A systematic review of the psychological correlates of adjustment outcomes in adults with inflammatory bowel disease

Inflammatory bowel disease (IBD) is a chronic long term condition which poses significant psychosocial adjustment challenges. The purpose of this review was to systematically identify psychological factors related to adjustment in adults with IBD with the aim of suggesting evidence based targets that may be modifiable though psychological intervention. Twenty five studies met inclusion criteria and were included in the systematic review and a narrative synthesis was conducted. A wide range of psychological variables were addressed covering six broad categories; personality traits, interpersonal traits, stress and coping, emotions and emotional control, IBD related cognitions and non IBD related cognitions. The most consistent relationship was found between certain emotion focused coping strategies and worse adjustment outcomes in IBD. Some evidence also hi-lighted a relationship between personality traits (such as neuroticism,) perceived stress, emotions and emotional control (such as alexithymia) and IBD related cognitions (such as illness perceptions) and negative adjustment outcomes. The results of this review suggest that interventions to improve adjustment in IBD may benefit from a focus on coping strategies, perceived stress and IBD related cognitions

A Prototype System for Measuring Microwave Frequency Reflections from the Breast

Microwave imaging of the breast is of interest for monitoring breast health, and approaches to active microwave imaging include tomography and radar-based methods. While the literature contains a growing body of work related to microwave breast imaging, there are only a few prototype systems that have been used to collect data from humans. In this paper, a prototype system for monostatic radar-based imaging that has been used in an initial study measuring reflections from volunteers is discussed. The performance of the system is explored by examining the mechanical positioning of sensor, as well as microwave measurement sensitivity. To gain insight into the measurement of reflected signals, simulations and measurements of a simple phantom are compared and discussed in relation to system sensitivity. Finally, a successful scan of a volunteer is described

Cluster spacecraft observations of a ULF wave enhanced by Space Plasma Exploration by Active Radar (SPEAR)

Space Plasma Exploration by Active Radar (SPEAR) is a high-latitude ionospheric heating facility capable of exciting ULF waves on local magnetic field lines. We examine an interval from 1 February 2006 when SPEAR was transmitting a 1 Hz modulation signal with a 10 min on-off cycle. Ground magnetometer data indicated that SPEAR modulated currents in the local ionosphere at 1 Hz, and enhanced a natural field line resonance with a 10 min period. During this interval the Cluster spacecraft passed over the heater site. Signatures of the SPEAR-enhanced field line resonance were present in the magnetic field data measured by the magnetometer on-board Cluster-2. These are the first joint ground- and space-based detections of field line tagging by SPEAR

ESTIMATING DIELECTRIC PROPERTIES OF BIOLOGICAL TISSUE

INTRODUCTION Microwave imaging has been of interest in recent decades, offering the potential of an affordable and non-ionizing medical diagnostic modality. This technique is sensitive to changes in dielectric properties such as permittivity and conductivity. One approach is microwave radar imaging, which creates images by focusing signals caused by reflections at material interfaces. In order to improve the images from radar approaches, patient-specific dielectric property estimations have been used to determine the speed of wave travel within the tissue [1]. Estimating dielectric properties of biological tissue can also be useful in emerging quantitative applications including bone health assessment. Methods such as local rod probes and antenna measurements of planar samples have been developed to estimate dielectric properties, but are of limited use for in vivo measurements. We have previously developed methods of permittivity estimation with a custom antenna, however this approach requires two measurements at different separation distances and is unable to estimate conductivity. This study aims to improve on methods of estimating permittivity and to add an estimate of conductivity of in vivo biological tissue by incorporating an antenna calibration method. METHODS In order to remove the influence of the antennas on measurements, a previously developed calibration method [2] was adapted to be used with a custom ultra-wideband antenna system [3], allowing permittivity and conductivity to be estimated over a range of frequencies. The two antennas are characterized as 2x2 matrices at each frequency, determined from two calibration measurements: the first is performed with the antennas separated by an electrical conductor, and the second measurement is done with the antennas in direct contact with one another. Measurements were performed using a vector network analyzer (Agilent, PNA-L, N5230A), and take less than 15 seconds. Measurement samples were placed between the two antennas, with their surfaces in contact with the entire antenna aperture. Dielectric properties were then estimated using the magnitude and phase of the calibrated transmission data. To validate this method, dielectric properties of several liquids were estimated and compared to literature values. RESULTS A general agreement was seen between the estimated and literature dielectric properties of several liquids, particularly for high permittivity materials. The estimated and literature permittivity of distilled water is shown in Figure 1. Several biological tissues were then measured such as human calf and heel, and porcine bone excisions. Literature values for these properties are limited as they are often done using local probes which only measure the properties at the surface of a sample.DISCUSSION AND CONCLUSIONS A calibration method has been adapted to enable an ultra-wideband antenna system to assess dielectric properties of in vivo tissue at microwave frequencies. The estimated properties of the tested liquids align closely to literature, providing confidence in estimates of biological tissues which have limited literature values. This technique can be used towards microwave radar signal speed estimates, and for quantitative property measurements. Future improvements could include a skin subtraction method to isolate the properties of bone or other tissue under the skin, and development towards microwave bone health assessment

A PRINCIPLE INVESTIGATION INTO THE FEASIBILITY OF USING MICROWAVE IMAGING TO MONITOR BONE HEALTH

INTRODUCTION Assessing bone health is of particular interest in age-associated disease and traumas such as osteoporosis, and fractures from extreme sports. Having tools that can safely and accurately assess bone health allows for the screening, diagnosis, and monitoring of disease or injury. The current gold standard for assessing bone health is high-resolution peripheral quantitative computed tomography (HR-pQCT) allowing direct three-dimensional (3D) visualization of bone. Recent evidence suggests microwave imaging can be a complementary medical imaging tool to HR-pQCT for dynamic assessment of full bone health [1]. Specifically, it was shown that microwave properties of cancellous bone are sensitive to physical changes in bone. However, this study was purely exploratory and provided no direct evidence for changes in dielectric properties with varying bone health. In this study, we aim to understand the interaction of electromagnetic waves with bone as a composite material, specifically the material anisotropy. Such information would be crucial to understanding how microwave measurements relate to the physical characteristics of the bone. METHODS Image data for the right and left tibia and radius of one female and two male subjects was acquired from HR-pQCT (XtremeCTII, Scanco Medical). The 3D image data was smoothed with a Gaussian filter (σ = 1.6) and segmented using histogram based segmentation. Cubes of edge length 82 voxels (5.002 mm) were extracted from the segmented images based on the bone center of geometry. The extracted cubes were imported into electromagnetic simulation software (SEMCAD X, Schmid & Partner Engineering AG). A parallel plate waveguide filled with air was excited with a Gaussian pulse polarized in the z-axis (f0 = 6.5 GHz, BW = 11 GHz). The bone and marrow were assigned material properties from literature [2]. Resulting data was exported and processed using custom MATLAB scripts (R2013a, MathWorks). Three simulations were performed per image such that the electromagnetic wave was polarized in each of the three anatomical directions: anterior-posterior, medial-lateral, and proximal-distal. RESULTS The effective permittivity, ε’r, was calculated for each of the anatomical directions and plotted across the frequency range of the input signal. A representative plot for all images is shown in Figure 1. The effective permittivity for each orientation tend to vary around a common permittivity.DISCUSSION AND CONCLUSIONS The results presented here provide a rudimentary but novel insight into the anisotropic behaviour of bone at microwave frequencies. Furthermore, it presents a technique for 3D model acquisition and simulation of bone not yet present in literature. This technique will allow further exploration of the electromagnetic properties of bone such as a deeper insight into the anisotropic behaviour and development of a model for the effective medium of bone as a composite material. With such information, the microwave measurements of bone could be directly related to the bone’s physical properties. This would prove the potential of microwaves to assess bone health for disease or trauma and allow the development of in vivo imaging tools for assessing disease and trauma

The interaction between transpolar arcs and cusp spots

Transpolar arcs and cusp spots are both auroral phenomena which occur when the interplanetary magnetic field is northward. Transpolar arcs are associated with magnetic reconnection in the magnetotail, which closes magnetic flux and results in a "wedge" of closed flux which remains trapped, embedded in the magnetotail lobe. The cusp spot is an indicator of lobe reconnection at the high-latitude magnetopause; in its simplest case, lobe reconnection redistributes open flux without resulting in any net change in the open flux content of the magnetosphere. We present observations of the two phenomena interacting--i.e., a transpolar arc intersecting a cusp spot during part of its lifetime. The significance of this observation is that lobe reconnection can have the effect of opening closed magnetotail flux. We argue that such events should not be rare

Flux ropes in the Hermean magnetotail: Distribution, properties, and formation

An automated method was applied to identify magnetotail flux rope encounters in MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) magnetometer data. The method identified significant deflections of the northâ south component of the magnetic field coincident with enhancements in the total field or dawnâ dusk component. Two hundred fortyâ eight flux ropes are identified that possess wellâ defined minimum variance analysis (MVA) coordinate systems, with clear rotations of the field. Approximately 30% can be well approximated by the cylindrically symmetric, linearly forceâ free model. Flux ropes are most common moving planetward, in the postmidnight sector. Observations are intermittent, with the majority (61%) of plasma sheet passages yielding no flux ropes; however, the peak rate of flux ropes during a reconnection episode is â ¼5 minâ 1. Overall, the peak postmidnight rate is â ¼0.25 minâ 1. Only 25% of flux ropes are observed in isolation. The radius of flux ropes is comparable to the ion inertial length within Mercury’s magnetotail plasma sheet. No clear statistical separation is observed between tailward and planetward moving flux ropes, suggesting the nearâ Mercury neutral line (NMNL) is highly variable. Flux ropes are more likely to be observed if the preceding lobe field is enhanced over background levels. A very weak correlation is observed between the flux rope core field and the preceding lobe field orientation; a stronger relationship is found with the orientation of the field within the plasma sheet. The core field strength measured is â ¼6 times stronger than the local dawnâ dusk plasma sheet magnetic field.Key PointsTwo hundred fortyâ eight flux ropes identified in Mercury’s magnetotail (74 cylindrical and linearly forceâ free)Flux ropes most commonly observed by MESSENGER postmidnight, moving planetwardFlux ropes observed intermittently, but most often when the preceding lobe field is enhancedPeer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/138858/1/jgra53697_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/138858/2/jgra53697.pd

2012), The IMF dependence of the local time of transpolar arcs: Implications for formation mechanism

[1] Transpolar arcs are auroral features that extend from the nightside auroral oval into the polar cap. It is well established that they occur predominantly when the interplanetary magnetic field (IMF) has a northward component (B z > 0). Results concerning how the magnetic local time at which transpolar arcs form might depend upon the IMF dawn-dusk component (B Y ) are more mixed. Some studies have found a correlation between these two variables, with Northern Hemisphere arcs forming predominantly premidnight when B Y > 0 and postmidnight when B Y < 0 and vice versa in the Southern Hemisphere. However, a more recent statistical study found that there was no significant correlation, and other studies find that the formation of moving arcs is triggered by a change in the sign of the IMF B Y component. In this paper, we investigate the relationship between the magnetic local time at which transpolar arcs form and the IMF B Y component. It is found that there is indeed a correlation between the magnetic local time at which transpolar arcs form and the IMF B Y component, which acts in opposite senses in the Northern and Southern hemispheres. However, this correlation is weak if the IMF is only averaged over the hour before the first emergence of the arc and becomes stronger if the IMF is averaged 3-4 h beforehand. This is consistent with a mechanism where the magnetic local time at which the arc first forms depends on the B Y component in the magnetotail adjacent to the plasma sheet, which is determined by the IMF B Y component during intervals of dayside reconnection in the hours preceding the first emergence of the arc. We do not find evidence for the triggering of arcs by an IMF B Y sign change

The effect of diamagnetic drift on motion of the dayside magnetopause reconnection line

Magnetic reconnection at the magnetopause occurs with a large density asymmetry and for a large range of magnetic shears. In these conditions, a motion of the X line has been predicted in the direction of the electron diamagnetic drift. When this motion is super Alfvenic, reconnection should be suppressed. We analysed a large data set of Double Star TC-1 dayside magnetopause crossings, which includes reconnection and nonreconnection events. Moreover, it also includes several events during which TC-1 is near the X line. With these close events, we verified the diamagnetic suppression condition with local observations near the X line. Moreover, with the same close events, we also studied the motion of the X line along the magnetopause. It is found that, when reconnection is not suppressed, the X line moves northward or southward according to the orientation of the guide field, which is related to the interplanetary magnetic field BY component, in agreement with the diamagnetic drift