Large magnetic gap at the Dirac point in Bi2Te3/MnBi2Te4 heterostructures.

Magnetically doped topological insulators enable the quantum anomalous Hall effect (QAHE), which provides quantized edge states for lossless charge-transport applications1-8. The edge states are hosted by a magnetic energy gap at the Dirac point2, but hitherto all attempts to observe this gap directly have been unsuccessful. Observing the gap is considered to be essential to overcoming the limitations of the QAHE, which so far occurs only at temperatures that are one to two orders of magnitude below the ferromagnetic Curie temperature, TC (ref. 8). Here we use low-temperature photoelectron spectroscopy to unambiguously reveal the magnetic gap of Mn-doped Bi2Te3, which displays ferromagnetic out-of-plane spin texture and opens up only below TC. Surprisingly, our analysis reveals large gap sizes at 1 kelvin of up to 90 millielectronvolts, which is five times larger than theoretically predicted9. Using multiscale analysis we show that this enhancement is due to a remarkable structure modification induced by Mn doping: instead of a disordered impurity system, a self-organized alternating sequence of MnBi2Te4 septuple and Bi2Te3 quintuple layers is formed. This enhances the wavefunction overlap and size of the magnetic gap10. Mn-doped Bi2Se3 (ref. 11) and Mn-doped Sb2Te3 form similar heterostructures, but for Bi2Se3 only a nonmagnetic gap is formed and the magnetization is in the surface plane. This is explained by the smaller spin-orbit interaction by comparison with Mn-doped Bi2Te3. Our findings provide insights that will be crucial in pushing lossless transport in topological insulators towards room-temperature applications.

Photogrammetric Variables Used by Physical Therapists to Detect Neck Pain and to Refer for Physiotherapeutic Intervention: A Cross-Sectional Study.

OBJECTIVE: The purpose of this study were as follows (1): to investigate photogrammetry variables that physiotherapists may detect by visually inspecting the static body posture that distinguishes young adults with or without neck pain, which may lead to referral to a physiotherapy intervention, and (2) to assess the reliability of postural assessment and clinical decision-making. METHODS: We conducted a cross-sectional, observational, balanced, controlled, single-blinded study. Fourteen physiotherapists aged 33 (6) years were recruited as raters for postural assessment of adults aged 28 (7) years with (n = 30) or without neck pain (n = 30). Photogrammetry was performed to quantify the static body posture alignments and angles. Visual inspection was performed to indicate the presence of postural misalignment and neck pain and to refer to physiotherapy intervention. RESULTS: Symptomatic participants showed low- to moderate-intensity neck pain, a high frequency of chronic neck pain, and low disability scores. Photogrammetry analysis revealed no statistically significant difference between groups. Classification of the participants according to the raters' visual inspection yielded sets of photogrammetry variables with significant differences, with a large variability among those sets. Intrarater and interrater reliability of photogrammetry varied from moderate to excellent (intraclass correlation coefficient2,1 = [0.502; 0.995]; intraclass correlation coefficient2,2 = [0.564; 0.996). Interrater reliability for visual inspection was no better than chance (κLight = -0.013 to 0.011; ι = -0.002). CONCLUSION: Neither photogrammetry nor visual inspection distinguished the presence of neck pain in young adults. Using visual inspection, physiotherapists had unreliable clinical decision-making owing to high variability of photogrammetry variables used to distinguish postural misalignments, the presence of neck pain, and whether to refer young adults for physiotherapy intervention.

Pain Characteristics and Their Relationship With Motor Dysfunction in Individuals With Parkinson Disease-A Cross-Sectional Study.

BACKGROUND: Pain is a common symptom in Parkinson disease (PD). OBJECTIVES: To analyze the relationship between pain and motor dysfunction in individuals with PD. METHODS: Fifty-four individuals with PD were screened: Hoehn and Yahr scale score = 2.5 (1 to 4); median (range) age in the "on" period of anti-Parkinson medication was 66 (44 to 85) years. Pain was assessed using King's Parkinson's Disease Pain Scale (KPPS) and the Brief Pain Inventory (BPI). Performance in routine activities and motor function were assessed using Unified Parkinson Disease Rating Scale (UPDRS II and III); gait was assessed using the Dynamic Gait Index; and balance was assessed using the Mini-BESTest. RESULTS: Thirty-eight participants (70.3%) reported mild to moderate pain. A positive correlation was found between the total KPPS score and performance in general activities (UPDRS II) (rho = 0.29, P = 0.04); a negative correlation was found between pain intensity (BPI intensity) and motor function (UPDRS III; rho = -0.28, P = 0.04); and a negative correlation was found between pain intensity (BPI intensity) and the bradykinesia subscore of the UPDRS III (rho = -0.29, P = 0.04). There was no correlation between pain and gait performance or balance. The musculoskeletal pain was the predominant type (in 81.5% of subjects), followed by nocturnal pain (52.6%) and fluctuation-related pain (47.3%). The most painful areas were lower limbs (33.0%) and shoulders/cervical area (31.0%). Twenty-one of 38 participants (55.3%) reported pain interference in their working and walking ability and general activities. CONCLUSIONS: Pain was weakly correlated with performance in general activities and with bradykinesia but was not correlated with the remaining classic motor PD symptoms, either gait or balance performance. Pain was a prevalent symptom in the present sample, and the individuals reported its interference with functionality.

Programmable computing with a single magnetoresistive element.

The development of transistor-based integrated circuits for modern computing is a story of great success. However, the proved concept for enhancing computational power by continuous miniaturization is approaching its fundamental limits. Alternative approaches consider logic elements that are reconfigurable at run-time to overcome the rigid architecture of the present hardware systems. Implementation of parallel algorithms on such 'chameleon' processors has the potential to yield a dramatic increase of computational speed, competitive with that of supercomputers. Owing to their functional flexibility, 'chameleon' processors can be readily optimized with respect to any computer application. In conventional microprocessors, information must be transferred to a memory to prevent it from getting lost, because electrically processed information is volatile. Therefore the computational performance can be improved if the logic gate is additionally capable of storing the output. Here we describe a simple hardware concept for a programmable logic element that is based on a single magnetic random access memory (MRAM) cell. It combines the inherent advantage of a non-volatile output with flexible functionality which can be selected at run-time to operate as an AND, OR, NAND or NOR gate.

Co-doped ZnO epitaxial films: from a Brillouin-like paramagnet to a phase-separated superparamagnetic ensemble.

Co-doped ZnO films are epitaxially grown on sapphire by reactive magnetron sputtering. The preparation conditions such as temperature and the composition of the sputtering gas are systematically varied. For optimized growth conditions virtually all Co dopant atoms are located on substitutional Zn lattice sites as revealed by X-ray linear dichroism (XLD). The material behaves as a Brillouin-like paramagnet with S = 3/2 and L = 1 as revealed by integral and element specific magnetometry. Reducing the oxygen content during preparation leads to the onset of phase separation as revealed by X-ray diffraction, and more clearly by a strong reduction of the XLD signal. Such samples behave like a blocked superparamagnetic ensemble. In the entire range of preparation conditions no signs of intrinsic ferromagnetism are found.

The molecular genetics of Marfan syndrome and related disorders.

Marfan syndrome (MFS), a relatively common autosomal dominant hereditary disorder of connective tissue with prominent manifestations in the skeletal, ocular, and cardiovascular systems, is caused by mutations in the gene for fibrillin-1 (FBN1). The leading cause of premature death in untreated individuals with MFS is acute aortic dissection, which often follows a period of progressive dilatation of the ascending aorta. Recent research on the molecular physiology of fibrillin and the pathophysiology of MFS and related disorders has changed our understanding of this disorder by demonstrating changes in growth factor signalling and in matrix-cell interactions. The purpose of this review is to provide a comprehensive overview of recent advances in the molecular biology of fibrillin and fibrillin-rich microfibrils. Mutations in FBN1 and other genes found in MFS and related disorders will be discussed, and novel concepts concerning the complex and multiple mechanisms of the pathogenesis of MFS will be explained.

Predictors of retained hemothorax after trauma and impact on patient outcomes.

PURPOSE: Hemo/pneumothoraces are a common result of thoracic injury. Some of these injuries will be complicated by retained hemothorax (RH), which has previously been shown to be associated with longer hospitalizations. It has been proposed that early versus delayed intervention with video-assisted thoracoscopic surgery can reduce the duration of mechanical ventilation, hospital and ICU LOS, and costs in patients with RH. However, little is known regarding the effect of RH on these outcomes relative to patients with uncomplicated hemo/pneumothoraces. The aim of our study was to characterize factors present on admission that may be associated with RH and assess the impact of RH on outcomes. METHODS: A retrospective chart review was conducted and included all patients who underwent tube thoracostomy (TT) for traumatic hemo/pneumothorax admitted to a single urban adult and pediatric level I trauma center from January 2008 to September 2013. RESULTS: The study cohort included 398 patients, 17.6 % developed RH. RH was associated with significantly longer total duration of TT drainage (p < 0.001), hospital LOS (p < 0.001), and total hospital charges (p < 0.001). These associations remained significant in a subgroup analysis excluding patients with traumatic brain injury. Patients with bilateral injuries (OR 4.25, p < 0.001) and patients intubated on the day of admission (OR 2.30, p = 0.002) were significantly more likely to develop RH. There was also a small, but highly significant, association between increasing ISS and the development of RH (OR 1.07, p < 0.001). CONCLUSIONS: Our study suggests patients requiring ventilator support on admission and those with bilateral injuries are at increased risk of developing RH. Early identification of patients at risk for RH may allow for earlier intervention and potential benefits to the patient.

The combination of micro-resonators with spatially resolved ferromagnetic resonance.

We present two new and complementary approaches to realize spatial resolution for ferromagnetic resonance (FMR) on the 100 nm-scale. Both experimental setups utilize lithographically fabricated micro-resonators. They offer a detection sensitivity that is increased by four orders of magnitude compared with resonator-based FMR. In the first setup, the magnetic properties are thermally modulated via the thermal near-field effect generated by the thermal probe of an atomic force microscope. In combination with lock-in detection of the absorbed microwave power in the micro-resonator, a spatial resolution of less than 100 nm is achieved. The second setup is a combination of a micro-resonator with a scanning transmission x-ray microscope (STXM). Here a conventional FMR is excited by the micro-resonator while focused x-rays are used for a time-resolved snap-shot detection of the FMR excitations via the x-ray magnetic circular dichroism effect. This technique allows a lateral resolution of nominally 35 nm given by the STXM. Both experimental setups combine the advantage of low-power FMR excitation in the linear regime with high spatial resolution to study single and coupled nanomagnets. As proof-of-principle experiments, two perpendicular magnetic micro-stripes (5 µm × 1 µm) were grown and their FMR excitations were investigated using both setups.

Nonmagnetic band gap at the Dirac point of the magnetic topological insulator (Bi(1-x)Mn(x))2Se3.

Magnetic doping is expected to open a band gap at the Dirac point of topological insulators by breaking time-reversal symmetry and to enable novel topological phases. Epitaxial (Bi(1-x)Mn(x))2Se3 is a prototypical magnetic topological insulator with a pronounced surface band gap of ∼100 meV. We show that this gap is neither due to ferromagnetic order in the bulk or at the surface nor to the local magnetic moment of the Mn, making the system unsuitable for realizing the novel phases. We further show that Mn doping does not affect the inverted bulk band gap and the system remains topologically nontrivial. We suggest that strong resonant scattering processes cause the gap at the Dirac point and support this by the observation of in-gap states using resonant photoemission. Our findings establish a mechanism for gap opening in topological surface states which challenges the currently known conditions for topological protection.

The antiepileptic activity of JSTX-3 is mediated by N-methyl-D-aspartate receptors in human hippocampal neurons.

We analyzed the effect of the acylpolyaminetoxin JSTX-3 on the epileptogenic discharges induced by perfusion of human hippocampal slices with artificial cerebrospinal fluid lacking Mg2+ or N-methyl-D-aspartate. Hippocampi were surgically removed from patients with refractory medial temporal lobe epilepsy, sliced in the surgical room and taken to the laboratory immersed in normal artificial cerebrospinal fluid. Epileptiform activity was induced by perfusion with Mg2+-free artificial cerebrospinal fluid or by iontophoretically applied N-methyl-D-aspartate and intracellular and field recordings of CA1 neurons were performed. The ictal-like discharges induced by Mg2+-free artificial cerebrospinal fluid and N-methyl-D-aspartate were blocked by incubation with JSTX-3. This effect was similar to that obtained with the N-methyl-D-aspartate receptor antagonist DL (-)2-amino-5 phosphonovaleric acid. Our findings suggest that in human hippocampal neurons, the antiepileptic effect of JSTX-3 is mediated by its action on N-methyl-D-aspartate receptor.

Polyvalent immune globulin and cytomegalovirus infection after renal transplantation.

To determine whether polyvalent, immune globulin (IgG) prevents cytomegalovirus (CMV) infection after cadaver renal transplantation, 28 patients were randomly allocated to receive 12 weekly infusions of 500 mg/kg of IgG (n = 15) or no treatment (n = 13). Both groups were similar with respect to age, sex, antigen mismatches, number of diabetics, and pretransplant donor/recipient CMV antibody titers. Moderately severe CMV infections occurred in 10 (77%) of 13 control subjects compared with 8 (53%) of 15 IgG-treated patients (not significant). Among those who developed CMV infections, prophylactic IgG had no effect on the severity or duration of fever, leukopenia, or hepatic enzyme elevations. Since none of the IgG-treated patients or control subjects in this study developed life-threatening CMV complications, a beneficial effect of prophylactic IgG in the small number of patients at risk for more severe CMV infections could not be excluded. However, this investigation suggests that the routine, prophylactic administration of polyvalent IgG, to prevent or to ameliorate CMV infection in unselected cadaver renal transplant recipients, is not warranted.

Influence of cadaver donor age on posttransplant renal function and graft outcome.

To assess the impact of cadaver donor age on posttransplant renal function and graft survival, we analyzed our clinical results in 17 recipients of younger donor kidneys (less than 10 years) and 48 recipients of older donor kidneys (greater than 50 years) and compared them with a control group of 598 patients who received kidneys from donors between 11 and 50 years of age. The 3 groups were comparable with respect to recipient age, duration of dialysis, prior transfusions, previous transplants, cold ischemia time, HLA AB mismatches, cytotoxic antibody profile, posttransplant ATN, and prophylactic ALG treatment. The cumulative patient survival at 1, 2, and 3 years was not significantly different among the 3 groups, but the graft survival in recipients of older donor kidneys was significantly lower than the control (71% vs. 62% at 2 years, P = .09 and 66% vs. 55% at 3 years, P = .0003. The short-term renal function assessed at 1 month posttransplant was significantly lower in the older donor group compared with the control (creatinine clearance 45 mL/min vs. 59 mL/min, P = .0003). Likewise, the long-term renal function assessed at the last follow-up was also lower in the older donor group than the control (creatinine clearance 40 mL/min vs. 49 mL/min, P = .07). There were no significant differences in graft survival or short- or long-term renal function between the younger donor group and the control group. These observations suggest that transplantation of a kidney from an older cadaver donor is associated with an inferior posttransplant outcome. The practical decision whether or not to use an older donor kidney should be individualized taking this as well as other factors into account.

Clinical impact of replacing Minnesota antilymphocyte globulin with ATGAM.

In August 1992, we replaced Minnesota antilymphocyte globulin (MALG) with lymphocyte immune globulin, antithymocyte globulin (equine) (ATGAM) in our immunosuppression protocols. The clinical impression of increased graft rejection prompted our assessment of the effect of this change on patient and graft outcome. The initial study group consisted of 426 renal transplant recipients transplanted between October 1, 1987, and September 21, 1993. After exclusions, 388 transplant events, with a minimum 8-month follow-up, made up the final study cohort: 323 patients received MALG and 65 received ATGAM. Immunosuppression included intravenous methylprednisolone, oral prednisone, oral AZA, CsA in some cases, and intravenous MALG or ATGAM, 15 mg/kg/day, for 7 to 14 days. Acute rejection was treated with high dose intravenous steroids and steroid-resistant episodes were treated additionally with either MALG or OKT3. Statistical comparisons were stratified for multiple patient characteristics and treatment variations. There was a greater incidence of rejection in general, and a higher incidence of steroid-resistant episodes requiring subsequent antilymphocyte globulin therapy (P = 0.0073) in patients receiving ATGAM versus MALG. No difference was seen in the incidence of CMV infection or blood-borne sepsis. Lymphoma occurred in 3 MALG and 2 ATGAM recipients. MALG recipients were significantly less likely to experience rejection within the first 60 days after transplant (P = 0.0127 using unstratified data; P < 0.0001 when data were stratified for patient characteristics). The relative risk of acute rejection for posttransplant days 5, 7, 10, and 14 was consistently higher for ATGAM-treated patients. We conclude that MALG and ATGAM are not equivalent drugs, and that MALG is a more effective immunosuppressant, and is just as safe as ATGAM in our protocol environment.

Irradiation of bilateral orbital lymphoma: a non-coplanar technique with case reports.

Bilateral synchronous involvement of the orbits by lymphoma is an uncommon event. Therefore, the irradiation techniques for this disease are not well refined. Depending on the technique used, one has to decide between underdosing the anterior segment of the orbit and the frequently involved lacrimal glands or to tolerate shield related in homogeneities in the range of 40 to 50% as well as higher doses to the midline structures, e.g. the optic chiasma. To avoid the above shortcomings we developed a technique by which half the prescribed dose is delivered by pairs of beams angulated in the transverse plane and the other half by pairs of beams angulated in the sagittal plane. Film dosimetry in a phantom confirms that the entire orbit, including its anterior portion, is well covered, the lens is protected, and the dose to the mid-sagittal structures is not increased. The dose inhomogeneity is in the range of 20% which represents a substantial improvement over alternative methods. Two irradiated patients with bilateral orbital lymphoma are presented with local control and no ophthalmic or other side effects as of last follow-up.

Tidal volume reduction in ARDS. Effect on cardiac output and arterial oxygenation.

During continuous positive pressure ventilation (CPPV), mean airway pressure and lung volume will be influenced both by the tidal volume (VT) employed and the amount of positive end-expiratory pressure (PEEP). The effect of varying levels of CPPV on PaO2 and cardiac output (Q) has been previously assessed by adjusting the level of PEEP at constant VT. This study examined the influence of a 200-ml reduction in VT, at a constant PEEP of 15 cm H2O, on the PaO2 and Q of 21 patients with adult respiratory distress syndrome (ARDS). The relationship between change in Q and change in total respiratory system compliance (Cst) after VT reduction was also examined. VT reduction from 14.1 +/- 0.8 ml/kg to 11.2 +/- 0.9 ml/kg yielded an increase in Q (+ 15 +/- 12 percent, p less than 0.01) without a significant change in PaO2 (-6.3 +/- 15.0 mm Hg, p = 0.08). Cst increased with VT reduction (+ 3.1 +/- 1.8 ml/cm H2O). There was only a modest correlation (r = +0.42, p = 0.06) between delta Q percent and delta Cst following VT reduction. VT reduction at high level PEEP may yield a significant improvement in Q and net O2 delivery, but the degree of hemodynamic improvement is variable and is not reliably predicted noninvasively by measurement of Cst.

Management of dialysis-associated steal syndrome complicating upper extremity arteriovenous fistulas: use of intraoperative digital photoplethysmography.

Dialysis-associated steal syndrome (DASS) occurring after creation of arteriovenous fistulas often necessitates ligation of the fistula. From June 1987 to June 1990, a total of 542 upper extremity arteriovenous fistulas were constructed: radiocephalic fistulas in 182 patients, 325 forearm loop grafts and 32 upper arm loop grafts. We managed 27 patients with DASS including two patients who were referred from other hospitals. DASS developed in two patients (1%) with radiocephalic fistulas and in 23 patients (6.4%) with arteriovenous grafts. Of the 27 patients, the fistula was ligated in nine because of tissue loss, severity of symptoms, or absence of improvement in digital pressure with the fistula occluded. Intraoperative digital photoplethysmography was used to guide the amount of graft narrowing in 16 patients. The goal was to obtain a digital blood pressure of 50 mm Hg or digital to brachial ratio of more than 0.6. Ten of the 16 patients had satisfactory graft function for more than 6 months, and all patients had improvement or resolution of the steal syndrome. We conclude that DASS is an uncommon complication of upper extremity arteriovenous shunts and narrowing of the fistula and that using intraoperative digital photoplethysmography as a guide is a useful method for relieving the steal syndrome and salvaging the shunt.

Abdominal vena caval injuries: outcomes remain dismal.

BACKGROUND: The mortality rate for abdominal vena caval injuries remains high. We examined the experience of a level I trauma center to determine factors significant to the outcome in these injuries. METHODS: Forty-seven patients were identified in a retrospective review (1989 to 1999) of patients were identified with abdominal vena caval injury. Data were analyzed by uni- and multivariate methods, including logistic regression. RESULTS: Most of the individuals with abdominal vena caval injuries were young male patients who were injured by penetrating trauma and who were hypotensive on arrival. The severity of injury and the number of organs injured was high. The overall mortality rate was 55%. Nonsurvivors were more often hypotensive in the field with physiologic derangement consistent with hemorrhagic shock. Type and location of injury as well as method of repair were associated with death. Multiple regression analysis revealed that prehospital initial systolic blood pressure and intraoperative bicarbonate levels were independent predictors of survival. CONCLUSIONS: We identified factors related to poor outcome, including suprarenal and retrohepatic location of injury and variables that reflected the evolution of shock. Management should include appropriate resuscitation and ultimately may require novel operative techniques.

Initial experience with laparoscopic live donor nephrectomy.

BACKGROUND: Advances in laparoscopic instruments and video technology have made laparoscopic donor nephrectomy (LDN) feasible. We report our initial experience with this technique. METHODS: A retrospective review of 30 open donor nephrectomies and our first 30 LDNs was performed to assess donor and recipient outcome and resource usage. RESULTS: LDN was successfully completed in 26 donors (87%). The increased operative time and costs were balanced by less postoperative pain, earlier discharge, earlier return to normal activity and work, fewer incision problems, and less personal financial loss. Recipient outcome was not affected. CONCLUSION: LDN is technically feasible and safe, and recipient graft outcomes are equivalent. Convalescence is shortened, and there is less personal financial loss. LDN offers significant benefit to the donor and may result in increased organ donation.

Assessment of the relationship between timing of fixation of the fracture and secondary brain injury in patients with multiple trauma.

BACKGROUND: It has been suggested that early fixation of a fracture is deleterious to eventual neurologic outcome. We undertook this study to determine whether the timing of fracture fixation is correlated to neurologic outcome. METHODS: We retrospectively reviewed patients with severe head and orthopedic injuries requiring fracture fixation. Patients were divided into two groups: early fracture fixation (< 24 hours after injury) and late fracture fixation (> 24 hours after injury). RESULTS: One hundred twenty-three patients met entry criteria. During fracture fixation, the early group had a significant 2-, 3-, and 2-fold increase in crystalloid, blood infusion, and blood loss, respectively. There was no difference in oxygen saturation and systolic blood pressure or episodes of cranial hypertension or hypoperfusion. There was no difference in outcomes as measured by in-hospital complications, stay in the intensive care unit or hospital, mortality rates, hospital discharge or follow-up Glasgow Coma Scores, or long-term orthopedic or neurologic results. CONCLUSIONS: Patients undergoing fracture fixation with severe head injury mandate monitoring of intracranial pressure and perfusion and tailored fluid resuscitation to meet specific organ end points. Integrating end organ perfusion and pressure with meticulous fluid status during the definitive repair phase may reduce the exposure to secondary brain injury in patients undergoing early fracture fixation.

Combined orthopedic and vascular injury in the lower extremities: indications for amputation.

A retrospective review was undertaken to determine risk factors associated with amputation after open fractures of the lower extremity that were complicated by vascular injury. During an 11-year period ending in December 1987, we observed open fractures in 31 patients and injuries to the popliteal artery in 16 patients, to the tibial arteries in eight patients, to the femoral artery in five patients, and to the dorsal artery of the foot in two patients. Vascular repair was accomplished in 25 patients; 12 patients had primary end-to-end anastomosis, 12 patients had reverse saphenous vein grafts, and one patient had a bovine graft. Of these 25 patients, five patients required amputation because of infection and three patients required amputation because of continued ischemia. Three patients with irreparable damage had immediate amputation, and three patients without distal ischemia had vessel ligation only. The risk factors associated with amputation were shock on admission (10 of 19 patients [p less than 0.02]) and a crushed extremity (10 of 18 patients [p less than 0.01]). The overall amputation rate, which included three immediate amputations and eight late amputations, was 35.2%. The data suggest that limb salvage is possible in two thirds of patients with combined orthopedic and vascular injuries of the lower extremity, but a history of shock or crush injury with vascular compromise is an unfavorable prognostic sign.