7,503 research outputs found
Six Peaks Visible in the Redshift Distribution of 46,400 SDSS Quasars Agree with the Preferred Redshifts Predicted by the Decreasing Intrinsic Redshift Model
The redshift distribution of all 46,400 quasars in the Sloan Digital Sky
Survey (SDSS) Quasar Catalog III, Third Data Release, is examined. Six Peaks
that fall within the redshift window below z = 4, are visible. Their positions
agree with the preferred redshift values predicted by the decreasing intrinsic
redshift (DIR) model, even though this model was derived using completely
independent evidence. A power spectrum analysis of the full dataset confirms
the presence of a single, significant power peak at the expected redshift
period. Power peaks with the predicted period are also obtained when the upper
and lower halves of the redshift distribution are examined separately. The
periodicity detected is in linear z, as opposed to log(1+z). Because the peaks
in the SDSS quasar redshift distribution agree well with the preferred
redshifts predicted by the intrinsic redshift relation, we conclude that this
relation, and the peaks in the redshift distribution, likely both have the same
origin, and this may be intrinsic redshifts, or a common selection effect.
However, because of the way the intrinsic redshift relation was determined it
seems unlikely that one selection effect could have been responsible for both.Comment: 12 pages, 12 figure, accepted for publication in the Astrophysical
Journa
Distances of Quasars and Quasar-Like Galaxies: Further Evidence that QSOs may be Ejected from Active Galaxies
If high-redshift QSOs are ejected from the nuclei of low-redshift galaxies,
as some have claimed, a large portion of their redshift must be intrinsic
(non-Doppler). If these intrinsic components have preferred values, redshifts
will tend to cluster around these preferred values and produce peaks in the
redshift distribution. Doppler ejection and Hubble flow components will broaden
each peak. Because ejection velocities are randomly directed and Hubble flow
components are always positive, in this model all peaks are expected to show an
asymmetry, extending further out in the red wing. If peaks are present showing
this predicted asymmetry, it can lead directly to an estimate of quasar
distances. Using two quasar samples, one with high redshifts and one with low,
it is shown here that not only do all peaks in these two redshift distributions
occur at previously predicted preferred values, they also all show the
predicted extra extension in the red wing. For the low and high redshift
samples the mean cosmological components are found to be z and
, respectively. The difference can be explained by the improved
detection limit of the high redshift sample. These results offer further
evidence in favor of the model proposing that QSOs are ejected from active
galaxies.Comment: 11 pages, 6 figures, accepted for publication in The Astrophysical
Journa
Critical Examinations of QSO Redshift Periodicities and Associations with Galaxies in Sloan Digital Sky Survey Data
We have used the publicly available data from the Sloan Digital Sky Survey
and 2dF QSO Redshift Survey to test the hypothesis that QSOs are ejected from
active galaxies with periodic non-cosmological redshifts. For two different
intrinsic redshift models, namely the Karlsson model and Bell's
decreasing intrinsic redshift (DIR) model, we do two tests respectively. First,
using different criteria, we generate four sets of QSO-galaxy pairs and find
there is no evidence for a periodicity at the predicted frequency in
, or at any other frequency. We then check the relationship between
high redshift QSOs and nearby active galaxies, and we find the distribution of
projected distance between high redshift QSOs and nearby active galaxies and
the distribution of redshifts of those active galaxies are consistent with a
distribution of simulated random pairs, completely different from Bell's
previous conclusion. We also analyze the periodicity in redshifts of QSOs, and
no periodicity is found in high completeness samples, contrary to the DIR
model. These results support that QSOs are not ejected from active galaxies.Comment: 25 pages, 13 figures, accepted for publication in Ap
The Distribution of Redshifts in New Samples of Quasi-stellar Objects
Two new samples of QSOs have been constructed from recent surveys to test the
hypothesis that the redshift distribution of bright QSOs is periodic in
. The first of these comprises 57 different redshifts among all
known close pairs or multiple QSOs, with image separations 10\arcsec,
and the second consists of 39 QSOs selected through their X-ray emission and
their proximity to bright comparatively nearby active galaxies. The redshift
distributions of the samples are found to exhibit distinct peaks with a
periodic separation of in identical to that claimed
in earlier samples but now extended out to higher redshift peaks and 4.47, predicted by the formula but never seen before. The periodicity
is also seen in a third sample, the 78 QSOs of the 3C and 3CR catalogues. It is
present in these three datasets at an overall significance level -
, and appears not to be explicable by spectroscopic or similar
selection effects. Possible interpretations are briefly discussed.Comment: submitted for publication in the Astronomical Journal, 15 figure
GW approximation with self-screening correction
The \emph{GW} approximation takes into account electrostatic self-interaction
contained in the Hartree potential through the exchange potential. However, it
has been known for a long time that the approximation contains self-screening
error as evident in the case of the hydrogen atom. When applied to the hydrogen
atom, the \emph{GW} approximation does not yield the exact result for the
electron removal spectra because of the presence of self-screening: the hole
left behind is erroneously screened by the only electron in the system which is
no longer present. We present a scheme to take into account self-screening and
show that the removal of self-screening is equivalent to including exchange
diagrams, as far as self-screening is concerned. The scheme is tested on a
model hydrogen dimer and it is shown that the scheme yields the exact result to
second order in where and are respectively
the onsite and offsite Hubbard interaction parameters and the hopping
parameter.Comment: 9 pages, 2 figures; Submitted to Phys. Rev.
Helicobacter suis infection alters glycosylation and decreases the pathogen growth inhibiting effect and binding avidity of gastric mucins
Helicobacter suis is the most prevalent non-Helicobacter pylori Helicobacter species in the human stomach and is associated with chronic gastritis, peptic ulcer disease, and gastric mucosa-associated lymphoid tissue (MALT) lymphoma. H. suis colonizes the gastric mucosa of 60-95% of pigs at slaughter age, and is associated with chronic gastritis, decreased weight gain, and ulcers. Here, we show that experimental H. suis infection changes the mucin composition and glycosylation, decreasing the amount of H. suis-binding glycan structures in the pig gastric mucus niche. Similarly, the H. suis-binding ability of mucins from H. pylori-infected humans is lower than that of noninfected individuals. Furthermore, the H. suis growth-inhibiting effect of mucins from both noninfected humans and pigs is replaced by a growth-enhancing effect by mucins from infected individuals/pigs. Thus, Helicobacter spp. infections impair the mucus barrier by decreasing the H. suis-binding ability of the mucins and by decreasing the antiprolific activity that mucins can have on H. suis. Inhibition of these mucus-based defenses creates a more stable and inhabitable niche for H. suis. This is likely of importance for long-term colonization and outcome of infection, and reversing these impairments may have therapeutic benefits
Exchange Gate on the Qudit Space and Fock Space
We construct the exchange gate with small elementary gates on the space of
qudits, which consist of three controlled shift gates and three "reverse"
gates. This is a natural extension of the qubit case.
We also consider a similar subject on the Fock space, but in this case we
meet with some different situation. However we can construct the exchange gate
by making use of generalized coherent operator based on the Lie algebra su(2)
which is a well--known method in Quantum Optics. We moreover make a brief
comment on "imperfect clone".Comment: Latex File, 12 pages. I could solve the problems in Sec. 3 in the
preceding manuscript, so many corrections including the title were mad
Quantum secret sharing between m-party and n-party with six states
We propose a quantum secret sharing scheme between -party and -party
using three conjugate bases, i.e. six states. A sequence of single photons,
each of which is prepared in one of the six states, is used directly to encode
classical information in the quantum secret sharing process. In this scheme,
each of all members in group 1 choose randomly their own secret key
individually and independently, and then directly encode their respective
secret information on the states of single photons via unitary operations, then
the last one (the th member of group 1) sends of the resulting qubits
to each of group 2. By measuring their respective qubits, all members in group
2 share the secret information shared by all members in group 1. The secret
message shared by group 1 and group 2 in such a way that neither subset of each
group nor the union of a subset of group 1 and a subset of group 2 can extract
the secret message, but each whole group (all the members of each group) can.
The scheme is asymptotically 100% in efficiency. It makes the Trojan horse
attack with a multi-photon signal, the fake-signal attack with EPR pairs, the
attack with single photons, and the attack with invisible photons to be
nullification. We show that it is secure and has an advantage over the one
based on two conjugate bases. We also give the upper bounds of the average
success probabilities for dishonest agent eavesdropping encryption using the
fake-signal attack with any two-particle entangled states. This protocol is
feasible with present-day technique.Comment: 7 page
The âins and outsâ of faecal microbiota transplant for recurrent Clostridium difficile diarrhoea at Wits Donald Gordon Medical Centre, Johannesburg, South Africa
Background. Clostridium difficile-associated diarrhoea (CDAD) is a potentially life-threatening condition that is becoming increasingly common. A persistent burden of this infectious illness has been demonstrated over the past 4 years at Wits Donald Gordon Medical Centre (WDGMC), Johannesburg, South Africa, through implementation of active surveillance of hospital-acquired infections as part of the infection prevention and control programme. Oral treatment with metronidazole or vancomycin is recommended, but there is a major problem with symptomatic recurrence after treatment. Replacement of normal flora by the administration of donor stool through colonoscopy or nasogastric/duodenal routes is becoming increasingly popular.Objectives. To identify risk factors for the development of CDAD in patients referred for faecal microbiota transplant (FMT) and evaluate the safety of administration of donor stool as an outpatient procedure, including via the nasogastric route.Methods. A retrospective record review of patients with recurrent CDAD referred for FMT at WDGMC between 1 January 2012 and 31 December 2016 was conducted.Results. Twenty-seven patients were identified, all of whom fulfilled the criteria for recurrent CDAD. One-third were aged >65 years, and the majority were female. The most common risk factors were prior exposure to antibiotics or proton-pump inhibitors and underlying inflammatory bowel disease. Three procedures were carried out as inpatients and 24 in the outpatient gastroenterology unit. At 4-week follow-up, all patients reported clinical resolution of their diarrhoea after a single treatment and there were no recurrences. The FMT procedure was associated with no morbidity (with particular reference to the risk of aspiration when administered via the nasogastric route) or mortality.Conclusions. This case series confirms that FMT is a safe and effective therapy for recurrent CDAD. In most cases it can be administered via the nasogastric route in the outpatient department. We propose that the recently published South African Gastroenterology Society guidelines be reviewed with regard to recommendations for the route of administration of FMT and hospital admission. Meticulous prescription practice by clinicians practising in hospitals and outpatient settings, with particular attention to antimicrobials and chronic medication, is urgently required to prevent this debilitating and potentially life-threatening condition
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