MULTISCALE EXAMINATION AND MODELING OF ELECTRON TRANSPORT IN NANOSCALE MATERIALS AND DEVICES

For half a century the integrated circuits (ICs) that make up the heart of electronic devices have been steadily improving by shrinking at an exponential rate. However, as the current crop of ICs get smaller and the insulating layers involved become thinner, electrons leak through due to quantum mechanical tunneling. This is one of several issues which will bring an end to this incredible streak of exponential improvement of this type of transistor device, after which future improvements will have to come from employing fundamentally different transistor architecture rather than fine tuning and miniaturizing the metal-oxide-semiconductor field effect transistors (MOSFETs) in use today. Several new transistor designs, some designed and built here at Michigan Tech, involve electrons tunneling their way through arrays of nanoparticles. We use a multi-scale approach to model these devices and study their behavior. For investigating the tunneling characteristics of the individual junctions, we use a first-principles approach to model conduction between sub-nanometer gold particles. To estimate the change in energy due to the movement of individual electrons, we use the finite element method to calculate electrostatic capacitances. The kinetic Monte Carlo method allows us to use our knowledge of these details to simulate the dynamics of an entire device— sometimes consisting of hundreds of individual particles—and watch as a device ‘turns on’ and starts conducting an electric current. Scanning tunneling microscopy (STM) and the closely related scanning tunneling spectroscopy (STS) are a family of powerful experimental techniques that allow for the probing and imaging of surfaces and molecules at atomic resolution. However, interpretation of the results often requires comparison with theoretical and computational models. We have developed a new method for calculating STM topographs and STS spectra. This method combines an established method for approximating the geometric variation of the electronic density of states, with a modern method for calculating spin-dependent tunneling currents, offering a unique balance between accuracy and accessibility.

[Primary malignant melanoma of the parotid gland: a case report and review of the literature]

Malignant melanomas (MMs) of the parotid gland are relatively uncommon. They occur almost invariably as metastases from a primary tumour located in the region of the scalp or the mucous membranes of the nose, paranasal sinuses, or throat. Primary MMs arising in the parotid gland are extremely rare. It is assumed that they originate in the glandular tissue or in intraglandular lymph nodes. We present a case report and review of the literature on the diagnosis, treatment, and prognosis of intraparotid malignant melanoma. Diagnosis is based primarily on B-scan ultrasonography and fine-needle aspiration cytology. Patients with a cytological diagnosis of MM are further evaluated by magnetic resonance imaging and positron emission tomography and receive a thorough ear-nose-throat and dermatological examination. The treatment of choice is total parotidectomy and selective neck dissection. The effectiveness of adjuvant treatments such as radiotherapy, chemotherapy, or immunotherapy remains controversial. Patients with primary MMs of the parotid gland appear to have a better prognosis than those with parotid metastases from melanomas of the skin or mucous membranes.

Ultrasound-guided needle positioning in sensory nerve conduction study of the sural nerve

OBJECTIVES: To evaluate the usefulness of ultrasound imaging to improve the positioning of the recording needle for nerve conduction studies (NCS) of the sural nerve. METHODS: Orthodromic NCS of the sural nerve was performed in 44 consecutive patients evaluated for polyneuropathy. Ultrasound-guided needle positioning (USNP) was compared to conventional "blind" needle positioning (BNP), electrically guided needle positioning (EGNP), and to recordings with surface electrodes (SFN). RESULTS: The mean distance between the needle tip and the nerve was 1.1 mm with USNP compared to 5.1 mm with BNP (p<0.0001). The mean amplitude of the sensory nerve action potential (SNAP) was 21 microV with USNP and 11 microV with BNP (p<0.0001). Compared to BNP, nerve-needle distances and SNAP amplitudes did not improve with EGNP. SNAP amplitudes recorded with SFN were significantly smaller than with BNP, EGNP and USNP. CONCLUSION: Ultrasound increases the precision of needle positioning markedly, compared to conventional methods. The amplitude of the recorded SNAP is usually clearly greater using USNP. In addition, USNP is faster, less painful and less dependent on the patient. SIGNIFICANCE: USNP is superior to BNP, EGNP, and SFN in accurate measurement of SNAP amplitude. It has a potential use in the routine near-nerve needle sensory NCS of pure sensory nerves.

[Periapical surgery with histologic examination of the periapical lesion. A case report]

Periapical surgery is required when periradicular pathosis associated with endodontically treated teeth cannot be resolved by nonsurgical root canal therapy (retreatment), or when retreatment was unsuccessful, not feasible or contraindicated. Endodontic failures can occur when irritants remain within the confines of the root canal, or when an extraradicular infection cannot be eradicated by orthograde root canal treatment. Foreign-body reponses towards filling materials, towards cholesterol crystals or radicular cysts might prevent complete periapical healing. Following enhanced microsurgical techniques in the last years the success rates of apical surgery have improved considerably. The aim of the current case report is to describe the therapeutical approach to a persistent periapical lesion and its histologic examination.

In vitro comparison of laser fluorescence performance with visual examination for detection of occlusal caries in permanent and primary molars

The aim of this study was to compare the performance of the DIAGNOdent 2095 with visual examination for occlusal caries detection in permanent and primary molars. The sample comprised 148 permanent human molars and 179 primary human molars. The samples were measured and visually examined three times by two examiners. After measurement, the teeth were histologically prepared and assessed for caries extension. Sensitivity, specificity, accuracy and area under the receiver operating characteristics (ROC) curve were calculated. Intra-class correlation (ICC), unweighted kappa and the Bland and Altman method were used to assess inter- and intra-examiner reproducibility. DIAGNOdent showed higher specificity and lower sensitivity than did visual examination. The ICC values indicated an excellent agreement between the examinations. Kappa values varied from good to excellent for DIAGNOdent but from poor to good for visual examination. In conclusion, the DIAGNOdent may be a useful adjunct to conventional methods for occlusal caries detection.

Oral examination and radiographic evaluation of the dentition in wild cats from Namibia

Feline tooth resorption has been widely reported in domestic cats and sporadically described in other felidae. The goal of the present study was to determine the prevalence of tooth resorption and to report other dental problems in a population of wild felidae. Observations of dental disorders and anomalies were made in skulls from 73 wild felidae (cheetahs, leopards, caracals, African wildcats, and lions) originating from Namibia. In addition, radiographs were taken in 43 cases to determine signs of bone and root pathology. Radiographs showed varying stages of tooth resorption in 16.0% of the specimens. Other dental anomalies found included fused teeth, supernumerary roots, or missing teeth. The prevalence of dental resorption in wild felidae was lower than reported in the domestic cat.

Early diagnosis of temporomandibular joint involvement in juvenile idiopathic arthritis: a pilot study comparing clinical examination and ultrasound to magnetic resonance imaging

OBJECTIVES: To study the validity of both rheumatological and orthodontic examinations and ultrasound (US) as screening methods for early diagnosis of TMJ arthritis against the gold standard MRI. METHODS: Thirty consecutive juvenile idiopathic arthritis (JIA) patients were included in this pilot study. Rheumatological and orthodontic examinations as well as US were performed within 1 month of the MRI in a blinded fashion. Joint effusion and/or increased contrast enhancement of synovium or bone were considered signs of active arthritis on MRI. RESULTS: A total of 19/30 (63%) patients and 33/60 (55%) joints had signs of TMJ involvement on MRI. This was associated with condylar deformity in 9/19 (47%) patients and 15/33 (45%) joints. Rheumatological, orthodontic and US examinations correctly diagnosed 11 (58%), 9 (47%) and 6 (33%) patients, respectively, with active TMJ arthritis, but misdiagnosed 8 (42%), 10 (53%) and 12 (67%) patients, respectively, as having no signs of inflammation. The best predictor for active arthritis on MRI was a reduced maximum mouth opening. CONCLUSION: None of the methods tested was able to reliably predict the presence or absence of MRI-proven inflammation in the TMJ in our cohort of JIA patients. US was the least useful of all methods tested to exclude active TMJ arthritis.

The Uses of Violence: An Examination of some Cross-Cutting Issues

A general theory of violence may only be possible in the sense of a meta-theoretical framework, As such it should comprise a parsimonious set of general mechanisms that operate across various manifestations of violence. In order to identify such mechanisms, a general theory of violence needs to equally consider all manifestations of violence, in all societies, and at all times. Departing from this assumption this paper argues that three theoretical approaches may be combined in a non-contradictory way to understand violence as goal-directed instrumental behaviour: a theory of the judgment and decision-making processes operating in the situations that give rise to violence; a theory of the evolutionary processes that have resulted in universal cognitive and emotional mechanisms associated with violence; and a theory of the way in which social institutions structure violence by selectively enhancing its effectiveness for some purposes (i.e legitimate use of force) and controlling other types of violence (i.e crime). To illustrate the potential use of such a perspective the paper then examines some general mechanisms that may explain many different types of violence. In particular, it examines how the mechanisms of moralistic aggression (Trivers) and moral disengagement (Bandura) may account for many different types of violence.

Physical examination during chemoradiation predicts outcome of locally advanced head and neck cancer. Secondary results of a randomized phase III trial (SAKK 10/94)

OBJECTIVES To analyze the prognostic value of clinical tumor response during chemoradiation for locally advanced head and neck cancer. PATIENTS AND METHODS The locoregional response at 50.4Gy was assessed by physical examination (PE) in patients treated within the randomized trial SAKK 10/94 using hyperfractionated radiotherapy (RT), median total dose 74.4Gy with or without cisplatin 20mg/m(2) chemotherapy on 5 consecutive days during weeks 1 and 5 or 6 of RT. Response was classified as a complete response (CR), complete response with uncertainty (Cru), partial response (PR), stable disease (SD), or progressive disease (PD). The primary endpoint was time to treatment failure (TTF) due to any cause. Secondary endpoints included locoregional-recurrence-free survival (LRRFS), distant metastasis-free survival (DMFS) and overall survival (OS). Univariate and multivariate Cox proportional hazards (PH) models were applied to analyze the associations between survival endpoints and clinical tumor response. RESULTS A total of 136, 131 and 97 patients were evaluable for response at the primary tumor, lymph nodes and both sites combined, respectively. At 50.4Gy 57/136 (42%), 46/131 (35%) and 21/97 (22%) patients had a good response (CR/Cru vs. PR/SD) at the primary tumor, the lymph nodes, and both sites combined, respectively. The median follow-up times were 11.4, 9.6 and 11.4years for the three groups. Good responses were all significantly associated with improved TTF, LRRFS, DMFS and OS in univariate analysis whereas good response at the primary tumor and lymph nodes remained significantly associated with TTF and OS after multivariate Cox PH models. CONCLUSIONS Locoregional response at 50.4Gy was identified as predictor of oncologic outcome. PE during treatment should not be underestimated in clinical practice.

Recent skin self-examination and doctor visits in relation to melanoma risk and tumour depth

BACKGROUND Little is known about the potential benefit of skin self-examination for melanoma prevention and early detection. Objectives: To determine whether skin self-examination is associated with reduced melanoma risk, self-detection of tumours, and reduced risk of deeper melanomas. METHODS We used data from a population-based case-control study (423 cases, 678 controls) to assess recent skin self-examination in relation to self-detection, melanoma risk and tumour depth ( ≤1 mm; > 1 mm). Logistic regression was used to estimate odds ratios (ORs) and confidence intervals (CIs) for associations of interest. RESULTS Skin self-examination conducted 1-11 times during a recent year was associated with a possible decrease in melanoma risk (OR 0·74; 95% CI 0·54-1·02). Melanoma risk was decreased for those who conducted skin self-examination and saw a doctor (OR 0·52; 95% CI 0·30-0·90). Among cases, those who examined their skin were twice as likely to self-detect the melanoma (OR 2·23; 95% CI 1·47-3·38), but self-detection was not associated with shallower tumours. Tumour depth was reduced for those who conducted skin self-examination 1-11 times during a recent year (OR 0·39; 95% CI 0·18-0·81), but was not influenced by seeing a doctor, or by conducting skin self-examination and seeing a doctor. CONCLUSIONS Risk of a deeper tumour and possibly risk of melanoma were reduced by skin self-examination 1-11 times annually. Melanoma risk was markedly reduced by skin self-examination coupled with a doctor visit. We cannot, however, exclude the possibility that our findings reflect bias or confounding. Additional studies are needed to elucidate the potential benefits of skin self-examination for melanoma prevention and early detection.

Comparison of Newer-Generation Drug-Eluting With Bare-Metal Stents in Patients With Acute ST-Segment Elevation Myocardial Infarction: A Pooled Analysis of the EXAMINATION (clinical Evaluation of the Xience-V stent in Acute Myocardial INfArcTION) and COMFORTABLE-AMI (Comparison of Biolimus Eluted From an Erodible Stent Coating With Bare Metal Stents in Acute ST-Elevation Myocardial Infarction) Trials

OBJECTIVES This study sought to study the efficacy and safety of newer-generation drug-eluting stents (DES) compared with bare-metal stents (BMS) in an appropriately powered population of patients with ST-segment elevation myocardial infarction (STEMI). BACKGROUND Among patients with STEMI, early generation DES improved efficacy but not safety compared with BMS. Newer-generation DES, everolimus-eluting stents, and biolimus A9-eluting stents, have been shown to improve clinical outcomes compared with early generation DES. METHODS Individual patient data for 2,665 STEMI patients enrolled in 2 large-scale randomized clinical trials comparing newer-generation DES with BMS were pooled: 1,326 patients received a newer-generation DES (everolimus-eluting stent or biolimus A9-eluting stent), whereas the remaining 1,329 patients received a BMS. Random-effects models were used to assess differences between the 2 groups for the device-oriented composite endpoint of cardiac death, target-vessel reinfarction, and target-lesion revascularization and the patient-oriented composite endpoint of all-cause death, any infarction, and any revascularization at 1 year. RESULTS Newer-generation DES substantially reduce the risk of the device-oriented composite endpoint compared with BMS at 1 year (relative risk [RR]: 0.58; 95% confidence interval [CI]: 0.43 to 0.79; p = 0.0004). Similarly, the risk of the patient-oriented composite endpoint was lower with newer-generation DES than BMS (RR: 0.78; 95% CI: 0.63 to 0.96; p = 0.02). Differences in favor of newer-generation DES were driven by both a lower risk of repeat revascularization of the target lesion (RR: 0.33; 95% CI: 0.20 to 0.52; p < 0.0001) and a lower risk of target-vessel infarction (RR: 0.36; 95% CI: 0.14 to 0.92; p = 0.03). Newer-generation DES also reduced the risk of definite stent thrombosis (RR: 0.35; 95% CI: 0.16 to 0.75; p = 0.006) compared with BMS. CONCLUSIONS Among patients with STEMI, newer-generation DES improve safety and efficacy compared with BMS throughout 1 year. It remains to be determined whether the differences in favor of newer-generation DES are sustained during long-term follow-up.

Unusual presentation of alveolar echinococcosis as prostatic and paraprostatic cysts in a dog

BACKGROUND: Alveolar echinococcosis (AE) is caused by the larval stage (metacestode) of Echinococcus multilocularis. The domestic dog can act as a definitive host and harbor adult cestodes in its small intestine or become an aberrant intermediate host carrying larval stages that may cause severe lesions in the liver, lungs and other organs with clinical signs similar to AE in humans. CASE PRESENTATION: A case of canine AE, affecting the liver and prostate with development of multilocular hydatid paraprostatic cysts and possible lung involvement is described in an 8-year-old neutered male Labrador retriever dog.The dog presented with progressive weight loss, acute constipation, stranguria and a suspected soft tissue mass in the sublumbar region. Further evaluation included computed tomography of the thorax and abdomen, which revealed cystic changes in the prostate, a paraprostatic cyst, as well as lesions in the liver and lungs. Cytological examination of fine-needle aspirates of the liver, prostate and paraprostatic cyst revealed parasitic hyaline membranes typical of an Echinococcus infection and the presence of E. multilocularis-DNA was confirmed by PCR. The dog was treated with albendazole and debulking surgery was considered in case there was a good response to antiparasitic treatment. Constipation and stranguria resolved completely. Six months after the definitive diagnosis, the dog was euthanized due to treatment-resistant ascites and acute anorexia and lethargy. CONCLUSIONS: To the authors' knowledge, this is the first publication of an E. multilocularis infection in a dog causing prostatic and paraprostatic cysts. Although rare, E. multilocularis infection should be considered as an extended differential diagnosis in dogs presenting with prostatic and paraprostatic disease, especially in areas where E. multilocularis is endemic.

Computed tomographic and radiographic examination of dental structures in South American camelid specimen of different ages.

BACKGROUND Tooth root problems and periodontal diseases are common in South American camelids (SAC). The objective was to evaluate and optimize the imaging technique for dental radiography in SAC and to describe the radiographic and computed tomographic (CT) anatomy of normal teeth at different ages. In this study, the heads of 20 healthy SAC slaughtered for meat production or euthanized for reasons not related to dental problems included 7 female and 10 male llamas and 3 male alpacas. Using a standardized protocol, radiographs and CT scans of the 20 specimen were performed. RESULTS The most useful radiographic projections for mandibular and maxillary cheek teeth evaluation turned out to be lateral30°ventral-laterodorsal and lateral30°dorsal-lateroventral with slight separation of the dental arcades respectively. Digital radiographic and CT appearance of the mandibular and maxillary teeth were described from the beginning of mineralization till maturity. In addition the normal range of the CT radio density of different cheek teeth and different dental tissues were measured. Hounsfield units of different dental tissues of SAC turned out to be similar to equids. Deviation, shortening and partial destruction of the distal tooth root of mandibular 09's and 10's and of maxillary 09's was observed and the existence of a common pulp chamber in younger teeth was revealed. CONCLUSIONS The present study provides information about the dental imaging morphology in clinically healthy SAC. This basic information provides fundamental knowledge for evaluating images and planning treatments in clinically affected animals.