Classification of dark solitons via topological vector potentials

Dark solitons are some of the most interesting nonlinear excitations and are considered to be the one-dimensional topological analogs of vortices. However, in contrast to their two-dimensional vortex counterparts, the topological characteristics of a dark soliton are far from fully understood because the topological charge defined according to the phase jump cannot reflect its essential property. Here, similar to the complex extension used in the exploration of the partition-function zeros to depict thermodynamic states, we extend the complex coordinate space to explore the density zeros of dark solitons. Surprisingly we find that these zeros constitute some pointlike magnetic fields, each of which has a quantized magnetic flux of elementary π. The corresponding vector potential fields demonstrate the topology of the Wess-Zumino term and can depict the essential characteristics of dark solitons. Then we classify the dark solitons according to the Euler characteristic of the topological manifold of the vector potential fields. Our study not only reveals the topological features of dark solitons but can also be applied to explore and identify new dark solitons with high topological complexity.

Consolidation With Pembrolizumab and Nab-Paclitaxel After Induction Platinum-Based Chemotherapy for Advanced Non-Small Cell Lung Cancer

Background

Induction with four cycles of platinum-based chemotherapy was the standard of care for metastatic non-small cell lung cancer (NSCLC) until the approval of immune checkpoint blockade (ICB) in the first-line setting. Switch maintenance therapy has shown promise in improving survival by exposing patients to novel, non-cross–resistant agents earlier in their treatment course.

Methods

We performed this open-label, three-arm, randomized phase II study (NCT02684461) to evaluate three sequences of consolidation with pembrolizumab and nab-paclitaxel in patients without progressive disease post induction chemotherapy. Consolidation was either sequential with pembrolizumab for four cycles followed by nab-paclitaxel for four cycles (P→A), nab-paclitaxel followed by pembrolizumab (A→P), or concurrent nab-paclitaxel and pembrolizumab for four cycles (AP).

Results

Twenty patients were randomized before the study was closed early due to the approval of first-line checkpoint inhibitors. We found that consolidation is feasible and well tolerated, with 30% of patients experiencing grade 3 toxicity. The median progression-free survival and OS in months (95% CI) in P→A were 10.1 (1.5–NR), 27.6 (1.7–NR); 8.4 (1.2–9.0), 12.7 (4.4–NR) in A→P; and 10.2 (5.1–NR), NR. Quality of life as measured by FACT-L improved in the majority of patients during the course of the study.

Conclusion

Sequential and concurrent consolidation regimens are well tolerated and have encouraging overall survival in patients with metastatic NSCLC.

Conditions stimulating neutral detergent fiber degradation by dosing branched-chain volatile fatty acids. I: Comparison with branched-chain amino acids and forage source in ruminal batch cultures

Three experiments assessed branched-chain volatile fatty acid (BCVFA) stimulation of neutral detergent fiber (NDF) disappearance after 24 h of incubation in batch cultures derived from ruminal fluid inocula that were enriched with particulate-phase bacteria. In experiment 1, a control was compared with 3 treatments with isomolar doses of all 3 BCVFA (plus valerate), all 3 branched-chain AA (BCAA), or half of each BCVFA and BCAA mix with either alfalfa or grass hays (50%) and ground corn grain (50%). A portion of the BCAA and BCVFA doses were enriched with ¹³C, and valerate (also enriched with ¹³C) was added with BCVFA. Although BCAA yielded a similar production of BCVFA compared with dosing BCVFA, equimolar substitution of BCVFA for BCAA decreased the percentage of N in bacterial pellets when alfalfa hay was fed but increased N when grass hay was fed. Substituting BCVFA for BCAA increased total fatty acid (FA) concentration with alfalfa hay. Dosing of BCAA or BCVFA did not affect total branched-chain FA, iso-FA, or anteiso-FA percentages in bacterial total FA, whereas numerous individual FA isomers and their ¹³C enrichments were affected by these treatments. Increasing recovery of the ¹³C dose from respective labeled BCVFA primers indicated facilitated BCVFA uptake and incorporation into FA compared with BCAA, whereas increased recovery of ¹³C from labeled BCAA in the bacteria pellet but not in the FA fraction suggested direct assimilation into bacterial protein. The BCVFA and valerate were dosed in varying combinations that either summed to 4 mM (experiment 2) or had only 1 mM no matter what combination (experiment 3). In general, grass hay was more responsive to stimulation in NDF digestibility by BCVFA than was alfalfa hay, which was attributed to the higher degradable protein in the latter. The net production of the BCVFA (after subtracting dose) was affected by source and combination of BCVFA. Isovalerate dosing tended to increase its own net production; in contrast, isobutyrate seemed to be used more when it was added alone, but 2-methylbutyrate seemed to be preferred over isobutyrate when 2-methylbutyrate was added. Results supported potential interactions, including potential feedback in production from feed BCAA or increased concentration-dependent competition for dosed BCVFA into cellular products. Under our conditions, the BCVFA appear to be more readily available than BCAA, probably because of regulated BCAA transport and metabolism. Valerate consistently provided no benefit. Using nonparametric ranking, all 3 BCVFA or either isovalerate or isobutyrate (both yielding iso-FA) should be combined with 2-methylbutyrate (yielding anteiso-FA) as a potential opportunity to improve NDF digestibility when rumen-degraded BCAA are limited in diets to decrease environmental impact from N in waste.

Relationship between urinary energy and urinary nitrogen or carbon excretion in lactating Jersey cows

Measurement of urinary energy (UE) excretion is essential to determine metabolizable energy (ME) supply. Our objectives were to evaluate the accuracy of using urinary N (UN) or C (UC) to estimate UE and ultimately improve the accuracy of estimating ME. Individual animal data (n = 433) were used from 11 studies with Jersey cows at the University of Nebraska-Lincoln, where samples were analyzed after drying (n = 299) or on an as-is basis (n = 134). Dried samples resulted in greater estimated error variance compared with as-is samples, and thus only as-is samples were used for final models. The as-is data set included a range (min to max) in dry matter intake (11.6-24.6 kg/d), N intake (282-642 g/d), UE excretion (1,390-3,160 kcal/d), UN excretion (85-220 g/d or 20.6-59.5% of N intake), and UC excretion (130-273 g/d). As indicated by a bias in residuals between observed and predicted ME as dietary crude protein (CP; range of 14.9-19.1%) increased, the National Research Council dairy model did not accurately predict ME of diets, as dietary CP varied. The relationship between UE (kcal/d) and UN (g/d) excretion was linear and had an intercept of 880 ± 140 kcal. Because an intercept of 880 is biologically unlikely, the intercept was forced through 0, resulting in linear and quadratic relationships. The regressions of UE (kcal/d) on UN (g/d) excretion were UE = 14.6 ± 0.32 × UN, and UE = 20.9 ± 1.0 × UN - 0.0357 ± 0.0056 × UN². In the quadratic regression, UE increased, but at a diminishing rate as UN excretion increased. As UC increased, UE linearly and quadratically increased. However, error variance was greater for regression with UC compared with UN as explanatory variables (8.42 vs. 7.42% of mean UE). The use of the quadratic regression between UN and UE excretion to predict ME resulted in a slope bias in ME predictions as dietary CP increased. The linear regression between UE and UN excretion removed slope bias between predicted ME and CP, and thus may be more appropriate for predicting UE across a wider range of dietary CP. Using equations to predict UE from UN should improve our ability to predict diet ME in Jersey cows compared with calculating ME directly from digestible energy.

Self-care research: How to grow the evidence base? (reprint)

BACKGROUND AND OBJECTIVE

The number of studies in the area of self-care is growing and international researchers are increasingly developing self-care interventions to improve outcomes of individual patients and communities. However, growth of the evidence is still slow due to challenges with designing and testing self-care interventions. In this article we address major methodological challenges with regard to the definition of self-care, use of theory, and research design, intended to provide guidance to researchers in this field.

METHOD

During the inaugural conference of the International Center for Self-Care Research held in Rome, Italy in June 2019 we identified important issues in existing self-care research. Discussion and literature review lead to eight recommendation for future self-care research.

RESULTS

In preparation, begin with a theoretically sound definition of self-care. In planning the intervention, build on and extend previous studies. Use theory to develop self-care interventions and consider translational models to guide development, evaluation and implementation of complex self-care interventions. Employ a study design that fits the current phase and objectives of the research and measure self-care and related factors carefully. In reporting, describe the sample and setting sufficiently so that others can draw conclusions about generalizability and applicability to their practice and patient population. In interpretation, describe how the intervention is assumed to work (causal assumptions) and its key components.

CONCLUSION

Our review of existing self-care research clearly illustrates that the recommendations we provide are needed if we are to substantially grow the evidence base supporting self-care. Embracing a core set of principles will allow us to build on each other's work. Tweetable abstract: A core set of methodological principles is needed to substantially grow the evidence base supporting self-care.

MULTIPHYSICS MODELING OF PRECURSORS IN MOLTEN SALT FAST REACTORS USING PROTEUS AND Nek5000

The goal of this work was to calculate the impact of the delayed neutron precursor drift in fast spectrum Molten Salt Reactors (MSRs) using coupled solutions from the neutronics code PROTEUS and the computational fluid dynamics code Nek5000. Specifically, using a multiphysics approach to solve the effective delayed neutron fraction (βeff) or delayed neutron precursor distribution for reactors with flowing fuel salts would provide valuable information for transient simulations and safety assessments. Given the multiple options for the flux solution and geometric resolution/fidelity in PROTEUS, two approaches were developed and applied to various test cases: PROTEUS-NODAL/Nek5000 and PROTEUS-SN/Nek5000. For the former, the precursors are tracked in the built-in precursor drift model in PROTEUS-NODAL, whereas in the latter, Nek5000 directly tracks the precursors. Both approaches were used to solve a single test channel problem and showed excellent agreement in the calculated βeff. Separately, a 3D hourglass-shaped core was modeled using the PROTEUS-SN/Nek5000 approach. This problem was designed to demonstrate the capability of the discrete ordinates (SN) solver and Nek5000 to model complex core designs with axially varying geometries and the ability for Nek5000 to track the precursors and calculate the resulting βeff. In addition, the Nek5000 calculations revealed the presence of recirculation zones in the hourglass design, which could lead to significant temperatures in the fuel salt and surrounding materials. These first coupled solutions show why these approaches may be necessary for not only predicting the precursor drift effect in fast MSRs but also for reactor design and performance assessments.

The application of virtual fencing technology effectively herds cattle and sheep

Context Herding and mustering procedures during livestock management can be time-consuming, labour intensive, and costly. The ability to gather animals virtually is an enticing notion but technology to do this is not widely commercially available. Aims The eShepherd® virtual fencing system being developed for cattle may be able to remotely herd animals. This system operates via global positioning system, and requires animals to wear a neckband device. Animals are trained to associate an audio tone with an electrical pulse to avoid a virtual boundary. Methods Experiments were conducted with cattle using pre-commercial prototypes of the automated virtual fencing neckbands, and with sheep using manually operated dog training collars implementing the same virtual fencing algorithm to explore the potential of this technology for herding, and optimal fence designs for herding success. In the first experiment, five groups of 12 cattle were moved down a 344 m paddock using three different fence placement designs. Results The most successful design for cattle herding was a back fence that followed behind the animals to prevent them from turning back in the wrong direction. The fences were manually activated by personnel based on the cattle movement. The same type of fence design was manually applied to two groups of six sheep to successfully herd them down a 140 m paddock in the second experiment. Conclusions All herding was highly dependent on the animal’s own pace of movement as no signals were applied to ‘push’ the animals, the systems only prevented movement back in the wrong direction. The pre-commercial prototype of the automated eShepherd® device used is now obsolete and testing with updated versions would be needed to confirm its application for animal herding. Implications These preliminary trials indicate potential for virtual fencing technology to herd livestock, but technology improvements are required, and an automated device for sheep is not yet available.

Effects of diet fermentability and supplementation of 2-hydroxy-4-(methylthio)-butanoic acid and isoacids on milk fat depression: 2. Ruminal fermentation, fatty acid, and bacterial community structure

The experiment was conducted to understand ruminal effects of diet modification during moderate milk fat depression (MFD) and ruminal effects of 2-hydroxy-4-(methylthio)-butanoic acid (HMTBa) and isoacids on alleviating MFD. Five ruminally cannulated cows were used in a 5 × 5 Latin square design with the following 5 dietary treatments (dry matter basis): a high-forage and low-starch control diet with 1.5% safflower oil (HF-C); a low-forage and high-starch control diet with 1.5% safflower oil (LF-C); the LF-C diet supplemented with HMTBa (0.11%; 28 g/d; LF-HMTBa); the LF-C diet supplemented with isoacids [(IA) 0.24%; 60 g/d; LF-IA]; and the LF-C diet supplemented with HMTBa and IA (LF-COMB). The experiment consisted of 5 periods with 21 d per period (14-d diet adaptation and 7-d sampling). Ruminal samples were collected to determine fermentation characteristics (0, 1, 3, and 6 h after feeding), long-chain fatty acid (FA) profile (6 h after feeding), and bacterial community structure by analyzing 16S gene amplicon sequences (3 h after feeding). Data were analyzed using the MIXED procedure of SAS (SAS Institute Inc., Cary, NC) in a Latin square design. Preplanned comparisons between HF-C and LF-C were conducted, and the main effects of HMTBa and IA and their interaction within the LF diets were examined. The LF-C diet decreased ruminal pH and the ratio of acetate to propionate, with no major changes detected in ruminal FA profile compared with HF-C. The α-diversity for LF-C was lower compared with HF-C, and β-diversity also differed between LF-C and HF-C. The relative abundance of bacterial phyla and genera associated indirectly with fiber degradation was influenced by LF-C versus HF-C. As the main effect of HMTBa within the LF diets, HMTBa increased the ratio of acetate to propionate and butyrate molar proportion. Ruminal saturated FA were increased and unsaturated FA concentration were decreased by HMTBa, with minimal changes detected in ruminal bacterial diversity and community. As the main effect of IA, IA supplementation increased ruminal concentration of all branched-chain volatile FA and valerate and increased the percentage of trans-10 C18 isomers in total FA. In addition, α-diversity and the number of functional features were increased for IA. Changes in the abundances of bacterial phyla and genera were minimal for IA. Interactions between HMTBa and IA were observed for ruminal variables and some bacterial taxa abundances. In conclusion, increasing diet fermentability (LF-C vs. HF-C) influenced rumen fermentation and bacterial community structure without major changes in FA profile. Supplementation of HMTBa increased biohydrogenation capacity, and supplemental IA increased bacterial diversity, possibly alleviating MFD. The combination of HMTBa and IA had no associative effects in the rumen and need further studies to understand the interactive mechanism.

Effects of diet fermentability and supplementation of 2-hydroxy-4-(methylthio)-butanoic acid and isoacids on milk fat depression: 1. Production, milk fatty acid profile, and nutrient digestibility

The objectives of this experiment were to determine the effects of increased diet fermentability and polyunsaturated fatty acids (FA) with or without supplemental 2-hydroxy-4-(methylthio)-butanoic acid (HMTBa), isoacids (IA; isobutyrate, 2-methylbutyrate, isovalerate, and valerate) or the combination of these on milk fat depression (MFD). Ten Holstein cows (194 ± 58 DIM, 691 ± 69 kg BW, 28 ± 5 kg milk yield) were used in a replicated 5 × 5 Latin square design. Treatments included a high-forage control diet (HF-C), a low-forage control diet (LF-C) causing MFD by increasing starch and decreasing neutral detergent fiber (NDF), the LF-C diet supplemented with HMTBa at 0.11% (28 g/d), the LF-C diet supplemented with IA at 0.24% of dietary dry matter (60 g/d), and the LF-C diet supplemented with HMTBa and IA. Preplanned contrasts were used to compare HF-C versus LF-C and to examine the main effects of HMTBa or IA and their interactions within the LF diets. Dry matter intake was greater for LF-C versus HF-C, but milk yield remained unchanged. The LF-C diet decreased milk fat yield (0.87 vs. 0.98 kg/d) but increased protein yield compared with HF-C. As a result, energy-corrected milk was lower (28.5 vs. 29.6 kg/d) for LF-C versus HF-C. Although the concentration of total de novo synthesized FA in milk fat was not affected, some short- and medium-chain FA were lower for LF-C versus HF-C, but the concentrations of C18 trans-10 isomers were not different. Total-tract NDF apparent digestibility was numerically lower (42.4 vs. 45.6%) for LF-C versus HF-C. As the main effects, the decrease in milk fat yield observed in LF-C was alleviated by supplementation of HMTBa through increasing milk yield without altering milk fat content and by IA through increasing milk fat content without altering milk yield so that HMTBa or IA, as the main effects, increased milk fat yield within the LF diets. However, interactions for milk fat yield and ECM were observed between HMTBa and IA, suggesting no additive effect when used in combination. Minimal changes were found on milk FA profile when HMTBa was provided. However, de novo synthesized FA increased for IA supplementation. We detected no main effect of HMTBa, IA, and interaction between those on total-tract NDF digestibility. In conclusion, the addition of HMTBa and IA to a low-forage and high-starch diet alleviated moderate MFD. Although the mechanism by which MFD was alleviated was different between HMTBa and IA, no additive effects of the combination were observed on milk fat yield and ECM.

3D wide-field multispectral photoacoustic imaging of human melanomas in vivo: a pilot study

BACKGROUND

The Breslow depth is an important parameter to determine the excision margin and prognosis of melanoma. However, it is difficult to accurately determine the actual Breslow depth before surgery using the existing ocular micrometer and biopsy technique.

OBJECTIVES

To evaluate the use of 3D wide-field multispectral photoacoustic imaging to non-invasively measure depth and outline the boundary of melanomas for optimal surgical margin selection.

METHODS

Six melanoma patients were examined in vivo using the 3D multispectral photoacoustic imaging system. For five cases of melanomas (one in situ, three nodular, and one acral lentiginous type melanoma), the spectrally unmixed photoacoustic depths were calculated and compared against histopathological depths.

RESULTS

Spectrally unmixed photoacoustic depths and histopathological depths match well within a mean absolute error of 0.36 mm. In particular, the measured minimum and maximum depths in the in situ and nodular type of melanoma were 0.6 and 9.1 mm, respectively. In the 3D photoacoustic image of one metastatic melanoma, feeding vessels were visualized in the melanoma, suggesting the neovascularization around the tumour.

CONCLUSIONS

The 3D multispectral photoacoustic imaging not only provides well-measured depth and sizes of various types of melanomas, it also visualizes the metastatic type of melanoma. Obtaining accurate depth and boundary information of melanoma before surgery would play a useful role in the complete excision of melanoma during surgery.

Clinical Trial Metrics: The Complexity of Conducting Clinical Trials in North American Cancer Centers

Cancer clinical trials offices (CTOs) support the investigation of cancer prevention, early detection, and treatment at cancer centers across North America. CTOs are a centralized resource for clinical trial conduct and typically use research staff with expertise in four functional areas of clinical research: finance, regulatory, clinical, and data operations. To our knowledge, there are no publicly available benchmark data sets that characterize the size, cost, volume, and efficiency of these offices, nor whether the metrics differ by National Cancer Institute (NCI) designation. The Association of American Cancer Institutes (AACI) Clinical Research Innovation (CRI) steering committee developed a survey to address this knowledge gap.

Men who live alone have high risk of NOAC discontinuation

Background/Introduction

Patients with atrial fibrillation (AF), who are considered at risk of stroke, are treated with oral anticoagulants (OACs), and non-vitamin K antagonist oral anticoagulants (NOACs) are preferred over vitamin K antagonists in recent guidelines. Poor NOAC compliance among patients with AF could result in an increased risk of thromboembolism and major bleeding, however, it has yet to be evaluated how cohabitant status and gender affects compliance with NOAC treatment among patients with AF.

Purpose

The aim of this study was to evaluate the risk of NOAC discontinuation among patients with AF according to cohabitant status and gender.

Methods

Using the Danish national registries we identified and included patients with AF aged 40–90 years in treatment with NOAC. The study period was from 2013 to 2017, and patients were followed for two years, or until death, outcome or emigration. The main outcome was discontinuation of NOAC-treatment for at least 30 days. Absolute risks were calculated as cumulative incidences using the Aalen Johansen estimator, and multiple covariate adjusted Cox regressions were used to calculate hazard ratios (HR).

Results

We included 32,380 patients with AF in NOAC treatment, where 16.8% were men living alone (median age 72 years), 25.8% were women living alone (median age 79 years), 37.2% were men living with a partner (median age 70 years), and 20.2% were women living with a partner (median age 79 years). Absolute two-year risk of NOAC discontinuation was highest among men living alone (Cumulative Incidence (CI) 0.19; 95% CI: 0.17 to 0.20), followed by men living with a partner (CI 0.18; 0.17 to 0.19), women living with a partner (CI 0.16; 0.15 to 0.17), and women living alone (CI 0.13; 0.12 to 0.14). After adjustment, living alone was associated with an increased risk of NOAC discontinuation among men (HR 1.15, 95% CI: 1.05 to 1.26), but not among women (HR 1.04, 95% CI: 0.93 to 1.15, interaction p=0.32). In an analysis evaluating gender, we found that being male was associated with a significantly higher risk of NOAC-discontinuation (HR 1.18, CI: 1.10 to 1.25) compared to women.

Results were similar when we used 60 days discontinuation instead of 30 days discontinuation as outcome.

Conclusion

Gender and cohabitant status was significantly associated with risk of NOAC discontinuation. Male gender and living alone was associated with a higher risk of NOAC discontinuation among patients with AF in a nationwide population.

Adjusted relative two-year risks

Funding Acknowledgement

Type of funding source: None