2,040 research outputs found
Primary ciliary dyskinesia: a big data genomics approach
How can the real-life frequency of a complicated condition that occurs irregularly, with a clinically variable presentation that is often difficult to diagnose, be calculated? This is a challenge for understanding the societal and medical impacts of an estimated 7000 rare disorders (those affecting more than one in 2000 people each) that can be poorly understood and often missed, especially if lacking clear-cut indicatory tests. The collective rare disease burden affects over one in 20 people, involving a disparate range of health-care services and creating unmet medical needs with potential for incorrect management. Better diagnostics and disease prevalence estimates are key to improving inequalities for millions of affected families worldwide
Sequential weak measurement
The notion of weak measurement provides a formalism for extracting
information from a quantum system in the limit of vanishing disturbance to its
state. Here we extend this formalism to the measurement of sequences of
observables. When these observables do not commute, we may obtain information
about joint properties of a quantum system that would be forbidden in the usual
strong measurement scenario. As an application, we provide a physically
compelling characterisation of the notion of counterfactual quantum
computation
Examination of smears for tubercle bacilli by Fluorescence Microscopy
IN underdeveloped countries, laboratory facilities for the bacteriological
diagnosis of tuberculosis are at present, very limited. Cultural methods are
unlikely to be used on a large scale for many years to come. It is, therefore, important to
investigate the most economical method of examining smears for
tubercle bacilli. Fluorescence microscopy was introduced by Hagemann (1937)
and has since been described by many authors, including Tanner (1941, 1948), Lind
and Shaughnessy (1941), Lempert (1944), Norman and Jelks (1945), Clegg and
Foster-Carter (1946), Wilson (1952), Von Haebler and Murray (1954), and Needham
(1957). The great advantage claimed for this method is that stained bacilli can be
detected using a much lower magnification than with the usual Ziehl-Neelsen
method. Considerable time is saved in examining smears and larger areas can be
searched. The method has not been widely employed for two reasons. In the
first place, the light source must be very bright and many of the optical systems
described previously have only supplied sufficient light if the equipment was used in
a darkened room. Secondly, some workers (Ritterhoff and Bowman, 1945; Kuster,
1939; Holm and Plum, 1943) consider that false positive results can be obtained,
since some smears may contain small naturally fluorescent particles which can be
confused with bacilli.
Equipment for fluorescence microscopy that can be used in normal daylight
has been in use at the Tuberculosis Chemotherapy Centre, Madras, for over two
years. When it was first introduced, a comparison between this method and the
conventional Ziehl-Neelsen method was undertaken to test their relative sensitivities,
and to see whether fluorescence microscopy yielded false positive results.
The results of this comparison are described
Transport enhancement from incoherent coupling between one-dimensional quantum conductors
We study the non-equilibrium transport properties of a highly anisotropic
two-dimensional lattice of spin-1/2 particles governed by a Heisenberg XXZ
Hamiltonian. The anisotropy of the lattice allows us to approximate the system
at finite temperature as an array of incoherently coupled one-dimensional
chains. We show that in the regime of strong intrachain interactions, the weak
interchain coupling considerably boosts spin transport in the driven system.
Interestingly, we show that this enhancement increases with the length of the
chains, which is related to superdiffusive spin transport. We describe the
mechanism behind this effect, compare it to a similar phenomenon in single
chains induced by dephasing, and explain why the former is much stronger
The Susceptibility to Hydrogen Peroxide of Indian and British Isoniazid-Sensitive and Isoniazid- Resistant Tubercle Bacilli
The present work describes an attempt to modify the method of Kreis and Le
Joubioux (1957a) so that it would accurately estimate the relative proportions of
catalase-positive and catalase-negative organisms in strains containing mixtures of
the two types. A bactericidal test was chosen in preference to a bacteriostatic test,
since it is difficult to obtain quantitative measurement with the latter technique. In
performing a bactericidal test residual peroxide must be inactivated or removed
by dilution so that it does not inhibit the growth of surviving organisms. Knox,
Meadow and Worssam (1956) removed peroxide by centrifugation and washing,
but this method was considered impracticable if this test were to be used on a large scale, and likely to produce inaccurate counts on the surviving organisms. In the
present work the method of removal of peroxide was studied as well as the determination
of the optimal peroxide concentration and period of exposure which would kill
all catalase-negative organisms, but would leave catalase-positive organisms
unaffected. In addition, the method of Kreis & Le Joubioux (1957a) was modified
by reducing the inoculum of organisms exposed to peroxide so that catalase-positive
bacilli would not be able to destroy peroxide during the test itself. The standardised
bactericidal test was then employed in comparing the susceptibility to peroxide of
isoniazid-sensitive strains from British and Indian patients, and in investigating
the relationship between the peroxide susceptibility and the catalase activity of their
isoniazid-resistant mutant strains
Loci for primary ciliary dyskinesia map to chromosome 16p12.1-12.2 and 15q13.1-15.1 in Faroe Islands and Israeli Druze genetic isolates
Nondestructive selective probing of phononic excitations in a cold Bose gas using impurities
We introduce a detector that selectively probes the phononic excitations of a
cold Bose gas. The detector is composed of a single impurity atom confined by a
double-well potential, where the two lowest eigenstates of the impurity form an
effective probe qubit that is coupled to the phonons via density-density
interactions with the bosons. The system is analogous to a two-level atom
coupled to photons of the radiation field. We demonstrate that tracking the
evolution of the qubit populations allows probing both thermal and coherent
excitations in targeted phonon modes. The targeted modes are selected in both
energy and momentum by adjusting the impurity's potential. We show how to use
the detector to observe coherent density waves and to measure temperatures of
the Bose gas down to the nano-Kelvin regime. We analyze how our scheme could be
realized experimentally, including the possibility of using an array of
multiple impurities to achieve greater precision from a single experimental
run.Comment: 11+4 pages, 7 figure
Altered Cerebellar Short-Term Plasticity but No Change in Postsynaptic AMPA-Type Glutamate Receptors in a Mouse Model of Juvenile Batten Disease
Juvenile Batten disease is the most common progressive neurodegenerative disorder of childhood. It is associated with mutations in the CLN3 gene, causing loss of function of CLN3 protein and degeneration of cerebellar and retinal neurons. It has been proposed that changes in granule cell AMPA-type glutamate receptors (AMPARs) contribute to the cerebellar dysfunction. In this study we compared AMPAR properties and synaptic transmission in cerebellar granule cells from wild-type and Cln3 knockout mice. In Cln3Δex1–6 cells the amplitude of AMPA-evoked whole-cell currents was unchanged. Similarly, we found no change in the amplitude, kinetics, or rectification of synaptic currents evoked by individual quanta, or in their underlying single-channel conductance. We found no change in cerebellar expression of GluA2 or GluA4 protein. By contrast, we observed a reduced number of quantal events following mossy-fiber stimulation in Sr2+, altered short-term plasticity in conditions of reduced extracellular Ca2+, and reduced mossy fiber vesicle number. Thus, while our results suggest early presynaptic changes in the Cln3Δex1–6 mouse model of juvenile Batten disease, they reveal no evidence for altered postsynaptic AMPARs
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