Characteristics of Alfven surface waves along moving cylindrical plasma columns

The dispersive and stability characteristics of Alfven surface waves (ASW) along the boundary of the moving cylindrical plasma column, surrounded by a stationary medium embedded in a parallel magnetic field is studied. The nature of the symmetric and asymmetric modes on the interface parameters is also discussed.

Development and Simulation of a Variable Rate Controller for an Air search and Air Sampling Unmanned Aerial System

This report describes the development and simulation of a variable rate controller for a 6-degree of freedom nonlinear model. The variable rate simulation model represents an off the shelf autopilot. Flight experiment involves risks and can be expensive. Therefore a dynamic model to understand the performance characteristics of the UAS in mission simulation before actual flight test or to obtain parameters needed for the flight is important. The control and guidance is implemented in Simulink. The report tests the use of the model for air search and air sampling path planning. A GUI in which a set of mission scenarios, in which two experts (mission expert, i.e. air sampling or air search and an UAV expert) interact, is presented showing the benefits of the method.

A cryptographic analysis of the TLS 1.3 handshake protocol candidates

The Internet Engineering Task Force (IETF) is currently developing the next version of the Transport Layer Security (TLS) protocol, version 1.3. The transparency of this standardization process allows comprehensive cryptographic analysis of the protocols prior to adoption, whereas previous TLS versions have been scrutinized in the cryptographic literature only after standardization. This is even more important as there are two related, yet slightly different, candidates in discussion for TLS 1.3, called draft-ietf-tls-tls13-05 and draft-ietf-tls-tls13-dh-based. We give a cryptographic analysis of the primary ephemeral Diffie–Hellman-based handshake protocol, which authenticates parties and establishes encryption keys, of both TLS 1.3 candidates. We show that both candidate handshakes achieve the main goal of providing secure authenticated key exchange according to an augmented multi-stage version of the Bellare–Rogaway model. Such a multi-stage approach is convenient for analyzing the design of the candidates, as they establish multiple session keys during the exchange. An important step in our analysis is to consider compositional security guarantees. We show that, since our multi-stage key exchange security notion is composable with arbitrary symmetric-key protocols, the use of session keys in the record layer protocol is safe. Moreover, since we can view the abbreviated TLS resumption procedure also as a symmetric-key protocol, our compositional analysis allows us to directly conclude security of the combined handshake with session resumption. We include a discussion on several design characteristics of the TLS 1.3 drafts based on the observations in our analysis.

Sleep-related crash characteristics: Implications for applying a fatigue definition to crash reports

Sleep-related (SR) crashes are an endemic problem the world over. However, police officers report difficulties in identifying sleepiness as a crash contributing factor. One approach to improving the sensitivity of SR crash identification is by applying a proxy definition post hoc to crash reports. To identify the prominent characteristics of SR crashes and highlight the influence of proxy definitions, ten years of Queensland (Australia) police reports of crashes occurring in ≥100 km/h speed zones were analysed. In Queensland, two approaches are routinely taken to identifying SR crashes. First, attending police officers identify crash causal factors; one possible option is ‘fatigue/fell asleep’. Second, a proxy definition is applied to all crash reports. Those meeting the definition are considered SR and added to the police-reported SR crashes. Of the 65,204 vehicle operators involved in crashes 3449 were police-reported as SR. Analyses of these data found that male drivers aged 16–24 years within the first two years of unsupervised driving were most likely to have a SR crash. Collision with a stationary object was more likely in SR than in not-SR crashes. Using the proxy definition 9739 (14.9%) crashes were classified as SR. Using the proxy definition removes the findings that SR crashes are more likely to involve males and be of high severity. Additionally, proxy defined SR crashes are no less likely at intersections than not-SR crashes. When interpreting crash data it is important to understand the implications of SR identification because strategies aimed at reducing the road toll are informed by such data. Without the correct interpretation, funding could be misdirected. Improving sleepiness identification should be a priority in terms of both improvement to police and proxy reporting.

Odour sampling. 2. Comparison of physical and aerodynamic characteristics of sampling devices: A review

Sampling devices differing greatly in shape, size and operating condition have been used to collect air samples to determine rates of emission of volatile substances, including odour. However, physical chemistry principles, in particular the partitioning of volatile substances between two phases as explained by Henrys Law and the relationship between wind velocity and emission rate, suggests that different devices cannot be expected to provide equivalent emission rate estimates. Thus several problems are associated with the use of static and dynamic emission chambers, but the more turbulent devices such as wind tunnels do not appear to be subject to these problems. In general, the ability to relate emission rate estimates obtained from wind tunnel measurements to those derived from device-independent techniques supports the use of wind tunnels to determine emission rates that can be used as input data for dispersion models.

Electrical transport and crystallization studies of glassy semiconducting Si20Te80 alloy at high pressure

The effect of pressure on the electrical resistivity of bulk Si20Te80 glass is reported. Results of calorimetric, X-ray and transmission electron microscopy investigations at different stages of crystallization of bulk Si20Te80 glass are also presented. A pressure induced glass-to-crystal transition occurs at a pressure of 7 GPa. Pressure and temperature dependence of the electrical resistivity of Si20Te80 glass show the observed transition is a pressure induced glassy semiconductor to crystalline metal transition. The glass also exhibits a double Tg effect and double stage crystallization, under heating. The differences between the temperature induced crystallization (primary crystallization) and pressure induced congruent crystallization are discussed.

Nonlinear I-V characteristics of senmiconducting paints

The oxide-based high resistivity semiconducting Paints can be used on high voltage insulators for improved performance. They were found to exhibit nonlinear I-V characteristics which are reported here. The paints exhibited power law relationship and a sharp transition in merhanism of conduction at a critical voltage.

Electrical Transport Studies in as-se Glasses

The DC and AC conductivity studies of As---Se glasses over a wide range of compositions have been reported and discussed. The contribution to conductivity from transport among extended states has been delineated and the possible existence of a characteristic temperature is indicated. Two conductivity maxima have been observed as a function of composition in AC conductivities at lower temperatures.

Multipath Dissemination in Regular Mesh Topologies

Mesh topologies are important for large-scale peer-to-peer systems that use low-power transceivers. The Quality of Service (QoS) in such systems is known to decrease as the scale increases. We present a scalable approach for dissemination that exploits all the shortest paths between a pair of nodes and improves the QoS. Despite th presence of multiple shortest paths in a system, we show that these paths cannot be exploited by spreading the messages over the paths in a simple round-robin manner; nodes along one of these paths will always handle more messages than the nodes along the other paths. We characterize the set of shortest paths between a pair of nodes in regular mesh topologies and derive rules, using this characterization, to effectively spread the messages over all the available paths. These rules ensure that all the nodes that are at the same distance from the source handle roughly the same number of messages. By modeling the multihop propagation in the mesh topology as a multistage queuing network, we present simulation results from a variety of scenarios that include link failures and propagation irregularities to reflect real-world characteristics. Our method achieves improved QoS in all these scenarios.

Processing of Stimulus Repetition and Change in the Somatosensory System: Recordings of Electrical and Magnetic Brain Responses

In the present work, effects of stimulus repetition and change in a continuous stimulus stream on the processing of somatosensory information in the human brain were studied. Human scalp-recorded somatosensory event-related potentials (ERPs) and magnetoencephalographic (MEG) responses rapidly diminished with stimulus repetition when mechanical or electric stimuli were applied to fingers. On the contrary, when the ERPs and multi-unit a ctivity (MUA) were directly recorded from the primary (SI) and secondary (SII) somatosensory cortices in a monkey, there was no marked decrement in the somatosensory responses as a function of stimulus repetition. These results suggest that this rate effect is not due to the response diminution in the SI and SII cortices. Obviously the responses to the first stimulus after a long "silent" period are nhanced due to unspecific initial orientation, originating in more broadly distributed and/or deeper neural structures, perhaps in the prefrontal cortices. With fast repetition rates not only the late unspecific but also some early specific somatosensory ERPs were diminished in amplitude. The fast decrease of the ERPs as a function of stimulus repetition is mainly due to the disappearance of the orientation effect and with faster repetition rates additively due to stimulus specific refractoriness. A sudden infrequent change in the continuous stimulus stream also enhanced somatosensory MEG responses to electric stimuli applied to different fingers. These responses were quite similar to those elicited by the deviant stimuli alone when the frequent standard stimuli were omitted. This enhancement was obviously due to the release from refractoriness because the neural structures generating the responses to the infrequent deviants had more time to recover from the refractoriness than the respective structures for the standards. Infrequent deviant mechanical stimuli among frequent standard stimuli also enhanced somatosensory ERPs and, in addition, they elicited a new negative wave which did not occur in the deviants-alone condition. This extra negativity could be recorded to deviations in the stimulation site and in the frequency of the vibratory stimuli. This response is probably a somatosensory analogue of the auditory mismatch negativity (MMN) which has been suggested to reflect a neural mismatch process between the sensory input and the sensory memory trace.

Finnish Homicides and Mental Disorders: An investigation of offense and offender characteristics

Although the majority of people with mental illness are not violent, scientific studies over the last decades show that certain psychiatric disorders increase the risk of violent behavior, including homicide. This thesis examined crime scene behaviors and offender background characteristics among mentally ill Finnish homicide offenders. Previously, homicide crime scene behaviors have been investigated in relation to offender demographic characteristics, whereas this study compares the behaviors of offenders with various mental illnesses. The study design was a retrospective chart review of the forensic psychiatric statements of Finnish homicide offenders. The work consists of four substudies. The aims of the study were as follows: To describe differences in the childhood and family backgrounds as well as in the adolescent and adult adjustment of Finnish homicide offenders belonging to different diagnostic categories (schizophrenia, personality disorder, alcoholism, drug addiction or no diagnosis). Further, the study examined associations between the crime scene behaviors and mental status of these offenders. Also, the distinguishing characteristics between two groups of offenders with schizophrenia were examined: early starters, who present antisocial behavior before the onset of schizophrenia, and late starters, who first offend after the onset of mental disorder. Finally, it was investigated how the use of excessive violence is associated with clinical and circumstantial variables as well as offender background characteristics among homicide offenders with schizophrenia. The main findings of the study can be summarized as follows. First, offenders with personality disorder or drug addiction had experienced multiple difficulties in their early environments: both family and individual problems were typical. Offenders with schizophrenia were relatively well-adjusted in childhood compared to the other groups. However, in adolescence and adulthood, social isolation, withdrawal and other difficulties attributable to these offenders illness became evident. In several aspects, offenders with alcohol dependency resembled offenders with no diagnosis in that these offenders had less problematic backgrounds compared to other groups. Second, the results showed that crime scene behaviors, victim gender and the victim-offender relationship differ between the groups. In particular, offenders with a diagnosis of schizophrenia or drug addiction have some unique features in their crime scene behaviors and choice of victims. Offenders with schizophrenia were more likely to kill a blood relative, to use a sharp weapon and to injure the victim s face. Drug addiction was associated with stealing from the victim and trying to cover up the body. Third, the results suggest that the offense characteristics of early- and late-start offenders with schizophrenia differ only modestly. However, several significant differences between the groups were found in characteristics of offenders: early starters had experienced a multitude of problems in their childhood surroundings and also later in life. Fourth, violent acts where the offender did not commit the offense alone or had previous homicidal history were predictive of excessive violence among offenders with schizophrenia. Positive psychotic symptoms did not predict the use of excessive violence. Nearly one third of the cases in the sample involved multiple and severe violence, including features such as sadism, mutilation, sexual components or extreme stabbing. In sum, mentally disordered homicide offenders are heterogeneous in their offense characteristics as well as their background characteristics. Empirically based information on how the offender s mental state is associated with specific crime scene behaviors can be utilized within the police force in developing methods of prioritizing suspects in unsolved homicide cases. Also, these results emphasise the importance of early interventions for problem families and children at risk of antisocial behavior. They may also contribute to the development of effective treatment for violent offenders.

Effects of increasing neuromuscular electrical stimulation current intensity on cortical sensorimotor network activation: A time domain fNIRS study

Neuroimaging studies have shown neuromuscular electrical stimulation (NMES)-evoked movements activate regions of the cortical sensorimotor network, including the primary sensorimotor cortex (SMC), premotor cortex (PMC), supplementary motor area (SMA), and secondary somatosensory area (S2), as well as regions of the prefrontal cortex (PFC) known to be involved in pain processing. The aim of this study, on nine healthy subjects, was to compare the cortical network activation profile and pain ratings during NMES of the right forearm wrist extensor muscles at increasing current intensities up to and slightly over the individual maximal tolerated intensity (MTI), and with reference to voluntary (VOL) wrist extension movements. By exploiting the capability of the multi-channel time domain functional near-infrared spectroscopy technique to relate depth information to the photon time-of-flight, the cortical and superficial oxygenated (O₂Hb) and deoxygenated (HHb) hemoglobin concentrations were estimated. The O₂Hb and HHb maps obtained using the General Linear Model (NIRS-SPM) analysis method, showed that the VOL and NMES-evoked movements significantly increased activation (i.e., increase in O₂Hb and corresponding decrease in HHb) in the cortical layer of the contralateral sensorimotor network (SMC, PMC/SMA, and S2). However, the level and area of contralateral sensorimotor network (including PFC) activation was significantly greater for NMES than VOL. Furthermore, there was greater bilateral sensorimotor network activation with the high NMES current intensities which corresponded with increased pain ratings. In conclusion, our findings suggest that greater bilateral sensorimotor network activation profile with high NMES current intensities could be in part attributable to increased attentional/pain processing and to increased bilateral sensorimotor integration in these cortical regions.

Weak rectifying behaviour of p-SnS/n-ITO heterojunctions

This work explores the electrical properties of p-SnS/n-ITO heterojunction at different temperatures. The p-type SnS film was deposited on n-type ITO substrate using the thermal evaporation technique and its junction properties were studied using two probe method. The as-grown p-n junction exhibited weak rectifying behaviour with a low Saturation current of the order of similar to 10(-6) A. While increasing temperature, the saturation current of the junction is increased and however, its series resistance decreased. At all temperatures the junction exhibited three types of transport mechanisms depending on applied bias-voltage. At lower voltages the junction showed nearly ideal diode characteristics. The junction behaviour with respect to bias-voltage and temperature is discussed with the help of existing theories and energy band diagram.