Spin Echo, Fidelity, and the Quantum Critical Fan in TmVO_{4}.

Using spin-echo nuclear magnetic resonance in the model transverse field Ising system TmVO_{4}, we show that low frequency quantum fluctuations at the quantum critical point have a very different effect on ^{51}V nuclear spins than classical low-frequency noise or fluctuations that arise at a finite temperature critical point. Spin echoes filter out the low-frequency classical noise but not the quantum fluctuations. This allows us to directly visualize the quantum critical fan and demonstrate the persistence of quantum fluctuations at the critical coupling strength in TmVO_{4} to high temperatures in an experiment that remains transparent to finite temperature classical phase transitions. These results show that while dynamical decoupling schemes can be quite effective in eliminating classical noise in a qubit, a quantum critical environment may lead to rapid entanglement and decoherence.

Using strain to uncover the interplay between two- and three-dimensional charge density waves in high-temperature superconducting YBa2Cu3Oy.

Uniaxial pressure provides an efficient approach to control charge density waves in YBa2Cu3Oy. It can enhance the correlation volume of ubiquitous short-range two-dimensional charge-density-wave correlations, and induces a long-range three-dimensional charge density wave, otherwise only accessible at large magnetic fields. Here, we use x-ray diffraction to study the strain dependence of these charge density waves and uncover direct evidence for a form of competition between them. We show that this interplay is qualitatively described by including strain effects in a nonlinear sigma model of competing superconducting and charge-density-wave orders. Our analysis suggests that strain stabilizes the 3D charge density wave in the regions between disorder-pinned domains of 2D charge density waves, and that the two orders compete at the boundaries of these domains. No signatures of discommensurations nor of pair density waves are observed. From a broader perspective, our results underscore the potential of strain tuning as a powerful tool for probing competing orders in quantum materials.

Inverse Laplace transformation analysis of stretched exponential relaxation.

We investigate the effectiveness of the Inverse Laplace Transform (ILT) analysis method to extract the distribution of relaxation rates from nuclear magnetic resonance data with stretched exponential relaxation. Stretched-relaxation is a hallmark of a distribution of relaxation rates, and an analytical expression exists for this distribution for the case of a spin-1/2 nucleus. We compare this theoretical distribution with those extracted via the ILT method for several values of the stretching exponent and at different levels of experimental noise. The ILT accurately captures the distributions for ß≲0.7, and for signal to noise ratios greater than ∼40; however the ILT distributions tend to introduce artificial oscillatory components. We further use the ILT approach to analyze stretched relaxation for spin I>1/2 and find that the distributions are accurately captured by the theoretical expression for I=1/2. Our results provide a solid foundation to interpret distributions of relaxation rates for general spin I in terms of stretched exponential fits.

Unusual Interplay between Superconductivity and Field-Induced Charge Order in YBa_{2}Cu_{3}O_{y}.

We present a detailed study of the temperature (T) and magnetic field (H) dependence of the electronic density of states (DOS) at the Fermi level, as deduced from specific heat and Knight shift measurements in underdoped YBa_{2}Cu_{3}O_{y}. We find that the DOS becomes field independent above a characteristic field H_{DOS}, and that the H_{DOS}(T) line displays an unusual inflection near the onset of the long-range 3D charge-density wave order. The unusual S shape of H_{DOS}(T) is suggestive of two mutually exclusive orders that eventually establish a form of cooperation in order to coexist at low T. On theoretical grounds, such a collaboration could result from the stabilization of a pair-density wave state, which calls for further investigation in this region of the phase diagram.

Quasiparticle Scattering off Defects and Possible Bound States in Charge-Ordered YBa_{2}Cu_{3}O_{y}.

We report the NMR observation of a skewed distribution of ^{17}O Knight shifts when a magnetic field quenches superconductivity and induces long-range charge-density-wave (CDW) order in YBa_{2}Cu_{3}O_{y}. This distribution is explained by an inhomogeneous pattern of the local density of states N(E_{F}) arising from quasiparticle scattering off, yet unidentified, defects in the CDW state. We argue that the effect is most likely related to the formation of quasiparticle bound states, as is known to occur, under specific circumstances, in some metals and superconductors (but not in the CDW state, in general, except for very few cases in 1D materials). These observations should provide insight into the microscopic nature of the CDW, especially regarding the reconstructed band structure and the sensitivity to disorder.

Factors associated with influenza vaccination among adult cancer patients: a case-control study.

Influenza vaccination is recommended for cancer patients; however, adherence is low. We aimed to identify predictive factors for vaccination among cancer patients. We conducted a case-control analysis of a patient cohort in the 2010-2011 influenza season. We included adult cancer patients with solid malignancies undergoing chemotherapy, and haematological patients with active disease. Patients who died between October and November 2010 (N = 43) were excluded from analysis. Cases received the 2011 seasonal influenza vaccine, and controls did not. Data were obtained from patients' records, and validated through personal interviews. We collected socio-demographic information, and data on the malignancy and co-morbidities and triggers for vaccination and non-vaccination. We performed bivariate and multivariable analyses, in which vaccination status was the dependent variable. Of 806 patients included in analysis, 387 (48%) were vaccinated. Variables associated with vaccination on bivariate analysis were older age, higher socio-economic status, lower crowding index, marital status (widowed > married > single), malignancy type (haematological > solid tumours) and time from diagnosis, low-risk malignancy, diabetes, past vaccination, country of birth (non-Russian origin), and physicians' recommendations. Predictive factors found to be independently associated with vaccination on multivariable analysis were past vaccinations, low-risk malignancy, and country of birth. In the analysis conducted among interviewees (N = 561), recommendations from the oncologist (OR 10.7, 95% CI 5.4-21.2) and from the primary-care physician (OR 3.35, 95% CI 2.05-5.49) were strong predictors for vaccination. We conclude that 'habitual vaccinees' continue influenza vaccinations when ill with cancer. Physicians' recommendations, especially the oncologist's, have a major influence on patients' compliance with influenza vaccination.

The postnatal management of congenital cystic adenomatoid malformation.

BACKGROUND: Routine prenatal ultrasound has increased the frequency of prenatal diagnosis of congenital cystic lung malformation, such as cystic adenomatoid malformation, pulmonary sequestration, congenital lobar emphysema, and bronchogenic cyst. OBJECTIVES: To evaluate the methods of postnatal diagnosis, the optimal age for operation since surgery is always required, and the optimal extent of lung resection. METHODS: The clinical courses of 11 patients with congenital lung cysts who underwent surgical lung resection (8 lobectomies and 3 segmentectomies) were reviewed. RESULTS: The diagnosis was confirmed by computed tomography scan in all. In nine patients the diagnosis was made prenatally. Chest X-ray was normal postnatally in all patients except for two who had recurrent pneumonia. Postoperative follow-up showed excellent recovery in all operated children. One patient who underwent surgery for CCAM following episodes of severe pneumonia died from another cause 5 months later. Postoperative chest CT scan showed no residual disease in eight patients. In two who had undergone limited resection, tomography showed a small segment of residual disease in one and a suspected residual lesion in the other. CONCLUSION: With prenatal ultrasound the true frequency of congenital cystic lung anomaly appears to be higher than previously reported. Postnatal CT is mandatory to confirm or to rule out the diagnosis. The mere presence of cystic lung malformation is an indication for surgery. Complete removal of the affected lung lobe is recommended. Segmental resection may be inadequate. Early operation is tolerated well by infants and small children and we recommend that surgery be performed in children between 6 and 12 months of age.

[Aortopexy for tracheomalacia in infants and children].

During the past 12 years (1985-1998), 28 infants and children were operated on here for tracheomalacia. The diagnosis was made in all using rigid bronchoscopy. During the examination the infants breathed spontaneously, but the trachea collapsed on forced expiration. Indications for surgery were repeated cyanotic spells ("dying spells") in 22, recurrent pneumonia, and inability to extubate (in 8). In 11 there were more than 1 indications. Age at surgery was from 7 days to 3 years (average 11.7 months). All 28 children underwent bronchoscopy and guided aortopexy via a left-third intercostal approach. The ascending aorta and aortic arch (and in 6 the proximal innominate artery as well) were lifted anteriorly, using 3-5 non-absorbable sutures (5.0). The sutures were placed through the adventitia of the great vessels and then passed through the sternum. Respiratory distress was significantly improved in 21. Another 2 required external tracheal stenting with autologous rib grafts, and in 1 other an internal Palmaz stent was introduced for tracheal stability. In 4 aortopexy failed, 1 of whom had tracheobronchomalacia throughout, and another 3 had laryngomalacia which required tracheostomy to relieve the respiratory symptoms. Postoperative complications were minor: pericardial effusion in 1 and relaxation of the left diaphragm in another. 1 infant subsequently died, of unknown cause 10 days after operation, after having been extubated on the 1st postoperative day. On long-term follow-up (6 months to 12 years) 25 were found free of residual respiratory symptoms and 3 remained with a tracheostomy. Thus, infants and children with severe tracheomalacia associated with severe respiratory symptoms, can be relieved by bronchoscopic guided suspension of the aortic arch to the sternum.

[Laser treatment of airway obstruction in infants and children].

Airway obstruction during infancy and childhood requiring surgical ablation is rare, and surgical intervention poses a significant challenge. During recent decades, appropriate endoscopic instrumentation, together with advanced laser beam technology have provided new operative modalities for such patients. From 1993 to 1995 we treated 40 infants and children, 26 males and 14 females, 13 days to 11 years old (mean 3.3 years) with Nd-YAG or CO2 laser. Obstructing lesions included granulation tissue or polyps (16 cases), septa or webs (27), or benign tumors (4). 7 had more than a single lesion. All were treated endoscopically under general anesthesia without any operative or postoperative deaths. Surgical intervention removed the obstruction and related symptoms in 34. In 6, laser treatment failed, necessitating additional surgical procedures. 3 had circumferential subglottic web. Operative complications included bleeding during removal of a hemangioma in 1 and recrudescence in another. Postoperative complications were transient respiratory failure and pneumonia in 6, all of which resolved with appropriate treatment. This series proves that laser technology is feasible in the treatment of airway obstruction during infancy and childhood, and is safe and effective.

[Atypical mycobacterial cervical lymphadenitis in children].

Scrofula (mycobacterial cervical lymphadenitis) has been well-known for thousands of years. Atypical mycobacteria were first categorized by Timpe and Runyon in 1954. Treatment has varied over the centuries, from exclusion therapy in ancient Greece, through digitalis, iodide, chemotherapy, and surgical excision. The varied differential diagnosis and consequent diagnostic and therapeutic challenges make reassessment of this almost forgotten disease necessary. 21 patients with typical mycobacterial cervical lymphadenitis seen in over the past 5 years were reviewed. Age distribution ranged from 1-14 years, with peak incidence at 4 years; 9 were boys and 12 girls. Most presented with nontender, palpable neck masses and minimal constitutional complaints. Adenopathy was unilateral in all cases but 2. Mycobacterium avium-intracellulare and M. fortuitum were the main causative organisms. All underwent excision of the affected nodes. Long-term follow-up has been uneventful, except for 1 case of local recurrence requiring re-excision. This study emphasizes the marked variability in the clinical presentation of scrofula in children, stressing the importance of the differential diagnosis between tuberculous and atypical mycobacterial cervical lymphadenitis. The treatment of choice for the latter is complete excision of the affected nodes. Other treatment is followed by recurrence and unnecessary complications and should be avoided.

[One-stage surgery for Hirschsprung's disease in children].

Traditionally Hirschsprung's disease has been treated by 2- or 3-stage procedures. During the past 6 years a 1-stage Duhamel procedure without stoma has become our treatment of choice for Hirschsprung's disease in neonates and young infants. Over a 6-year period, 15 infants and children with colonic Hirschsprung's disease were treated with the 1-stage Duhamel retro-rectal pull-through procedure without a stoma, with the Lester-Martin modification. All patients had the usual short segment aganglionosis, but 1 had a long segment which included the splenic flexure. Early complications included wound infection in 1 and minor rectal bleeding in 3. Late complications included constipation in 1 and enterocolitis in 4. Long-term functional results were very good in all those operated except for 1 with rectal achalasia. We conclude that Hirschsprung's disease can be successfully treated with a 1-stage pull-through operation, the child usually benefitting from the shorter hospital stay and the avoidance of a colostomy.

Giant omental cyst in children presenting as pseudoascites.

An unusual case of omental cyst is described. During a period of 3 years, a child was hospitalized seven times in five different hospitals for evaluation of ascites of unknown origin. Extensive and repetitive diagnostic workup did not reveal the cause of his problem, and recurrent paracentesis improved his condition partially, but for very short periods. A diagnostic laparoscopy, followed by explorative laparotomy, led to the correct diagnosis and appropriate surgical treatment, with complete relief of his complaints.

Bacteriology of cholelithiasis in infants and children.

Today, laparoscopic cholecystectomy is rapidly replacing traditional cholecystectomy as the standard treatment of symptomatic cholelithiasis in children. We reviewed the bile cultures and postoperative course of 30 children who underwent laparoscopic cholecystectomy with the aim of establishing a routine policy for perioperative antibiotic treatment and for the management of biliary leak during that procedure. A positive bile culture was found in only one child (Salmonella Group D). All patients, including six children with intraoperative bile spillage, had a completely normal and uneventful postoperative course. We concluded that the use of preoperative antibiotic treatment should be limited in laparoscopic cholecystectomy in children and is probably not required at all, awaiting proof from a further study. The present study further showed that intraoperative bile spillage is of no clinical significance and can be treated simply with local saline irrigation during the laparoscopic procedure.

Intussusception: a 9-year survey (1986-1995).

BACKGROUND: Acute intussusception has different clinical features in various parts of the world. The goal of this study was to determine the clinical presentation in different ethnic groups in Israel. METHODS: A retrospective chart review of a 9-year period (1985-1995) was carried out at a university medical center. Data extracted included age, sex, ethnic origin, presenting symptoms and signs, the type of enema (barium or air), and the success rate of non-surgical reduction of the intussusception. RESULTS: Ninety patients suffering from intestinal obstruction due to acute intussusception were admitted. The triad of intermittent screaming attacks, lethargy, and vomiting was observed in 37.5% of study subjects. The majority of patients were admitted during the warmer months of the year. The average age of the patients was 7.8 +/- 3.7 months; 70% of them were between the ages of 4 and 9 months and 92.5% under 1 year of age. The female-to-male ratio was 1:2.1. Air enema was superior to the barium enema in achieving reduction (p < 0.01). The incidence in the Jewish population was similar to that observed in other surveys, and twice that found in the Arab population in our region (p < 0.05). CONCLUSIONS: The overall clinical presentation of acute intussusception found in our study does not differ from other studies. The lower incidence of acute intussusception found in the Arab population can be explained by ethnic, genetic, or nutritional factors.

Dumping syndrome following Nissen fundoplication, diagnosis, and treatment.

We evaluated the prevalence, diagnosis, and treatment of dumping syndrome (DS) following Nissen fundoplication in 50 consecutive infants and children who underwent the operation for gastroesophageal reflux. Examination included a preoperative dietary assessment with emphasis on specific postprandial clinical symptoms and technetium scintigraphy to evaluate gastric emptying. In the immediate postoperative period, postprandial glucose levels were examined in all patients with symptoms clinically suggestive of DS. In the late postoperative period (6 months to 5.5 years), all patients with more than one specific clinical symptom of DS were further evaluated by glucose tolerance test (GTT), HbA1C levels, and gastric technetium scintigraphy. DS was diagnosed in 15 patients (30%). Five patients had immediate severe DS (SDS), and 10 in the late postoperative course had latent postoperative DS (LDS). In all patients with DS, preoperative and postoperative gastric emptying scan T1/2 did not show any statistical significance. High levels of HbA1C ranging from 7.9 to 9% (mean, 8.25 +/- 0.5) were found in only three patients. Treatment included parenteral nutrition in one patient. All the others were successfully managed with nutritional manipulation alone, using a combination of lactose-free formula and fat emulsion. In patients whose postprandial symptoms persisted, pectin 5-15 g/day divided into six doses was added to the diet. Following 6 months of dietary treatment, the postprandial normoglycomic response was restored. Eleven patients experienced complete resolution of symptoms (78.5%), and three patients (21.4%) showed significant clinical improvement. This study indicates that DS is a common complication following Nissen fundoplication. The GTT is the most reliable examination for establishing the diagnosis. Treatment is simple and effective. The technetium gastric emptying scan and HbA1C level do not play a significant role in the diagnosis.

Acute appendicitis following abdominal trauma.

Acute appendicitis (AA) is generally considered to be a consequence of lumenal obstruction and inflammation of the appendix. At the beginning of the 20th century, trauma was considered to be one of the possible causes of AA but this relationship has not been examined much since then. Our experience with three cases of AA following blunt abdominal trauma led to an extensive review of the world literature on the subject. We believe that abdominal trauma might be causative of AA. The potential for this hazardous and easily missed diagnostic entity should be appreciated in cases of blunt abdominal trauma both for sound clinical decision making and for its potential medical and legal implications.