Adaptive antennas at the mobile and base stations in an OFDM/TDMA system

In recent years, several smart antenna systems have been proposed and demonstrated at the base station (BS) of wire-less communications systems, and these have shown that significant system performance improvement is possible. In this paper, we consider the use of adaptive antennas at the BS and mobile stations (MS), operating jointly, in combination with orthogonal frequency-division multiplexing. The advantages of the proposed system includes reductions in average error probability and increases in capacity compared to conventional systems. Multiuser access, in space, time, and through subcarriers, is also possible and expressions for the exact joint optimal antenna weights at the BS and MS under cochannel interference conditions for fading channels are derived. To demonstrate the potential of our proposed system, analytical along with Monte Carlo simulation results are provided

Train unit scheduling with bi-level capacity requirements

Train unit scheduling concerns the assignment of train unit vehicles to cover all the journeys in a fixed timetable allowing the possibility of coupling and decoupling to achieve optimal utilization while satisfying passenger demands. While the scheduling methods usually assume unique and well-defined train capacity requirements, in practice most UK train operators consider different levels of capacity provisions. Those capacity provisions are normally influenced by information such as passenger count surveys, historic provisions and absolute minimums required by the authorities. In this paper, we study the problem of train unit scheduling with bi-level capacity requirements and propose a new integer multicommodity flow model based on previous researches. Computational experiments on real-world data show the effectiveness of our proposed methodology

Fibonacci anyons and charge density order in the 12/5 and 13/5 plateaus

The $\nu=12/5$ fractional quantum Hall plateau observed in GaAs wells is a suspect in the search for non-Abelian Fibonacci anyons. Using the infinite density matrix renormalization group, we find clear evidence that---in the absence of Landau level mixing---fillings $\nu = 12/5$ and $\nu=13/5$ are in the $k = 3$ Read-Rezayi phase. The lowest energy charged excitation is a non-Abelian Fibonacci anyon which can be trapped by a one-body potential. We point out extremely close energetic competition between the Read-Rezayi phase and a charge-density ordered phase, which suggests that even small particle-hole symmetry breaking perturbations can explain the experimentally observed asymmetry between $\nu = 12/5$ and $13/5$. Reducing the thickness of the quantum well drives a transition from the homogeneous Read-Rezayi phase to the charge-density ordered phase, providing a plausible explanation for the absence of a $\nu=12/5$ plateau in narrow GaAs wells

Imaging Anyons with Scanning Tunneling Microscopy

Anyons are exotic quasiparticles with fractional charge that can emerge as fundamental excitations of strongly interacting topological quantum phases of matter. Unlike ordinary fermions and bosons, they may obey non-Abelian statistics—a property that would help realize fault-tolerant quantum computation. Non-Abelian anyons have long been predicted to occur in the fractional quantum Hall (FQH) phases that form in two-dimensional electron gases in the presence of a large magnetic field, such as the ν=5/2 FQH state. However, direct experimental evidence of anyons and tests that can distinguish between Abelian and non-Abelian quantum ground states with such excitations have remained elusive. Here, we propose a new experimental approach to directly visualize the structure of interacting electronic states of FQH states with the STM. Our theoretical calculations show how spectroscopy mapping with the STM near individual impurity defects can be used to image fractional statistics in FQH states, identifying unique signatures in such measurements that can distinguish different proposed ground states. The presence of locally trapped anyons should leave distinct signatures in STM spectroscopic maps, and enables a new approach to directly detect—and perhaps ultimately manipulate—these exotic quasiparticles

Short-latency somatosensory-evoked potential in patients with central nervous system space-occupying lesions: a study of 261 cases

INTRODUCTION: Short-latency somatosensory-evoked potential (SSEP) is an electrophysiological technique to study the dorsal column–medial lemniscal sensory system. Its application in central nervous system spaceoccupying lesions (CNS SOLs) has sparsely been published. METHODS: A total of 261 patients with CNS SOLs underwent SSEP before neurosurgeries. Anatomical locations of the lesions, histopathological diagnoses and prognosis were tried to correlate with the SSEP variables. RESULTS: The spinal SOLs, especially nerve sheath tumours, was associated with significant abnormalities in various variables including the central conduction time. Other anatomical sites and histopathologies did not correlate with the SSEP findings. Also SSEP did not reflect clinical prognosis. CONCLUSION: Short-latency somatosensory-evoked potential is probably not a sensitive test for CNS SOLs except spinal cord lesions. This is probably due to anatomy of the somatosensory pathway. The fact that SSEP has different sensitivities to various tumours may reflect that sensory neurons have heterogenous susceptibilities to different pathologies.published_or_final_versionThe 15th Medical Research Conference; Department of Medicine, The University of Hong Kong, Hong Kong, 16 January 2010. In Hong Kong Medical Journal, 2010, v. 16 suppl 1, p. 13, abstract no. 1

Feasibility of T1rho MR imaging in identification of the epileptogenic zone in patients with mesial temporal lobe epilepsy

Poster PresentationPURPOSE: T1rho is sensitive to physiochemical exchange and early molecular changes. We aim to investigate the feasibility and utility of T1rho MR imaging in identification of epileptogenic zone in patient with mesial temporal lobe epilepsy (MTLE). METHODS: 7 patients (male 28.6%, female 71.4%; mean age of 36.29±8.77 yrs) with estab…published_or_final_versio

A case of Hemiplegia Vegetativa Alterna, Paroxysmal Sympathetic Hyperactivity and Ogilvie's Syndrome: the role of central sympathetic pathways in their pathophysiology

Meeting Theme: Degenerative Lumbar SpineOral-Poster Presentation 1Hemiplegia vegetativa alterna (HVA) is the clinical syndrome of contralateral hemiparesis, hemisensory loss, hemihyperhydrosis and ipsilateral Horner’s syndrome1,2. The term vegetativa alterna denotes that a single brainstem lesion manifests with ipsilateral and contralateral, i.e. crossed, signs of autonomic (“vegetative”) sympathetic nervous system dysfunction. Fewer than five cases have been reported and most were a result of stroke involving the occlusion of posterior cerebral artery (PCA) perforators that supply the anterolateral mesencephalon. We describe a 46 year old male who suffered from aneurysmal subarachnoid hemorrhage and exhibited HVA as …published_or_final_versio

Central nervous system inflammatory demyelinating disorders in Hong Kong Chinese

Poster PresentationBACKGROUND: Classical multiple sclerosis (CMS) must be differentiated from neuromyelitis optica (NMO) as treatments are different. Serum aquaporin-4 autoantibodies (AQP4 Ab) are specific for NMO spectrum disorders (NMOSD). We aimed to study the diagnoses of CNS inflammatory demyelinating disorder (IDD) patients presenting to a hospital over 29 years. METHODS: Chinese patients presenting with CNS IDD to our hospital from 1981 to 2009 were studied. Patients referred from other centres were excluded. Since 2008, patients had yearly magnetic resonance imaging (MRI) brain and cord for 3 years even without relap…published_or_final_versio