Gray Regions Research Articles

Feature-driven topology optimization method with signed distance function

In this paper, a feature-driven topology optimization method is developed. This is the first study on layout design of multiple engineering features using level-set functions (LSFs) and Boolean operations. The novelty of this work is threefold. First, multiple engineering features of arbitrary shape are considered as basic design primitives and topology variation is achieved via the layout and shape optimization of the features. Kreisselmeier–Steinhauser (KS) function constructed by means of Boolean operations is adopted as the LSF, which uses an implicit function to ensure a smooth description and topological changes of basic features and the whole structure. Second, using a modified Heaviside function to smooth the void–solid material transition over a fixed computing mesh, a narrow-band domain integral scheme is developed for the efficient sensitivity analysis. Third, the gray material distribution regions at the feature-connecting portions are analyzed and the underlying reason for that is traced to the non-equidistant distribution of level-set contours of specific features. To avoid the gray regions, an approximated signed distance function is proposed to regularize the LSF and KS function. The bounded normalization property of the KS function is highlighted for its construction with the signed distance functions or normalized first-order approximations. Numerical examples are finally tested to demonstrate the validity and merits of the proposed feature-driven topology optimization for complicated design problems.

Tuning the brain for motherhood: prolactin-like central signalling in virgin, pregnant, and lactating female mice.

Prolactin is fundamental for the expression of maternal behaviour. In virgin female rats, prolactin administered upon steroid hormone priming accelerates the onset of maternal care. By contrast, the role of prolactin in mice maternal behaviour remains unclear. This study aims at characterizing central prolactin activity patterns in female mice and their variation through pregnancy and lactation. This was revealed by immunoreactivity of phosphorylated (active) signal transducer and activator of transcription 5 (pSTAT5-ir), a key molecule in the signalling cascade of prolactin receptors. We also evaluated non-hypophyseal lactogenic activity during pregnancy by administering bromocriptine, which suppresses hypophyseal prolactin release. Late-pregnant and lactating females showed significantly increased pSTAT5-ir resulting in a widespread pattern of immunostaining with minor variations between pregnant and lactating animals, which comprises nuclei of the sociosexual and maternal brain, including telencephalic (septum, nucleus of the stria terminalis, and amygdala), hypothalamic (preoptic, paraventricular, supraoptic, and ventromedial), and midbrain (periaqueductal grey) regions. During late pregnancy, this pattern was not affected by the administration of bromocriptine, suggesting it to be elicited mostly by non-hypophyseal lactogenic agents, likely placental lactogens. Virgin females displayed, instead, a variable pattern of pSTAT5-ir restricted to a subset of the brain nuclei labelled in pregnant and lactating mice. A hormonal substitution experiment confirmed that estradiol and progesterone contribute to the variability found in virgin females. Our results reflect how the shaping of the maternal brain takes place prior to parturition and suggest that lactogenic agents are important candidates in the development of maternal behaviours already during pregnancy.

The initial fall in arterial pressure evoked by endotoxin is mediated by the ventrolateral periaqueductal gray.

This study tested the hypothesis that the initial fall in arterial pressure evoked by lipopolysaccharide (LPS) is mediated by the ventrolateral column of the midbrain periaqueductal gray region (vlPAG). To test this hypothesis, the local anaesthetic lidocaine (2%; 0.1μL, 0.2μL or 1.0μL), the delta opioid receptor antagonist naltrindole (2nmol) or saline was microinjected into the vlPAG of isoflurane-anaesthetized rats bilaterally and LPS (1mg/kg) or saline was administered intravenously 2min later. Both lidocaine and naltrindole inhibited LPS-evoked hypotension significantly but did not affect arterial pressure in saline-treated control animals. Neither lidocaine nor naltrindole altered heart rate significantly in either LPS-treated or control animals. Microinjection of lidocaine or naltrindole into the dorsolateral PAG was ineffective. These data indicate that the vlPAG plays an important role in the initiation of endotoxic hypotension and further show that delta opioid receptors in the vlPAG participate in the response.

Decoding evolutionary history of provenance from beach placer monazites: A case study from Kanyakumari coast, southwest India

Mineral chemical and geochronological studies of beach placer monazites from Kanyakumari coast, SW India were carried out to understand growth history of monazite and its bearing on tectono-thermal evolution of the source rock. In chemically zoned monazites lowest backscattered electron (BSE) response domains (dark gray) comprising the thick core region are mantled by highest BSE response rim domains (light gray region). Dark gray BSE domains are enriched in LREEs (La and Ce), U and Y, and depleted in Th and Pb compared to the light gray BSE domains. Chemical variability between these two domains can be linked with dominantly huttonitic substitution. Two U–Th–total Pb chemical age clusters between 555–578Ma and 508–536Ma were obtained respectively for low Th/U monazite cores and high Th/U monazite rims.147Sm/144Nd ratios in the analyzed monazites vary from 0.0733 to 0.1039 with an average value of 0.0902. High negative εNd (t=0) values in the range of −26.5 to −30.8 indicate derivation of monazites from light LREE enriched igneous and metamorphic rocks. TCHUR and TDM model ages vary from 1687Ma to 2364Ma and 2035Ma to 2702Ma respectively. Average TDM age of 2375 (+96/−44) Ma for placer monazites fits with ~2.4Ga crustal accretionary episode in Southern Granulite Terrane (SGT). EPMA Sm–Nd ratios of beach placer monazites (~0.153) are similar with the monazites in granites and granodiorites (0.150) of Nagercoil (NG) and Trivandrum Block (TB) of SGT. A comparison with available Th–U–total Pb EPMA monazite ages from various tectonic units within SGT suggests that growth history and crystallization age of monazites also correlate well with the Pan-African granulite facies metamorphism (570Ma) and post-peak evolution (535Ma) of NG and TB.The results obtained in this study augment the growing evidences that beach placer monazites can be used as a proxy for provenance study. A corollary of the study further confirms similar geological history of NG and TB since 2.1Ga.

FMRI of spinal and supra-spinal correlates of temporal pain summation in fibromyalgia patients.

Fibromyalgia syndrome (FM) is a debilitating chronic pain condition, which afflicts primarily females. Although the etiology of this illness is not completely understood, FM pain is thought to rely on enhanced pain sensitivity maintained by central mechanisms. One of these mechanisms is central pain amplification, which is characterized by altered temporal summation of second pain (TSSP). Here we use a TSSP paradigm and functional MRI (fMRI) of the spinal cord, brainstem, and brain to noninvasively examine the central nervous system contributions to TSSP in FM patients and normal controls (NC). Functional MRI of pain-free female adults (N = 15) and FM patients (N = 14) was conducted while brief, repetitive heat pain stimuli (0.33 Hz) were applied to the thenar eminence of the hand (C6 dermatome). The stimulus intensity was adjusted to each participant's heat pain sensitivity to achieve moderate pain. Data were analyzed by means of a General Linear Model and region-of-interest analyses. All participants demonstrated significant pain summation in the TSSP condition. FM subjects, however, required significantly lower stimulus intensities than NC to achieve similar TSSP. fMRI analyses of perceptually equal TSSP identified similar brain activity in NC and FM subjects; however, multiple areas in the brainstem (rostral ventromedial medulla and periaqueductal grey region) and spinal cord (dorsal horn) exhibited greater activity in NC subjects. Finally, increased after-sensations and enhanced dorsal horn activity was demonstrated in FM patients. In conclusion, the spinal and brainstem BOLD responses to TSSP are different between NC and FM patients, which may indicate alterations to descending pain control mechanisms suggesting contributions of these mechanisms to central sensitization and pain of FM patients.

West Nile Virus Population Structure, Injury, and Interferon-Stimulated Gene Expression in the Brain From a Fatal Case of Encephalitis.

Background. West Nile virus (WNV) infection in humans can result in severe, acute encephalitis typically involving subcortical gray matter brain regions. West Nile virus replication within specific human brain regions from a human case of acute encephalitis has not been studied.Methods. We describe a fatal case of WNV encephalitis in which we obtained tissue from specific brain regions at autopsy to evaluate viral-host interactions using next-generation sequencing and immunohistochemistry analysis.Results. We found that WNV populations in the injured subcortical brain regions exhibited increased amino acid variation and increased expression of specific interferon genes compared with cortical tissues despite similar viral burden.Conclusions. These observational, patient-based data suggest that neuronal injury and the strength of viral selection pressure may be associated with the level of the innate immune responses. Further studies in human and animal models evaluating the role of innate immune responses on injury patterns and viral selection pressure are needed.

Abstract 12095: Altered Brain Functional Connectivity During Valsalva Maneuver in Heart Failure

Introduction: Heart failure (HF) patients have abnormal autonomic (ANS) activity, which is linked to damage in specific gray matter brain regions (such as the insulae). Abnormal ANS activity in HF may be due to changes in both structural injury and functional connectivity (FC; temporal correlations between neural structures which indicate connection status and sequence of activation). While insular/brain structural injury has been reported in HF, FC has not been explored. Hypothesis: FC between brain regions during an autonomic challenge will be less in HF in comparison to controls. Methods: We collected functional MRI data with Valsalva maneuver block design task in 12 HF (age 55.6±8.1 years; Females 3; BMI 25.2±3.8 kg/m2; LVEF, 26.7±11.5%) and 33 controls (51.6±5.5 years; Females 13; BMI 25.7±3.2 kg/m2), using a 3.0 Tesla MRI scanner. Group independent component analysis was applied to identify individual task-related FC maps, which were compared between HF and controls (ANCOVA; covariates, age and gender; P<0.005) Results: No significant differences in age, gender, or BMI emerged between the two groups (P>0.05). Decreased FC in HF (Figure 1; p<0.005) were found in the left supramarginal gyrus/inferior parietal lobule, left middle temporal gyrus, bilateral thalamus, left fusiform gyrus, left ligual gyrus, right precuneus, left hippocampus, and left insula. However, increased FC in HF compared to controls were found in the left inferior frontal gyrus, right superior temporal gyrus, left cerebellar cortex, and right insula (P<0.005). Conclusions: These findings suggest that autonomic, cognitive, and affective deficits in HF may be related to altered FC. The outcomes likely result from the prominent structural changes in both axons and nuclear structures reported earlier in HF. Future interventions may need to address structural and functional deficits in both gray and white matter regions in HF.

Color changing effects with anisotropic halftone prints on metal

We propose a color reproduction framework for creating specularly reflecting color images printed on a metallic substrate that change hue or chroma upon in-plane rotation by 90°. This framework is based on the anisotropic dot gain of line halftones when viewed under specular reflection. The proposed framework relies on a spectral prediction model specially conceived for predicting the color of non-rotated and of 90° in-plane rotated cross-halftones formed of superpositions of horizontal and vertical cyan, magenta and yellow line halftones. Desired non-rotated and rotated image colors are mapped onto the sub-gamut allowing for the desired hue or chroma shift and then, using a 6D correspondence table, converted to optimal cross-halftone ink surface coverages. The proposed recolorization and decolorization framework is especially effective for creating surprising effects such as image parts whose hues change, or gray regions that become colorful. It can be adapted to commercial printers capable of printing with cyan, magenta and yellow inks on substrates formed by an ink attracting polymer lying on top of a metallic film layer. Applications may include art, advertisement, exhibitions and document security.

How does magnetization transfer influence mcDESPOT results?

PurposeA steady‐state approach that was termed multicomponent driven equilibrium single pulse observation of T1 and T2 (mcDESPOT) has recently been proposed for myelin water fraction (fM) mapping in brain development and demyelinating diseases. However, fMs estimated by mcDESPOT are significantly higher than myelin water fraction derived from multiecho spin echo T2‐decay curve approaches. Magnetization transfer (MT), enhanced by the use of short, relatively high amplitude radiofrequency (RF) pulses in mcDESPOT, may artifactually influence fM maps. Our goal was to investigate the role of MT in mcDESPOT.MethodsmcDESPOT data was collected twice from three healthy volunteers using short RF pulses with higher MT effect and long RF pulses with lower MT effect. MR parameters from 11 white and gray regions were compared using a paired student t‐test. Whole slice difference images were also compared.ResultsMT effects had a substantial influence on the signal generated by the balanced steady‐state free procession sequences used in mcDESPOT. However, these MT effects were not clearly evident in the fM values determined by the conventional two‐pool mcDESPOT analysis.ConclusionThe signal generated from mcDESPOT is sensitive to MT, but the extracted myelin water fractions are relatively insensitive to changes of MT. Magn Reson Med 74:1327–1335, 2015. © 2014 Wiley Periodicals, Inc.

Three dimensional polymer waveguide using hybrid lithography.

A three dimensional polymer waveguide with taper structure was demonstrated and fabricated by a reliable and effective hybrid lithography. The hybrid lithography consists of lithography to fabricate a polymer waveguide and gray scale lithography to fabricate a polymer taper structure. Laser ablation and shadow aluminum evaporation were designed for gray scale lithography. The length of the gray scale region ranging from 20 to 400 μm could be controlled by the laser power, the ablation speed, and the aluminum thickness. The slope angle was determined by the length of the gray scale region and the thickness of the photoresist. The waveguide taper structure could be transferred to the lower layer by the etching method. The taper structure can be used for integration of the waveguide with different dimensions.

Recruitment of dorsal midbrain catecholaminergic pathways in the recovery from nerve injury evoked disabilities.

BackgroundThe periaqueductal gray region (PAG) is one of several brain areas identified to be vulnerable to structural and functional change following peripheral nerve injury. Sciatic nerve constriction injury (CCI) triggers neuropathic pain and three distinct profiles of changes in complex behaviours, which include altered social and sleep–wake behaviours as well as changes in endocrine function. The PAG encompasses subgroups of the A10 dopaminergic and A6 noradrenergic cell groups; the origins of significant ascending projections to hypothalamic and forebrain regions, which regulate sleep, complex behaviours and endocrine function. We used RT-PCR, western blots and immunohistochemistry for tyrosine hydroxylase to determine whether (1) tyrosine hydroxylase increased in the A10/A6 cells and/or; (2) de novo synthesis of tyrosine hydroxylase, in a ‘TH-naïve’ population of ventral PAG neurons characterized rats with distinct patterns of behavioural and endocrine change co-morbid with CCI evoked-pain.ResultsEvidence for increased tyrosine hydroxylase transcription and translation in the constitutive A10/A6 cells was found in the midbrain of rats that showed an initial 2–3 day post-CCI, behavioural and endocrine change, which recovered by days 5–6 post-CCI. Furthermore these rats showed significant increases in the density of TH-IR fibres in the vPAG.ConclusionsOur data provide evidence for: (1) potential increases in dopamine and noradrenaline synthesis in vPAG cells; and (2) increased catecholaminergic drive on vPAG neurons in rats in which transient changes in social behavior are seen following CCI. The data suggests a role for dopaminergic and noradrenergic outputs, and catecholaminergic inputs of the vPAG in the expression of one of the profiles of behavioural and endocrine change triggered by nerve injury.

Low - voltage FIB/SEM Tomography for 3D Microstructure Evolution of LiFePO4/C Electrode

Li-ion batteries find widespread use in many electricity storage applications, from portable devices to electric vehicles [1-3], and LiFePO4 (LFP) is one of the most common cathodes because of its long durability and high safety [4, 5] but, since its low ionic and electronic conduction, it is always mixed with carbon black (CB) additives to increase electronic percolation in the electrode. Focused Ion Beam (FIB)/Scanning Electron Microscopy (SEM) Tomography is one of the most used techniques for the study of the three-dimensional microstructure of porous electrodes [6-8]. Imaging at low-kV has been shown to be an excellent technique for studying electron percolation in Ni-network in solid oxide fuel cells [9]. In this work we study the degradation process that occurs in a LFP/C electrode by Low-kV FIB/SEM Tomography, using the low-voltage percolation technique to identify compositional changes in the CB network in three-dimensions. FIB/SEM images of a fresh and degraded cathode are compared and LFP grains are seen to crack with cycling, resulting in the formation of secondary disconnected particles with increased ionic resistivity; CB particles are instead observed to agglomerate, reducing the electrochemically active surface area. Using low voltage imaging (1 kV) a significant fraction of the large carbon agglomerates found in the aged electrode show a higher secondary electron yield compared to the fresh CB particles at low accelerating voltage. This suggests that degradation occurs both due to morphological changes and due to amorphous-crystalline phase transitions in the carbon network, resulting in non-percolating CB agglomerates. Figure 1 shows lateral Everhart – Thornley (E-T) and in-lens detector images of fresh (a, b) and degraded cathode (c, d) collected after FIB slicing. White grains are LFP, black particles are CB additive and grey regions are pores infiltrated with silicon resin to improve phase contrast [7]. The CB network appears entirely dark in the in-lens detector image of the fresh electrode (Fig. 1b). It is possible to notice some charging effects from the insulating silicon resin. The in-lens detector image of the degraded electrode (Fig. 1d) is instead characterized by the presence of big carbon agglomerates (red rings) which are brighter because they charge as the electron beam hit them. This indicates a lower electric conductivity. 3D reconstruction of the entire network (Fig. 2) revealed that the carbon phase with lower electric conductivity accounted for approximately 25% of the volume of the total carbon in the sample. This of course affects electrode capacity since a reduced electron percolation in the CB network impedes (de)lithiation process of LFP particles. References M. Armand, J. M. Tarascon, Nature, 451, 652-657 (2008).B. Scrosati, J. Hassoun, and Y.K. Sun, Energy Environ. Sci., 4, 3287-3295 (2011).J.M. Tarascon, M. Armand, Nature, 414, 359-367 (2001).A.K. Padhi, K.S. Nanjundaswamy, and J. B. Goodenough, J. Electrochem. Soc., 144(4), 1188-1194 (1997).Y. Wang, P. He, and H. Zhou, Energy Environ. Sci., 4, 805-817 (2010).T. Hutzenlaub et al., Electrochemical and Solid-State Letters, 15 (3), A33-A36 (2012).M. Ender et al, J. Electrochem. Soc., 159(7), A972-A980 (2012).Z. Liu et al., J. Power Sources, 227, 267-274 (2013).K. Thydén, Y.L. Liu, and J.B. Bilde-Sørensen, Solid State Ionics, 178, 1984-1989 (2008). Figure 1

Region of interest correction factors improve reliability of diffusion imaging measures within and across scanners and field strengths

Diffusion tensor imaging (DTI) measures are commonly used as imaging markers to investigate individual differences in relation to behavioral and health-related characteristics. However, the ability to detect reliable associations in cross-sectional or longitudinal studies is limited by the reliability of the diffusion measures. Several studies have examined the reliability of diffusion measures within (i.e. intra-site) and across (i.e. inter-site) scanners with mixed results. Our study compares the test–retest reliability of diffusion measures within and across scanners and field strengths in cognitively normal older adults with a follow-up interval less than 2.25years. Intra-class correlation (ICC) and coefficient of variation (CoV) of fractional anisotropy (FA) and mean diffusivity (MD) were evaluated in sixteen white matter and twenty-six gray matter bilateral regions. The ICC for intra-site reliability (0.32 to 0.96 for FA and 0.18 to 0.95 for MD in white matter regions; 0.27 to 0.89 for MD and 0.03 to 0.79 for FA in gray matter regions) and inter-site reliability (0.28 to 0.95 for FA in white matter regions, 0.02 to 0.86 for MD in gray matter regions) with longer follow-up intervals were similar to earlier studies using shorter follow-up intervals. The reliability of across field strengths comparisons was lower than intra- and inter-site reliabilities. Within and across scanner comparisons showed that diffusion measures were more stable in larger white matter regions (>1500mm3). For gray matter regions, the MD measure showed stability in specific regions and was not dependent on region size. Linear correction factor estimated from cross-sectional or longitudinal data improved the reliability across field strengths. Our findings indicate that investigations relating diffusion measures to external variables must consider variable reliability across the distinct regions of interest and that correction factors can be used to improve consistency of measurement across field strengths. An important result of this work is that inter-scanner and field strength effects can be partially mitigated with linear correction factors specific to regions of interest. These data-driven linear correction techniques can be applied in cross-sectional or longitudinal studies.

Failure of hippocampal deactivation during loss events in treatment-resistant depression.

Major depressive disorder is characterized by anhedonia, cognitive biases, ruminations, hopelessness and increased anxiety. Blunted responses to rewards have been reported in a number of recent neuroimaging and behavioural studies of major depressive disorder. In contrast, neural responses to aversive events remain an under-studied area. While selective serotonergic reuptake inhibitors are often effective in treating major depressive disorder, their mechanism of action remains unclear. Following a series of animal model investigations of depressive illness and serotonergic function, Deakin and Graeff predicted that brain activity in patients with major depressive disorder is associated with an overactive dorsal raphe nucleus with overactive projections to the amygdala, periaqueductal grey and striatum, and an underactive median raphe nucleus with underactive projections to the hippocampus. Here we describe an instrumental loss-avoidance and win-gain reinforcement learning functional magnetic resonance imaging study with 40 patients with highly treatment-resistant major depressive disorder and never-depressed controls. The dorsal raphe nucleus/ periaqueductal grey region of the midbrain and hippocampus were found to be overactive in major depressive disorder during unsuccessful loss-avoidance although the median raphe nucleus was not found to be underactive. Hippocampal overactivity was due to a failure to deactivate during loss events in comparison to controls, and hippocampal over-activity correlated with depression severity, self-report 'hopelessness' and anxiety. Deakin and Graeff argued that the median raphe nucleus normally acts to inhibit consolidation of aversive memories via the hippocampus and this system is underactive in major depressive disorder, facilitating the development of ruminations, while the dorsal raphe nucleus system is engaged by distal cues predictive of threats and is overactive in major depressive disorder. During win events the striatum was underactive in major depressive disorder. We tested individual patient consistency of these findings using within-study replication. Abnormal hippocampal activity correctly predicted individual patient diagnostic status in 97% (sensitivity 95%, specificity 100%) of subjects, and abnormal striatal activity predicted diagnostic status in 84% (sensitivity 79%, specificity 89%) of subjects. We conclude that the neuroimaging findings were largely consistent with Deaken and Graeff's predictions, abnormally increased hippocampal activity during loss events was an especially consistent abnormality, and brainstem serotonergic nuclei merit further study in depressive illness.

Anatomical Distribution of Cuprizone-Induced Lesions in C57BL6 Mice.

Although multiple sclerosis (MS) has been considered a white matter disease, MS lesions occur frequently in the gray matter parts of the brain. Gray matter demyelination and atrophy are found during earliest disease stages, and a growing body of evidence demonstrates a positive correlation between gray matter pathology and various measures of motor disability and cognitive impairment. The cuprizone model is classically regarded as white matter demyelination model. However, recent evidence suggests that different gray matter areas are also affected. In this study, we address the vulnerability of white and gray matter forebrain regions in the cuprizone model. While the corpus callosum as interhemispheric white matter tract is affected in this model, other white matter tracts such as the mammillo-thalamic tract, the columns of the fornix, the stria terminalis, the optic tract, or hippocampal fimbria do not present overt demyelination after 5-week cuprizone intoxication. In contrast, gray matter demyelination is widespread in this model. Furthermore, vulnerable white matter tracts display extensive acute axonal damage. These results highlight the relevance of the cuprizone model to study MS-related gray matter pathology and neurodegeneration.

Three Regions for Space–Time Spectrum Sensing and Access in Cognitive Radio Networks

In this paper, spectrum holes in space–time dimensions are exploited to improve the spectrum utilization of cognitive radio networks (CRNs). To achieve this goal, we design the architecture of three regions, which are separately known as the black region, the gray region, and the white region. Temporal spectrum holes exist in the gray region, where secondary users (SUs) can opportunistically access the licensed spectrum with interweave spectrum sharing. In the white region, SUs can exploit spatial spectrum opportunities and transmit at any time by taking advantage of their long distances from the primary users (PUs), without causing severe interference to PUs. Moreover, the existence condition of the transition zone between the gray region and the white region is theoretically analyzed, where power control should be implemented in SUs. Closed-form bounds of three regions are obtained, which can be used in space–time spectrum sensing and access in CRNs. Finally, we provide numerical results to evaluate the relations among the key parameters in the three regions.

Identification of a common neurobiological substrate for mental illness.

Psychiatric diagnoses are currently distinguished based on sets of specific symptoms. However, genetic and clinical analyses find similarities across a wide variety of diagnoses, suggesting that a common neurobiological substrate may exist across mental illness. To conduct a meta-analysis of structural neuroimaging studies across multiple psychiatric diagnoses, followed by parallel analyses of 3 large-scale healthy participant data sets to help interpret structural findings in the meta-analysis. PubMed was searched to identify voxel-based morphometry studies through July 2012 comparing psychiatric patients to healthy control individuals for the meta-analysis. The 3 parallel healthy participant data sets included resting-state functional magnetic resonance imaging, a database of activation foci across thousands of neuroimaging experiments, and a data set with structural imaging and cognitive task performance data. Studies were included in the meta-analysis if they reported voxel-based morphometry differences between patients with an Axis I diagnosis and control individuals in stereotactic coordinates across the whole brain, did not present predominantly in childhood, and had at least 10 studies contributing to that diagnosis (or across closely related diagnoses). The meta-analysis was conducted on peak voxel coordinates using an activation likelihood estimation approach. We tested for areas of common gray matter volume increase or decrease across Axis I diagnoses, as well as areas differing between diagnoses. Follow-up analyses on other healthy participant data sets tested connectivity related to regions arising from the meta-analysis and the relationship of gray matter volume to cognition. Based on the voxel-based morphometry meta-analysis of 193 studies comprising 15 892 individuals across 6 diverse diagnostic groups (schizophrenia, bipolar disorder, depression, addiction, obsessive-compulsive disorder, and anxiety), we found that gray matter loss converged across diagnoses in 3 regions: the dorsal anterior cingulate, right insula, and left insula. By contrast, there were few diagnosis-specific effects, distinguishing only schizophrenia and depression from other diagnoses. In the parallel follow-up analyses of the 3 independent healthy participant data sets, we found that the common gray matter loss regions formed a tightly interconnected network during tasks and at resting and that lower gray matter in this network was associated with poor executive functioning. We identified a concordance across psychiatric diagnoses in terms of integrity of an anterior insula/dorsal anterior cingulate-based network, which may relate to executive function deficits observed across diagnoses. This concordance provides an organizing model that emphasizes the importance of shared neural substrates across psychopathology, despite likely diverse etiologies, which is currently not an explicit component of psychiatric nosology.

Disconnection of network hubs and cognitive impairment after traumatic brain injury.

Traumatic brain injury affects brain connectivity by producing traumatic axonal injury. This disrupts the function of large-scale networks that support cognition. The best way to describe this relationship is unclear, but one elegant approach is to view networks as graphs. Brain regions become nodes in the graph, and white matter tracts the connections. The overall effect of an injury can then be estimated by calculating graph metrics of network structure and function. Here we test which graph metrics best predict the presence of traumatic axonal injury, as well as which are most highly associated with cognitive impairment. A comprehensive range of graph metrics was calculated from structural connectivity measures for 52 patients with traumatic brain injury, 21 of whom had microbleed evidence of traumatic axonal injury, and 25 age-matched controls. White matter connections between 165 grey matter brain regions were defined using tractography, and structural connectivity matrices calculated from skeletonized diffusion tensor imaging data. This technique estimates injury at the centre of tract, but is insensitive to damage at tract edges. Graph metrics were calculated from the resulting connectivity matrices and machine-learning techniques used to select the metrics that best predicted the presence of traumatic brain injury. In addition, we used regularization and variable selection via the elastic net to predict patient behaviour on tests of information processing speed, executive function and associative memory. Support vector machines trained with graph metrics of white matter connectivity matrices from the microbleed group were able to identify patients with a history of traumatic brain injury with 93.4% accuracy, a result robust to different ways of sampling the data. Graph metrics were significantly associated with cognitive performance: information processing speed (R(2) = 0.64), executive function (R(2) = 0.56) and associative memory (R(2) = 0.25). These results were then replicated in a separate group of patients without microbleeds. The most influential graph metrics were betweenness centrality and eigenvector centrality, which provide measures of the extent to which a given brain region connects other regions in the network. Reductions in betweenness centrality and eigenvector centrality were particularly evident within hub regions including the cingulate cortex and caudate. Our results demonstrate that betweenness centrality and eigenvector centrality are reduced within network hubs, due to the impact of traumatic axonal injury on network connections. The dominance of betweenness centrality and eigenvector centrality suggests that cognitive impairment after traumatic brain injury results from the disconnection of network hubs by traumatic axonal injury.

Human detection based on the generation of a background image by using a far-infrared light camera.

The need for computer vision-based human detection has increased in fields, such as security, intelligent surveillance and monitoring systems. However, performance enhancement of human detection based on visible light cameras is limited, because of factors, such as nonuniform illumination, shadows and low external light in the evening and night. Consequently, human detection based on thermal (far-infrared light) cameras has been considered as an alternative. However, its performance is influenced by the factors, such as low image resolution, low contrast and the large noises of thermal images. It is also affected by the high temperature of backgrounds during the day. To solve these problems, we propose a new method for detecting human areas in thermal camera images. Compared to previous works, the proposed research is novel in the following four aspects. One background image is generated by median and average filtering. Additional filtering procedures based on maximum gray level, size filtering and region erasing are applied to remove the human areas from the background image. Secondly, candidate human regions in the input image are located by combining the pixel and edge difference images between the input and background images. The thresholds for the difference images are adaptively determined based on the brightness of the generated background image. Noise components are removed by component labeling, a morphological operation and size filtering. Third, detected areas that may have more than two human regions are merged or separated based on the information in the horizontal and vertical histograms of the detected area. This procedure is adaptively operated based on the brightness of the generated background image. Fourth, a further procedure for the separation and removal of the candidate human regions is performed based on the size and ratio of the height to width information of the candidate regions considering the camera viewing direction and perspective projection. Experimental results with two types of databases confirm that the proposed method outperforms other methods.

Optical diagnosis of malaria infection in human plasma using Raman spectroscopy

We present the prediction of malaria infection in human plasma using Raman spectroscopy. Raman spectra of malaria-infected samples are compared with those of healthy and dengue virus infected ones for disease recognition. Raman spectra were acquired using a laser at 532 nm as an excitation source and 10 distinct spectral signatures that statistically differentiated malaria from healthy and dengue-infected cases were found. A multivariate regression model has been developed that utilized Raman spectra of 20 malaria-infected, 10 non-malarial with fever, 10 healthy, and 6 dengue-infected samples to optically predict the malaria infection. The model yields the correlation coefficient r(2) value of 0.981 between the predicted values and clinically known results of trainee samples, and the root mean square error in cross validation was found to be 0.09; both these parameters validated the model. The model was further blindly tested for 30 unknown suspected samples and found to be 86% accurate compared with the clinical results, with the inaccuracy due to three samples which were predicted in the gray region. Standard deviation and root mean square error in prediction for unknown samples were found to be 0.150 and 0.149, which are accepted for the clinical validation of the model.