859 research outputs found
Ultracold molecules: vehicles to scalable quantum information processing
We describe a novel scheme to implement scalable quantum information
processing using Li-Cs molecular state to entangle Li and Cs
ultracold atoms held in independent optical lattices. The Li atoms will
act as quantum bits to store information, and Cs atoms will serve as
messenger bits that aid in quantum gate operations and mediate entanglement
between distant qubit atoms. Each atomic species is held in a separate optical
lattice and the atoms can be overlapped by translating the lattices with
respect to each other. When the messenger and qubit atoms are overlapped,
targeted single spin operations and entangling operations can be performed by
coupling the atomic states to a molecular state with radio-frequency pulses. By
controlling the frequency and duration of the radio-frequency pulses,
entanglement can either be created or swapped between a qubit messenger pair.
We estimate operation fidelities for entangling two distant qubits and discuss
scalability of this scheme and constraints on the optical lattice lasers
The characterization of depressive disorders in serious juvenile offenders
The authors systematically evaluated a selected population of juvenile offenders for the prevalence of affective disorders. Seventy-one (40 male, 31 female) serious juvenile offenders were interviewed using the Schedule for Affective Disorders and Schizophrenia (SADS). They were then diagnosed using the Research Diagnostic Criteria (RDC) and the DSM-III. The Hamilton Rating Scales (HRS), Carroll Self-Rating Scale (CSRS), and Global Rating Scale for Depression (GRS) were also obtained for each subject. Eleven (15%) subjects were diagnosed as having an active major depressive disorder (MDDa), 6 (8%) subjects were diagnosed as having a major depressive disorder in remission (MDDr), and 9 (13%) as having a minor depressive disorder (mDD). The HRS, CSRS, and GRS differentiated the MDDa from the other three groups including MDDr, mDD and all other psychiatric diagnoses. RDC subtypes of depressive disorders were identified in those juvenile offenders with active major depressive disorders (MDDa) and compared to a population of hospitalized adolescents with major depressive disorders. There were significant differences in the distribution of the subtypes identified. Secondary, gitated and endogenous subtypes occured significantly more often. The diagnostic, prognostic and therapeutic significance of these findings are discussed.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/24911/1/0000338.pd
Phase Control of Trapped Ion Quantum Gates
There are several known schemes for entangling trapped ion quantum bits for
large-scale quantum computation. Most are based on an interaction between the
ions and external optical fields, coupling internal qubit states of
trapped-ions to their Coulomb-coupled motion. In this paper, we examine the
sensitivity of these motional gate schemes to phase fluctuations introduced
through noisy external control fields, and suggest techniques to suppress the
resulting phase decoherence.Comment: 21 pages 12 figure
Magneto-optical Trapping of Cadmium
We report the laser-cooling and confinement of Cd atoms in a magneto-optical
trap, and characterize the loading process from the background Cd vapor. The
trapping laser drives the 1S0-1P1 transition at 229 nm in this two-electron
atom and also photoionizes atoms directly from the 1P1 state. This
photoionization overwhelms the other loss mechanisms and allows a direct
measurement of the photoionization cross section, which we measure to be
2(1)x10^(-16)cm^(2) from the 1P1 state. When combined with nearby laser-cooled
and trapped Cd^(+) ions, this apparatus could facilitate studies in ultracold
interactions between atoms and ions.Comment: 8 pages, 11 figure
Notes about the Caratheodory number
In this paper we give sufficient conditions for a compactum in
to have Carath\'{e}odory number less than , generalizing an old result of
Fenchel. Then we prove the corresponding versions of the colorful
Carath\'{e}odory theorem and give a Tverberg type theorem for families of
convex compacta
Baseline White Matter Hyperintensities and Hippocampal Volume are Associated With Conversion From Normal Cognition to Mild Cognitive Impairment in the Framingham Offspring Study.
INTRODUCTION: We examined associations between magnetic resonance imaging (MRI) markers of cerebrovascular disease and neurodegeneration with mild cognitive impairment (MCI) diagnosis at baseline and conversion from normal cognition to MCI at follow-up.
METHODS: Framingham Offspring participants underwent brain MRI and neuropsychological assessment at baseline (n=1049) and follow-up (n=561). Participants were classified at baseline and at follow-up as cognitively normal or MCI using sensitive neuropsychological criteria. White matter hyperintensity (WMH) volume, covert brain infarcts, hippocampal volume, and total cerebral brain volume were quantified.
RESULTS: Baseline measures of WMH and hippocampal volume were associated with MCI status cross-sectionally and also with conversion from normal cognition to MCI at 6.5-year follow-up. Annualized change rates in total cerebral brain volume and hippocampal volume were associated with conversion from normal cognition to MCI to follow-up.
DISCUSSION: Baseline WMH and hippocampal volume are markers that are both associated with conversion from normal cognition to MCI, highlighting the role of both vascular lesions and neurodegeneration in MCI
Agroecology and climate change rapid evidence review: Performance of agroecological approaches in low- and middle- income countries
Agroecology is increasingly seen as being able, or even necessary, to transform food systems (HLPE 2019). The Foreign, Commonwealth and Development Office (FCDO) and the CGIAR Research Programme on Climate Change, Agriculture and Food Security (CCAFS) commissioned this rapid evidence-based review to assess the quality and strength of evidence regarding (i) the impact of agroecological approaches on climate change mitigation and adaptation in low- and middle-income countries (LMICs) and (ii) the programming approaches and conditions supporting large-scale transitions to agroecology and transitions. The review also aims to identify knowledge gaps critical to understand and inform future public and private investment in research, development, and deployment of agroecological approaches. The focus here is on the science of agroecology at the field and landscape level, not on social movement, value chain or business aspects. We use the Food and Agriculture Organization of the United Nations (FAO) 10 elements of agroecology with the Gliessman (2016) framework to identify agroecology practices (transition level 2) and agroecology systems (transition level 3).
To assess evidence related to agroecologyâs climate change outcomes we conducted a systematic literature review of i) synthesis papers and ii) primary empirical studies related to nutrient and pest and disease management. For the latter we documented the presence of evidence for climate change outcome indicators, but not the magnitude or direction of the change. We also conducted semi-structured interviews with representatives from 12 organizations supporting or implementing on-the-ground agricultural development programmes to better understand the feasibility of scaling out agroecology
Efficient Photoionization-Loading of Trapped Cadmium Ions with Ultrafast Pulses
Atomic cadmium ions are loaded into radiofrequency ion traps by
photoionization of atoms in a cadmium vapor with ultrafast laser pulses. The
photoionization is driven through an intermediate atomic resonance with a
frequency-quadrupled mode-locked Ti:Sapphire laser that produces pulses of
either 100 fsec or 1 psec duration at a central wavelength of 229 nm. The large
bandwidth of the pulses photoionizes all velocity classes of the Cd vapor,
resulting in high loading efficiencies compared to previous ion trap loading
techniques. Measured loading rates are compared with a simple theoretical
model, and we conclude that this technique can potentially ionize every atom
traversing the laser beam within the trapping volume. This may allow the
operation of ion traps with lower levels of background pressures and less trap
electrode surface contamination. The technique and laser system reported here
should be applicable to loading most laser-cooled ion species.Comment: 11 pages, 12 figure
Membranous nephropathy in a patient with hereditary angioedema: a case report
<p>Abstract</p> <p>Introduction</p> <p>Hereditary angioedema is the commonest inherited disorder of the complement system and has been associated with several immune glomerular diseases. A case of nephrotic syndrome and renal impairment due to idiopathic membranous glomerulonephritis in a patient with hereditary angioedema has not been described before.</p> <p>Case presentation</p> <p>We present the first reported case of the association of membranous nephropathy and hereditary angioedema in a 43-year-old male Caucasian patient who presented with acute intestinal angioedema, hypertension, acute pancreatitis, renal impairment and generalised body swelling due to severe nephrotic syndrome. We present the challenges involved in the clinical management of the patient.</p> <p>Conclusion</p> <p>This patient's presentation with severe nephrotic syndrome, renal impairment and hypertension required aggressive treatment of the membranous nephropathy given the high risk for progression to end stage renal failure. The contraindication to angiotensin converting enzyme inhibitors and angiotensin II receptor blockers in this patient, the lack of published evidence on the use of alkylating agents and other immunosuppressive agents in patients with hereditary angioedema and the lack of published data on the management of similar cases presented a clinical challenge in this patient's management.</p
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