This paper describes the science motivation, measurement objectives, performance requirements, detailed design, approach and implementation, and calibration of the four Hot Plasma Composition ...Analyzers (HPCA) for the Magnetospheric Multiscale mission. The HPCA is based entirely on electrostatic optics combining an electrostatic energy analyzer with a carbon-foil based time-of-flight analyzer. In order to fulfill mission requirements, the HPCA incorporates three unique technologies that give it very wide dynamic range capabilities essential to measuring minor ion species in the presence of extremely high proton fluxes found in the region of magnetopause reconnection. Dynamic range is controlled primarily by a novel radio frequency system analogous to an RF mass spectrometer. The RF, in combination with capabilities for high TOF event processing rates and high current micro-channel plates, ensures the dynamic range and sensitivity needed for accurate measurements of ion fluxes between ∼1 eV and 40 keV that are expected in the region of reconnection events. A third technology enhances mass resolution in the presence of high proton flux.
In order to calibrate the four HPCA instruments we have developed a unique ion calibration system. The system delivers a multi-species beam resolved to
M
/Δ
M
∼100 and current densities between 0.05 and 200 pA/cm
2
with a stability of ±5 %. The entire system is controlled by a dedicated computer synchronized with the HPCA ground support equipment. This approach results not only in accurate calibration but also in a comprehensive set of coordinated instrument and auxiliary data that makes analysis straightforward and ensures archival of all relevant data.
► We model the (multi commodity) crude oil tanker routing and scheduling problem. ► Special about the model is arbitrary split of pickup and delivery quantities. ► Pickup and delivery time windows do ...not form pairs for transportation. ► Quantity split and non-paired time windows show potential compared to fixed cargoes.
The maritime oil tanker routing and scheduling problem is known to the literature since before 1950. In the presented problem, oil tankers transport crude oil from supply points to demand locations around the globe. The objective is to find ship routes, load sizes, as well as port arrival and departure times, in a way that minimizes transportation costs. We introduce a path flow model where paths are ship routes. Continuous variables distribute the cargo between the different routes. Multiple products are transported by a heterogeneous fleet of tankers. Pickup and delivery requirements are not paired to cargos beforehand and arbitrary split of amounts is allowed. Small realistic test instances can be solved with route pre-generation for this model. The results indicate possible simplifications and stimulate further research.
Abstract Accelerometry (ACC) shows promise as an easily implemented clinical measure of balance. The purpose of the study was to estimate test–retest reliability of ACC measures and determine the ...relationship between ACC measured at the pelvis and underfoot center of pressure (COP) measures during sensory organization test (SOT) conditions. Eighty-one subjects were recruited from the community with no known orthopedic or vestibular deficits (19–85 years). Subjects completed three consecutive, ninety second trials for each of the six SOT conditions, while wearing the accelerometer. ACC and COP time series were described by calculating the normalized path length, root mean square (RMS), and peak-to-peak values. The test–retest reliability of the three measures within each SOT condition was estimated over three trials using the intraclass correlation coefficient. ACC and COP test–retest reliability were similar, ranging from 0.63 to 0.80 using ACC and 0.42 to 0.81 using COP for the measure of normalized path length. Linear regression between ACC and COP measures showed significant correlation under almost every SOT condition using both single and average measures across trials. The degree of association between COP and ACC was equivalent when using the first trial or the 3-trial average, suggesting that one trial may be sufficient. The use of accelerometry may have value in estimating balance function and minimizing clinical evaluation time.
Previous research suggested that panic disorder with agoraphobia is associated with abnormalities on vestibular and balance function tests. The purpose of this study was to further examine ...psychiatric correlates of vestibular/balance dysfunction in patients with anxiety disorders and the specific nature of the correlated vestibular abnormalities. The psychiatric variables considered included anxiety disorder versus normal control status, panic disorder versus non-panic anxiety disorder diagnosis, presence or absence of comorbid fear of heights, and degree of space and motion discomfort (SMD). The role of anxiety responses to vestibular testing was also re-examined.
104 subjects were recruited: 29 psychiatrically normal individuals and 75 psychiatric patients with anxiety disorders. Anxiety patients were assigned to four subgroups depending on whether or not they had panic disorder and comorbid fear of heights. SMD and anxiety responses were measured by questionnaires. Subjects were examined for abnormal unilateral vestibular hypofunction on caloric testing indicative of peripheral vestibular dysfunction, asymmetric responses on rotational testing as an indicator of an ongoing vestibular imbalance and balance function using Equitest dynamic posturography as an indicator of balance control. Logistic regression was used to establish the association between the psychiatric variables and vestibular or balance test abnormalities.
Rotational test results were not significantly related to any of the psychiatric variables. The presence of either panic attacks or fear of heights increased the probability of having caloric hypofunction in a non-additive fashion. SMD and anxiety responses were independently associated with abnormal balance. Among specific posturography conditions, the association with SMD was significant for a condition that involved the balance platform tilting codirectionally with body sway, suggesting an abnormal dependence on somatosensory cues in the control of balance.
In patients with anxiety disorders, higher SMD is indicative of somatosensory dependence in the control of balance. The absence of both panic and fear of heights reduces the probability of having peripheral vestibular dysfunction. Future research should examine if vestibular rehabilitation can be of value for patients with anxiety disorders complicated by SMD.
During Cassini's initial orbit, we observed a dynamic magnetosphere composed primarily of a complex mixture of water-derived atomic and molecular ions. We have identified four distinct regions ...characterized by differences in both bulk plasma properties and ion composition. Protons are the dominant species outside about 9 Rsubscript S (where Rsubscript S is the radial distance from the center of Saturn), whereas inside, the plasma consists primarily of a corotating comet-like mix of water-derived ions with approximately3% N⁺. Over the A and B rings, we found an ionosphere in which O₂⁺ and O⁺ are dominant, which suggests the possible existence of a layer of O₂ gas similar to the atmospheres of Europa and Ganymede.
Dizziness can be associated with otologic, neurologic, medical, and psychiatric conditions. This paper focuses on the interface between otologic and psychiatric conditions. Because dizziness often is ...situation specific, concepts of space and motion sensitivity (SMS), space and motion discomfort (SMD), and space and motion phobia (SMP) are needed to understand the interface. We present a framework involving several categories of interactions between balance and psychiatric disorders. The first category is that of dizziness caused by psychiatric disorder (psychiatric dizziness), including hyperventilation-induced dizziness during panic attacks. The second category involves chance cooccurrence of a psychiatric disorder and a balance disorder in the same patient. The third category involves problematic coping with balance symptoms (psychiatric overlay). The fourth category provides psychological explanations for the relationship between anxiety and balance disorders, including somatopsychic and psychosomatic relationships. The final category, neurological linkage, focuses on the overlap in the neurological circuitry involved in balance disorders and anxiety disorders.
Acrophobia (fear of heights) may be related to a high degree of height vertigo caused by visual dependence in the maintenance of standing balance. The purpose of this case report is to describe the ...use of vestibular physical therapy intervention following behavioral therapy to reduce a patient's visual dependence and height vertigo.
Mr N was a 37-year-old man with agoraphobia (fear of open spaces) that included symptoms of height phobia. Exposure to heights triggered symptoms of dizziness. Intervention. Mr N underwent 8 sessions of behavioral therapy that involved exposure to heights using a head-mounted virtual reality device. Subsequently, he underwent 8 weeks of physical therapy for an individualized vestibular physical therapy exercise program.
After behavioral therapy, the patient demonstrated improvements on the behavioral avoidance test and the Illness Intrusiveness Rating Scale, but dizziness and body sway responses to moving visual scenes did not decrease. After physical therapy, his dizziness and sway responses decreased and his balance confidence increased.
Symptoms of acrophobia and sway responses to full-field visual motion appeared to respond to vestibular physical therapy administered after completion of a course of behavioral therapy. Vestibular physical therapy may have a role in the management of height phobia related to excessive height vertigo.
Otoneurological abnormalities have been reported in panic disorder. The purpose of this investigation was to determine the prevalence of such findings in panic disorder with and without agoraphobia ...and to discern whether vestibular dysfunction was associated with specific symptoms.
Clinical audiological and vestibular tests were administered to 30 patients with uncomplicated panic disorder (without agoraphobia or with only mild agoraphobia), 29 patients with panic disorder with moderate to severe agoraphobia, 27 patients with anxiety but no history of panic attacks, 13 patients with depressive disorders but no history of anxiety or panic attacks, and 45 normal comparison subjects. Evaluators were blind to subjects' diagnostic group. Quantitative measures of subjects' discomfort with space and motion and of the frequency of certain symptoms between and during panic attacks were obtained. Anxiety state levels were measured during the vestibular tests.
Vestibular abnormalities were common in all the groups but most prevalent in the patients with panic disorder with moderate to severe agoraphobia. Vestibular dysfunction was associated with space and motion discomfort and with frequency of vestibular symptoms between, but not during, panic attacks. There were no major differences between the two panic groups in anxiety levels during vestibular testing. There were no significant differences between groups on the audiological component of the test battery. Exploratory data analysis indicated that the constellation of vestibular tests most specific for agoraphobia was one indicating compensated peripheral vestibular dysfunction.
Subclinical vestibular dysfunction, as identified by clinical tests, may contribute to the phenomenology of panic disorder, particularly to the development of agoraphobia in panic disorder patients.
PDF
