1,174 research outputs found
Plasmonic nanogap enhanced phase change devices with dual electrical-optical functionality
Modern-day computers use electrical signaling for processing and storing data
which is bandwidth limited and power-hungry. These limitations are bypassed in
the field of communications, where optical signaling is the norm. To exploit
optical signaling in computing, however, new on-chip devices that work
seamlessly in both electrical and optical domains are needed. Phase change
devices can in principle provide such functionality, but doing so in a single
device has proved elusive due to conflicting requirements of size-limited
electrical switching and diffraction-limited photonic devices. Here, we combine
plasmonics, photonics and electronics to deliver a novel integrated
phase-change memory and computing cell that can be electrically or optically
switched between binary or multilevel states, and read-out in either mode, thus
merging computing and communications technologies
Alemtuzumab pre-conditioning with tacrolimus monotherapy in pediatric renal transplantation
We employed antibody pre-conditioning with alemtuzumab and posttransplant immunosuppression with low-dose tacrolimus monotherapy in 26 consecutive pediatric kidney transplant recipients between January 2004 and December 2005. Mean recipient age was 10.7 ± 5.8 years, 7.7% were undergoing retransplantation, and 3.8% were sensitized, with a PRA >20%. Mean donor age was 32.8 ± 9.2 years. Living donors were utilized in 65% of the transplants. Mean cold ischemia time was 27.6 ± 6.4 h. The mean number of HLA mismatches was 3.3 ± 1.3. Mean follow-up was 25 ± 8 months. One and 2 year patient survival was 100% and 96%. One and 2 year graft survival was 96% and 88%. Mean serum creatinine was 1.1 ± 0.6 mg/dL, and calculated creatinine clearance was 82.3 ± 29.4 mL/min/1.73 m 2. The incidence of pre-weaning acute rejection was 11.5%; the incidence of delayed graft function was 7.7%. Eighteen (69%) of the children were tapered to spaced tacrolimus monotherapy, 10.5 ± 2.2 months after transplantation. The incidence of CMV, PTLD and BK virus was 0%; the incidence of posttransplant diabetes was 7.7%. Although more follow-up is clearly needed, antibody pre-conditioning with alemtuzumab and tacrolimus monotherapy may be a safe and effective regimen in pediatric renal transplantation. © 2007 The Authors
Structure and dynamics of aqueous 2-propanol: a THz-TDS, NMR and neutron diffraction study.
Aqueous liquid mixtures, in particular, those involving amphiphilic species, play an important role in many physical, chemical and biological processes. Of particular interest are alcohol/water mixtures; however, the structural dynamics of such systems are still not fully understood. Herein, a combination of terahertz time-domain spectroscopy (THz-TDS) and NMR relaxation time analysis has been applied to investigate 2-propanol/water mixtures across the entire composition range; while neutron diffraction studies have been carried out at two specific concentrations. Excellent agreement is seen between the techniques with a maximum in both the relative absorption coefficient and the activation energy to molecular motion occurring at ∼90 mol% H2O. Furthermore, this is the same value at which well-established excess thermodynamic functions exhibit a maximum/minimum. Additionally, both neutron diffraction and THz-TDS have been used to provide estimates of the size of the hydration shell around 2-propanol in solution. Both methods determine that between 4 and 5 H2O molecules per 2-propanol are found in the 2-propanol/water clusters at 90 mol% H2O. Based on the acquired data, a description of the structure of 2-propanol/water across the composition range is presented.The authors would like to acknowledge CASTech (EPSRC grant EP/G011397/1), RCUK Basic Technology Grant (EP/E048811/1), STFC for beamtime allocation (RB910286) and Jon Mitchell (Cambridge) for valuable discussions.This is the final version of the article. It was first available from RSC via http://dx.doi.org/10.1039/C5CP01132
Manifold Elastic Net: A Unified Framework for Sparse Dimension Reduction
It is difficult to find the optimal sparse solution of a manifold learning
based dimensionality reduction algorithm. The lasso or the elastic net
penalized manifold learning based dimensionality reduction is not directly a
lasso penalized least square problem and thus the least angle regression (LARS)
(Efron et al. \cite{LARS}), one of the most popular algorithms in sparse
learning, cannot be applied. Therefore, most current approaches take indirect
ways or have strict settings, which can be inconvenient for applications. In
this paper, we proposed the manifold elastic net or MEN for short. MEN
incorporates the merits of both the manifold learning based dimensionality
reduction and the sparse learning based dimensionality reduction. By using a
series of equivalent transformations, we show MEN is equivalent to the lasso
penalized least square problem and thus LARS is adopted to obtain the optimal
sparse solution of MEN. In particular, MEN has the following advantages for
subsequent classification: 1) the local geometry of samples is well preserved
for low dimensional data representation, 2) both the margin maximization and
the classification error minimization are considered for sparse projection
calculation, 3) the projection matrix of MEN improves the parsimony in
computation, 4) the elastic net penalty reduces the over-fitting problem, and
5) the projection matrix of MEN can be interpreted psychologically and
physiologically. Experimental evidence on face recognition over various popular
datasets suggests that MEN is superior to top level dimensionality reduction
algorithms.Comment: 33 pages, 12 figure
3D human skin bioprinting: a view from the bio side
Based on the 3D printing technologies and the concepts developed in tissue engineering during the last decades, 3D bioprinting is emerging as the most innovative and promising technology for the generation of human tissues and organs. In the case of skin bioprinting, thanks to the research process carried out during the last years, interfollicular skin has been printed with a structural and functional quality that paves the way for clinical and industrial applications. This review analyzes the present achievements and the future improvements that this area must bring about if bioprinted skin is to become widely used. We have made an effort to integrate the technological and the biological/biomedical sides of the subject.We thank the Spanish Fundación Ramón Areces for its continuous support.
This work was partially supported by grant DPI2014-61887-EXP from the Spanish Ministerio de EconomÃa y Competitividad
Cavity Induced Interfacing of Atoms and Light
This chapter introduces cavity-based light-matter quantum interfaces, with a
single atom or ion in strong coupling to a high-finesse optical cavity. We
discuss the deterministic generation of indistinguishable single photons from
these systems; the atom-photon entanglement intractably linked to this process;
and the information encoding using spatio-temporal modes within these photons.
Furthermore, we show how to establish a time-reversal of the aforementioned
emission process to use a coupled atom-cavity system as a quantum memory. Along
the line, we also discuss the performance and characterisation of cavity
photons in elementary linear-optics arrangements with single beam splitters for
quantum-homodyne measurements.Comment: to appear as a book chapter in a compilation "Engineering the
Atom-Photon Interaction" published by Springer in 2015, edited by A.
Predojevic and M. W. Mitchel
Comparison of contact patterns relevant for transmission of respiratory pathogens in Thailand and the Netherlands using respondent-driven sampling
Understanding infection dynamics of respiratory diseases requires the identification and quantification of behavioural, social and environmental factors that permit the transmission of these infections between humans. Little empirical information is available about contact patterns within real-world social networks, let alone on differences in these contact networks between populations that differ considerably on a socio-cultural level. Here we compared contact network data that were collected in the Netherlands and Thailand using a similar online respondent-driven method. By asking participants to recruit contact persons we studied network links relevant for the transmission of respiratory infections. We studied correlations between recruiter and recruited contacts to investigate mixing patterns in the observed social network components. In both countries, mixing patterns were assortative by demographic variables and random by total numbers of contacts. However, in Thailand participants reported overall more contacts which resulted in higher effective contact rates. Our findings provide new insights on numbers of contacts and mixing patterns in two different populations. These data could be used to improve parameterisation of mathematical models used to design control strategies. Although the spread of infections through populations depends on more factors, found similarities suggest that spread may be similar in the Netherlands and Thailand
Current Methods for Hyperpolarized [1-13C]pyruvate MRI Human Studies
MRI with hyperpolarized (HP) 13C agents, also known as HP 13C MRI, can
measure processes such as localized metabolism that is altered in numerous
cancers, liver, heart, kidney diseases, and more. It has been translated into
human studies during the past 10 years, with recent rapid growth in studies
largely based on increasing availability of hyperpolarized agent preparation
methods suitable for use in humans. This paper aims to capture the current
successful practices for HP MRI human studies with [1-13C]pyruvate - by far the
most commonly used agent, which sits at a key metabolic junction in glycolysis.
The paper is divided into four major topic areas: (1) HP 13C-pyruvate
preparation, (2) MRI system setup and calibrations, (3) data acquisition and
image reconstruction, and (4) data analysis and quantification. In each area,
we identified the key components for a successful study, summarized both
published studies and current practices, and discuss evidence gaps, strengths,
and limitations. This paper is the output of the HP 13C MRI Consensus Group as
well as the ISMRM Hyperpolarized Media MR and Hyperpolarized Methods &
Equipment study groups. It further aims to provide a comprehensive reference
for future consensus building as the field continues to advance human studies
with this metabolic imaging modality
- …