the results against analytical models. We then modify the quantum dot's state distribution to match a PbS 850 nm quantum dot's absorption spectra to see how the complete quasi-band structure affects their coupling to gold nanoislands. Finally, we compare the results with previously published work to demonstrate where the complete quantum dot description is necessary.

Extreme cost of rivalry in a monandrous species: male-male interactions result in failure to acquire mates and reduced longevity.

Mating system variation is profound in animals. In insects, female willingness to remate varies from mating with hundreds of males (extreme polyandry) to never remating (monandry). This variation in female behaviour is predicted to affect the pattern of selection on males, with intense pre-copulatory sexual selection under monandry compared to a mix of pre- and post-copulatory forces affecting fitness under polyandry. We tested the hypothesis that differences in female mating biology would be reflected in different costs of pre-copulatory competition between males. We observed that exposure to rival males early in life was highly costly for males of a monandrous species, but had lower costs in the polyandrous species. Males from the monandrous species housed with competitors showed reduced ability to obtain a mate and decreased longevity. These effects were specific to exposure to rivals compared with other types of social interactions (heterospecific male and mated female) and were either absent or weaker in males of the polyandrous species. We conclude that males in monandrous species suffer severe physiological costs from interactions with rivals and note the significance of male-male interactions as a source of stress in laboratory culture.

Polymeric frustrated Lewis pairs in CO2/cyclic ether coupling catalysis.

Frustrated Lewis pairs (FLPs) are now ubiquitous as metal-free catalysts in an array of different chemical transformations. In this paper we show that this reactivity can be transferred to a polymeric system, offering advantageous opportunities at the interface between catalysis and stimuli-responsive materials. Formation of cyclic carbonates from cyclic ethers using CO2 as a C1 feedstock continues to be dominated by metal-based systems. When paired with a suitable nucleophile, discrete aryl or alkyl boranes have shown significant promise as metal-free Lewis acidic alternatives, although catalyst reuse remains illusive. Herein, we leverage the reactivity of FLPs in a polymeric system to promote CO2/cyclic ether coupling catalysis that can be tuned for the desired epoxide or oxetane substrate. Moreover, these macromolecular FLPs can be reused across multiple reaction cycles, further increasing their appeal over analogous small molecule systems.

The influence of maternal effects on indirect benefits associated with polyandry.

Despite numerous and diverse theoretical models for the indirect benefits of polyandry, empirical support is mixed. One reason for the difficulty in detecting indirect benefits of polyandry may be that these are subtle and are mediated by environmental effects, such as maternal effects. Maternal effects may be especially important if females allocate resources to their offspring depending on the characteristics of their mating partners. We test this hypothesis in the burying beetle Nicrophorus vespilloides, a species that provides extensive and direct parental care to offspring. We used a fully factorial design and mated females to one, two, three, four or five different males and manipulated conditions so that their offspring received reduced (12 h) or full (ca 72 h) maternal care. We found that average offspring fitness increased with full maternal care but there was no significant effect of polyandry or the interaction between the duration of maternal care and the level of polyandry on offspring fitness. Thus, although polyandry could provide a mechanism for biasing paternity towards high quality or compatible males, and variation in parental care matters, we found no evidence that female N. vespilloides gain indirect benefits by using parental care to bias the allocation of resources under different mating conditions.

Suction diathermy for adenoidectomy: complications and risk of recurrence.

OBJECTIVES: When introduced, suction coagulation was initially utilised for haemorrhage control following curettage of the adenoid pad. More recently the whole procedure has been performed using the technique. This study aims to report post-operative haemorrhage rates and risk of recurrence in adenoidectomy performed solely by suction diathermy in children. METHODS: A retrospective study of 1411 consecutive paediatric patients. Surgery was performed using suction diathermy. No patients were excluded. All patients were followed up. RESULTS: There were no cases of post-operative haemorrhage. 1.7% of patients remained symptomatic and underwent revision adenoidectomy. None required a third procedure. CONCLUSIONS: Re-growth of adenoid tissue may occur despite visualisation of the nasopharynx at the time of surgery. The incidence of re-growth is similar to that reported in patients undergoing conventional adenoidectomy by curettage. Post-operative haemorrhage was not encountered in children having adenoidectomy by suction diathermy. The authors suggest suction diathermy as the most appropriate method for adenoidectomy in children.

The nasopharyngeal prong airway: an effective post-operative adjunct after adenotonsillectomy for obstructive sleep apnoea in children.

OBJECTIVES: Obstructive sleep apnoea is a common childhood disorder. Adenotonsillar enlargement is most commonly implicated, with adenotonsillectomy representing an effective treatment in the majority of cases. Such children may develop respiratory compromise post-operatively, sometimes necessitating admission to the intensive care unit. We describe insertion of a nasopharyngeal "prong" airway and evaluate its benefits after adenotonsillectomy for obstructive sleep apnoea and milder forms of sleep-disordered breathing. METHODS: The prong is easily fashioned from a paediatric endotracheal tube. It is inserted once surgery is complete, remaining in situ overnight. We retrospectively examine its elective use over an 18-month period in selected children considered to be at high risk of post-operative respiratory compromise. Existing practice over the preceding 18-month period is also examined, by way of comparison. RESULTS: Forty-three children underwent adenotonsillectomy for sleep-disordered breathing/OSAS in the 18 months prior to introduction of the prong. Ten were considered "high risk" cases: post-operative intensive care beds were pre-booked for these, but none were eventually required. During the subsequent 18 months, 60 children underwent adenotonsillectomy for the same indication. Seventeen "high risk" cases received the prong post-operatively. No intensive care beds were pre-booked and all children were managed safely on the ENT ward, with minimal intervention. CONCLUSIONS: Use of a nasopharyngeal prong significantly improves the post-operative course of selected children who are at high risk of respiratory compromise after adenotonsillectomy. This largely avoids the need for medical intervention and intensive care admission.

Evaluation of Staphylococcus aureus Eradication Therapy in Vascular Surgery.

INTRODUCTION: Surgical site infections (SSI) are a serious complication in vascular surgery which may lead to severe morbidity and mortality. Staphylococcus aureus nasal carriage is associated with increased risk for development of SSIs in central vascular surgery. The risk for SSI can be reduced by perioperative eradication of S. aureus carriage in cardiothoracic and orthopedic surgery. This study analyzes the relation between S. aureus eradication therapy and SSI in a vascular surgery population. METHODS: A prospective cohort study was performed, including all patients undergoing vascular surgery between February 2013 and April 2015. Patients were screened for S. aureus nasal carriage and, when tested positive, were subsequently treated with eradication therapy. The presence of SSI was recorded based on criteria of the CDC. The control group consisted of a cohort of vascular surgery patients in 2010, who were screened, but received no treatment. RESULTS: A total of 444 patients were screened. 104 nasal swabs were positive for S. aureus, these patients were included in the intervention group. 204 patients were screened in the 2010 cohort. 51 tested positive and were included in the control group. The incidence of S. aureus infection was 5 out of 51 (9.8%) in the control group versus 3 out of 104 in the eradication group (2.2%; 95% confidence interval 0.02-1.39; P = 0.13). A subgroup analysis showed that the incidence of S. aureus infection was 3 out of 23 (13.0%) in the control group in central reconstructive surgery versus 0 out of 44 in the intervention group (P = 0.074). The reduction of infection pressure by S. aureus was stronger than the reduction of infection pressure by other pathogens (exact maximum likelihood estimation; OR = 0.0724; 95% CI: 0.001-0.98; p = 0.0475). CONCLUSION: S. aureus eradication therapy reduces the infection pressure of S. aureus, resulting in a reduction of SSIs caused by S. aureus.

Modern concepts of paediatric analgesia.

Laboratory data, economic pressures, and the wish for humane treatment have been some of the driving forces behind improvements in paediatric pain management. Within the space of 10 years, there have been dramatic changes in the quality of treatment received by children undergoing surgical operations. Moreover, those receiving medical treatment, for example, sickle cell disease, have also benefited from increased experience in pain management. Children receiving care in specialised centres can now expect to benefit from up-to-date techniques of pain management, such as patient-controlled analgesia, nurse-controlled analgesia, and epidural infusions. They will be managed by ward nurses experienced and trained in paediatric pain relief, they will be attended by nurses whose special interest and training is the management of children's pain, and they will be provided with the techniques of analgesia by competent, trained anaesthetic staff. Improved care, with close attention to pain relief, is not only humane, but improves the patient turnaround by enhancing rapid discharge. Further education is required to spread these benefits to children being managed outside highly specialised centres. Not only education, but investment, is needed also to ensure that all children receive a standard of care second to none.

Molecular determination of perivesical and lymph node metastasis after radical cystectomy for urothelial carcinoma of the bladder.

PURPOSE: Current methods used to determine the pathological stage of the primary tumor and associated lymphatics after radical cystectomy are tedious, costly, and may lack the sensitivity afforded by molecular approaches such as reverse transcription-PCR (RT-PCR) for markers specific for urothelial tissue such as the uroplakin II (UPII) gene. Thus, we sought to evaluate an objective and sensitive molecular approach for the assessment of perivesical extension and lymph node status after radical cystectomy, based on the detection of UPII expression using RT-PCR and compare this assay to standard clinical and pathological examination. EXPERIMENTAL DESIGN: From November 1999 to September 2000, 27 patients with clinical T(a)-T(3)N(0)M(0) urothelial bladder cancer underwent radical cystectomy, 19 (70%) of which also had pelvic lymphadenectomy. At the completion of cystectomy, systematic biopsies of the external surface of the bladder specimen as well as from the largest palpable lymph node found at lymphadenectomy were obtained for molecular analysis. RT-PCR analysis for UPII mRNA was carried out on these biopsy specimens, and results were compared with data obtained from conventional pathological examination. RESULTS: Pathologically organ-confined tumors had a 42% (5 of 12) incidence of positive signals in the perivesical tissues and 17% (1 of 7) in the lymph nodes. Corresponding percentages for pT(3a)N(0) and pT(3b)-T(4)N(0) lesions were 67% (4 of 6)/25% (1 of 4) and 67% (4 of 6)/33% (2 of 6), respectively. Overall, pathologically node-negative cancers had a perivesical positivity rate of 54% (13 of 24) and a lymph node positivity rate of 25% (4 of 16). All patients with pathologically positive nodes had positive UPII signals in the lymph node sample. CONCLUSIONS: This molecular assay aimed at assessing perivesical extension and lymph node status after radical cystectomy appears to identify patients that may harbor residual disease not appreciated by conventional histology. Larger studies with 5-7-year follow-up will be required to determine the prognostic significance of such molecular information.

Dyeing insects for behavioral assays: the mating behavior of anesthetized Drosophila.

Mating experiments using Drosophila have contributed greatly to the understanding of sexual selection and behavior. Experiments often require simple, easy and cheap methods to distinguish between individuals in a trial. A standard technique for this is CO2 anaesthesia and then labelling or wing clipping each fly. However, this is invasive and has been shown to affect behavior. Other techniques have used coloration to identify flies. This article presents a simple and non-invasive method for labelling Drosophila that allows them to be individually identified within experiments, using food coloring. This method is used in trials where two males compete to mate with a female. Dyeing allowed quick and easy identification. There was, however, some difference in the strength of the coloration across the three species tested. Data is presented showing the dye has a lower impact on mating behavior than CO2 in Drosophila melanogaster. The impact of CO2 anaesthesia is shown to depend on the species of Drosophila, with D. pseudoobscura and D. subobscura showing no impact, whereas D. melanogaster males had reduced mating success. The dye method presented is applicable to a wide range of experimental designs.

Coevolutionary dynamics of polyandry and sex-linked meiotic drive.

Segregation distorters located on sex chromosomes are predicted to sweep to fixation and cause extinction via a shortage of one sex, but in nature they are often found at low, stable frequencies. One potential resolution to this longstanding puzzle involves female multiple mating (polyandry). Because many meiotic drivers severely reduce the sperm competitive ability of their male carriers, females are predicted to evolve more frequent polyandry and thereby promote sperm competition when a meiotic driver invades. Consequently, the driving chromosome's relative fitness should decline, halting or reversing its spread. We used formal modeling to show that this initially appealing hypothesis cannot resolve the puzzle alone: other selective pressures (e.g., low fitness of drive homozygotes) are required to establish a stable meiotic drive polymorphism. However, polyandry and meiotic drive can strongly affect one another's frequency, and polyandrous populations may be resistant to the invasion of rare drive mutants.

Breast-feeding among women exposed to polybrominated biphenyls in Michigan.

In the early 1970s, the largest industrial accident in the United States resulted in widespread contamination of the food supply in Michigan with polybrominated biphenyls (PBBs). The chemical similarity of PBBs to compounds implicated as endocrine disruptors has raised the question of whether PBBs could affect the reproductive system. In the present analysis we examine the relation between serum measurements of PBBs and the frequency and duration of lactation. Persons who lived on or received food from farms exposed to PBBs were enrolled in a registry by the Michigan Department of Public Health. Female members of the cohort were invited to participate in a telephone survey of reproductive outcomes. The three outcomes of interest in the present analysis were a) the decision to breast-feed (yes/no); b) the duration, in months, of breast-feeding as the main source of nutrition; and c) the total duration, in months, of breast-feeding. None of the three outcomes was significantly associated with serum PBB levels, even after controlling for maternal age, previous history of breast-feeding, body mass index, maternal education, household income, history of smoking in the year before pregnancy, consumption of alcohol during the first trimester of pregnancy, history of thyroid disorder, gestational age of the infant in weeks, time to pregnancy, and year of birth.