75 research outputs found
Fractionalisation and dynamics of anyons at in fractional quantum Hall effect and their experimental signatures
We show the low-lying excitations at filling factor with
realistic interactions are contained completely within the well-defined Hilbert
space of "Gaffnian quasiholes". Each Laughlin quasihole can thus be understood
as a bound state of two Gaffnian quasiholes, which in the lowest Landau level
(LLL) behaves like "partons" with "asymptotic freedom" mediated by neutral
excitations acting as "gluons". Near the experimentally observed nematic FQH
phase in higher LLs, quasiholes become weakly bounded and fractionalise with
rich dynamical properties. By studying the effective interactions between
quasiholes, we predict a finite temperature phase transition of the Laughlin
quasiholes even when the Laughlin ground state remains incompressible, and
derive relevant experimental conditions for its possible observations.Comment: 4+ pages, 4 figures. Comments welcom
Spin-statistics relation and the Abelian braiding phase for anyons in fractional quantum Hall effect
Quasihole excitations in fractional quantum Hall (FQH) systems exhibit
fractional statistics and fractional spin, but how the spin-statistics relation
emerges from many-body physics remains poorly understood. Here we prove a
spin-statistics relation using only FQH wave functions, on both the sphere and
disk geometry. In particular, the proof on the disk generalizes to all
quasiholes in realistic systems, which have a finite size and could be deformed
into arbitrary shapes. Different components of the quasihole spins are linked
to different conformal Hilbert spaces (CHS), which are nullspaces of model
Hamiltonians that host the respective FQH ground states and quasihole states.
Understanding how the intrinsic spin of the quasiholes is linked to different
CHS is crucial for the generalized spin-statistics relation that takes into
account the effect of metric deformation. In terms of the experimental
relevance, this enables us to study the effect of deformation and disorder that
introduces an additional source of Berry curvature, an aspect of anyon braiding
that has been largely neglected in previous literature.Comment: 5 pages, 4 figures, comments very welcom
On the Interference Alignment Designs for Secure Multiuser MIMO Systems
In this paper, we propose two secure multiuser multiple-input multiple-output
transmission approaches based on interference alignment (IA) in the presence of
an eavesdropper. To deal with the information leakage to the eavesdropper as
well as the interference signals from undesired transmitters (Txs) at desired
receivers (Rxs), our approaches aim to design the transmit precoding and
receive subspace matrices to minimize both the total inter-main-link
interference and the wiretapped signals (WSs). The first proposed IA scheme
focuses on aligning the WSs into proper subspaces while the second one imposes
a new structure on the precoding matrices to force the WSs to zero. When the
channel state information is perfectly known at all Txs, in each proposed IA
scheme, the precoding matrices at Txs and the receive subspaces at Rxs or the
eavesdropper are alternatively selected to minimize the cost function of an
convex optimization problem for every iteration. We provide the feasible
conditions and the proofs of convergence for both IA approaches. The simulation
results indicate that our two IA approaches outperform the conventional IA
algorithm in terms of average secrecy sum rate.Comment: Updated version, updated author list, accepted to be appear in IEICE
Transaction
Vietnamese Word Segmentation with CRFs and SVMs: An Investigation
PACLIC 20 / Wuhan, China / 1-3 November, 200
Enhancement of current-voltage characteristics of multilayer organic light emitting diodes by using nanostructured composite films
With the aim of improving the photonic efficiency of an organic light emitting diode (OLED) and its display duration, both the hole transport layer (HTL) and the emitting layer (EL) were prepared as nanostructured thin films. For the HTL, nanocomposite films were prepared by spin-coating a homogeneous solution of low molecular weight poly(4-styrenesulfonate) (PEDOT-PSS) and surfactant-capped TiO2 nanocrystals onto low resistivity indium tin oxide (ITO) substrates; for the EL, nancrystalline titatium oxide (nc-TiO2)-embedded Poly[2-methoxy-5-(2′-ethyl-hexyloxy)-1,4-phenylene vinylene] (MEH-PPV+nc-TiO2) conjugate polymers were spin-coated onto the HTL. Also, for a shallow contact of Al/LiF/MEH-PPV instead of Al/MEH-PPV a super LiF thin film was deposited onto the EL by vacuum evaporation. The resulting multilayer OLED had the following structure of Al/LiF/MEH-PPV+nc-TiO2/PEDOT-PSS+nc-TiO2/ITO. Characterization of the nanocomposite films showed that both the current-voltage (I-V) characteristics and the photoluminescent properties of the nanocomposite materials were significantly enhanced in comparison with the standard polymers. OLEDs made from these layers would exhibit a large photonic efficiency
Simulation of the Heavy Charged Particle Impacts on Electrical Characteristics of N-MOSFET Device Structure
The paper presents the results of simulation of the impacts of a heavy charged particle with a value of linear energy transfer equal to 1.81 MeV•cm2 /mg, 10.1 MeV•cm2 /mg, 18.8 MeV•cm2 /mg, 55.0 MeV•cm2 /mg, corresponding to nitrogen ions 15N+4 with energy E = 1.87 MeV, argon 40Ar+12 with energy E = 372 MeV, ferrum 56Fe+15 with energy E = 523 MeV, xenon 131Xe+35 with energy E = 1217 MeV, on electrical characteristics of n-MOSFET device structure when there are variations in the motion trajectory and ambient temperature
Sero-epidemiological status and risk factors of toxoplasmosis in pregnant women in Northern Vietnam
Background: In Vietnam, few studies have determined the epidemiological status of toxoplasmosis in pregnant women and no routine prenatal screening is in place. This study was conducted to evaluate the seroprevalence of this zoonotic parasitic infection in pregnant women in Northern Vietnam and to assess the association with awareness, risk factors and congenital toxoplasmosis.
Methods: Approximately 800 pregnant women were included in the study from two hospitals, one in Hanoi and one in Thai Binh province, which is known to have a dense cat population. Serological immunoglobulin G (IgG) and immunoglobulin M (IgM) detection was performed to estimate the seroprevalence of toxoplasmosis and sero-incidence of maternal and congenital toxoplasmosis. In addition, a survey was conducted about awareness, clinical history, presentation of signs and symptoms relating to toxoplasmosis and to detect biologically plausible and socio-demographic risk factors associated with toxoplasmosis. Associations with seroprevalence were assessed using univariable and multivariable analysis.
Results: The mean IgG seroprevalence after the full diagnostic process was 4.5% (95% confidence interval(CI): 2.7–7.0) and 5.8% (95% CI: 3.7–8.6) in Hanoi and Thai Binh hospital, respectively, and included one seroconversion diagnosed in Thai Binh hospital. Only 2.0% of the pregnant women in Hanoi hospital and 3.3% in Thai Binh hospital had heard about toxoplasmosis before this study.
Conclusion: Since the percentage of seronegative, and thus susceptible, pregnant women was high and the awareness was low, we suggest to distribute information about toxoplasmosis and its prevention among women of child bearing age. Furthermore, future studies are recommended to investigate why such a low seroprevalence was seen in pregnant women in Northern Vietnam compared to other countries in South East Asia and globally
Effect of Silver Nanowire Dimension to Ammonia Adsorption of Graphene-silver Nanowires Hybrid
In this report, we study the effect of silver nanowires (AgNws) dimension to electrical properties of rGO/AgNws hybrid. The alteration of these electrical properties leads the difference of ammonia sensibility of the rGO/AgNws hybrid based sensing devices. When the rGO is accompanied by AgNws of different sizes from \sim 500$~\text{nm to } 10\;\mum, the ammonia sensitivity of these hybrids change from 60% to 340% alteration compared with the bare rGO material
A modern purification by accelerated solvent extraction and centrifugal partition chromatography and biological evaluation of capsaicin from Capsicum chinense
A special alkaloid compound known as capsaicin, which can only be found in the fruit of the Capsicum plant, was isolated and tested for its anti-inflammatory activity. The purpose of this work is to establish a simple and quick approach for capsaicin purification utilizing centrifugal partition chromatography (CPC) as well as an effective method - accelerated solvent extraction (ASE), for extracting capsaicin from Capsicum chinense. After purification, capsaicin was validated by HPLC-DAD at 281 nm to be > 90% purity. The in vivo anti-inflammatory activity of the isolated capsaicin was also investigated, and the IC50 value of the capsaicin was determined to be 57.61 µg/mL. The current work emphasizes how an ASE and CPC system may combine to extract high-purity capsaicin from Capsicum chinense, which have the anti-inflammatory activity, as we evaluated in the experiment
Economic Burden of Chronic Obstructive Pulmonary Disease: A Systematic Review
Globally, providing evidence on the economic burden of chronic obstructive pulmonary disease (COPD) is becoming essential as it assists the health authorities to efficiently allocate resources. This study aimed to summarize the literature on economic burden evidence for COPD from 1990 to 2019. This study examined the economic burden of COPD through a systematic review of studies from 1990 to 2019. A search was done in online databases, including Web of Science, PubMed/Medline, Scopus, and the Cochrane Library. After screening 12,734 studies, 43 articles that met the inclusion criteria were identified. General study information and data on direct, indirect, and intangible costs were extracted and converted to 2018 international dollars (Int 52.08 (India) to Int 70.07 (Vietnam) to Int 1,207.8 (Greece). This study underscores the limited research on COPD caregivers’ economic burdens, particularly in developing countries, emphasizing the importance of increased research support, particularly in high-resource settings. This study provides information about the demographics and economic burden of COPD from 1990 to 2019. More strategies to reduce the frequency of hospital admissions and acute care services should be implemented to improve the quality of COPD patients’ lives and reduce the disease’s rising economic burden
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