Sweet-spot operation of a germanium hole spin qubit with highly anisotropic noise sensitivity.

Spin qubits defined by valence band hole states are attractive for quantum information processing due to their inherent coupling to electric fields, enabling fast and scalable qubit control. Heavy holes in germanium are particularly promising, with recent demonstrations of fast and high-fidelity qubit operations. However, the mechanisms and anisotropies that underlie qubit driving and decoherence remain mostly unclear. Here we report the highly anisotropic heavy-hole g-tensor and its dependence on electric fields, revealing how qubit driving and decoherence originate from electric modulations of the g-tensor. Furthermore, we confirm the predicted Ising-type hyperfine interaction and show that qubit coherence is ultimately limited by 1/f charge noise, where f is the frequency. Finally, operating the qubit at low magnetic field, we measure a dephasing time of T 2 * = 17.6 µs, maintaining single-qubit gate fidelities well above 99% even at elevated temperatures of T > 1 K. This understanding of qubit driving and decoherence mechanisms is key towards realizing scalable and highly coherent hole qubit arrays.

Pedunculated liposarcoma of the esophagus.

Polypoid tumours of the esophagus present diagnostic and therapeutic problems. Liposarcomas are infrequent among them. We report a recent case. A 73-year-old male patient was seen in May 1995 in the Ear, Nose and Throat (ENT) Department, Clinica Modelo de Morón, with intermittent dysphagia and dyspnoea due to recurrent vomiting. A laryngeal lineal tomography showed a subglottic obstruction due to extrinsic compression. The patient was referred to the Gastroenterology Department, where an upper gastrointestinal (upper GI) series demonstrated mega-esophagus with abundant retained food. Endoscopy showed a large intraluminal mass covered by normal mucosa which arose on the posterior wall. Videofluoroscopy and chest CT diagnosed a probable polypoid lipoma due to its densitometric characteristics. The tumour was resected by left cervicotomy and left esophagotomy. The patient's progress to date is favourable. Pathology studies showed a well-differentiated liposarcoma. According to the literature, the first case was reported in 1983, and ours is only the seventh case in the world to be documented.

Foreign body impaction in the esophagus: are there underlying motor disorders?

RESULTS: Compared with the control group, the impacted subjects presented marked reduction in amplitude and duration of esophageal contraction in the proximal esophagus. CONCLUSIONS: These motor disorders could be responsible for the foreign body impaction in the esophagus. However, we believe this patient group should be further studied by 24-hour esophageal manometry to reach a more accurate diagnosis by studying each patient's entire circadian cycle.

Current-Controlled Spin Precession of Quasistationary Electrons in a Cubic Spin-Orbit Field.

Space- and time-resolved measurements of spin drift and diffusion are performed on a GaAs-hosted two-dimensional electron gas. For spins where forward drift is compensated by backward diffusion, we find a precession frequency in the absence of an external magnetic field. The frequency depends linearly on the drift velocity and is explained by the cubic Dresselhaus spin-orbit interaction, for which drift leads to a spin precession angle twice that of spins that diffuse the same distance.

A rare case of hypopharyngeal screw migration after spine stabilization with plating.

Anterior cervical spine fusion and stabilization with plating are well-established surgical procedures for the treatment of myelopathy, cervical spine traumas, and spinal infectious diseases. Various complications have been described in the literature, more frequently, intraoperative bleeding, peri- or postoperative hypopharyngeal, and/or esophageal ruptures with mediastinal deep infection and loosening and extrusion of the screws from the plating. Screw migration has also been observed as a complication of the procedure, either early in the postoperative period or delayed, even after many years. In some instances, the esophageal perforation can recover spontaneously with absence of complications, even if a case of plate failure and graft migration with lethal sudden airways obstruction has been reported. We describe a case of hypopharyngeal screw migration after cervical spine stabilization with plating never described before in the literature.

Beyond the compact magnetic domain wall.

Domain wall dynamics in wide submicrometer wires is investigated to understand the fundamental mechanisms that limit wall mobility, both experimentally by magneto-optical Kerr effect and by micromagnetic simulations. It is found that the dynamic domain wall structure departs significantly from the current description of a compact entity when evolving along the wire. The wall is composed of several substructures, each one propagating and evolving in a different dynamic regime with very different velocities.

Impact of a chronic care model based on patient empowerment on the management of Type 2 diabetes: effects of the SINERGIA programme.

AIMS: Several chronic care models for diabetes have been implemented in Italy, although conclusive data on their effectiveness are lacking. In the Cusano-Milanino diabetes clinic, patients with Type 2 diabetes with a stable disease/therapy (i.e. a steady level of HbA(1c) without need for therapy changes) are included in the SINERGIA programme: diabetologists, nurses and dietitians empower patients and telemedicine resources are utilized efficiently. METHODS: Clinical outcomes measured in the year before and after the initiation of SINERGIA were compared. A generalized hierarchical linear regression model for repeated measures was used. RESULTS: Altogether, 1004 patients were included; baseline characteristics were (mean ± sd): age 66.6 ± 6.2 years, 54.1% male, diabetes duration 10.8 ± 7.7 years, BMI 29.5 ± 4.8 kg/m(2) , HbA(1c) 6.9 ± 0.9% (52 ± 14 mmol/mol); 72.9% of patients were treated with anti-hypertensive drugs; 32.7% were treated with lipid-lowering drugs. After a median follow-up of 12 months (range 6-24 months), the proportion of patients with HbA(1c) ≤ 7.0% (≤ 53 mmol/mol) increased from 32.7 to 45.8% (P<0.0001), while those with HbA(1c) ≥9% (≥75 mmol/mol) decreased from 10.5 to 4.3% (P<0.0001). Patients with LDL cholesterol <100 mg/dl (<2.59 mmol/l) increased from 40 to 47% (P <0.0001), while those with LDL cholesterol ≥130 mg/dl (≥3.36 mmol/l) decreased from 26.6 to 19.7%; blood pressure levels were slightly improved. The mean number of face-to-face encounters decreased from (median and range) 2.8 (2.3-3.4) to 2.3 (1.9-2.7) (P<0.0001) visits per patient/year. CONCLUSIONS: The SINERGIA model is effective in improving metabolic control and major cardiovascular risk factors, while allowing diabetologists to dedicate more time to patients with more acute disease.

Endoscopic transnasal dacryocystorhinostomy without stenting: results in 64 consecutive procedures.

Dacryocystorhinostomy allows by-passing saccal and post-saccal stenoses and has traditionally been performed via an external approach, namely, external dacryocystorhinostomy. Over the past two decades, advances in endoscopic equipment have led to the widespread use of the endoscopic transnasal approach to the lacrimal pathway. A retrospective evaluation has been made of personal success rates in endoscopic dacryocystorhinostomy without stenting in 56 patients (15 male, 41 female) treated for nasolacrimal duct obstruction (48 unilateral, 8 bilateral). Of these, 53 were primary endoscopic dacryocystorhinostomy and 11 procedures were revisions of external dacryocystorhinostomy. A total of 64 endoscopic dacryocystorhinostomies were performed. Mean follow-up was 37.3 months (range 12-84 months). The success of surgery was defined by resolution of signs (epiphora and dacryocystitis) and objectively by endoscopic evaluation of the rhinostomy on routine follow-up. Results from patients undergoing primary endoscopic dacryocystorhinostomy were better than those for revision of external dacryocystorhinostomy with overall anatomical and functional results of 94.3% and 90.9%, in our series. The present study confirms that endoscopic dacryocystorhinostomy without stenting is effective for the treatment of nasolacrimal duct obstruction. The endoscopic approach allows simultaneous treatment of associated anatomic anomalies and sino-nasal disorders. Results obtained confirm that a functionally patent dacryocystorhinostomy can be achieved without the need for routine nasolacrimal stenting..

Gate-controlled spin-orbit interaction in a parabolic GaAs/AlGaAs quantum well.

We study the tunability of the spin-orbit interaction in a two-dimensional electron gas with a front and a back gate electrode by monitoring the spin precession frequency of drifting electrons using time-resolved Kerr rotation. The Rashba spin splitting can be tuned by the gate biases, while we find a small Dresselhaus splitting that depends only weakly on the gating. We determine the absolute values and signs of the two components and show that for zero Rashba spin splitting the anisotropy of the spin-dephasing rate vanishes.

Interferometric detection of spin-polarized transport in the depletion layer of a metal-GaAs Schottky barrier.

It is shown that the Kerr rotation of spin-polarized electrons is modulated by the distance of the electrons from the sample surface. Time-resolved Kerr rotation of optically excited spin-polarized electrons in the depletion layer of n-doped GaAs displays fast oscillations that originate from interference between the light reflected from the semiconductor surface and from the front of the electron distribution moving into the semiconductor. Using this effect, the dynamics of the photogenerated charge carriers in the depletion layer of the biased Schottky barrier is measured.

Prevalence, clinical spectrum and atypical symptoms of gastro-oesophageal reflux in Argentina: a nationwide population-based study.

BACKGROUND: Population-based data on gastro-oesophageal reflux in Latin America are lacking. AIM: To assess gastro-oesophageal reflux symptom prevalence, clinical spectrum and association with the atypical symptoms in our country. METHODS: Gastro-oesophageal reflux self-report questionnaires validated at Mayo Clinic, USA, were submitted to a sample of 1000 residents (aged 18-80 years) from 17 representative geographical areas of Argentina. The samples were selected and stratified according to age, gender, geographical areas and size of town of residence provided by the Argentine Bureau of Statistics and Census. RESULTS: The overall prevalence of any typical gastro-oesophageal reflux symptom experienced in the previous year was 61.2% (95% CI, 57.9-64.6), the prevalence of frequent gastro-oesophageal reflux symptoms was 23.0% (95% CI, 20.1-25.9) and the prevalence of gastro-oesophageal reflux disease was 11.9% (95% CI, 9.6-14.1). Frequent gastro-oesophageal reflux symptoms were associated with dysphagia (OR 2.12, 95% CI, 1.27-3.54, P < 0.01), globus (OR 2.22, 95% CI, 1.35-3.66, P < 0.01) and non-cardiac chest pain (OR 1.55, 95% CI, 1.04-2.31, P < 0.05). CONCLUSIONS: In Argentina, typical symptoms of gastro-oesophageal reflux are highly prevalent at the national level, and frequent gastro-oesophageal reflux symptoms are significantly associated with dysphagia, globus and non-cardiac chest pain.

Revision stapes surgery for recurrent transmissional hearing loss after stapedectomy and stapedotomy for otosclerosis.

A total of 20 stapedotomy and 24 stapedectomy cases were retrospectively reviewed to establish the causes of failure, and to evaluate hearing results after revision surgery. Our series included 23 male and 21 female patients. Mean age at revision time was 42 years, and the mean interval from primary surgery and revision stapes surgery was 27 months. The retrospective review of our data, revealed that the most common cause for revision surgery was a displaced prosthesis (47.7%). After revision surgery, the mean post-operative air-bone gap was 14.78 dB. A mean post-operative air-bone gap within 10 dB occurred in 24 patients (54.5%), in 14 patients (31.5%) this was between 11 and 20 dB, in 5 patients (11.5%) between 21 and 30 dB, and in one patient (2.5%) > 30 dB. There were no "dead ears" in this series. Our results compare to other reported series, and confirm that after revision stape surgery, an air-bone gap closure within 10 dB is difficult to obtain. In the present series, the use of the total ossicular replacement prosthesis resulted in the poorest functional hearing results.

Pneumatic dilatation in achalasia of the esophagus: a report from Argentina.

We review the treatment of esophageal achalasia by means of pneumatic dilatation (PD), analyzing its results and comparing them with those of the literature. We conclude that our personal experience is similar to that of the literature: PD and surgery produce similar results (67-95%), morbidity (2-9.5%), and mortality (0.7-1%); and PD is cheaper than surgery. According to these conclusions, we believe that the decision of the appropriate treatment should be based on a combination of the choice of the properly informed patient and the operator's experience. However, we also conclude that surgery is mandatory in selected cases, such as achalasia associated with hiatus hernia, esophageal diverticula and neoplasia, history of previous PD failure (since in our experience the results after a second PD are very poor), postoperative relapse, and patients with grade IV mega-esophagus according to Resano-Malenchini's classification.

Endoscopic CO2 laser treatment of supraglottic carcinoma.

Aim of the study was to evaluate whether laser endoscopic microsurgery is a reliable and appropriate approach to treatment of laryngeal supraglottic cancer. A retrospective study was made of 12 patients (11 M/1 F; mean age 62.5 years) treated from December 1995 to October 2001 in the Department of Surgical Sciences and Organ Transplantations, Section of Otorhinolaryngology, University of Cagliari, Italy. Surgical steps and oncologic results are reported. These 12 patients with supraglottic cancer underwent transoral laser surgery (TNM classification: T1, 3 patients; T2, 9 patients; N-, 9 patients; N+, 3 patients; M-, 12 patients). On the basis of the different subsites removed, the following resections were performed: 1 limited excisional biopsy (false chord), 3 wide excisional biopsies (2 or 3 subsites), 2 simple epiglottectomies, 1 extended epiglottectomy, 3 horizontal supraglottic laryngectomies, and 2 horizontal supraglottic laryngectomies that were extended to the anterior commissure and to one arytenoid, respectively. Five patients underwent functional neck dissection, and one patient underwent post-operative radiotherapy at sites of tumour and lymph nodes. Temporary tracheotomy was carried out in 10 patients. Mean follow-up was 33.3 months. No local recurrences were noted. Local control was thus 100%. Aspiration was the main post-operative problem, but there were no cases of aspiration-associated pneumonia. Moreover, no patient needed laryngectomy or a permanent tracheotomy for aspiration. In conclusion, although our experience with supraglottic cancers treated by endoscopy is still too limited to confirm the definitive oncologic validity of this type of surgery, in our hands, it seems to be a reasonable tool in selected cases and a safe, time- and cost-effective alternative to traditional surgery or radiotherapy for selected supraglottic carcinomas.

Heterotopic gastric mucosa in the upper esophagus: report of a case with a fistula.

We report the case of a 36-year-old man with a patch of heterotopic gastric mucosa in the upper esophagus complicated by an esophageal fistula.

Electrical control of spin coherence in semiconductor nanostructures.

The processing of quantum information based on the electron spin degree of freedom requires fast and coherent manipulation of local spins. One approach is to provide spatially selective tuning of the spin splitting--which depends on the g-factor--by using magnetic fields, but this requires their precise control at reduced length scales. Alternative proposals employ electrical gating and spin engineering in semiconductor heterostructures involving materials with different g-factors. Here we show that spin coherence can be controlled in a specially designed AlxGa1-xAs quantum well in which the Al concentration x is gradually varied across the structure. Application of an electric field leads to a displacement of the electron wavefunction within the quantum well, and because the electron g-factor varies strongly with x, the spin splitting is therefore also changed. Using time-resolved optical techniques, we demonstrate gate-voltage-mediated control of coherent spin precession over a 13-GHz frequency range in a fixed magnetic field of 6 T, including complete suppression of precession, reversal of the sign of g, and operation up to room temperature.

Ferromagnetic imprinting of nuclear spins in semiconductors.

We examine how a ferromagnetic layer affects the coherent electron spin dynamics in a neighboring gallium arsenide semiconductor. Ultrafast optical pump-probe measurements reveal that the spin dynamics are unexpectedly dominated by hyperpolarized nuclear spins that align along the ferromagnet's magnetization. We find evidence that photoexcited carriers acquire spin-polarization from the ferromagnet, and dynamically polarize these nuclear spins. The resulting hyperfine fields are as high as 9000 gauss in small external fields (less than 1000 gauss), enabling ferromagnetic control of local electron spin coherence.

Optical manipulation of nuclear spin by a two-dimensional electron gas.

Conduction electrons are used to optically polarize, detect, and manipulate nuclear spin in a (110) GaAs quantum well. Using optical Larmor magnetometry, we find that nuclear spin can be polarized along or against the applied magnetic field, depending on field polarity and tilting of the sample with respect to the optical pump beam. Periodic optical excitation of the quantum-confined electron spin reveals a complete spectrum of optically induced and quadrupolar-split nuclear resonances, as well as evidence for Deltam = 2 transitions.

[Barrett s epithelium: clinical review]. / Epitelio de Barrett: revisión clínica.

In this paper we review the literature about regarding etiology, natural history, methods of study and treatment of Barrett's esophagus. Likewise we review our personal experience as well as the one at national level.