1,011 research outputs found
The PL calibration for Milky Way Cepheids and its implications for the distance scale
The rationale behind recent calibrations of the Cepheid PL relation using the
Wesenheit formulation is reviewed and reanalyzed, and it is shown that recent
conclusions regarding a possible change in slope of the PL relation for
short-period and long-period Cepheids are tied to a pathological distribution
of HST calibrators within the instability strip. A recalibration of the
period-luminosity relation is obtained using Galactic Cepheids in open clusters
and groups, the resulting relationship, described by log L/L_sun =
2.415(+-0.035) + 1.148(+-0.044)log P, exhibiting only the moderate scatter
expected from color spread within the instability strip. The relationship is
confirmed by Cepheids with HST parallaxes, although without the need for
Lutz-Kelker corrections, and in general by Cepheids with revised Hipparcos
parallaxes, albeit with concerns about the cited precisions of the latter. A
Wesenheit formulation of Wv = -2.259(+-0.083) - 4.185(+-0.103)log P for
Galactic Cepheids is tested successfully using Cepheids in the inner regions of
the galaxy NGC 4258, confirming the independent geometrical distance
established for the galaxy from OH masers. Differences between the extinction
properties of interstellar and extragalactic dust may yet play an important
role in the further calibration of the Cepheid PL relation and its application
to the extragalactic distance scale.Comment: Accepted for Publication (Astrophysics & Space Science
Consequences of Aberrant Insulin Regulation in the Brain: Can Treating Diabetes be Effective for Alzheimer’s Disease
There is an urgent need for new ways to treat Alzheimer’s disease (AD), the most common cause of dementia in the elderly. Current therapies are modestly effective at treating the symptoms, and do not significantly alter the course of the disease. Over the years, a range of epidemiological and experimental studies have demonstrated interactions between diabetes mellitus and AD. As both diseases are leading causes of morbidity and mortality in the elderly and are frequent co-morbid conditions, it has raised the possibility that treating diabetes might be effective in slowing AD. This is currently being attempted with drugs such as the insulin sensitizer rosiglitazone. These two diseases share many clinical and biochemical features, such as elevated oxidative stress, vascular dysfunction, amyloidogenesis and impaired glucose metabolism suggesting common pathogenic mechanisms. The main thrust of this review will be to explore the evidence from a pathological point of view to determine whether diabetes can cause or exacerbate AD. This was supported by a number of animal models of AD that have been shown to have enhanced pathology when diabetic conditions were induced. The one drawback in linking diabetes and insulin to AD has been the postmortem studies of diabetic brains demonstrating that AD pathology was not increased; in fact decreased pathology has often been reported. In addition, diabetes induces its own distinct features of neuropathology different from AD. There are common pathological features to be considered including vascular abnormalities, a major feature arising from diabetes; there is increasing evidence that vascular abnormalities can contribute to AD. The most important common mechanism between insulin-resistant (type II) diabetes and AD could be impaired insulin signaling; a form of toxic amyloid can damage neuronal insulin receptors and affect insulin signaling and cell survival. It has even been suggested that AD could be considered as “type 3 diabetes” since insulin can be produced in brain. Another common feature of diabetes and AD are increased advanced glycation endproduct-modified proteins are found in diabetes and in the AD brain; the receptor for advanced glycation endproducts plays a prominent role in both diseases. In addition, a major role for insulin degrading enzyme in the degradation of Aβ peptide has been identified. Although clinical trials of certain types of diabetic medications for treatment of AD have been conducted, further understanding the common pathological processes of diabetes and AD are needed to determine whether these diseases share common therapeutic targets
Typhoid and Paratyphoid Fever in Children
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/67979/2/10.1177_000992286900800412.pd
Loading a vapor cell magneto-optic trap using light-induced atom desorption
Low intensity white light was used to increase the loading rate of Rb
atoms into a vapor cell magneto-optic trap by inducing non-thermal desorption
of Rb atoms from the stainless steel walls of the vapor cell. An increased Rb
partial pressure reached a new equilibrium value in less than 10 seconds after
switching on the broadband light source. After the source was turned off, the
partial pressure returned to its previous value in times as short as 10
seconds.Comment: 7 pages, 6 figure
What Attracts Men Who Batter to Their Partners? An Exploratory Study
Men who batter, because of particular personality traits and sense of entitlement,
may select partners whom they perceive will be dependent on them,
meet their emotional needs, or be “objects” of physical attractiveness. During
treatment intake, 181 offenders responded to the question, “What attracted
you to her (your partner)?” We explored whether men who mentioned their
own needs or her physical traits would engage in more frequent and severe
violence and would have specific forms of personality disorder dimensions or
personality traits. Six categories of attraction, including “her physical traits”
and “his needs,” were derived from the men’s responses. The results showed
that men who focused on their partners’ physical attractiveness were more
likely to be violent after treatment. Men who cited their own needs for their
attraction had higher scores on borderline personality, alcohol abuse, and
psychotic thinking and lower scores on compulsive-conformingPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/89970/1/Saunders-Kurko-Barlow-Crane 2011 What Attracts Men Who Batter to Their Partners JIV.pd
Effect of prior laser microstructural refinement on the formation of amorphous layer in an Al86Co7.6Ce6.4 alloy
Laser surface melting (LSM) pre-treatment was conducted before large area electron beam (LAEB) treatment in an attempt to eliminate the cracking of the amorphous layer. In our previous work, LAEB treatment successfully generated an amorphous layer on a cast polycrystalline Al-Co-Ce glass forming alloy. However, cracking was found and was associated with large and brittle Al8Co2Ce phase in the bulk material. Results show that prior LSM treatment in this present work can effectively refine the microstructure of as-cast material, decreasing the particle size and particle spacing of Al8Co2Ce phase. This decrease in the microstructural length scale greatly reduced the results of cracking of the amorphous layer. The LAEB pulse number required for the homogenisation and amorphisation of treated layer was also decreased for the laser pre-treated sample compared to as-cast material
The Large Magellanic Cloud and the Distance Scale
The Magellanic Clouds, especially the Large Magellanic Cloud, are places
where multiple distance indicators can be compared with each other in a
straight-forward manner at considerable precision. We here review the distances
derived from Cepheids, Red Variables, RR Lyraes, Red Clump Stars and Eclipsing
Binaries, and show that the results from these distance indicators generally
agree to within their errors, and the distance modulus to the Large Magellanic
Cloud appears to be defined to 3% with a mean value of 18.48 mag, corresponding
to 49.7 Kpc. The utility of the Magellanic Clouds in constructing and testing
the distance scale will remain as we move into the era of Gaia.Comment: 23 pages, accepted for publication in Astrophysics and Space Science.
From a presentation at the conference The Fundamental Cosmic Distance Scale:
State of the Art and the Gaia Perspective, Naples, May 201
Amorphous layer formation in Al86.0Co7.6Ce6.4 glass-forming alloy by large-area electron beam irradiation
Amorphous Al-Co-Ce alloys are of interest because of their resistance to corrosion, but high cooling rates are generally required to suppress the formation of crystalline phases. In this study, the surface of a bulk crystalline Al-Co-Ce alloy of a glass-forming composition was treated using large area electron beam (LAEB) irradiation. Scanning electron microscopy shows that, compared to the microstructure of the original crystalline material, the treated surface exhibits greatly improved microstructural and compositional uniformity. Glancing angle X-ray diffraction conducted on the surface of treated samples indicates the formation of the amorphous phase following 25 and 50 pulses at 35 kV cathode voltage. However, when the samples are treated with 100 and 150 pulses at 35 kV cathode voltage of electron beam irradiation, the treated layer comprises localised crystalline regions in an amorphous matrix. In addition, the formation of cracks in the treated layer is found to be localised around the Al8Co2Ce phase in the bulk material. Overall, crack length per unit area had no clear change with an increase in the number of pulses
Professional closure by proxy: the impact of changing educational requirements on class mobility for a cohort of Big 8 partners
Closure events impacting on class mobility may include mechanisms initiated by bodies other than the professional body. The research examines if the introduction of full-time study requirements at universities for aspiring accountants effectively introduced a closure mechanism in the accounting profession. Data was derived from an Oral History study of partners in large firms. The younger partners (born after the Second World War) completed full-time degree study at university, but did not provide evidence of class mobility into the profession. The older cohort, born between 1928 and 1946, completed part-time studies only, few completed a degree, and, in contrast to the younger cohort, shows a perceptible upward movement from lower socio-economic classes into the professional class. This suggests that changing the preferred educational routes for new accountants entering the large chartered accounting (CA) firms compromised the "stepping stone" function of accounting as a portal into the professional class
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