4,430 research outputs found
A light scattering instrument for investigating cloud ice microcrystal morphology
We describe an optical scattering instrument designed to assess the shapes and sizes of microscopic atmospheric cloud particles, especially the smallest ice crystals that can profoundly affect cloud processes and radiative properties yet cannot be seen clearly using in situ cloud particle imaging probes. The new instrument captures high-resolution spatial light scattering patterns from individual particles down to ~1 μm in size passing through a laser beam. Its significance lies in the ability of these patterns to provide morphological data for particle sizes well below the optical resolution limits of current probes
Magnetic anisotropy of asbestos fibres
Original article can be found at : http://jap.aip.org/jap/ Copyright American Institute of PhysicsThe anisotropy of magnetic susceptibility of single asbestos fibers is measured. The alignment of both chrysotile and crocidolite fibers in magnetic fields is found to be due to the anisotropy. The average measured anisotropy of volume susceptibility is 0.40×10−6 for chrysotile and 83×10−6 for crocidolite. Fiber shape effects are estimated to contribute, on average, about 10% and 6%, respectively, to the total anisotropy of the two types of fiber. There is no evidence of significant permanent magnetic moments. The magnitude of the observed alignment makes the effect potentially useful in real-time detection of airborne asbestos fibers. The experimental technique developed in the study can be used for measuring the anisotropy of small particles of well-defined shape. High sensitivity of the technique permits the measurement of torques lower than 10−21 Nm on particles down to picogram mass.Peer reviewe
Universal Programmable Quantum Circuit Schemes to Emulate an Operator
Unlike fixed designs, programmable circuit designs support an infinite number
of operators. The functionality of a programmable circuit can be altered by
simply changing the angle values of the rotation gates in the circuit. Here, we
present a new quantum circuit design technique resulting in two general
programmable circuit schemes. The circuit schemes can be used to simulate any
given operator by setting the angle values in the circuit. This provides a
fixed circuit design whose angles are determined from the elements of the given
matrix-which can be non-unitary-in an efficient way. We also give both the
classical and quantum complexity analysis for these circuits and show that the
circuits require a few classical computations. They have almost the same
quantum complexities as non-general circuits. Since the presented circuit
designs are independent from the matrix decomposition techniques and the global
optimization processes used to find quantum circuits for a given operator, high
accuracy simulations can be done for the unitary propagators of molecular
Hamiltonians on quantum computers. As an example, we show how to build the
circuit design for the hydrogen molecule.Comment: combined with former arXiv:1207.174
Quantum information reclaiming after amplitude damping
We investigate the quantum information reclaim from the environment after
amplitude damping has occurred. In particular we address the question of
optimal measurement on the environment to perform the best possible correction
on two and three dimensional quantum systems. Depending on the dimension we
show that the entanglement fidelity (the measure quantifying the correction
performance) is or is not the same for all possible measurements and uncover
the optimal measurement leading to the maximum entanglement fidelity
State-space distribution and dynamical flow for closed and open quantum systems
We present a general formalism for studying the effects of dynamical
heterogeneity in open quantum systems. We develop this formalism in the state
space of density operators, on which ensembles of quantum states can be
conveniently represented by probability distributions. We describe how this
representation reduces ambiguity in the definition of quantum ensembles by
providing the ability to explicitly separate classical and quantum sources of
probabilistic uncertainty. We then derive explicit equations of motion for
state space distributions of both open and closed quantum systems and
demonstrate that resulting dynamics take a fluid mechanical form analogous to a
classical probability fluid on Hamiltonian phase space, thus enabling a
straightforward quantum generalization of Liouville's theorem. We illustrate
the utility of our formalism by analyzing the dynamics of an open two-level
system using the state-space formalism that are shown to be consistent with the
derived analytical results
Can Jury Trial Innovations Improve Juror Understanding of DNA Evidence?
A single spot of blood on a pink windowsill will tell investigators who broke a windowpane, turned a lock, and kidnapped 2-year-old Molly Evans from her bedroom in the middle of the night. An expert witness will testify that the DNA profile of the blood evidence recovered from the windowsill was entered into CODIS, an electronic database of DNA profiles. That process yielded a “hit,” identifying the defendant as the most likely source of the blood inside Molly’s room.
But will jurors be able to understand the expert’s intricate analysis and use it to reach a verdict? And what—if any—steps can be taken to increase jurors’ comprehension of complex DNA evidence? Questions such as these prompted an NIJ-funded study on the impact of jury trial innovations upon mock jurors’ understanding of contested mitochondrial DNA (mtNDA) evidence. By examining how jurors in different experimental conditions performed on a Juror Comprehension Scale both before and after deliberations, researchers were able to assess whether four specific innovations improved jurors’ understanding of this complex evidence and identify which innovations worked best
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Neural hypersensitivity to pleasant touch in women remitted from anorexia nervosa.
Interoception, or the sensing and integration of bodily state signals, has been implicated in anorexia nervosa (AN), given that the hallmark symptoms involve food restriction and body image disturbance. Here we focus on brain response to the anticipation and experience of affective interoceptive stimuli. Women remitted from AN (RAN; N = 18) and healthy comparison women (CW; N = 26) underwent a pleasant affective touch paradigm consisting of gentle strokes with a soft brush administered to the forearm or palm during functional neuroimaging. RAN had a lower brain response relative to CW during anticipation of touch, but a greater response when experiencing touch in the right ventral mid-insula. In RAN, this reduced anticipatory response was associated with higher levels of harm avoidance. Exploratory analyses in RAN also suggested that lower response during touch anticipation was associated with greater body dissatisfaction and higher perceived touch intensity ratings. This reduced responsivity to the anticipation of pleasant affective interoceptive stimuli in association with higher harm avoidance, along with an elevated response to the experience of touch, suggests an impaired ability in AN to predict and interpret incoming physiological stimuli. Impaired interoception may thus impact one's sense of self, thereby supporting observations of disturbed body image and avoidance of affective and social stimuli. Therapeutic approaches that help AN to better anticipate and interpret salient affective stimuli or improve tolerance of interoceptive experiences may be an important addition to current interventions
Statistics in the Jury Box: How Jurors Respond to Mitochondrial DNA Match Probabilities
This article describes parts of an unusually realistic experiment on the comprehension of expert testimony on mitochondrial DNA (mtDNA) sequencing in a criminal trial for robbery. Specifically, we examine how jurors who responded to summonses for jury duty evaluated portions of videotaped testimony involving probabilities and statistics. Although some jurors showed susceptibility to classic fallacies in interpreting conditional probabilities, the jurors as a whole were not overwhelmed by a 99.98% exclusion probability that the prosecution presented. Cognitive errors favoring the defense were more prevalent than ones favoring the prosecution. These findings lend scant support to the legal argument that mtDNA evidence (with modest exclusion probabilities) should be excluded because jurors are prone to overvalue such evidence. The article also introduces a new method for inferring the perceived probability of guilt that satisfies the burden of persuasion for most jurors
A Water-Damaged Home and Health of Occupants: A Case Study
A family of five and pet dog who rented a water-damaged home and developed multiple health problems. The home was analyzed for species of mold and bacteria. The diagnostics included MRI for chronic sinusitis with ENT and sinus surgery, and neurological testing for neurocognitive deficits. Bulk samples from the home, tissue from the sinuses, urine, nasal secretions, placenta, umbilical cord, and breast milk were tested for the presence of trichothecenes, aflatoxins, and Ochratoxin A. The family had the following diagnosed conditions: chronic sinusitis, neurological deficits, coughing with wheeze, nose bleeds, and fatigue among other symptoms. An infant was born with a total body flare, developed multiple Cafe-au-Lait pigmented skin spots and diagnoses with NF1 at age 2. The mycotoxins were detected in bulk samples, urine and nasal secretions, breast milk, placenta, and umbilical cord. Pseudomonas aueroginosa, Acinetobacter, Penicillium, and Aspergillus fumigatus were cultured from nasal secretions (father and daughter). RT-PCR revealed A. fumigatus DNA in sinus tissues of the daughter. The dog had 72 skin lesions (sebaceous glands and lipomas) from which trichothecenes and ochratoxin A. were detected. The health of the family is discussed in relation to the most recent published literature regarding microbial contamination and toxic by-products present in water-damaged buildings
Light scattering and phase behavior of Lysozyme-PEG mixtures
Measurements of liquid-liquid phase transition temperatures (cloud points) of
mixtures of a protein (lysozyme) and a polymer, poly(ethylene glycol) (PEG)
show that the addition of low molecular weight PEG stabilizes the mixture
whereas high molecular weight PEG was destabilizing. We demonstrate that this
behavior is inconsistent with an entropic depletion interaction between
lysozyme and PEG and suggest that an energetic attraction between lysozyme and
PEG is responsible. In order to independently characterize the lysozyme/PEG
interactions, light scattering experiments on the same mixtures were performed
to measure second and third virial coefficients. These measurements indicate
that PEG induces repulsion between lysozyme molecules, contrary to the
depletion prediction. Furthermore, it is shown that third virial terms must be
included in the mixture's free energy in order to qualitatively capture our
cloud point and light scattering data. The light scattering results were
consistent with the cloud point measurements and indicate that attractions do
exist between lysozyme and PEG.Comment: 5 pages, 2 figures, 1 tabl
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