Probing magnetism in 2D materials at the nanoscale with single-spin microscopy.

The discovery of ferromagnetism in two-dimensional (2D) van der Waals (vdW) crystals has generated widespread interest. Making further progress in this area requires quantitative knowledge of the magnetic properties of vdW magnets at the nanoscale. We used scanning single-spin magnetometry based on diamond nitrogen-vacancy centers to image the magnetization, localized defects, and magnetic domains of atomically thin crystals of the vdW magnet chromium(III) iodide (CrI3). We determined the magnetization of CrI3 monolayers to be ≈16 Bohr magnetons per square nanometer, with comparable values in samples with odd numbers of layers; however, the magnetization vanishes when the number of layers is even. We also found that structural modifications can induce switching between ferromagnetic and antiferromagnetic interlayer ordering. These results demonstrate the benefit of using single-spin scanning magnetometry to study the magnetism of 2D vdW magnets.

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.

Influence of two types of self-retaining retractors on multifidus muscle blood flow during dorsolateral thoracolumbar hemilaminectomy in dogs.

OBJECTIVES: To assess the influence of the use of Gelpi and Grevel retractors on multifidus muscle blood flow during hemilaminectomy, using a dorsolateral approach, for acute disc extrusion in dogs as measured by laser speckle contrast imaging (LSCI). METHODS: Blood flow in the multifidus muscles was measured intra-operatively using LSCI prior to insertion of the retractors, immediately after hemilaminectomy and removal of the retractors, and after 10 minutes of lavage of the surgical site. Plasma creatine kinase levels were measured preoperatively and 12-24 hours postoperatively. RESULTS: Muscular blood flow was significantly decreased following retraction and remained lower than initial values 10 minutes after lavage in all dogs. The decrease in blood flow was significantly greater with Gelpi retractors (n = 8) than with Grevel retractors (n = 10). No significant relation was found between the duration of retraction and postoperative changes in creatine kinase levels or blood flow. CLINICAL SIGNIFICANCE: Findings in this study demonstrate a drop in blood flow within the multifidus muscles using the dorsolateral approach regardless of retractor type used. Gelpi retractors seem to have greater influence on muscular blood flow than Grevel retractors. Further studies are warranted to confirm this second finding.

Optimization of the interface between radiology, surgery, radiotherapy, and pathology in head and neck tumor surgery: a navigation-assisted multidisciplinary network.

A navigation-assisted multidisciplinary network to improve the interface between radiology, surgery, radiotherapy, and pathology in the field of head and neck cancer is described. All implicated fields are integrated by a common server platform and have remote data access in a ready-to-use format. The margins of resection and exact locations of biopsies are mapped intraoperatively. The pathologist uses the numerical coordinates of these samples to precisely trace each specimen in the anatomical field. Subsequently, map-guided radiotherapy is planned. In addition to the benefits of image-guided resection, this model enables radiotherapy planning according to the specific coordinates of the resection defect plus any residually affected sites identified by the pathologist. Irradiation of adjacent healthy structures is thereby minimized. In summary, the navigation-assisted network described grants timely multidisciplinary feedback between all fields involved, attains meticulous pathological definition, and permits optimized coordinate-directed radiotherapy.

Le Fort I osteotomies using Bio-Oss® collagen to promote bony union: a prospective clinical split-mouth study.

The purpose of this study was to evaluate whether a bone substitute can be used to promote bony union in patients undergoing maxillary advancement after Le Fort l osteotomy. Nine patients were treated bilaterally with Le Fort I osteotomies and maxillary advancements of 5mm or less. In each patient, one gap was grafted with the bone substitute Bio-Oss(®) Collagen (BOC). The contralateral site was left empty and served as control. After 6 months there were still empty gaps in the control sites of three patients, while in the grafted sites all gaps were completely filled with bone. The histomorphometric analysis performed with biopsies from the region of the original gap showed a similar amount of new bone in both groups, however, in the test group the mean overall amount of the mineralized fraction was higher compared to the control group (test site 65.0±6.2%, control site 38.9±32.6%). The bone substitute seemed to be a suitable material to promote bony union in Le Fort I osteotomies. Further studies are needed to analyse whether this technique is efficient in preventing relapse and promoting bony union in larger advancements.

Virtual restoration of anatomic jaw relationship to obtain a precise 3D model for total joint prosthesis construction for treatment of TMJ ankylosis with open bite.

Temporomandibular joint (TMJ) reconstruction with a TMJ Concepts total joint prosthesis (TMJ Concepts, Ventura, USA) requires a precise 3D model of the jaws in centric occlusion. The authors present a virtual procedure for repositioning the lower jaw in centric occlusion to obtain a precise stereolithographic model for TMJ reconstruction using a custom-made total joint prosthesis in a case of TMJ ankylosis and anterior open bite.

Investigation of microstructural features in regenerating bone using micro computed tomography.

We illustrate some of the uses of micro-computed tomography (micro-CT) to study tissue-engineered bone using a micro-CT facility for imaging and visualizing biomaterials in three dimensions (3-D). The micro-CT is capable of acquiring 3D X-ray CT images made up of 2000(3) voxels on specimens up to 5 cm in extent with resolutions down to 2 microm. This allows the 3-D structure of tissue-engineered materials to be imaged across orders of magnitude in resolution. This capability is used to examine an explanted, tissue-engineered bone material based on a polycaprolactone scaffold and autologous bone marrow cells. Imaging of the tissue-engineered bone at a scale of 1 cm and resolutions of 10 microm allows one to visualize the complex ingrowth of bone into the polymer scaffold. From a theoretical viewpoint the voxel data may also be used to calculate expected mechanical properties of the tissue-engineered implant. These observations illustrate the benefits of tomography over traditional techniques for the characterization of bone morphology and interconnectivity. As the method is nondestructive it can perform a complimentary role to current histomorphometric techniques.

Bone response to unloaded titanium implants in the fibula, iliac crest, and scapula: an animal study in the Yorkshire pig.

The reconstruction of extended maxillary and mandibular defects with prefabricated free flaps is a two stage procedure, that allows immediate function with implant supported dentures. The appropriate delay between prefabrication and reconstruction depends on the interfacial strength of the bone-implant surface. The purpose of this animal study was to evaluate the removal torque of unloaded titanium implants in the fibula, the scapula and the iliac crest. Ninety implants with a sandblasted and acid-etched (SLA) surface were tested after healing periods of 3, 6, and 12 weeks, respectively. Removal torque values (RTV) were collected using a computerized counterclockwise torque driver. The bicortical anchored 8mm implants in the fibula revealed values of 63.73 Ncm, 91.50 Ncm, and 101.83 Ncm at 3, 6, and 12 weeks, respectively. The monocortical anchorage in the iliac crest showed values of 71.40 Ncm, 63.14 Ncm, and 61.59 Ncm with 12 mm implants at the corresponding times. The monocortical anchorage in the scapula demonstrated mean RTV of 62.28 Ncm, 97.63 Ncm, and 99.7 Ncm with 12 mm implants at 3, 6, and 12 weeks, respectively. The study showed an increase of removal torque with increasing healing time. The interfacial strength for bicortical anchored 8mm implants in the fibula was comparable to monocortical anchored 12 mm implants in the iliac crest and the scapula at the corresponding times. The resistance to shear seemed to be determined by the type of anchorage (monocortical vs. bicortical) and the length of the implant with greater amount of bone-implant interface.

[Endoscopically assisted Le Fort 1 osteotomy: a study in human cadaver heads]. / Endoskopisch gestützte LeFort-1-Osteotomie.

METHODS AND RESULTS: Endoscopically assisted Le Fort 1-osteotomy was performed in a cadaver study with six human skulls. Vertical incisions were used to approach the maxilla using the endoscope. The bone cuts could be carried out with a 4-mm osteotome preserving the buccal mucosa. The downfracture of the maxilla was accomplished without damaging the descending palatal arteries, which could be verified endoscopically. Rigid fixation was performed using 1.5-mm titanium plates (Synthes, Mathys AG, Bettlach, Switzerland) and self-drilling screws. DISCUSSION: This cadaver study showed that the Le Fort 1 osteotomy could be carried out through limited approaches using endoscopic techniques and self-drilling fixation tools. Further experimental work and improvements will help to introduce this technique into clinical application.

[Individually CAD-CAM technique designed, bioresorbable 3-dimensional polycaprolactone framework for experimental reconstruction of craniofacial defects in the pig]. / Individuell mit CAD-CAM-Technik hergestellte, bioresorbierbare dreidimensionale Polycaprolaktongerüste zur experimentellen Rekonstruktion von kraniofazialen Defekten beim Schwein.

METHODS: Twenty orbital defects (2 x 2 cm) were created in ten adult Yorkshire pigs. Two software products (Velocity and Mimix) were evaluated with regard to image processing, three-dimensional reconstruction, and fabrication of individually shaped polycaprolactone (PCL) scaffolds to reconstruct these defects. Four different techniques were tested for the reconstruction: group 1 = no reconstruction, group 2 = polylactide sheet, group 3 = PCL scaffold, group 4 = bone marrow-coated PCL scaffold. The pigs were sacrificed at 3 months. RESULTS: In group 1 soft tissue scar formation could be found, but without any new bone. Group 2 showed a thick fibrous capsule around the PLLA sheet, whereas at the border zone of the defect signs of new bone formation could be detected. In group 3 the PCL scaffolds were filled with fibrous tissue and some areas that showed new bone formation (6.4% of the area of the defect). In group 4 the new bone formation (17.8% of the area of the defect) was significantly higher in quantity than in group 3. CONCLUSION: The PCL scaffold coated with bone marrow seems to be a material that effectively provides osteoinduction with formation of new bone. Long-term results at 12 months are still pending.

[Long-term follow-up of 37 patients with retrofixation of the temporomandibular joint disk 1987-1995]. / Langzeitkontrolle von 37 Patienten mit Diskusretrofixation im Zeitraum von 1986-1995.

Between January 1986 and December 1995 64 patients with anterior disc displacement were operated on, the technique being disc retrofixation. Follow-up of 37 patients was possible. Successful treatment was determined using the following criteria: one single operation, the clinical examination and the patient's opinion. The operative treatment was considered as unsuccessful if the patient had to undergo more than one operation or if, postoperatively, the clinical symptoms remained unchanged or even increased. 6 out of 37 patients were operated on twice or three times, another four patients postoperatively complained of unchanged or increased clinical symptoms. Using these criteria, disc retrofixation was ineffective in 30%. Using the correct anatomic position as an additional criterion of effective treatment, unsuccessful retrofixation would be even more than 30%. As a consequence we no longer recommend this technique.

Repair of composite zygomatico-maxillary defects with free bone grafts and free vascularized tissue transfer.

INTRODUCTION: Three-dimensional repair of the zygomatico-maxillary defect calls for an elaborate technique to achieve facial symmetry and correct globe position. We present a technique, which combines the use of a free vascularized soft tissue flap and free bone grafts for repair of composite zygomatico-maxillary defects. PATIENTS: Three patients that underwent radical resection of the maxilla and the zygoma have undergone facial reconstruction using this technique. The mean follow up was 9 months. METHODS: The key points of this technique are: (1) precise reconstruction of the zygomatico-maxillary complex including the orbit; (2) creation of a skeletal framework for canthopexy and suspension of the free flap; (3) repair of through-and-through soft tissue defects with a folded musculocutaneous free flap; and (4) simultaneous harvesting and reconstruction using two surgical teams to reduce the duration of surgery. RESULTS: Reconstruction of the zygomatico-maxillary complex could be successfully accomplished in a single surgical procedure. CONCLUSION: This paper presents a method of repairing zygomatico-maxillary defects with free bone grafts and vascularized soft tissue. However, this concept has yet to be reviewed in the long term.

Endoscopically assisted Le Fort I osteotomy.

OBJECTIVES: A new technique of the Le Fort I osteotomy using endoscopic techniques through limited approaches has been evaluated. PATIENTS: This technique was first carried out successfully in a study on six cadavers. Thereafter we performed endoscopically assisted Le Fort l osteotomy in two patients. METHODS: Four vertical incisions were used in the vestibule (paranasally and posteriorly) as approaches. The endoscope allowed direct visualization of the osteotomy of the maxilla including the pterygomaxillary junction. The osteotomies could be accomplished with a straight 4 mm osteotome for medial and lateral antral walls and nasal septum and a curved osteotome for the pterygomaxillary junction. RESULTS: The procedures were successful. The descending palatal arteries could be preserved in all cases as a result of endoscopic control. Rigid fixation of the downfractured maxillae was carried out using self-drilling titanium screws and plates. CONCLUSION: Endoscopic visualization allowed safe osteotomy of the medial antral wall preserving the descending palatal artery in all cases and hence less bleeding. Postoperative oedema and swelling in the two clinical cases was definitely reduced when compared with the conventional technique. The time needed for these first two clinical cases was approximately 1 h 30 min, i.e., about 30 min more than with the open technique. Further experience and experimental work, and refinements in technique will help to improve this procedure in its clinical application.

[New possibilities for reconstructing extensive jaw defects with prefabricated microvascular fibula transplants and ITI implants]. / Neue Rekonstruktionsmöglichkeiten von ausgedehnten Kieferdefekten mit vorbereiteten mikrovaskulären Fibulatransplantaten und ITI-Implantaten.

The reconstruction of extensive jaw defects is frequently only possible with microvascular bone flaps. Here we are presenting an operative technique using prefabricated fibular flaps and osseointegrated implants. In a first operation, the fibula is prepared with implants, split skin graft, and a nonresorbable membrane. The jaw defect is reconstructed 6 weeks later and can be treated directly with a prosthesis thanks to osseointegrated implants. The technique is described with reference to 5 patients already operated according to this technique and the initial findings are evaluated.

Attitudes toward health-care, HIV infection, and perinatal transmission interventions in a cohort of inner-city, pregnant women.

The objective of this article is to explore attitudes of an inner-city, pregnant cohort about general and HIV-related prenatal care. Responses to an interview at initial prenatal care enrollment were compared using Chi-square and Fisher's exact tests. Of 75 women, drug users (51%) were more likely to say that they would defer initiating prenatal care (P = 0.03) and to minimize the risk of drug or alcohol use to the fetus (P = 0.04). Most (85%) viewed pregnancy as inappropriate for HIV infected women and primarily drug users (P = 0.06) would abort if HIV infected. Over half thought HIV transmission occurred most times or always. Only 20% had heard of a drug to reduce this risk, but 95% would take such a therapy. These inner-city, pregnant women disapproved of pregnancy if HIV infected and thought the risk of transmission was high. They knew little of how to reduce this risk but nearly all would accept a drug to prevent transmission.

Fluoroaluminate induces pertussis toxin-sensitive protein phosphorylation: differences in MC3T3-E1 osteoblastic and NIH3T3 fibroblastic cells.

Fluoride is an acknowledged bone-forming agent that may act through stimulation of osteoblast proliferation. Fluoride's action on osteoblasts and bone is potentiated by aluminum, which can form a complex with fluoride (fluoroaluminate) and activate heterotrimeric G proteins. Here we examined signaling pathways activated by fluoroaluminate in MC3T3-E1 osteoblastic and in NIH3T3 fibroblastic cells. In MC3T3-E1 cells, fluoroaluminate induced a decrease in cAMP levels and an increase in MAP and p70 S6 kinase phosphorylations. These responses were partially or completely prevented by pertussis toxin, an inhibitor of G alpha i proteins. In NIH3T3 cells, fluoroaluminate induced weaker tyrosine and MAP kinase phosphorylations. Fluoroaluminate, but not PDGF, induced a long-lasting tyrosine phosphorylation of a 130 kDa protein only in MC3T3-E1 cells. The expression of G alpha i2, but not of G alpha s and G alpha q/11 proteins was about 10-fold higher in MC3T3-E1 cells. Thus, different signaling in osteoblastic and fibroblastic cells may be due to differential expression of G alpha i proteins and tyrosine kinase substrates and could underlie fluoride's pharmacological action in bone.

Differences in binding of PI 3-kinase to the src-homology domains 2 and 3 of p56 lck and p59 fyn tyrosine kinases.

Two T cell-specific src-family tyrosine kinases, p56 lck (lck) and p59 fyn (fyn), are implicated in regulating PI 3-kinase activity in response to interleukin-2 (IL-2), a cytokine that induces T cell proliferation. The src- homology domains 3 (SH3) of src-family kinases can directly interact with the PI 3-kinase regulatory subunit p85 and this may be a mechanism to regulate PI 3-kinase activity. In order to understand the mode of PI 3-kinase activation by the IL-2 receptor, we examined the association of PI 3-kinase to SH2 and SH3 domains of lck and fyn in IL-2-dependent kit 225 cells. The fyn SH3 domain bound more PI 3-kinase and its p85 subunit than the lck SH3 domain, while the lck SH2 domain bound more PI 3-kinase than the fyn SH2 domain. None of these interactions were regulated by IL-2. Low binding of PI 3-kinase to the lck SH3 domain was not observed in IL-2-independent Jurkat T cells. Thus, SH3 and SH2 domains of lck and fyn bound different amounts of PI 3-kinase, a feature that was dependent on a T cell type, but was not influenced by IL-2.

Needs assessment for persons with severe mental illness: what services are needed for successful community living?

The development and implementation of effective community support systems are goals of many public mental health authorities who are attempting to shift the focus and dollars for mental health services from inpatient to community care. This article presents the results of a survey which asked 90 community mental health agency case managers to assess the community support and residential needs of over 1400 of their clients. Medication monitoring and therapy were rated high priority needs. Psychosocial treatment, day and vocational activities also ranked high. Survey responses regarding residential services indicated a need for more supported and supervised options.

Catheter ablation of ventricular tachycardia using defibrillator pulses: electrophysiological findings and long-term results.

Catheter ablation of ventricular tachycardia (VT) was attempted in 24 patients (mean age 49 +/- 15.1 years) with a history of recurrent sustained VT resistant to previous antiarrhythmic drug therapy. 14 patients (58.3%) had also failed to respond to long-term administration of amiodarone alone and in combination with class I antiarrhythmic drugs. Endocardial catheter mapping during induced or spontaneous VT and/or pacemapping were performed to identify the site of origin of VT. Direct-current high-energy anodal shocks were delivered from a conventional cardioverter with stored energies of 100, 200 or 400 J via the distal electrode of conventional catheters. A total of 139 shocks was delivered during the ablation procedure. One patient died from wall perforation. Within 1 week of ablation, nine patients developed spontaneous recurrences of monomorphic sustained VT, identical to the clinical VT, and one patient developed a VT with a new morphology. In addition, four patients had a recurrence of their clinical VT after several weeks. In seven of 14 patients with spontaneous recurrences after the first ablation procedure and in three patients in whom VT was again inducible at the end of the first week, a second ablation procedure was performed. One patient with inducible VT after the first and second ablation sessions was given a third ablation procedure, and was discharged from hospital on anti-arrhythmic drugs which were successful despite being previously ineffective. After a mean follow-up period of 14.1 +/- 9.1 months, there were no spontaneous recurrences of sustained VT in 17 patients (71%) (nine without antiarrhythmic drugs and eight on antiarrhythmic drugs). In the remaining patients, incessant non-sustained VT (n = 2) or recurrent sustained VT (n = 2) occurred, and two patients died suddenly (at 2 and 21 months). There was no correlation between catheter mapping data or the results of pre-discharge electrophysiological study and clinical outcome during long-term follow-up. Complications related to catheter ablation included pulmonary oedema, cardiac tamponade, femoral artery occlusion, multiple episodes of ventricular tachycardia/fibrillation and thrombus formation, each in one patient (major complications; n = 7,29.1%), as well as transient third degree AV block, transient right or left bundle branch block, transient marked ST elevation or transient atrial tachycardia (minor complications; n = 8, 33.3%). The results suggest that catheter ablation might become an effective procedure for the non-pharmacological treatment of sustained VT.(ABSTRACT TRUNCATED AT 400 WORDS)