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The Murchison Widefield Array (MWA) is an open access telescope dedicated to studying the low-frequency (80–300 MHz) southern sky. Since beginning operations in mid-2013, the MWA has opened a new observational window in the southern hemisphere enabling many science areas. The driving science objectives of the original design were to observe 21 cm radiation from the Epoch of Reionisation (EoR), explore the radio time domain, perform Galactic and extragalactic surveys, and monitor solar, heliospheric, and ionospheric phenomena. All together
programs recorded 20 000 h producing 146 papers to date. In 2016, the telescope underwent a major upgrade resulting in alternating compact and extended configurations. Other upgrades, including digital back-ends and a rapid-response triggering system, have been developed since the original array was commissioned. In this paper, we review the major results from the prior operation of the MWA and then discuss the new science paths enabled by the improved capabilities. We group these science opportunities by the four original science themes but also include ideas for directions outside these categories.
Positive symptoms are a useful predictor of aggression in schizophrenia. Although a similar pattern of abnormal brain structures related to both positive symptoms and aggression has been reported, this observation has not yet been confirmed in a single sample.
To study the association between positive symptoms and aggression in schizophrenia on a neurobiological level, a prospective meta-analytic approach was employed to analyze harmonized structural neuroimaging data from 10 research centers worldwide. We analyzed brain MRI scans from 902 individuals with a primary diagnosis of schizophrenia and 952 healthy controls.
The result identified a widespread cortical thickness reduction in schizophrenia compared to their controls. Two separate meta-regression analyses revealed that a common pattern of reduced cortical gray matter thickness within the left lateral temporal lobe and right midcingulate cortex was significantly associated with both positive symptoms and aggression.
These findings suggested that positive symptoms such as formal thought disorder and auditory misperception, combined with cognitive impairments reflecting difficulties in deploying an adaptive control toward perceived threats, could escalate the likelihood of aggression in schizophrenia.
Structure and optical properties have been successfully determined for a series of niobium- and tantalum-containing layered alkaline-earth silicate compounds, Ba3(Nb6−xTax)Si4O26 (x = 0.6, 1.8, 3.0, 4.2, 5.4). The structure of this solid solution was found to be hexagonal P-62m (No. 189), with Z = 1. With x increases from 0.6 to 5.4, the lattice parameter a increases from 8.98804(8) to 9.00565(9) Å and c decreases from 7.83721(10) to 7.75212(12) Å. As a result, the volume decreases from 548.304(11) to 544.479(14) Å3. The (Nb/Ta)O6 distorted octahedra form continuous chains along the c-axis. These (Nb/Ta)O6 chains are in turn linked with the Si2O7 groups to form distorted pentagonal channels in which Ba ions were found. These Ba2+ ions have full occupancy and a 13-fold coordination environment with neighboring oxygen sites. Another salient feature of the structure is the linear Si–O–Si chains. When x in Ba3(Nb6−xTax)Si4O26 increases, the bond valence sum (BVS) values of the Ba sites increase slightly (2.09–2.20), indicating the size of the cage becoming progressively smaller (over-bonding). While SiO cages are also slightly smaller than ideal (BVS range from 4.16 to 4.19), the (Nb/Ta)O6 octahedral cages are slightly larger than ideal (BVS range from 4.87 to 4.90), giving rise to an under-bonding situation. The bandgaps of the solid solution members were measured between 3.39 and 3.59 eV, and the x = 3.0 member was modeled by density functional theory techniques to be 3.07 eV. The bandgaps of these materials indicate that they are potential candidates for ultraviolet photocatalyst.
Better understanding of interplay among symptoms, cognition and functioning in first-episode psychosis (FEP) is crucial to promoting functional recovery. Network analysis is a promising data-driven approach to elucidating complex interactions among psychopathological variables in psychosis, but has not been applied in FEP.
This study employed network analysis to examine inter-relationships among a wide array of variables encompassing psychopathology, premorbid and onset characteristics, cognition, subjective quality-of-life and psychosocial functioning in 323 adult FEP patients in Hong Kong. Graphical Least Absolute Shrinkage and Selection Operator (LASSO) combined with extended Bayesian information criterion (BIC) model selection was used for network construction. Importance of individual nodes in a generated network was quantified by centrality analyses.
Our results showed that amotivation played the most central role and had the strongest associations with other variables in the network, as indexed by node strength. Amotivation and diminished expression displayed differential relationships with other nodes, supporting the validity of two-factor negative symptom structure. Psychosocial functioning was most strongly connected with amotivation and was weakly linked to several other variables. Within cognitive domain, digit span demonstrated the highest centrality and was connected with most of the other cognitive variables. Exploratory analysis revealed no significant gender differences in network structure and global strength.
Our results suggest the pivotal role of amotivation in psychopathology network of FEP and indicate its critical association with psychosocial functioning. Further research is required to verify the clinical significance of diminished motivation on functional outcome in the early course of psychotic illness.
Structural characterization and X-ray reference powder pattern determination have been conducted for the Co- and Zn-containing tridymite derivatives Ba(Co1−xZnx)SiO4 (x = 0.2, 0.4, 0.6, 0.8). The bright blue series of Ba(Co1−xZnx)SiO4 crystallized in the hexagonal P63 space group (No. 173), with Z = 6. While the lattice parameter “a” decreases from 9.126 (2) Å to 9.10374(6) Å from x = 0.2 to 0.8, the lattice parameter “c” increases from 8.69477(12) Å to 8.72200(10) Å, respectively. Apparently, despite the similarity of ionic sizes of Zn2+ and Co2+, these opposing trends are due to the framework tetrahedral tilting of (ZnCo)O4. The lattice volume, V, remains comparable between 626.27 Å3 and 626.017 (7) Å3 from x = 0 to x = 0.8. UV-visible absorption spectrum measurements indicate the band gap of these two materials to be ≈3.3 and ≈3.5 eV, respectively, therefore potential UV photocatalytic materials. Reference powder X-ray diffraction patterns of these compounds have been submitted to be included in the Powder Diffraction File (PDF).
A series of double-perovskite oxides, Sr2RNbO6 (R = Sm, Gd, Dy, Ho, Y, Tm, and Lu) were prepared and their crystal structure and powder diffraction reference patterns were determined using the Rietveld analysis technique. The crystal structure of each of the Sr2RNbO6 phase is reported in this paper. The R = Gd, Ho, and Lu samples were studied using synchrotron radiation, while R = Sm, Dy, Y, and Tm samples were studied using laboratory X-ray diffraction. Members of Sr2RNbO6 are monoclinic with a space group of P21/n and are isostructural with each other. Following the trend of “lanthanide contraction”, from R = Sm to Lu, the lattice parameters “a” of these compounds decreases from 5.84672(10) to 5.78100(3) Å, b from 5.93192(13) to 5.80977(3) Å, c from 8.3142(2) to 8.18957(5) Å, and V decreases from 288.355(11) to 275.057(2) Å3. In this double-perovskite series, the R3+ and Nb5+ ions are structurally ordered. The average Nb–O bond length is nearly constant, while the average R–O bond length decreases with the decreasing ionic radius of R3+. Powder diffraction patterns for these compounds have been submitted to the Powder Diffraction File (PDF).
Evidence suggests that autism and schizophrenia share similarities in genetic, neuropsychological and behavioural aspects. Although both disorders are associated with theory of mind (ToM) impairments, a few studies have directly compared ToM between autism patients and schizophrenia patients. This study aimed to investigate to what extent high-functioning autism patients and schizophrenia patients share and differ in ToM performance.
Thirty high-functioning autism patients, 30 schizophrenia patients and 30 healthy individuals were recruited. Participants were matched in age, gender and estimated intelligence quotient. The verbal-based Faux Pas Task and the visual-based Yoni Task were utilised to examine first- and higher-order, affective and cognitive ToM. The task/item difficulty of two paradigms was examined using mixed model analyses of variance (ANOVAs). Multiple ANOVAs and mixed model ANOVAs were used to examine group differences in ToM.
The Faux Pas Task was more difficult than the Yoni Task. High-functioning autism patients showed more severely impaired verbal-based ToM in the Faux Pas Task, but shared similar visual-based ToM impairments in the Yoni Task with schizophrenia patients.
The findings that individuals with high-functioning autism shared similar but more severe impairments in verbal ToM than individuals with schizophrenia support the autism–schizophrenia continuum. The finding that verbal-based but not visual-based ToM was more impaired in high-functioning autism patients than schizophrenia patients could be attributable to the varied task/item difficulty between the two paradigms.
The purpose of this study was to dosimetrically compare TomoDirect, TomoHelical and linear accelerator-based 3D-conformal radiotherapy (Linac-3DCRT) for craniospinal irradiation (CSI) in the treatment of medulloblastoma.
Five CSI patients were replanned with Linac-3DCRT, TomoHelical, TomoDirect-3DCRT and TomoDirect-intensity-modulated radiotherapy (IMRT). Dose of 36 Gy in 20 fractions was prescribed to the planning target volume (PTV). Homogeneity index (HI), non-target integral dose (NTID), dose–volume histograms, organs-at-risk (OARs) Dmax, Dmean and treatment times were compared.
TomoHelical achieved the best PTV homogeneity compared with Linac-3DCRT, TomoDirect-3DCRT and TomoDirect-IMRT (HI of 3·6 versus 20·9, 8·7 and 9·4%, respectively). TomoDirect-IMRT achieved the lowest NTID compared with TomoDirect-3DCRT, TomoHelical and Linac-3DCRT (141 J versus 151 J, 181 J and 250 J), indicating least biological damage to normal tissues. TomoHelical plans achieved the lowest Dmax in all organs except the breasts, and lowest Dmean for most OARs, except in laterally situated OARs, where TomoDirect triumphed. Beam-on time was longest for TomoHelical, followed by TomoDirect and Linac-3DCRT.
TomoDirect has the potential to lower NTID and shorten treatment times compared with TomoHelical. It reduces PTV inhomogeneity and better spares OARs compared with Linac-3DCRT. Therefore, TomoDirect may be a CSI treatment alternative to TomoHelical and in place of Linac-3DCRT.
Psychiatric assessment and care of people with Intellectual Disability (ID) is complex due to their cognitive and communication impairments. Demand for further training in this area by trainees in psychiatry has been well documented. The main of aims of this study were to explore the attitudes and perceptions of psychiatry residents and non-residents (non-trainees) with regards to care of patients with ID as well as their knowledge and training in this area.
The study was conducted as an anonymous survey at the Institute of Mental Health, Singapore. A survey questionnaire developed by the study team was sent to residents and non-residents in psychiatry.
Forty-eight out of the 76 questionnaires were returned with a response rate of 63.16%. Twenty-eight participants described themselves as non-residents and the rest were residents. All participants responded that postgraduate training was required in the area of ID and mental health and majority reported that available training was inadequate. Ninety percent of respondents believed that people with ID were vulnerable to exploitation by other patients in the inpatient unit and 94% of respondents believed that people with ID should be managed by a specialist team.
Currently residents and non-residents in psychiatry see that training in ID and mental health as well as services for people with ID as inadequate. Efforts should be made to include specialist training in psychiatry of ID in the Singapore psychiatry curriculum to enhance the confidence and expertise of psychiatrists in this field.
Screening for depression in older adults is recommended.
To evaluate the diagnostic accuracy of the Two-Question Screen for older adults and compare it with other screening instruments for depression.
We undertook a literature search for studies assessing the diagnostic performance of depression screening instruments in older adults. Combined diagnostic accuracy including sensitivity and specificity were the primary outcomes. Potential risks of bias and the quality of studies were also assessed.
A total of 46506 participants from 132 studies were identified evaluating 16 screening instruments. The majority of studies (63/132) used various versions of the Geriatric Depression Scale (GDS) and 6 used the Two-Question Screen. The combined sensitivity and specificity for the Two-Question Screen were 91.8% (95% CI 85.2–95.6) and 67.7% (95% CI 58.1–76.0), respectively; the diagnostic performance area under the curve (AUC) was 90%. The Two-Question Screen showed comparable performance with other instruments, including clinician-rated scales. The One-Question Screen showed the lowest diagnostic performance with an AUC of 78%. In subgroup analysis, the Two-Question Screen also had good diagnostic performance in screening for major depressive disorder.
The Two-Question Screen is a simple and short instrument for depression screening. Its diagnostic performance is comparable with other instruments and, therefore, it would be favourable to use it for older adult screening programmes.
Mobile devices (e.g., smartphones and tablets) have become a commodity in our daily lives. While these devices already support many different types of applications and services, there will be a continual increase in demand for mobile data traffic due to web applications, real-time and streaming video traffic, and applications related to the Internet of Things (IoT). The future fifth generation (5G) wireless cellular systems aim not only to provide a higher aggregate throughput, but also to support applications which have stringent quality of service (QoS) requirements, such as seamless mobility, ultra-low latency (e.g., Tactile Internet), and high reliability (e.g., vehicular communications). Further improvements in spectrum efficiency, energy efficiency, and cost per bit are also important. In order to meet these demands, fundamental changes to the network architecture and all layers of the protocol stack compared with fourth generation (4G) wireless systems are needed.
This book aims to provide a comprehensive treatment of the ongoing research into and state-of-the-art techniques for addressing the challenges arising from the design of 5G wireless systems. Written by leading experts on the subject, this book includes 22 chapters, which cover various aspects of 5G systems, including network architecture design, physical layer techniques, algorithms, and network protocol design. Chapter 1 serves as an introductory chapter and provides an overview of the different key technologies related to 5G systems. Each of the other chapters tackles one specific challenge for system design. The chapters can be read independently.
This book will be of interest to a readership from the communications, signal processing, and networking communities. The primary audience for this book is researchers and engineers who are interested in studying advanced communication and networking techniques, as well as state-of-the-art research on 5G systems. This book will serve as a resource for self-study and as a reference book for researchers and engineers involved in the design of wireless communication systems. It is also suitable for graduate students who are interested in 5G systems and the related communication and networking issues. It may serve as a reference book for graduate-level courses for students in electrical engineering, communication engineering, and networking.
We would like to thank all the authors for their outstanding contributions and their timeliness in completing their respective chapters. In addition, we would like to thank Elizabeth Horne and Heather Brolly from Cambridge University Press for their valuable advice throughout the production of this book.
Gain a detailed understanding of the protocols, network architectures and techniques being considered for 5G wireless networks with this authoritative guide to the state of the art.Get up to speed with key topics such as cloud radio access networks, mobile edge computing, full duplexing, massive MIMO, mmWave, NOMA, Internet of things, M2M communications, D2D communications, mobile data offloading, interference mitigation techniques, radio resource management, visible light communications, and smart data pricing.Learn from leading researchers in academia and industry about the most recent theoretical developments in the field.Discover how each potential technology can increase the capacity, spectral efficiency, and energy efficiency of wireless systems. Providing the most comprehensive overview of 5G technologies to date, this is an essential reference for researchers, practicing engineers and graduate students working in wireless communications and networking.
In recent years, wireless service providers in different countries have deployed both the Third Generation Partnership Project (3GPP) Long Term Evolution (LTE) and LTE-Advanced systems. Despite the unprecedented data rates and quality of service (QoS) provided by these new networks, user demand is beginning to exceed their capabilities. For example, the proliferation of smartphones and tablets has caused a significant and sustained increase in mobile data traffic. In fact, in 2015 alone, global mobile data traffic grew by 74% from 2.1 to 3.7 exabytes . Furthermore, the existing networks are not well suited for the exceedingly large number of devices and appliances that are expected to be connected wirelessly to the Internet in future Internet of Things (IoT) applications and machine-to-machine (M2M) communications. Moreover, to make the growth of networks and the number of connected devices economically and ecologically sustainable, energy efficiency has to be substantially improved. Also, emerging new applications such as remote surgery in healthcare, autonomous driving, and wireless control of industrial robots require ultra-low latencies in the sub-millisecond range and ultra-high reliability, giving rise to the notion of the Tactile Internet. In order to support the exponential growth of existing mobile traffic and the emergence of new wireless applications and services, researchers and standardization bodies worldwide have set out to develop a fifth generation (5G) of wireless networks [2–6]. Some of the stringent requirements for this next generation of wireless networks are listed in Table 1.1 .
To meet these challenging requirements, a mere evolution of the current networks is not sufficient. Instead, a true revolution of technologies in both the radio access network and the mobile core network is needed (Figure 1.1). In the radio access network, fundamentally new physical layer technologies such as massive multiple-input multiple-output (MIMO), non-orthogonal multiple access (NOMA), full-duplex (FD) communication, millimeter wave (mmWave) communication, device-to-device (D2D) communication, and visible light communication (VLC) will be deployed. Furthermore, leveraging cloud computing, the cloud radio access network (C-RAN) has emerged as a promising and cost-efficient mobile network architecture to enhance the spectrum and energy efficiency of 5G networks. In addition, different access technologies, including LTE and Wireless Fidelity (Wi-Fi), may be integrated to guarantee seamless coverage, and to support high data-rate transmission and data offloading.