Universal Features of Entanglement Entropy in the Honeycomb Hubbard Model.

The entanglement entropy is a unique probe to reveal universal features of strongly interacting many-body systems. In two or more dimensions these features are subtle, and detecting them numerically requires extreme precision, a notoriously difficult task. This is especially challenging in models of interacting fermions, where many such universal features have yet to be observed. In this Letter we tackle this challenge by introducing a new method to compute the Rényi entanglement entropy in auxiliary-field quantum Monte Carlo simulations, where we treat the entangling region itself as a stochastic variable. We demonstrate the efficiency of this method by extracting, for the first time, universal subleading logarithmic terms in a two-dimensional model of interacting fermions, focusing on the half-filled honeycomb Hubbard model at T=0. We detect the universal corner contribution due to gapless fermions throughout the Dirac semi-metal phase and at the Gross-Neveu-Yukawa critical point, where the latter shows a pronounced enhancement depending on the type of entangling cut. Finally, we observe the universal Goldstone mode contribution in the antiferromagnetic Mott insulating phase.

Odd Nonlinear Conductivity under Spatial Inversion in Chiral Tellurium.

Electrical transport in noncentrosymmetric materials departs from the well-established phenomenological Ohm's law. Instead of a linear relation between current and electric field, a nonlinear conductivity emerges along specific crystallographic directions. This nonlinear transport is fundamentally related to the lack of spatial inversion symmetry. However, the experimental implications of an inversion symmetry operation on the nonlinear conductivity remain to be explored. Here, we report on a large, nonlinear conductivity in chiral tellurium. By measuring samples with opposite handedness, we demonstrate that the nonlinear transport is odd under spatial inversion. Furthermore, by applying an electrostatic gate, we modulate the nonlinear output by a factor of 300, reaching the highest reported value excluding engineered heterostructures. Our results establish chiral tellurium as an ideal compound not just to study the fundamental interplay between crystal structure, symmetry operations and nonlinear transport; but also to develop wireless rectifiers and energy-harvesting chiral devices.

Quasi-One-Dimensional Transition-Metal Chalcogenide Semiconductor (Nb4Se15I2)I2.

The discovery of new low-dimensional transition-metal chalcogenides is contributing to the already prosperous family of these materials. In this study, needle-shaped single crystals of a quasi-one-dimensional (1D) material, (Nb4Se15I2)I2, were grown by chemical vapor transport, and the structure was solved by single-crystal X-ray diffraction (XRD). The structure has 1D (Nb4Se15I2)n chains along the [101] direction, with two I- ions per formula unit directly bonded to Nb5+. The other two I- ions are loosely coordinated and intercalated between the chains. Individual chains are chiral and stack along the b axis in opposing directions, giving space group P21/c. The phase purity and crystal structure were verified by powder XRD. Density functional theory calculations show (Nb4Se15I2)I2 to be a semiconductor with a direct band gap of around 0.6 eV. Resistivity measurements of bulk crystals and micropatterned devices demonstrate that (Nb4Se15I2)I2 has an activation energy of around 0.1 eV, and no anomaly or transition was seen upon cooling. Low-temperature XRD shows that (Nb4Se15I2)I2 does not undergo a structural phase transformation from room temperature to 8.2 K, unlike related compounds (NbSe4)nI (n = 2, 3, or 3.33), which all exhibit charge-density waves. This compound represents a well-characterized and valence-precise member of a diverse family of anisotropic transition-metal chalcogenides.

Influence of Preoperative Educational Intervention for Patients Undergoing Fecal Ostomy Surgery: A Comparison Cohort Study.

PURPOSE: This aim of this study was to compare the impact on hospital stay and short-term overall complications prior to and following the introduction of an outpatient preoperative ostomy education program to an existing inpatient ostomy education program. DESIGN: A comparison cohort study. SUBJECTS AND SETTING: One hundred thirty-eight consecutive patients undergoing ostomy surgery were included. One group (n = 65, 47%) was given an experimental preoperative ostomy education intervention, along with standard care including a postoperative educational intervention during the initial hospital course. A second group (n = 73, 53%) received the same standardized education in the postoperative period. Data were collected from a single tertiary center located in Seville, Spain, during a 12-month period between July 2014 and June 2015. METHODS: Data were collected in 2 phases. Data from participants undergoing postoperative (standard) education were collected retrospectively. Data for the group receiving preoperative education were collective prospectively. Outcome variables were postoperative length of stay, surgical complications (severity was assessed by the Clavien-Dindo grading system), subsequent interventions, and readmission rates. RESULTS: Analysis indicated no differences between the average length of postoperative hospital stay (12.32 days in the preoperative education group vs 12.76 days in the postoperative education group, P = .401). In contrast, overall complications, mortality, and readmission rates were significantly higher in the preoperative education program group (P = .027, P = .047, and P = .046, respectively). CONCLUSIONS: Delivering a standardized educational intervention during the preoperative period versus postoperative education delivery during the ostomy surgery hospital course did not reduce length of stay. Analysis indicated that overall complications, mortality, and readmission rates were significantly higher in the preoperative education program group but we hypothesize that intervening factors may have influenced these outcomes.

Clostridium septicum endophthalmitis as the first manifestation of a colon adenocarcinoma: A case report.

Clostridium septicum endophthalmitis is an extremely rare infection with only a few cases reported in the literature. It has an endogenous origin and is associated with gastrointestinal and haematological malignancies. We present the case of a 62-year-old male who presented this infection as the first manifestation of a colon adenocarcinoma.

Large Multidirectional Spin-to-Charge Conversion in Low-Symmetry Semimetal MoTe2 at Room Temperature.

Efficient and versatile spin-to-charge current conversion is crucial for the development of spintronic applications, which strongly rely on the ability to electrically generate and detect spin currents. In this context, the spin Hall effect has been widely studied in heavy metals with strong spin-orbit coupling. While the high crystal symmetry in these materials limits the conversion to the orthogonal configuration, unusual configurations are expected in low-symmetry transition-metal dichalcogenide semimetals, which could add flexibility to the electrical injection and detection of pure spin currents. Here, we report the observation of spin-to-charge conversion in MoTe2 flakes, which are stacked in graphene lateral spin valves. We detect two distinct contributions arising from the conversion of two different spin orientations. In addition to the conventional conversion where the spin polarization is orthogonal to the charge current, we also detect a conversion where the spin polarization and the charge current are parallel. Both contributions, which could arise either from bulk spin Hall effect or surface Edelstein effect, show large efficiencies comparable to the best spin Hall metals and topological insulators. Our finding enables the simultaneous conversion of spin currents with any in-plane spin polarization in one single experimental configuration.

A Tetra-Panel of Serum Circulating miRNAs for the Diagnosis of the Four Most Prevalent Tumor Types.

The purpose of this study is to clinically validate a series of circulating miRNAs that distinguish between the 4 most prevalent tumor types (lung cancer (LC); breast cancer (BC); colorectal cancer (CRC); and prostate cancer (PCa)) and healthy donors (HDs). A total of 18 miRNAs and 3 housekeeping miRNA genes were evaluated by qRT-PCR on RNA extracted from serum of cancer patients, 44 LC, 45 BC, 27 CRC, and 40 PCa, and on 45 HDs. The cancer detection performance of the miRNA expression levels was evaluated by studying the area under the curve (AUC) of receiver operating characteristic (ROC) curves at univariate and multivariate levels. miR-21 was significantly overexpressed in all cancer types compared with HDs, with accuracy of 67.5% (p = 0.001) for all 4 tumor types and of 80.8% (p < 0.0001) when PCa cases were removed from the analysis. For each tumor type, a panel of miRNAs was defined that provided cancer-detection accuracies of 91%, 94%, 89%, and 77%, respectively. In conclusion, we have described a series of circulating miRNAs that define different tumor types with a very high diagnostic performance. These panels of miRNAs would constitute the basis of different approaches of cancer-detection systems for which clinical utility should be validated in prospective cohorts.

[Impact of the pandemic on surgical activity in colorectal cancer in Spain. Results of a national survey]. / Impacto de la pandemia sobre la actividad quirúrgica en cáncer colorrectal en España. Resultados de una encuesta nacional.

INTRODUCTION: The pandemic has had an impact on colorectal cancer surgery in hospitals. In 2020, up to 75% of colorectal cancer patients are estimated to require surgery. No objective data on the impact of the pandemic on the management of surgical waiting lists is available. We conducted a survey in colorectal surgery units to assess the impact on colorectal cancer surgery waiting lists. METHOD: All personnel in charge of colorectal surgery units nationwide received a survey (from February to April, 2020) with eight questions divided into three sections-cessation date of colorectal cancer surgeries, number of patients waiting for treatment, and use of neoadjuvant therapy to postpone surgery. RESULTS: Sixty-seven units participated in the study, with 79.1% of units ceasing some type of activity (32.8% total and 46.3% partial cessation) and 20.9% continuing all surgical activity. In addition, 65% of units used or prolonged neoadjuvant therapy in rectal cancer patients and 40% of units performed at least five emergency colorectal cancer surgeries. It was estimated that at least one month of intense surgical activity will be required to catch up. CONCLUSIONS: Currently, patients from units with a long waiting list must be redistributed, at least within the country. In the future, in the event of a second wave of the pandemic, an effective program to manage each unit's resources should be developed to prevent total collapse.

C reactive protein as a predictor of anastomotic leakage in colorectal surgery. Comparison between open and laparoscopic surgery. / Proteína C reactiva como predictor de fuga anastomótica en cirugía colorrectal. Comparación entre cirugía abierta y laparoscópica.

INTRODUCTION: Anastomotic leak (AL) is a serious complication in colorectal surgery due to its increase in morbidity and mortality. The aim of this prospective non-randomised study is to determine whether C-reactive Protein (CRP) is useful as a predictor of AL in patients undergoing open versus laparoscopic surgery. METHODS: A total of 168 patients undergoing elective colorectal surgery were included. CRP was measured daily during the first 5postoperative days. Complications, specially AL, were analysed. RESULTS: Following an open approach 32 patients (45.7%) presented complications, 15 (18.7%) in the laparoscopic group and 12 (29.4%) in the converted group (P=0.153). Following open surgery 9 patients experienced AL, 5 were detected in the laparoscopic group and none in those converted (P=0.153). There were significant differences in CRP values between the 3 groups (P=0.03). ROC Curves showed AUC for the open and laparoscopic approach of 0.731 and 0.760 respectively. On day 4 the AUC was 0.867 for the open group and 0.914 for the laparoscopic group. Cut-off points on day 4 were: Open: 159.2mg/L; sensitivity 75%, specificity 89% and NPP 96% (P<0.001). Following laparoscopic surgery the cut-off point was 67.3%; sensitivity 100%, specificity 89.5% and NPP 100% (P=0.016). CONCLUSION: CRP on day 4 is useful to diagnose AL. Different cut-off values should be taken into account depending on the approach used.

Sprue-like enteropathy associated with olmesartan in a patient with villous atrophy, HLA-DQ2 genotype and antinuclear antibodies.

We describe a new case of enteropathy with villous atrophy in a patient suffering from arterial hypertension treated with olmesartan. The molecular and serological studies showed anti-nuclear antibodies (ANA) and haplotype HLA-DQ2 positive, as well as negative results for anti-transglutaminase, anti-endomysium and anti-enterocytes antibodies. A duodenal villous atrophy was suspected by upper gastrointestinal endoscopy, which was confirmed by histopathology. The morphological picture was suggestive of sprue-like enteropathy with severe lymphoid infiltration and predominant T lymphoid cells.

[Histological factors predicting loco-regional lymph node metastasis in early invasive colorectal adenocarcinoma pT1]. / Estudio de factores histológicos predictivos de metástasis ganglionar locorregional en adenocarcinoma colorrectal mínimamente invasivo pT1.

INTRODUCTION: Endoscopic resection is the common treatment in pT1 colorectal adenocarcinoma whenever possible. The presence of adverse histological factors requires subsequent lymph node evaluation. MATERIALS AND METHODS: We selected 29 colorectal pT1 adenocarcinoma including endoscopic polypectomies and the corresponding surgical specimens. All histologic parameters associated with N+ were evaluated by 2 pathologists, including: tumor differentiation grade, depth of invasion in the submucosa, angiolymphatic invasion (ALI), perineural invasion, chronic inflammation, tumor budding, poorly differentiated cluster, pre-existing adenoma, tumor border, and endoscopic resection margin. Univariate and multivariate logistic regression analysis were performed to assess the individual capacity of each variable to predict N+. RESULTS: In the univariate analysis, rectal tumor localization, ALI and poorly differentiated cluster was significantly associated with N+. Among the significant parameters, ALI had the highest area under the ROC curve (0.875). Multivariate analysis showed no independent variables associated with N+. CONCLUSIONS: We confirm that ALI and the presence of poorly differentiated cluster are frequently associated with N+ in early colorectal cancer. Consequently, these parameters should be routinely evaluated by pathologists.

Spin-Based Mach-Zehnder Interferometry in Topological Insulator p-n Junctions.

Transport in three-dimensional topological insulators relies on the existence of a spin-momentum locked surface state that encloses the insulating bulk. In this work we show how, in a topological insulator p-n junction, a magnetic field turns this surface state into an electronic Mach-Zehnder interferometer. Transmission of the junction can be tuned from zero to unity, resulting in virtually perfect visibility of the interference pattern, and the reflected and transmitted currents carry opposite spin polarization so that the junction also acts as a spin filter. Our setup therefore realizes a novel and highly tunable spintronic device where the effects of spin-momentum locking in topological insulator surface states can be probed directly in a transport experiment.

Emergence of an Out-of-Plane Optical Phonon (ZO) Kohn Anomaly in Quasifreestanding Epitaxial Graphene.

In neutral graphene, two prominent cusps known as Kohn anomalies are found in the phonon dispersion of the highest optical phonon at q=Γ (LO branch) and q=K (TO branch), reflecting a significant electron-phonon coupling (EPC) to undoped Dirac electrons. In this work, high-resolution electron energy loss spectroscopy is used to measure the phonon dispersion around the Γ point in quasifreestanding graphene epitaxially grown on Pt(111). The Kohn anomaly for the LO phonon is observed at finite momentum q~2k_{F} from Γ, with a shape in excellent agreement with the theory and consistent with known values of the EPC and the Fermi level. More strikingly, we also observe a Kohn anomaly at the same momentum for the out-of-plane optical phonon (ZO) branch. This observation is the first direct evidence of the coupling of the ZO mode with Dirac electrons, which is forbidden for freestanding graphene but becomes allowed in the presence of a substrate. Moreover, we estimate the EPC to be even greater than that of the LO mode, making graphene on Pt(111) an optimal system to explore the effects of this new coupling in the electronic properties.

Robust transport signatures of topological superconductivity in topological insulator nanowires.

Finding a clear signature of topological superconductivity in transport experiments remains an outstanding challenge. In this work, we propose exploiting the unique properties of three-dimensional topological insulator nanowires to generate a normal-superconductor junction in the single-mode regime where an exactly quantized 2e2/h zero-bias conductance can be observed over a wide range of realistic system parameters. This is achieved by inducing superconductivity in half of the wire, which can be tuned at will from trivial to topological with a parallel magnetic field, while a perpendicular field is used to gap out the normal part, except for two spatially separated chiral channels. The combination of chiral mode transport and perfect Andreev reflection makes the measurement robust to moderate disorder, and the quantization of conductance survives to much higher temperatures than in tunnel junction experiments. Our proposal may be understood as a variant of a Majorana interferometer which is easily realizable in experiments.

Analysis of conversion factors in robotic-assisted rectal cancer surgery.

BACKGROUND: Robotic surgical management of rectal cancer has a series of advantages which might facilitate the surgical approach to the pelvic cavity and reduce conversion rates. The aim of the present study is to identify independent factors for conversion during robotic rectal cancer surgery. METHODS: A total of 67 patients underwent preoperative CT scan in order to obtain a three-dimensional image of the pelvis, the tumour and prostate. We measured maximum and minimum ilio-iliac, sacral promontory-pubis, coccyx-pubis diameters and maximum lateral axis. Further variables under consideration were age, BMI and use of neoadjuvant therapy. We recorded short-term follow-up outcomes of the resected tumour. RESULTS: The present study included 67 patients (39 males) with an average age of 65.11 ± 10.30 years and a BMI of 27.70 ± 3.97 kg/m(2). Operative procedures included nine abdominoperineal resections and 58 low anterior resections. There were 15 (22.38 %) conversions. Mean operating time was 192.2 ± 42.73 min. Minimum ilio-iliac, maximum ilio-iliac, promontory-pubic and coccyx-pubis diameter as well as maximum lateral axis were 100.38 ± 7.65, 107.10 ± 10.01, 109.97 ± 9.20, 105.61 ± 9.27 and 129.01 ± 9.94 mm, respectively. Mean tumour volume was 37.06 ± 44.08 cc; mean prostate volume was 42.07 ± 17.49 cc. The univariate analysis of the variables showed a correlation between conversion and BMI and minimum ilio-iliac and coccyx-pubis diameters (p = 0.004, 0.047, 0.046). In the multivariate analysis, the only independent predictive factor for conversion was the BMI (p = 0.004).No correlation was found between conversion and sex, age, tumour volume or the rest of pelvic diameters. CONCLUSION: BMI is an independent factor for conversion in robotic-assisted rectal cancer surgery.

Diagnostic Accuracy of Highest-Grade or Predominant Histological Differentiation of T1 Colorectal Cancer in Predicting Lymph Node Metastasis: A Systematic Review and Meta-Analysis.

INTRODUCTION: Treatment guidelines for colorectal cancer (CRC) suggest 2 classifications for histological differentiation-highest grade and predominant. However, the optimal predictor of lymph node metastasis (LNM) in T1 CRC remains unknown. This systematic review aimed to evaluate the impact of the use of highest-grade or predominant differentiation on LNM determination in T1 CRC. METHODS: The study protocol is registered in the International Prospective Register of Systematic Reviews (PROSPERO, registration number: CRD42023416971) and was published in OSF ( https://osf.io/TMAUN/ ) on April 13, 2023. We searched 5 electronic databases for studies assessing the diagnostic accuracy of highest-grade or predominant differentiation to determine LNM in T1 CRC. The outcomes were sensitivity and specificity. We simulated 100 cases with T1 CRC, with an LNM incidence of 11.2%, to calculate the differences in false positives and negatives between the highest-grade and predominant differentiations using a bootstrap method. RESULTS: In 42 studies involving 41,290 patients, the differentiation classification had a pooled sensitivity of 0.18 (95% confidence interval [CI] 0.13-0.24) and 0.06 (95% CI 0.04-0.09) ( P < 0.0001) and specificity of 0.95 (95% CI 0.93-0.96) and 0.98 (95% CI 0.97-0.99) ( P < 0.0001) for the highest-grade and predominant differentiations, respectively. In the simulation, the differences in false positives and negatives between the highest-grade and predominant differentiations were 3.0% (range 1.6-4.4) and -1.3% (range -2.0 to -0.7), respectively. DISCUSSION: Highest-grade differentiation may reduce the risk of misclassifying cases with LNM as negative, whereas predominant differentiation may prevent unnecessary surgeries. Further studies should examine differentiation classification using other predictive factors.