Real-space imaging of non-collinear antiferromagnetic order with a single-spin magnetometer.

Although ferromagnets have many applications, their large magnetization and the resulting energy cost for switching magnetic moments bring into question their suitability for reliable low-power spintronic devices. Non-collinear antiferromagnetic systems do not suffer from this problem, and often have extra functionalities: non-collinear spin order may break space-inversion symmetry and thus allow electric-field control of magnetism, or may produce emergent spin-orbit effects that enable efficient spin-charge interconversion. To harness these traits for next-generation spintronics, the nanoscale control and imaging capabilities that are now routine for ferromagnets must be developed for antiferromagnetic systems. Here, using a non-invasive, scanning single-spin magnetometer based on a nitrogen-vacancy defect in diamond, we demonstrate real-space visualization of non-collinear antiferromagnetic order in a magnetic thin film at room temperature. We image the spin cycloid of a multiferroic bismuth ferrite (BiFeO3) thin film and extract a period of about 70 nanometres, consistent with values determined by macroscopic diffraction. In addition, we take advantage of the magnetoelectric coupling present in BiFeO3 to manipulate the cycloid propagation direction by an electric field. Besides highlighting the potential of nitrogen-vacancy magnetometry for imaging complex antiferromagnetic orders at the nanoscale, these results demonstrate how BiFeO3 can be used in the design of reconfigurable nanoscale spin textures.

Effects of dentifrices differing in fluoride compounds on artificial enamel caries lesions in vitro.

The aim of this study was to compare the caries-preventive effect of a stabilized stannous fluoride/sodium fluoride dentifrice containing sodium hexametaphosphate with those of a regular, solely sodium fluoride-containing and amine fluoride-containing dentifrice on pre-demineralized bovine enamel specimens using a pH-cycling model. Bovine enamel specimens with two artificial lesions each were prepared. Baseline mineral loss of both lesions was analyzed using transversal microradiography (TMR). Eighty-five specimens with a mean (SD) baseline mineral loss of 3393 (683) vol% × µm were selected and randomly allocated to five groups (n = 13/15). Treatments during pH-cycling (28 days and 2 × 20 min demineralization/day) were: brushing twice daily with slurries of AmF (1400 ppm F-), NaF (1450 ppm F-), SnF2/NaF (1100 ppm F-/350 ppm F-), and fluoride-free (FF) dentifrices or they were immersed in distilled water and remained unbrushed (NB). Subsequently, from each specimen one lesion was covered with acid-resistant varnish, while the remaining lesion was demineralized for another 14 days. Differences in integrated mineral loss (∆∆Z) were calculated between values before and after pH-cycling (∆∆Z E1) as well as before pH-cycling and after second demineralization (∆∆Z E2) using TMR. Treatments AmF and NaF induced a significantly higher mineral gain (∆∆Z E1/∆∆Z E2) compared to treatments FF and NB (p < 0.05; ANOVA test). Except for treatments AmF and NaF no significant differences in mineral loss between before and after pH-cycling could be observed (p < 0.05; t test) [∆∆Z E1: AmF:1563 (767); NaF:1222 (1246); SnF2/NaF:258 (1259); FF:-52 (1223); NB:-151 (834)]. Both dentifrices with either AmF or NaF promoted remineralization, whereas SnF2/NaF dentifrice did not promote remineralization in a biofilm-free pH-cycling model.

Quantitative nanoscale vortex imaging using a cryogenic quantum magnetometer.

Microscopic studies of superconductors and their vortices play a pivotal role in understanding the mechanisms underlying superconductivity. Local measurements of penetration depths or magnetic stray fields enable access to fundamental aspects such as nanoscale variations in superfluid densities or the order parameter symmetry of superconductors. However, experimental tools that offer quantitative, nanoscale magnetometry and operate over large ranges of temperature and magnetic fields are still lacking. Here, we demonstrate the first operation of a cryogenic scanning quantum sensor in the form of a single nitrogen-vacancy electronic spin in diamond, which is capable of overcoming these existing limitations. To demonstrate the power of our approach, we perform quantitative, nanoscale magnetic imaging of Pearl vortices in the cuprate superconductor YBa2Cu3O7-δ. With a sensor-to-sample distance of ∼10 nm, we observe striking deviations from the prevalent monopole approximation in our vortex stray-field images, and find excellent quantitative agreement with Pearl's analytic model. Our experiments provide a non-invasive and unambiguous determination of the system's local penetration depth and are readily extended to higher temperatures and magnetic fields. These results demonstrate the potential of quantitative quantum sensors in benchmarking microscopic models of complex electronic systems and open the door for further exploration of strongly correlated electron physics using scanning nitrogen-vacancy magnetometry.

Strain coupling of a nitrogen-vacancy center spin to a diamond mechanical oscillator.

We report on single electronic spins coupled to the motion of mechanical resonators by a novel mechanism based on crystal strain. Our device consists of single-crystal diamond cantilevers with embedded nitrogen-vacancy center spins. Using optically detected electron spin resonance, we determine the unknown spin-strain coupling constants and demonstrate that our system resides well within the resolved sideband regime. We realize coupling strengths exceeding 10 MHz under mechanical driving and show that our system has the potential to reach strong coupling. Our novel hybrid system forms a resource for future experiments on spin-based cantilever cooling and coherent spin-oscillator coupling.

Randomized controlled multicenter international clinical trial of self-gripping Parietex™ ProGrip™ polyester mesh versus lightweight polypropylene mesh in open inguinal hernia repair: interim results at 3 months.

PURPOSE: To compare clinical outcomes following sutureless Parietex™ ProGrip™ mesh repair to traditional Lichtenstein repair with lightweight polypropylene mesh secured with sutures. METHODS: This is a 3-month interim report of a 1-year multicenter international study. Three hundred and two patients were randomized; 153 were treated with Lichtenstein repair (L group) and 149 with Parietex™ ProGrip™ precut mesh (P group) with or without fixation. The primary outcome measure was postoperative pain using the visual analog scale (VAS, 0-150 mm); other outcomes were assessed prior to surgery and up to 3 months postoperatively. RESULTS: Compared to baseline, pain score was lower in the P group at discharge (-10%) and at 7 days (-13%), while pain increased in the L group at discharge (+39%) and at 7 days (+21%). The difference between groups was significant at both time points (P = 0.007 and P = 0.039, respectively). In the P group, patients without fixation suffered less pain compared to those with single-suture fixation (1 month: -20.9 vs. -6.15%, P = 0.02; 3 months: -24.3 vs. -7.7%, P = 0.01). The infection rate was significantly lower in the P group during the 3-month follow-up (2.0 vs. 7.2%, P = 0.032). Surgery duration was significantly shorter in the P group (32.4 vs. 39.1 min; P < 0.001). No recurrence was observed at 3 months in both groups. CONCLUSIONS: Surgery duration, early postoperative, pain and infection rates were significantly reduced with self-gripping polyester mesh compared to Lichtenstein repair with polypropylene mesh. The use of fixation increased postoperative pain in the P group. The absence of early recurrence highlights the gripping efficiency effect.

[Heterotopic pancreas in the gallbladder. Diagnosis, therapy, and course of a rare developmental anomaly of the pancreas]. / Heterotopes Pankreasgewebe in der Gallenblase. Diagnostik, Therapie und Verlauf einer seltenen Entwicklungsanomalie der Bauchspeicheldrüse.

Ectopic pancreas is a rare entity but the second most prevalent pancreatic anomaly. Heterotopic pancreas is defined as the presence of pancreatic tissue without any anatomic or vascular continuity with the main body of the pancreas. Its aetiology is not clearly established. In 1916, Poppi published for the first time evidence of heterotopic pancreas in the gallbladder. A review of the literature up to the present showed only 28 more cases worldwide of ectopic pancreas in the gallbladder. Aberrant pancreas is incidentally discovered in 2% of autopsies and has been estimated to occur once in every 500 upper abdominal explorations. Ninety per cent of ectopic pancreas is found in the stomach, duodenum, and jejunum. Mostly it is asymptomatic and benign. For this reason, therapy is indicated only in patients with symptoms such as pyloric obstruction, bleeding, and malignant transformation. Surgical resection or endoscopic mucosal resection as a newer method are recommended.

Automated sampling of stormwater runoff in an urban watershed, north-central Texas.

Automated samplers were used to collect urban runoff in Pecan Creek, Denton, Texas. Runoff from four storm events was sampled at four stations. Concentrations of some heavy metals (cadmium and arsenic), as well as pesticides (atrazine and diazinon), exceeded maximum contaminant levels for drinking water, but were within ranges typical for urban runoff. Calcium and phosphorous concentrations were high compared to previous studies, which was attributed to soils, building materials, and fertilizer applications in the study area. First flush samples were more concentrated than composite samples for most of the constituents analyzed, but statistically different for only five constituents. Concentrations of four constituents differed significantly among stations, and six differed significantly among storms, due to variations in land use, channel composition, and storm conditions. Overall, the automated samplers were an effective way to sample urban runoff in Pecan Creek.

Comparison of self-report and hair analysis in detecting cocaine use in a homeless/transient sample.

Detection of current (past 30 days) drug use by analysis of hair was examined along with self-reports of current use in a 1994 treatment needs assessment survey; the sample was 179 homeless/transient adults in New York state. Results of radioimmunoassay of hair (RIAH) were used to evaluate the veracity of self-reports of current cocaine use. Only 26% of those persons whose hair tested positive for cocaine (n=115) admitted to having used cocaine in the past 30 days. Subjects eligible for treatment, as indicated by a DSM-III-R diagnosis of cocaine dependency, were nearly four times as likely to admit current cocaine use than those who were not dependent. These results are consistent with other studies of populations at high risk for substance use.

Selected in-treatment outcomes of long-term methadone maintenance treatment patients in New York State.

The New York State Office of Alcoholism and Substance Abuse Services (OASAS) licenses the largest system of methadone maintenance clinics nationwide. In 1996, a survey was undertaken to evaluate the functioning of patients continuously active in treatment for ten or more years. Information was obtained on a 10% random sample from the OASAS client data system and the records of the clinics. Data were collected concerning methadone dose, illicit drug and problematic alcohol use, employment, criminal activity, health, living situations, and the primary type of payment for treatment. A contrast group was constructed of discharged patients who had no more than 5 years of continuous treatment. The long-term active patients in the study sample showed superior outcomes on all variables, although some of the differences were small. However, the arrest rate for the discharged contrast group was 20 times as large as the arrest rate for the active study sample. These results are consistent with nationwide evaluations of methadone maintenance treatment. Factors that negatively impacted on the adjustments of the active patients were heavy use of crack/cocaine and disabilities. The long-term active patients in this sample belong to distinct subgroups with different levels of functioning, achievement, and ongoing health and social needs that must be investigated and addressed.

Causes and rates of death among methadone maintenance patients before and after the onset of the HIV/AIDS epidemic.

Causes of death and the mortality rates of active methadone patients and those who had left treatment were compared. Prior to the HIV epidemic, death rates among discharged methadone patients were more than twice that of patients who continued with their methadone treatment. However, the death rate from heroin-related causes in the post-treatment period was 51 times the rate among active patients. Alcohol-related conditions were the leading causes of death in patients more than 30 years old on methadone. During the post-treatment period, alcohol-related deaths were second to those of heroin-related causes. Alcohol-related deaths were particularly pronounced among black patients. Death rates among active male and female patients were identical, but the death rate for discharged female patients was greater than for discharged males. With the onset of the HIV epidemic in the 1980s, AIDS-related causes became the major cause of death in treatment. However, other causes of death, such as alcohol and other medical conditions, identified prior to the AIDS epidemic, persisted. AIDS-related deaths peaked in the mid-1990s and have recently subsided. However, within the past two years, deaths related to HCV have increased to 9% of all patient deaths in a major methadone program. With the emergence of HCV, deaths from this cause are expected to eclipse AIDS-related deaths within the next decade.

Introduction of proton pump inhibitors--consequences for surgical treatment of peptic ulcer.

BACKGROUND/AIMS: This retrospective study analyzes the influence of different factors on morbidity and mortality after surgical treatment of peptic ulcer. METHODOLOGY: At the Municipal Hospital of Offenbach, Germany, from 1985-1996, 485 patients underwent surgery. RESULTS: Of the 485 patients, 70.7% (343) were diagnosed to have duodenal ulcer and 29.2% (142) had suffered from gastric ulcer. During this period, 79.2% (384) of the operations were performed under emergency conditions because of acute complications (56% of these with perforation, 20% with penetration, 24% with ulcer bleeding), whereas the rest was done electively. Two hundred and ninety-one (60%) patients were male, the average age was 59 years and 71.7% (348) of the patients had certain concomitant diseases. We observed complications in 48% of the cases with a total postoperative mortality of 21%. CONCLUSIONS: Between 1985 and 1996 the total number of ulcer surgeries performed at the Municipal Hospital Offenbach per year has stayed almost constant. However, a definite increase of acute operations in addition to a decrease of elective interventions was noticed. The dissatisfying results of surgical treatment of peptic ulcer after the introduction of proton pump inhibitors seems to be the consequence of the negative selection of patients mentioned above. A connection could be proved between the age and condition of the patient, the type of the surgical intervention (acute or elective) and the morbidity and mortality after the surgery.

A hypnotically mediated guided imagery intervention for intrusive imagery: creating ground for figure.

Intrusive imagery can be seen as a cognitive dysfunction in the assimilation and accommodation of the psychological material represented by those images. From a gestalt psychological perspective, the intrusive image represents a figure without a ground that can provide meaning and context. Hypnotically mediated guided imagery interventions can be used to create a ground for the rogue image that metaphorically is an unassimilated figure; and thus allow for the creation of a new cognitive scheme. Four case examples are presented as well as a model for the intervention.

Colorectales Carcinom--Behandlungsalternative durch intraoperative Radiotherapie mittels Afterloading-flab-Technik?

Intraoperative radiotherapy (IORT) is a new concept in the treatment of recurrent and primary advanced colorectal tumors. Between October 1994 and December 1997 27 patients (primary tumor: 8, first recurrent tumor: 12, second recurrent tumor: 7) received IORT (32 applications). Chemotherapy and percutaneous radiotherapy had already been given to all patients with advanced and recurrent colorectal tumors. The intraoperative irradiation was performed through HDR iridium afterloading. A flexible flab--individually adapted to the "tumor bed"--was used as applicator. The contact dose ranged from 10 to 15 Gy. The mean operation time (rectum resection: 5, rectum amputation: 14, debulking: 8) increased by 30 min on average. Eight patients had postoperative complications: perianal wound infections (3), sacrovesical fistulas (3), leakage of anastomosis (1) and neural ureter dysfunction (1). To date--on average 17.1 months (range: 3-33) after operation--13 patients are free of tumor recurrence or show stable disease. Ten patients--all of them had macroscopic residual tumor--have local tumor progression combined with good quality of life. Only 4 patients died (acute kidney failure, stroke, marasmus, systemic progression). The afterloading flab technique represents a technically simple, minimally harmful procedure in the therapy of colorectal tumor. Even when IORT with electrons is not feasible or the patients have already been irradiated, a higher radiation dose is possible. Given the demonstrated rate of local tumor recurrence, the afterloading flab technique seems to be a valuable treatment alternative to extended, high-risk resections. Long-term follow-ups will be necessary.

Noninvasive physiologic monitoring of high-risk surgical patients.

OBJECTIVES: To study the feasibility of multicomponent noninvasive monitoring, consisting of a new bioimpedance method for estimating cardiac output together with routine pulse oximetry and transcutaneous oximetry, and to compare physiologic data obtained noninvasively with hemodynamic and oxygen transport data obtained by standard invasive pulmonary artery thermodilution catheter to evaluate circulatory function in high-risk surgical patients. DESIGN: Prospective descriptive analysis of the time course of physiologic patterns in surgical patients. SETTING: University-run county hospital. PATIENTS: Seventy-one consecutively monitored, high-risk critically ill surgical patients in their perioperative period. OUTCOME MEASURES: Simultaneous measurements by invasive and noninvasive methods to describe and compare the temporal physiologic patterns of survivors and nonsurvivors. RESULTS: The new impedance cardiac output estimations closely approximated those of the thermodilution method (r = 0.82, P < .001). Episodes of hypotension, tachycardia, low cardiac index, arterial hemoglobin desaturation, low transcutaneous oximetry, reduced oxygen delivery, and low oxygen consumption occurred with both groups but were more pronounced in the nonsurvivors than in the survivors. Noninvasive monitoring provided information similar to that of the thermodilution method. Both approaches indicated low flow and poor tissue perfusion (oxygenation) that was worse in the nonsurvivors. CONCLUSIONS: The multicomponent noninvasive monitoring provides continuous online, real-time displays of physiologic data that allow immediate recognition of circulatory dysfunction as well as the means to titrate therapy to appropriate predetermined therapeutic goals. The noninvasive systems are easy to apply, safe, inexpensive, reasonably accurate, and cost-effective.

Prospective, randomized trial of survivor values of cardiac index, oxygen delivery, and oxygen consumption as resuscitation endpoints in severe trauma.

The objective was to test prospectively supranormal values of cardiac index (CI), oxygen delivery index (DO2I), and oxygen consumption index (VO2I) as resuscitation goals to improve outcome in severely traumatized patients. We included patients > or = 16 years of age who had either (1) an estimated blood loss > or = 2000 mL or (2) a pelvic fracture and/or two or more major long bone fractures with > or = four units of packed red cells given within six hours of admission. The protocol resuscitation goals were CI > or = 4.5 L/min/m2, DO2I > or = 670 mL/min/m2, and VO2I > or = 166 mL/min/m2 within 24 hours of admission. The control resuscitation goals were normal vital signs, urine output, and central venous pressure. The 50 protocol patients had a significantly lower mortality (9 of 50, 18% vs. 24 of 65, 37%) and fewer organ failures per patient (0.74 +/- 0.28 vs. 1.62 +/- 0.45) than did the 75 control patients. We conclude that increased CI, DO2I, and VO2I seen in survivors of severe trauma are primary compensations that have survival value; augmentation of these compensations compared to conventional therapy decreases mortality.

Multicenter trial of a new thoracic electrical bioimpedance device for cardiac output estimation.

OBJECTIVE: To evaluate the capacity of a new thoracic electric bioimpedance system to estimate cardiac output compared with the conventional thermodilution method. DESIGN: Prospective, multicenter study. SETTING: A university-run county hospital, a university-run U.S. Veterans Affairs hospital, and a university-affiliated U.S. military hospital. PATIENTS: A series of 68 critically ill patients whose conditions required pulmonary artery catheter insertion. MEASUREMENTS AND MAIN RESULTS: A total of 842 simultaneous pairs of cardiac output estimations by conventional thermodilution and a new thoracic electric bioimpedance system that uses an improved signal processing technique based on an all-integer-coefficient filtering technology, using a time-frequency distribution that provides a high signal/noise ratio were evaluated. The r value was .86, r2 = .74, and p < .001 by regression analysis; the mean difference between the two methods relative to their average value was 16.6 +/- 12.9 (SD) %; the precision was 1.4 L/min or 0.8 L/min/m2; the bias was -0.013 L/min. The mean difference between successive pairs of thermodilution measurements was 8.6 +/- 0.6 (SD) %, which was about half the difference between simultaneous pairs of measurement by the two methods. The changes in impedance estimations were close to simultaneously measured changes in thermodilution estimates of cardiac output. CONCLUSIONS: The new bioimpedance system satisfactorily estimated cardiac output as measured by the thermodilution technique. The difference between the two estimations is more than made up for by the continuous noninvasive capability of the impedance system.

Temporal patterns of radiographic infiltration in severely traumatized patients with and without adult respiratory distress syndrome.

We prospectively evaluated the patterns of pulmonary structural and functional changes in 100 consecutive surgical intensive care unit trauma patients who had (1) emergent major surgery, (2) a pelvic fracture, or (3) two or more major long bone fractures. For each patient, arterial blood gas measurements (ABGs), central venous pressure (CVP), pulmonary capillary occlusion pressure (PAOP), thoracic compliance, arterial oxygen tension/fraction of inspired oxygen (PAO2/FIO2), pulmonary venous admixture (Qs/Qt), and portable chest roentgenograms were sequentially tracked. The senior staff radiologist interpreted all chest roentgenograms. Pulmonary infiltration was quantitated in each of six fields using a scale ranging from 0 to 4, with 0 being no infiltration and 4 being the maximum. Adult respiratory distress syndrome (ARDS) was defined as follows: Qs/Qt > or = 20%, PAO2/FIO2 < 250 or both; dependence on mechanical ventilation for life support for > or = 24 hours; PAOP or CVP or both < 20 mm Hg; and thoracic compliance < 50 mL/cm H2O. Time zero (T0) the time of onset of ARDS, was defined as the time these criteria were met. Eighty-three of 100 study group patients had penetrating injuries, and 17 were admitted with blunt trauma. Fifty-one of 100 patients developed ARDS: 36 of 51 died. Only 4 of 49 (8%) patients without ARDS died. The injured lungs of patients with and without ARDS had similar amounts of infiltration over most measured time intervals. The noninjured lungs of the ARDS patients, however, had significantly greater infiltration than those without ARDS at T0 and over subsequent time intervals.(ABSTRACT TRUNCATED AT 250 WORDS)

Sequence of physiologic patterns in surgical septic shock.

OBJECTIVES: Gradual, almost imperceptible transitions occur between localized infection, generalized infection, systemic manifestations of the sepsis syndrome, septic shock, and death. The aim of this study was to describe the sequential pattern of hemodynamic and oxygen transport patterns of survivors and nonsurvivors of septic shock, so as to differentiate primary from secondary and tertiary events, to evaluate possible physiologic mechanisms, and to provide a template to relate the appearance of biochemical mediators to the sequence of physiologic events. DESIGN: Prospective, cohort study. SETTING: University-run county hospital. PATIENTS: A series of 300 consecutive surgical patients with septic shock; 85 survived and 215 died. INTERVENTIONS: We used specific criteria to define stages as: a) early period, the first recorded increase in cardiac output; b) middle period, time of maximal metabolic activity defined as the highest recorded oxygen consumption (VO2); and c) late period, the time of death or recovery. MEASUREMENTS AND MAIN RESULTS: Hemodynamic and oxygen transport variables were measured at frequent intervals throughout the course of septic shock. Beginning with increased cardiac index and oxygen delivery (Do2), which were the earliest observed hemodynamic changes, there were progressive increases in cardiac index, DO2, and VO2. The values of these variables in the survivors were both greater than normal and greater than those values of the nonsurvivors at comparable time periods. These values decreased in the late stage in nonsurvivors. There were early transient reductions in VO2 that preceded the increase in temperature and the decrease in blood pressure in both survivors and nonsurvivors. Although 86% of the septic patients were hyperdynamic, there were transient hypodynamic episodes (defined as cardiac index < 2.5 L/min/m2) in < 10% of the measurements. Transient preterminal hypermetabolic periods occurred in 9% of the nonsurvivors. CONCLUSIONS: Increased cardiac index and DO2 represent compensations for circulatory deficiencies that limit body metabolism, as reflected by inadequate VO2. Survivors have higher cardiac index, DO2, and VO2 values than those values of both the nonsurvivors and normal values. These data suggest that therapy should be directed toward increasing cardiac index to > 5.5 L/min/m2, DO2 to > 1000 mL/min/m2, and VO2 to > 190 mL/min/m2 as therapeutic goals; these supranormal values were empirically determined by the patterns of the survivors. Further studies to describe temporal relationships of biochemical mediators of these physiologic patterns are needed.