Directional dipole dice enabled by anisotropic chirality.

Directional radiation and scattering play an essential role in light manipulation for various applications in integrated nanophotonics, antenna and metasurface designs, quantum optics, etc. The most elemental system with this property is the class of directional dipoles, including the circular dipole, Huygens dipole, and Janus dipole. A unified realization of all three dipole types and a mechanism to freely switch among them are previously unreported, yet highly desirable for developing compact and multifunctional directional sources. Here, we theoretically and experimentally demonstrate that the synergy of chirality and anisotropy can give rise to all three directional dipoles in one structure at the same frequency under linearly polarized plane wave excitations. This mechanism enables a simple helix particle to serve as a directional dipole dice (DDD), achieving selective manipulation of optical directionality via different "faces" of the particle. We employ three "faces" of the DDD to realize face-multiplexed routing of guided waves in three orthogonal directions with the directionality determined by spin, power flow, and reactive power, respectively. This construction of the complete directionality space can enable high-dimensional control of both near-field and far-field directionality with broad applications in photonic integrated circuits, quantum information processing, and subwavelength-resolution imaging.

Broadband efficient anomalous reflection using an aggressively discretized metasurface.

Aggressive discretization in metasurface design-using the least number of unit cells required-can dramatically decrease the phase coverage requirement, thus allowing the use of simple structure and avoiding unit cells with strong resonance, leading to a simple design with broadband performance. An aggressively discretized metasurface with two unit cells per period can realize efficient anomalous reflection. In this work, we investigate the power efficiency and bandwidth of an aggressively discretized metasurface featuring anomalous reflection. Through spectral domain considerations, we find that the theoretical upper limit for the bandwidth of this metasurface reflecting all the incident power into the desired mode is 67%. With aggressive discretization, we design a metasurface with a simple unit cell structure. By tuning the two unit cells, we achieve a metasurface design that reflects more than 80% of the incidence power into the desired anomalous reflection mode over a broad bandwidth of 53.6%. Such bandwidth is unprecedented for an anomalous reflection metasurface. Finally, we fabricate and experimentally demonstrate our anomalous reflection metasurface and obtain bandwidth and efficiency performances which agree well with simulation.

Schizencephaly in children: A single medical center retrospective study.

BACKGROUND: The aim of this study was to evaluate the clinical, and neuroimaging features, outcomes, and other associated systemic disorders in children with schizencephaly at a single medical center in Taiwan. METHODS: We retrospectively reviewed the medical records and magnetic resonance images (MRI) of children with schizencephaly between January 2000 and December 2014. The MRI findings of schizencephaly were recorded along with the presence of associated cerebral disorders. Clinical, electroencephalographic and additional systemic disorders were also recorded. RESULTS: A total of 21 patients (13 males and 8 females) were included in the study. According to the location of schizencephaly, the patients were classified into two groups: unilateral (n = 16) and bilateral (n = 5). The majority of the patients with neurological deficits were detected before 1 year of age, especially in bilateral clefts. The most common initial presentation was hemiparesis in unilateral schizencephaly, and seizures in bilateral schizencephalies. Ventriculomegaly was the most common associated cerebral disorder, and the most common additional systemic disorders included congenital heart disease, hydronephrosis, and strabismus. Seventeen patients suffered from epileptic seizures with generalized tonic-clonic seizures being the most common. Eight patients developed refractory epilepsy. The majority of the patients had motor deficits, intellectual disabilities, and language deficits, especially in bilateral clefts. CONCLUSIONS: This study demonstrates that the clinical features of schizencephaly vary widely, with their severity closely related to the cleft. Determining the type, size, and extent of schizencephaly is useful to plan management and predict the prognosis.

Clinical and neuroimaging findings in children with gray matter heterotopias: A single institution experience of 36 patients.

OBJECTIVE: To describe the clinical spectrum and neuroimaging features of childhood gray matter heterotopias in a single tertiary hospital in Taiwan. METHODS: We retrospectively reviewed the medical records and magnetic resonance images (MRI) of 36 patients with gray matter heterotopias, 19 females and 17 males, between July 1999 and June 2014. The MRI morphologic findings of gray matter heterotopias were recorded along with the presence of associated cerebral malformations. The clinical, electrophysiological and associated systemic malformation data were also recorded. RESULTS: A total of 36 patients were included in the study. Their ages ranged from 1 month to 18 years with a mean age of 3 years 6 months. According to the location of gray matter heterotopias, patients were classified into two groups: periventricular (26) and band (10). The phenotypic spectrum in our population differed from that described previously. In the periventricular group, additional cerebral malformations were found in 18/26 (69%) and systemic malformations in 14/26 (54%). In the band group, additional cerebral malformations were found in 5/10 (50%) and systemic malformations in 2/10 (20%). The majority of patients had developmental delay and intellectual deficit. Twenty-two patients suffered from epileptic seizures with 12 developing refractory epilepsy. CONCLUSIONS: In periventricular heterotopias, the most common associated cerebral malformation was ventriculomegaly, followed by agenesis of corpus callosum. Congenital heart disease was the most common additional systemic malformation. However, the most common associated cerebral malformation was pachygyria in band form. The majority of patients had developmental delay, intellectual deficit, especially in band heterotopias.

Assessment of vessel permeability by combining dynamic contrast-enhanced and arterial spin labeling MRI.

The forward volumetric transfer constant (K(trans)), a physiological parameter extracted from dynamic contrast-enhanced (DCE) MRI, is weighted by vessel permeability and tissue blood flow. The permeability × surface area product per unit mass of tissue (PS) in brain tumors was estimated in this study by combining the blood flow obtained through pseudo-continuous arterial spin labeling (PCASL) and K(trans) obtained through DCE MRI. An analytical analysis and a numerical simulation were conducted to understand how errors in the flow and K(trans) estimates would propagate to the resulting PS. Fourteen pediatric patients with brain tumors were scanned on a clinical 3-T MRI scanner. PCASL perfusion imaging was performed using a three-dimensional (3D) fast-spin-echo readout module to determine blood flow. DCE imaging was performed using a 3D spoiled gradient-echo sequence, and the K(trans) map was obtained with the extended Tofts model. The numerical analysis demonstrated that the uncertainty of PS was predominantly dependent on that of K(trans) and was relatively insensitive to the flow. The average PS values of the whole tumors ranged from 0.006 to 0.217 min(-1), with a mean of 0.050 min(-1) among the patients. The mean K(trans) value was 18% lower than the PS value, with a maximum discrepancy of 25%. When the parametric maps were compared on a voxel-by-voxel basis, the discrepancies between PS and K(trans) appeared to be heterogeneous within the tumors. The PS values could be more than two-fold higher than the K(trans) values for voxels with high K(trans) levels. This study proposes a method that is easy to implement in clinical practice and has the potential to improve the quantification of the microvascular properties of brain tumors.

Superoscillations without sidebands: power-efficient sub-diffraction imaging with propagating waves.

A superoscillation wave is a special superposition of propagating electromagnetic (EM) waves which varies with sub-diffraction resolution inside a fixed region. This special property allows superoscillation waves to carry sub-diffraction details of an object into the far-field, and makes it an attractive candidate technology for super-resolution devices. However, the Shannon limit seemingly requires that superoscillations must exist alongside high-energy sidebands, which can impede its widespread application. In this work we show that, contrary to prior understanding, one can selectively synthesize a portion of a superoscillation wave and thereby remove its high-energy region. Moreover, we show that by removing the high-energy region of a superoscillation wave-based imaging device, one can increase its power efficiency by two orders of magnitude. We describe the concept behind this development, elucidate conditions under which this phenomenon occurs, then report fullwave simulations which demonstrate the successful, power-efficient generation of sub-wavelength focal spots from propagating waves.

Childhood encephalitis: relationship between diffusion abnormalities and clinical outcome.

INTRODUCTION: The impact of restricted diffusion on clinical outcome has not been well studied in childhood encephalitis. We hypothesized that the patients with lesions with restricted diffusion (LRD) would have worse clinical outcome. METHODS: We reviewed the MR studies of 83 children with encephalitis for LRD. An MRI scoring system (0-12) based on fluid-attenuated inversion recovery (FLAIR) imaging was created to evaluate the extent of imaging abnormality. Clinical outcome was graded by using Glasgow outcome scale (GOS) (1-5) in 1st and 12th month: 1 for death and five for full recovery. With respect to diffusion, the correlation between imaging score and GOS was assessed. Logistic regression analysis was used to explore the impact of diffusion and imaging score on clinical outcome. The patients were divided into three subgroups regarding imaging score: I, 0-4; II, 5-8; and III, 9-12. RESULTS: LRD was found in 28 patients. Negative significant correlation was found between imaging score and GOS in the group with LRD in both 1st month (R = -0.67, P < 0.001) and 12th month (R = -0.56, P = 0.001). Multivariate logistic regression showed that LRD (P < 0.001) and age (P = 0.026) were significant independent risk factors for unfavorable outcome in 1st month, and both LRD (P = 0.001) and imaging score (P = 0.043) were significant risk factors for unfavorable outcome in 12th month. CONCLUSIONS: Patients with LRD have a worse clinical outcome than those without LRD. In patients with LRD, those with a greater extent of abnormality have a poorer outcome.

Fetal magnetic resonance imaging of normal spinal cord: evaluating cord visualization and conus medullaris position by T2-weighted sequences.

BACKGROUND: Prenatal magnetic resonance (MR) imaging demonstration of the normal spinal cord and the conus medullaris location has not been well studied. We compared balanced fast field echo (bFFE) with single-shot turbo spin-echo (SSh-TSE) MR sequences for visualizing the normal spinal cord and position of conus medullaris in fetuses. METHODS: This retrospective study was approved by the Institutional Review Board of Chang Gung Medical Foundation. We reviewed the MR images of 141 fetuses aged between 16 and 39 gestational weeks, to determine the position of the conus and visualize the spinal cord by using a signal intensity ratio of cerebral spinal fluid (CSF) to the spinal cord. RESULTS: Of the 75 subjects having normal spinal cord and being examined by both bFFE and SSh-TSE studies, the signal intensity ratio of CSF/cord was greater on bFFE images (2.18 ± 0.53) than that on SSh-TSE images (1.21 ± 0.13) (p < 0.05). The conus level identified in the 50 subjects, in whom the lumbosacral spine was appropriately imaged, was located from L1 to L5 levels. The ascendance of the conus correlated moderately with gestational age. CONCLUSIONS: With greater signal contrast ratio of CSF to spinal cord, bFFE sequence, when compared with SSh-TSE sequence, provides better visualization of normal spinal cord. The fetal conus medullaris ascends from L5 to L1 levels as the gestational age increases.

Comparison of three-dimensional pseudo-continuous arterial spin labeling perfusion imaging with gradient-echo and spin-echo dynamic susceptibility contrast MRI.

PURPOSE: To compare the relative cerebral blood flow (CBF) obtained by pseudo-continuous arterial spin labeling sequence incorporated with volumetric fast spin-echo readout (3D-PCASL) with those by gradient-echo (GE) and spin-echo (SE) dynamic susceptibility contrast (DSC) MRI. MATERIALS AND METHODS: Thirty patients with various neurological diseases participated in this study. In addition to 3D-PCASL, 15 patients received GE-DSC and the others received SE-DSC imaging on a 3 Tesla scanner. A cortical gray matter (GM) to white matter (WM) and a thalamus (TM) to WM CBF ratio were determined from each perfusion scan. In addition, histograms of relative CBF distributions were obtained from each method for comparison. RESULTS: Significant correlations of CBF ratios were found between 3D-PCASL and the two DSC methods (P < 0.05). The 3D-PCASL resulted in GM/WM CBF ratios similar to SE-DSC but significantly smaller than GE-DSC (P = 2.3 × 10(-7) ). TM/WM CBF ratio obtained by 3D-PCASL was significantly smaller than those by GE- and SE-DSC (P = 4.1 × 10(-7) and 1.2 × 10(-6) , respectively). The histogram of relative CBF maps obtained from SE-DSC, after applied spatial smoothing, agreed well with that from 3D-PCASL. CONCLUSION: This study suggested that perfusion images obtained from 3D-PCASL exhibited significant correlations with DSC-MRI, with greater microvascular weighting like SE-DSC.

Cervical spinal cord compression in a child with cervicofacial actinomycosis.

Actinomycosis is a rare, chronic, suppurative, and slowly progressive granulomatous disease caused by a group of filamentous gram-positive anaerobic bacteria belonging to the normal flora of the oral cavity, gastrointestinal, and genitourinary tracts. It may involve several organs; however, spinal cord compression has rarely been reported. We report a 7-year-3-month-old girl who suffered from neck pain with restricted movement, poor appetite, body weight loss, mild right limbs weakness, and a non-tender neck mass. Histopathology of the neck mass revealed sulfur granules of actinomyces. Since actinomycosis was strongly suspected, she was treated with high dose of parenteral penicillin G followed by oral penicillin with complete recovery. The unusual features of our case suggested that actinomycosis should be considered as a differential diagnosis of neck mass and cervical spinal cord compression.

Plasmapheresis as adjuvant therapy in Stevens-Johnson syndrome and hepatic encephalopathy.

Stevens-Johnson syndrome (SJS) is a severe idiosyncratic reaction, most commonly triggered by medications, which is characterized by fever and mucocutaneous lesions, leading to necrosis and sloughing of the epidermis. Aside from skin and mucosal manifestations, SJS may also compromise heart, liver, kidney, lung, and gastrointestinal tract. Although cholestatic liver disease has been reported to occur in SJS, hepatic encephalopathy (HE) as a delayed complication has never been reported. We report a 4-year-old female child with anticonvulsant-induced SJS complicated by HE who was completely cured with a combination of systemic corticosteroid, intravenous immunoglobulin (IVIG), and plasmapheresis therapy. We suggested that plasmapheresis may be used as an adjuvant therapy for SJS with HE.

Pain and pain-related situations surrounding community-dwelling older persons.

AIMS AND OBJECTIVES: To examine the pain prevalence in community-dwelling older adults and to explore the relationships between pain and physical and psychological parameters. BACKGROUND: Uncontrolled chronic pain is one of the barriers preventing older people from achieving active ageing. Effective pain management can enhance their mobility, increasing the happiness level and thus the quality of life. DESIGN: Exploratory cross-sectional study. METHOD: Cognitively intact community-dwelling older persons aged over 60 in Hong Kong were invited for a 20-25-minute interview. RESULTS: A total of 173 participants were recruited, with a mean age of 73.2. The average pain intensity was 3.97 ± 1.80. Oral analgesic drugs were used by 47.1% of participants, and 86.0% used nonpharmacological methods to relieve pain. Compared with participants free of chronic pain, participants with pain had lower happiness levels (p < 0.05). In addition, levels of mobility (p < 0.05) and physical quality of life (p < 0.05) were lower for older people with pain. Pain intensity was negatively correlated with physical quality of life (p < 0.05) and self-efficacy (p < 0.05), and positively correlated with mystery (p < 0.05), permanence (p < 0.05) and self-blame (p < 0.05) in pain belief. CONCLUSION: It was noted that nonpharmacological methods were commonly used by older persons as pain relief and that older persons with pain were less happy, less mobile and had a poorer quality of life as compared to their counterparts without pain. RELEVANCE TO CLINICAL PRACTICE: It is important to educate community-dwelling older persons on methods of pain management and to maintain their physical and psychological well-being in order to engage them in the community and lead a healthy and happy ageing.

An optical super-microscope for far-field, real-time imaging beyond the diffraction limit.

Optical microscopy suffers from a fundamental resolution limitation arising from the diffractive nature of light. While current solutions to sub-diffraction optical microscopy involve combinations of near-field, non-linear and fine scanning operations, we hereby propose and demonstrate the optical super-microscope (OSM) - a superoscillation-based linear imaging system with far-field working and observation distances - which can image an object in real-time and with sub-diffraction resolution. With our proof-of-principle prototype we report a point spread function with a spot size clearly reduced from the diffraction limit, and demonstrate corresponding improvements in two-point resolution experiments. Harnessing a new understanding of superoscillations, based on antenna array theory, our OSM achieves far-field, sub-diffraction optical imaging of an object without the need for fine scanning, data post-processing or object pre-treatment. Hence the OSM can be used in a wide variety of imaging applications beyond the diffraction limit, including real-time imaging of moving objects.

Acute disseminated encephalomyelitis in children: a single institution experience of 28 patients.

The aim of this study is to describe the clinical, laboratory, and neuroimaging features, treatment and outcome of acute disseminated encephalomyelitis (ADEM) in Taiwanese children to compare with two series from United States of America and Japan. We retrospectively reviewed the medical records and magnetic resonance images of 28 children, 23 boys and 5 girls, with ADEM between January 2001 and December 2009. Their mean age at disease onset was 6 years 9 months. Twenty four children experienced a prodromal illness. There was no special seasonal distribution in our patients. They presented mostly with impaired consciousness and headache. Cerebrospinal fluid samples of 21 patients were analyzed and none showed intrathecal oligoclonal bands. Magnetic resonance imaging showed variable findings: lesions with abnormal signal changes frequently found in the subcortical white matter of frontal and parietal lobes. No patient showed cortical gray matter involvement. We also found a high rate of deep gray matter involvement including thalami and basal ganglia. Treating with steroids was usually associated with a rapid recovery and both intravenous high dose methylprednisolone and dexamethasone had the same effect. All patients survived. Twenty three patients recovered completely with only mild sequelae in the remaining five children.

Prenatal MR imaging of Dandy-Walker complex: midline sagittal area analysis.

OBJECTIVE: To measure the mid-sagittal areas of vermis (VA) and of posterior fossa (PFA) and determine their differences among fetuses with various Dandy-Walker (DW) entities and control subjects. METHODS: We reviewed data in 25 fetal patients with a MR diagnosis of DW complex including hypoplastic vermis (HV), HV with rotation (HVR), and mega cistern magna (MCM), and in 85 fetal controls with normal CNS. PFA and VA of each subject were manually traced on mid-sagittal MR images. Regarding each of VA and PFA, after age correction, we determined statistically significant differences among HVR, HV, MCM, and control groups. RESULTS: The mean VA residue of MCM was greater than that of the control, which was in turn greater than those of HVR and HV. The mean PF residue of the control was smaller than all other groups. CONCLUSION: Fetuses with HVR or HV had smaller VA than fetuses with MCM or control subjects. Fetuses with MCM, HVR, or HV had larger PFA than control subjects. These results may be an early step leading to better understanding of the confusion about the PF anomalies in future.

Moyamoya syndrome in a child with Noonan syndrome.

Previous studies have rarely described the association between Noonan syndrome and moyamoya syndrome. Although most affected children with moyamoya exhibit ischemic symptoms, headache is also a frequent symptom. We report the case of a 9-year-old girl with Noonan syndrome and moyamoya syndrome that manifested as recurrent headaches without history of transient ischemic attack. Brain magnetic resonance imaging and magnetic resonance angiography revealed bilateral moyamoya syndrome and mild ventriculomegaly with focal encephalomalacia at right peritrigonal region. Disruption of vascular development during the prenatal stage has been proposed as the cause of cerebrovascular disease in Noonan syndrome. However, genetic factors may also contribute.

Plasmonic meta-screen for alleviating the trade-offs in the near-field optics.

We propose a "meta-screen" design, consisting of a metallic sheet patterned with a dense array of nano-sized slot antennas, for inducing sub-wavelength optical spots in the near-field. Compared to other transmission screen topologies, our design overcomes the trade-off of low throughput versus resolution of a sub-wavelength aperture by inducing resonance in the slots. In addition, the antenna array serves to effectively narrow the spot size through the superposition of spatially shifted beams produced by each slot element. Such a design offers a practical approach for extending the near-field sensing/imaging distance at optical frequencies. The effectiveness of narrowing the spot size through the array topology is demonstrated by evaluating the full-width-half-maximum (FWHM) beamwidth at a distance of 0.1lambda(0) away from the screen. We show that an array with just three elements improves the beamwidth by more than 30% compared to a single resonant slot element. In this paper, important issues such as the operating principle and the design process of the meta-screen, the characteristics of plasmonic slot antenna, the impact of the number of array elements, and the effect of asymmetry due to the presence of a supporting substrate are discussed.

Chinese patients with defective IL-12/23-interferon-gamma circuit in Taiwan: partial dominant interferon-gamma receptor 1 mutation presenting as cutaneous granuloma and IL-12 receptor beta1 mutation as pneumatocele.

BACKGROUND: IL-12/23-interferon-gamma circuit enhances reactive oxygen species (ROS) synthesis in macrophage to attack intracellular pathogens such as mycobacteria and salmonella. Defective ROS in patients with chronic granulomatous disease (CGD) have increased susceptibility to these pathogens. However, patients with defective IL-12/23-interferon-gamma circuit rather than CGD are not recognized in Taiwan, endemic for tuberculosis and salmonella. AIM: The purpose of this study was to identify Taiwanese patients with defective IL-12/23-IFN-gamma circuit. PATIENTS AND METHODS: In a long-term molecular study of primary immunodeficiency diseases (PIDD), the tentative CGD patients presenting with Bacille Calmette-Guerin (BCG)-induced infection, refractory atypical mycobacterial cutaneous granuloma and osteomyelitis, recurrent salmonella sepsis, and pneumatocele were studied for the IL-12/23-IFN-gamma circuit. ROS was first measured to exclude CGD. Candidate genes of IL12RB1, IFNRG1, IL12p40, IFNRG2, signal transducer and activator of transcription-1, and NF-kappaB essential modulator and their encoding protein expressions were analyzed. RESULTS: Of the 175 Taiwanese PIDD patients during a 28-year period, three patients from two unrelated families were identified with the hotspot INFRG1 deletion mutation (818del4) and had CGD features, presenting as cutaneous granuloma, and multiple osteomyelitis infected by non-tuberculosis mycobacteria, Mycobacteria avium complex and Mycobacterium scrofulaceum. Another with mis-sense IL12RB1 mutation (Arg211Pro) was noted as recurrent Salmonella enteritidis D sepsis and pneumatocele. CONCLUSION: Patients with defective IL-12/23-IFN-gamma circuit may resemble or overlap CGD manifestations of refractory cutaneous atypical mycobacterial granuloma and salmonella pneumatocele.