Bringing Machine-Learning Enhanced Quantum Chemistry and Microwave Spectroscopy to Conformational Landscape Exploration: the Paradigmatic Case of 4-Fluoro-Threonine.

A combined experimental and theoretical study has been carried out on 4-fluoro-threonine, the only naturally occurring fluorinated amino acid. Fluorination of the methyl group significantly increases the conformational complexity with respect to the parent amino acid threonine. The conformational landscape has been characterized in great detail, with special attention given to the inter-conversion pathways between different conformers. This led to the identification of 13 stable low-energy minima. The equilibrium population of so many conformers produces a very complicated and congested rotational spectrum that could be assigned through a strategy that combines several levels of quantum chemical calculations with the principles of machine learning. Twelve conformers out of 13 could be experimentally characterized. The results obtained from the analysis of the intra-molecular interactions can be exploited to accurately model fluorine-substitution effects in biomolecules.

Unveiling the Shape of N-Acetylgalactosamine: A Cancer-Associated Sugar Derivative.

In the present work, we report the first rotational study of N-acetylgalactosamine, a cancer-associated sugar derivative, by means of high-resolution rotational spectroscopy. Two different conformers have been conclusively characterized using broadband Fourier transform microwave spectroscopy coupled with a laser ablation vaporization system. Additionally, we performed a comprehensive analysis of the intramolecular interactions that govern these structures, which allowed us to both characterize the existence of intramolecular hydrogen bond networks that drive the intrinsic conformation panorama of N-acetylgalactosamine and further rationalize the biological role of this aminosugar derivative as part of the Tn antigen.

Analysis of the effectiveness of the prophylaxis of vestibular migraine depending on the diagnostic category and the prescribed drug.

INTRODUCTION: Vestibular migraine (VM) consists of recurrent episodes of vestibular symptoms that are accompanied by migraine in at least 50% of the episodes. The criteria of the Bárány Society include two diagnostic categories: "actual" vestibular migraine and probable vestibular migraine. There is a wide range of drugs that can be prescribed for the prophylactic treatment of VM, but recommendations for the selection of the most appropriate drug are currently lacking. OBJECTIVE: To measure the extent to which the prophylactic treatment of VM reduces vestibular symptoms, headache and the number of crises depending on the diagnostic category of the Bárány Society and the drug used for prophylaxis. MATERIAL AND METHODS: This is a multicenter prospective study. Patients with VM who presented to any of the participating centers and who subsequently met the VM criteria were prescribed one of the following types of prophylaxis: acetazolamide, amitriptyline, flunarizine, propranolol or topiramate. Patients were called back for a follow-up visit 5 weeks later. This allowed the intensity of vestibular symptoms, headache and the number of crises before and during treatment to be compared. RESULTS: 31 Patients met the inclusion criteria. During the treatment, all the measured variables decreased significantly. In a visual analogue scale, the intensity of vestibular symptoms decreased by 45.8 points, the intensity of headache decreased by 47.8 points and patients suffered from 15.6 less monthly crises compared to the period before the treatment. No significant between-group differences were found when patients were divided based on their diagnostic category or the choice of prophylaxis prescribed to them. CONCLUSION: The treatment of VM produces a reduction of symptoms and crises with no significant differences based on patients' diagnostic categories or the choice of prophylaxis prescribed to them.

Healing criteria: How should an episode of benign paroxistic positional vertigo of posterior semicircular canal's resolution be defined? Prospective observational study.

OBJECTIVES: To compare the outcome of the Epley maneuver (EM) in benign paroxysmal positional vertigo of the posterior canal (CSP-BPPV) depending on the definition used for recovery. DESIGN: Multicenter observational prospective study. SETTING: Otoneurology Units of 5 tertiary reference hospitals. PARTICIPANTS: All patients presenting with unilateral CSP-BPPV assisted for 1-year period. EXCLUSION CRITERIA: Spontaneous nystagmus, positive McClure-Pagnini maneuver, positive bilateral Dix-Hallpike maneuver (DHM), positive DHM for vertigo but negative for nystagmus and atypical nystagmus. MAIN OUTCOME MEASURES: Response to EM was measured after 7 days in 3 different outcomes: disappearance of nystagmus during the DHM in the follow-up visit, disappearance of vertigo during the DHM and general status (GS) during daily life activities. RESULTS: 264 patients were recruited (68 male/166 female, mean age 62 years). After the EM, nystagmus disappeared in 67% of them, vertigo in 54% and 36% were asymptomatic in their daily life. These outcomes were strongly correlated, but they were not concordant in a clinically significant group of cases; only the 26% of patients met all of them. The healing process follows the next sequence: negativization of positional nystagmus, then disappearance of positional vertigo and, finally, the improvement of GS during daily life activities. CONCLUSION: Nowadays, healing criteria for the resolution of an PSC-BPPV episode have not been specifically defined yet. Provided that other otoneurological disorders have been ruled out, the next resolution criterion is proposed: absence of nystagmus and specifically during control DHM and disappearance of symptoms during daily life activities.

Mirage Andreev Spectra Generated by Mesoscopic Leads in Nanowire Quantum Dots.

We study transport mediated by Andreev bound states formed in InSb nanowire quantum dots. Two kinds of superconducting source and drain contacts are used: epitaxial Al/InSb devices exhibit a doubling of tunneling resonances, while, in NbTiN/InSb devices, Andreev spectra of the dot appear to be replicated multiple times at increasing source-drain bias voltages. In both devices, a mirage of a crowded spectrum is created. To describe the observations a model is developed that combines the effects of a soft induced gap and of additional Andreev bound states both in the quantum dot and in the finite regions of the nanowire adjacent to the quantum dot. Understanding of Andreev spectroscopy is important for the correct interpretation of Majorana experiments done on the same structures.

Analysis of risk factors influencing the outcome of the Epley maneuver.

Benign paroxysmal positional vertigo (BPPV) is the most frequent type of vertigo. The treatment of canalithiasis of the posterior semicircular canal consists in performing a particle-repositioning maneuver, such as the Epley maneuver (EM). However, the EM is not effective in all cases. The objective of this study is to identify risk factors, which predict the EM failure, among the clinical variables recorded in anamnesis and patient examination. This is an observational prospective multicentric study. All patients presenting with BPPV were recruited and applied the EM and appointed for a follow-up visit 7 days later. The following variables were recorded: sex, age, arterial hypertension, diabetes, hyperlipidemia, smoking habit, alcohol consumption, migraine, osteoporosis, diseases of the inner ear, previous ipsilateral BPPV, previous traumatic brain injury, previous sudden head deceleration, time of evolution, sulpiride or betahistine treatment, experienced symptoms, outcome of the Halmagyi maneuver, laterality, cephalic hyperextension of the neck, intensity of nystagmus, intensity of vertigo, duration of nystagmus, occurrence of orthotropic nystagmus, symptoms immediately after the EM, postural restrictions, and symptoms 7 days after the EM. Significant differences in the rate of loss of nystagmus were found for six variables: hyperlipidemia, previous ipsilateral BPPV, intensity of nystagmus, duration of nystagmus, post-maneuver sweating, and subjective status. The most useful significant variables in the clinical practice to predict the success of the EM are previous BPPV and intensity of nystagmus. In the other significant variables, no physiopathological hypothesis can be formulated or differences between groups are too small.

External urology consultation quality at a third-level public hospital in Mexico.

INTRODUCTION: Patient satisfaction is the degree of conformity with the healthcare they receive. It is real evidence and one of the most important factors in determining the effectiveness and quality of healthcare systems. OBJECTIVE: To identify the quality of care in the Urology outpatient department of a third-level hospital. MATERIALS AND METHODS: The NHS (National Health Service) 2018 quality of care questionnaire with 11 sections, 133 items, and duration of approximately 25min was randomly administered to 250 patients attending Urology outpatients at a third-level public hospital in Mexico. RESULTS: According to responses, 92% (n=230) knew the reason for the consultation. 64.8% (n=162) had a consultation with the same physician by whom they were initially seen. The longest reported hospital wait time before being seen was more than 2h in 29.6% (n=74). As for consultation time, 212 patients responded and the duration was 11-20min in 52.8% (n=112). Finally, 33.2% (n=83) considered the quality of service to be good. CONCLUSIONS: The use of the NHS 2018 survey in the Urology service at a third-level public hospital in Mexico is feasible, since we managed to obtain a significant and continuous improvement in all its indicators which is satisfactory for all.

Magnetic-field probing of an SU(4) Kondo resonance in a single-atom transistor.

Semiconductor devices have been scaled to the point that transport can be dominated by only a single dopant atom. As a result, in a Si fin-type field effect transistor Kondo physics can govern transport when one electron is bound to the single dopant. Orbital (valley) degrees of freedom, apart from the standard spin, strongly modify the Kondo effect in such systems. Owing to the small size and the s-like orbital symmetry of the ground state of the dopant, these orbital degrees of freedom do not couple to external magnetic fields which allows us to tune the symmetry of the Kondo effect. Here we study this tunable Kondo effect and demonstrate experimentally a symmetry crossover from an SU(4) ground state to a pure orbital SU(2) ground state as a function of magnetic field. Our claim is supported by theoretical calculations that unambiguously show that the SU(2) symmetric case corresponds to a pure valley Kondo effect of fully polarized electrons.

The eight structures of caffeic acid: a jet-cooled laser ablated rotational study.

This work reports a complete conformational analysis of caffeic acid, an exceptionally versatile pharmacophore, using laser ablation chirped-pulse Fourier transform microwave spectroscopy. The whole conformational space consisting of eight distinct species has been fully deciphered based on the trend of the rotational constants supported by theoretical computations. We show how rotational spectroscopy can be confidently used to distinguish between conformers even when the structural differences are minimal, such as those involved in the conformational panorama of caffeic acid. Additionally, the structural information here provided, such as the planarity observed in all the conformers, could help to elucidate the mechanisms underlying the biological and pharmacological activity of hydroxycinnamic acids.

Coupling nitrogen-vacancy centers in diamond to superconducting flux qubits.

We propose a method to achieve coherent coupling between nitrogen-vacancy (NV) centers in diamond and superconducting (SC) flux qubits. The resulting coupling can be used to create a coherent interaction between the spin states of distant NV centers mediated by the flux qubit. Furthermore, the magnetic coupling can be used to achieve a coherent transfer of quantum information between the flux qubit and an ensemble of NV centers. This enables a long-term memory for a SC quantum processor and possibly an interface between SC qubits and light.

Charge localization and reentrant superconductivity in a quasi-ballistic InAs nanowire coupled to superconductors.

A semiconductor nanowire with strong spin-orbit coupling in proximity to a superconductor is predicted to display Majorana edge states emerging under a properly oriented magnetic field. The experimental investigation of these exotic states requires assessing the one-dimensional (1D) character of the nanowire and understanding the superconducting proximity effect in the presence of a magnetic field. Here, we explore the quasi-ballistic 1D transport regime of an InAs nanowire with Ta contacts. Fine-tuned by means of local gates, the observed plateaus of approximately quantized conductance hide the presence of a localized electron, giving rise to a lurking Coulomb blockade effect and Kondo physics. When Ta becomes superconducting, this local charge causes an unusual, reentrant magnetic field dependence of the supercurrent, which we ascribe to a 0 - π transition. Our results underline the relevant role of unintentional charge localization in the few-channel regime where helical subbands and Majorana quasi-particles are expected to arise.

Probable benign paroxysmal positional vertigo, spontaneously resolved: Incidence in medical practice, patients' characteristics and the natural course.

BACKGROUND: Probable benign paroxysmal positional vertigo, spontaneously resolved (pBPPVsr), is a variant of benign paroxysmal positional vertigo (BPPV) in which there is no observable nystagmus and no vertigo with any positional maneuver. OBJECTIVES: To calculate the incidence pBPPVsr, compare the characteristics of the patients with pBPPVsr and BPPV not spontaneously resolved and describe the spontaneous resolution in the natural course of BPPV. METHODS: Multicenter prospective descriptive study. During a one-year period, all patients with suspected BPPV that presented to the Neurotology Units of five participating centers were recruited. The incidence of pBPPVsr was calculated as a percentage of the total number of patients with BPPV. The prevalence of several variables was compared between pBPPVsr and BPPV not spontaneously resolved. The timing of spontaneous resolution was estimated using Kaplan-Meier curves. RESULTS: 457 patients met the inclusion criteria. The incidence of pBPPVsr was 33.5%. It was significantly higher in males, in patients with normal bone mass and in patients who were not taking sulpiride. A rate of 18% of spontaneous resolution after the first month and 51% after the first year was found. This percentage did not change in a significant way after this moment. The curves for males, patients under 50 and patients with normal blood pressure decreased significantly faster. CONCLUSIONS: In our serie, BPPV spontaneously resolved in half of the patients with BPPV during the first year. This seemed to occur more commonly in males and could have been hindered by sulpiride intake, osteoporosis, advanced age and high blood pressure.

Awareness with recall during general anaesthesia: a prospective observational evaluation of 4001 patients.

BACKGROUND: We have prospectively evaluated the incidence and characteristics of awareness with recall (AWR) during general anaesthesia in a tertiary care hospital. METHODS: This study involves a prospective observational investigation of AWR in patients undergoing general anaesthesia. Blinded structured interviews were conducted in the postanaesthesia care unit, on postoperative day 7 and day 30. Definition of AWR was 'when the patient stated or remembered that he or she had been awake at a time when consciousness was not intended'. Patient characteristics, perioperative, and drug-related factors were investigated. Patients were classified as not awake during surgery, AWR, AWR-possible, AWR-not evaluable. The perceived quality of the awareness episode, intraoperative dreaming, and sequelae were investigated. The anaesthetic records were reviewed to search for data that might explain the awareness episode. RESULTS: The study included 4001 patients. Incidence of AWR was 1.0% (39/3921 patients). If high risk for AWR patients were excluded, the incidence was 0.8%. After the interview on the seventh day, six patients denied having been conscious during anaesthesia; hence, the incidence of AWR in elective surgery was 0.6%. Factors associated with AWR were: anaesthetic technique incidence of 1.1% TIVA-propofol vs 0.59% balanced anaesthesia vs 5.0% O2/N2O-based anaesthesia vs 0.9% other anaesthetic techniques (mainly propofol boluses for short procedures), P=0.008; age (AWR 42.3 yr old vs 50.6 yr old, P=0.041), absence of i.v. benzodiazepine premedication (P=0.001), Caesarean section (C-section) (P=0.019), and surgery performed at night (P=0.013). More than 50% of patients reported intraoperative dreaming in the early interview, mainly pleasant. Avoidable human factors were detected from the anaesthetic records of most patients. Subjective auditory perceptions prevailed, together with trying to move or communicate, and touch or pain perception. CONCLUSIONS: A relatively high incidence of AWR and dreams during general anaesthesia was found. Techniques without halogenated drugs showed more patients. The use of benzodiazepine premedication was associated with a lower incidence of AWR. Age, C-section with general anaesthesia, and surgery performed at night are risk factors.

Product distribution modelling in the thermal pyrolysis of high density polyethylene.

The thermal fast pyrolysis of high density polyethylene (HDPE) has been carried out in a conical spouted bed reactor in the 450-715 degrees C range, and individual products have been monitored with the aim of obtaining kinetic data for the design and simulation of this process at large scale. Kinetic schemes have been proposed in order to explain both the results obtained in the laboratory plant and those obtained in the literature by other authors operating at laboratory and larger scale. Discrimination has been carried out based on the contribution of the variance of model parameters (stepwise regression) to the total variance explained by the model. The models based on that of Westerhout et al. [R.W.J. Westerhout, J. Waanders, W.P.M. Van Swaaij, Recycling of polyethene and polypropene in a novel bench-scale rotating cone reactor by high-temperature pyrolysis. Ind. Eng. Chem. Res. 37 (6) (1998) 2293-2300] do not adequately predict the experimental results, especially those corresponding to aromatics and char, which is probably due to the very short residence times attained in the conical spouted bed and, consequently, to the lower yields of aromatics and char. The model of best fit is the one where polyethylene degrades to give gas, liquid (oil) and wax fractions. Furthermore, the latter undergoes secondary reactions to give liquid and aromatics, which in turn produce more char.

Magnetically-driven colossal supercurrent enhancement in InAs nanowire Josephson junctions.

The Josephson effect is a fundamental quantum phenomenon where a dissipationless supercurrent is introduced in a weak link between two superconducting electrodes by Andreev reflections. The physical details and topology of the junction drastically modify the properties of the supercurrent and a strong enhancement of the critical supercurrent is expected to occur when the topology of the junction allows an emergence of Majorana bound states. Here we report charge transport measurements in mesoscopic Josephson junctions formed by InAs nanowires and Ti/Al superconducting leads. Our main observation is a colossal enhancement of the critical supercurrent induced by an external magnetic field applied perpendicular to the substrate. This striking and anomalous supercurrent enhancement cannot be described by any known conventional phenomenon of Josephson junctions. We consider these results in the context of topological superconductivity, and show that the observed critical supercurrent enhancement is compatible with a magnetic field-induced topological transition.

Laparoscopic Nissen fundoplication with Baska Mask® laryngeal mask. / Funduplicatura de Nissen Laparoscópica con mascarilla laríngea Baska Mask®.

Tracheal intubation has historically been considered the ideal technique to handle the airway in laparoscopic surgical procedures. The introduction of such procedures in ambulatory surgery requires the use of anesthetic techniques that offer optimal and early postoperative recovery under strict security conditions. Laryngeal mask is proposed as a suitable alternative to tracheal intubation, even in high risk patients due to new devices which have been modified to improve their characteristics, becoming great alternatives in the overall management of the airway. We report the first case of laparoscopic Nissen fundoplication performed with a laryngeal Baska Mask in patient with high risk of regurgitation due to its gastroesophageal reflux.

Double quantum dots as detectors of high-frequency quantum noise in mesoscopic conductors

We propose a measurement setup for detecting quantum noise over a wide frequency range using inelastic transitions in a tunable two-level system as a detector. The frequency-resolving detector consists of a double quantum dot which is capacitively coupled to the leads of a nearby mesoscopic conductor. The inelastic current through the double quantum dot is calculated in response to equilibrium and nonequilibrium current fluctuations in the nearby conductor, including zero-point fluctuations at very low temperatures. As a specific example, the fluctuations across a quantum point contact are discussed.

Out-of-equilibrium kondo effect in double quantum dots

The out-of-equilibrium transport properties of a double quantum dot system in the Kondo regime are studied theoretically by means of a two-impurity Anderson Hamiltonian with interimpurity hopping. The Hamiltonian is solved by means of a nonequilibrium generalization of the slave-boson mean-field theory. It is demonstrated that measurements of the differential conductance dI/dV, for appropriate values of voltages and tunneling couplings, can give a direct observation of the coherent superposition between the many-body Kondo states of each dot. For large voltages and arbitrarily large interdot tunneling, there is a critical voltage above which the physical behavior of the system again resembles that of two decoupled quantum dots.