Meeting report: International symposium on the genetics of aging and life history II

The second International Symposium on the Genetics of Aging and Life History was held at the campus of Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu, South Korea, from May 14 to 16, 2014. Many leading scientists in the field of aging research from all over the world contributed to the symposium by attending and presenting their recent work and thoughts. The aim of the symposium was to stimulate international collaborations and interactions among scientists who work on the biology of aging. In the symposium, the most recent and exciting work on aging research was presented, covering a wide range of topics, including the genetics of aging, age-associated diseases, and cellular senescence. The work was conducted in various organisms, including C. elegans, mice, plants, and humans. Topics covered in the symposium stimulated discussion of novel directions for future research on aging. The meeting ended with a commitment for the third International Symposium on the Genetics of Aging and Life History, which will be held in 2016. © Artan et al11sciescopu

Pre-Loaded high strength bolted connections of aluminium members with steel members

Bu araştırmada alüminyum ve çelik iki farklı malzemenin öngerilmeli yüksek mukavemetli bulonla sürtünme ile yük aktaran birleşimi incelenmiştir. Sürtünme ile yük aktaran birleşimlerin davranışını belirlemek amacı ile, iki farklı grup deney gerçekleştirilmiştir. Bunlar, kısa süreli ve uzun süreli kayma deneyleridir. Kısa süreli kayma deneyleri ile öngerilmeli yüksek mukavemetli bulonlu birleşimlerde, hem alüminyum ve hem de galvanizli çelik temas yüzeylerine herhangi bir işlem yapılmadan sadece yüzeyler yağdan arındırılmış durum için ve alkali silikat çinko boya ile boyanmış durum için, sürtünme katsayısı belirlenmiştir. Yukarıda belirtilen iki farklı temas yüzeyi haline ait yük-yer değiştirme diyagramları, kayma yükü ve sonrasında kopma haline kadar incelenmiştir. Deney sırasında yük altında bulonlardaki öngerilme kuvvetindeki değişim araştırılmıştır. Kısa süreli deneylerde sürtünme yüzeylerine boya kullanılmaması durumunda birleşimler ekonomik olmaktan uzaktır. Sürtünme arttırıcı alkali silikat çinko boya kullanılması durumunda bir bulonun sürtünme ile taşıyabileceği kuvvet yaklaşık olarak 3.5 kat daha fazladır. Yapılan ondört adet kısa süreli deneyden elde edilen verilerden yararlanılarak uzun süreli deney sistemi hazırlanmış ve toplam onbeş adet uzun süreli birleşim numunesi bir yıl boyunca üç farklı çerçevede 90 kN, 78 kN ve 60 kN’luk sürekli yük altında gözlenmiştir. Bu deney sonuçlarının irdelenmesinde daha önce literatürde rastlanmayan sabit aralıklı ayrıklaştırma uygulanmak suretiyle elli yılsonundaki davranış tahmin edilmeye çalışılmıştır. Bu araştırma ile alüminyum ve çelikten oluşan farklı iki malzemenin birleşimi için alkali silikat çinko boyanın kullanılabileceği ve sürtünme katsayısını arttırdığı gösterilmiştir.  Anahtar Kelimeler: Birleşim, öngerilmeli yüksek mukavemetli bulon, alüminyum elemanlar.A certain amount of research and studies has been done on the connections of the same kind of material such as aluminum to aluminum or steel to steel connections. However, as far as the connections of two different materials are concerned, there are no systematic works on the subject. In order to connect hot dip galvanized steel material with aluminum material, it is necessary to use high strength pre-loaded bolts. The use of weld is not possible because of the different properties of materials. The presented work is the result of the studies conducted on two different materials- aluminium and steel and their friction grip pre-loaded high strength bolted connections. For this reason, two different types of experiments have been done. These tests are the short-term and the long-term tests, performed on four different dimensions of thickness: 10.0 mm, 9.7 mm, 8.0 mm and 5.0 mm, and on three different aluminum alloys: AlMgSi1 (6082), AlMgSi0.5 (6063) and AlZn4.5Mg1 (7020). In each specimen two 10.9 M16 bolts have been used. In the first five tests of the short-term tests, friction surfaces are only treated oil-free and in the latter 9 test specimens are painted with alkali silicate zinc. In pre-loaded high strength bolted connections, the friction coefficient had been determined for the aluminum and steel specimens with oil-free contact surfaces and also for the alkali silicate zinc painted contact surfaces. For the above mentioned two different cases of treatment of the contact surface, loading-displacement diagrams are studied for shear loads and after it then, up to the occurrence of the rupture. After having subjected the bolts to pre-loading, the loss of pre-load had been studied for 30 min. prior to the beginning of the test. During the test under load, the specimen was monitored to determine whether a sudden loss in pre-load occurred. In the short-term tests after applying the pre-loading to the bolts, no big loss on the pre-load was noticed, because of the creep behavior of aluminum in time. In the short-term tests, when no paint on the friction surfaces was used, the number of the bolts necessary for the proper connections would be too high to be considered economical. In case of using the friction-increasing alkali silicate zinc paint, the limit friction force of one bolt increases 3.5 times. A change of the thickness has no effect on the friction coefficient in short-term tests. When the aluminum alloy has lower yield stress than the steel, an indent under the washer will be observed. This observation is valid only for the AlMgSi0.5 (6063) alloy. That's why it is necessary to transfer the pre-load to a greater surface. To prevent the indent from happening, a thicker and wider washer could be used. After evaluating the short-term test results statistically, it has been noticed that the standard deviation of the distribution of friction coefficient does not exceed 10% limit. With the help of the results of fourteen short-term tests that were conducted, a long-term testing system was prepared and a total of fifteen long-term connection specimens in three different frames with 90 kN, 78 kN and 60 kN of continuous loading was monitored. The loading on each frame was determined so that the friction surface of each specimen was loaded with 75%, 65% and 50% ratios. To prepare the friction surfaces of long-term test specimens, all surfaces were treated with alkali silicate zinc paint. The long-term test had been carried out within one - year time span, during which the loading of each frame, the pre-loading on bolts and the slip between aluminum and steel plates were observed. The effect of small thickness on friction in the long-term tests causes the slip of contact surfaces in time. By using thinner aluminum plates, contact pressure was distributed on a smaller area of contact surface. This explains the earlier shear observed in the long-term tests under constant tension force. The thinner the specimen, the earlier the slip occurs. For the study of the long-term test results using constant distance separation - a method not found in the literature, an attempt has been made to predict the behavior of specimens within 50 years onwards. Inspecting of the 10 mm thick aluminum plate specimens after the period of one year shows that the predicted displacement in 50 years' time will be within the 0.30 mm slip limit range. The conclusion can be drawn that the alkali silicate zinc paint increases the friction coefficient of connections made of two different materials- aluminum and steel. Keywords: Connections, high strength bolts, aluminum members

Atmospheric and oceanic conditions associated with early and late onset for Eastern Africa short rains

Timing of the rainy season is essential for a number of climate sensitive sectors over Eastern Africa. This is particularly true for the agricultural sector, where most activities depend on both the spatial and temporal distribution of rainfall throughout the season. Using a combination of observational and reanalysis datasets, the present study investigates the atmospheric and oceanic conditions associated with early and late onset for Eastern Africa short rains season (October–December). Our results indicate enhanced rainfall in October and November during years with early onset and rainfall deficit in years with late onset for the same months. Early onset years are found to be associated with warmer sea surface temperatures (SSTs) in the western Indian Ocean, and an enhanced moisture flux and anomalous low-level flow into Eastern Africa from as early as the first dekad of September. The late onset years are characterized by cooler SSTs in the western Indian Ocean, anomalous westerly moisture flux and zonal flow limiting moisture supply to the region. The variability in onset date is separated into the interannual and decadal components, and the links with SSTs and low-level circulation over the Indian Ocean basin are examined separately for both timescales. Significant correlations are found between the interannual variability of the onset and the Indian Ocean dipole mode index. On decadal timescales the onset is shown to be partly driven by the variability of the SSTs over the Indian Ocean. Understanding the influence of these potentially predictable SST and moisture patterns on onset variability has huge potential to improve forecasts of the East African short rains. Improved prediction of the variability of the rainy season onset has huge implications for improving key strategic decisions and preparedness action in many sectors, including agriculture

The Deconfinement Phase Transition in One-Flavour QCD

We present a study of the deconfinement phase transition of one-flavour QCD, using the multiboson algorithm. The mass of the Wilson fermions relevant for this study is moderately large and the non-hermitian multiboson method is a superior simulation algorithm. Finite size scaling is studied on lattices of size $8^3\times 4$, $12^3\times 4$ and $16^3\times 4$. The behaviours of the peak of the Polyakov loop susceptibility, the deconfinement ratio and the distribution of the norm of the Polyakov loop are all characteristic of a first-order phase transition for heavy quarks. As the quark mass decreases, the first-order transition gets weaker and turns into a crossover. To investigate finite size scaling on larger spatial lattices we use an effective action in the same universality class as QCD. This effective action is constructed by replacing the fermionic determinant with the Polyakov loop identified as the most relevant Z(3) symmetry breaking term. Higher-order effects are incorporated in an effective Z(3)-breaking field, $h$, which couples to the Polyakov loop. Finite size scaling determines the value of $h$ where the first order transition ends. Our analysis at the end - point, $h_{ep}$, indicates that the effective model and thus QCD is consistent with the universality class of the three dimensional Ising model. Matching the field strength at the end point, $h_{ep}$, to the $\kappa$ values used in the dynamical quark simulations we estimate the end point, $\kappa_{ep}$, of the first-order phase transition. We find $\kappa_{ep}\sim 0.08$ which corresponds to a quark mass of about 1.4 GeV .Comment: LaTex, 25 pages, 18 figure

Nasal Carriage and Antimicrobial Susceptibility of Staphylococcus aureus in healthy preschool children in Ujjain, India

<p>Abstract</p> <p>Background</p> <p>There is increasing evidence that community acquired <it>S. aureus </it>infections are spreading among healthy children. Nasal colonization with <it>S. aureus </it>plays pivotal role in the increasing prevalence of resistant community acquired <it>S. aureus </it>infections worldwide. A regular surveillance system is important in ensuring quality of patient care. The aim of the study was to assess the prevalence of and the factors associated with nasal carriage of <it>S. aureus </it>and its antibiotic sensitivity pattern among healthy children in Ujjain, India.</p> <p>Methods</p> <p>A prospective study was done in paediatric outpatient clinics of R.D. Gardi medical college Ujjain, India. Healthy children from 1 month to 59 months of age were included. Information on previously known risk factors for nasal colonization was collected using a pre-tested questionnaire. Swabs from anterior nares were collected and transported in Amies transport media with charcoal and cultured on 5% sheep blood agar. Antibiotic sensitivity tests were performed using Kirby Bauer's disc diffusion method according to performance standards of Clinical and Laboratory Standard Institute guidelines.</p> <p>Results</p> <p>Of the 1,562 children from 1-month up-to five years of age included in the study 98 children tested positive for nasal carriage of <it>S. aureus</it>. The prevalence of nasal carriage of <it>S. aureus </it>was 6.3% (95% CI 5.1-7.5) out of which 16.3% (95% CI 8.9-23.8) were methicillin-resistant <it>S. aureus </it>(MRSA). The factors associated with nasal carriage were "child attending preschool" (OR 4.26, 95% CI 2.25-8.03; <it>P </it>= 0.007) or "school" (OR 3.02, 95% CI 1.27-7.18; <it>P </it>< 0.001) and "family size more than 10 members" (OR 2.76 95% CI 1.06-7.15; <it>P </it>= 0.03). The sensitivity pattern of isolated <it>S. aureus </it>showed resistance to commonly used oral antibiotics while resistance to glycopeptides was not noted.</p> <p>Conclusions</p> <p>We found a relatively low rate of nasal carriage of <it>S. aureus </it>in children below five years when compared to children of older age groups in India. Yet, prevalence of MRSA was relatively high.</p

Diacetyl odor shortens longevity conferred by food deprivation in C. elegans via downregulation of DAF-16/FOXO

Dietary restriction extends lifespan in various organisms by reducing the levels of both nutrients and non-nutritional food-derived cues. However, the identity of specific food-derived chemical cues that alter lifespan remains unclear. Here, we identified several volatile attractants that decreased the longevity on food deprivation, a dietary restriction regimen in Caenorhabditis elegans. In particular, we found that the odor of diacetyl decreased the activity of DAF-16/FOXO, a life-extending transcription factor acting downstream of insulin/IGF-1 signaling. We then demonstrated that the odor of lactic acid bacteria, which produce diacetyl, reduced the nuclear accumulation of DAF-16/FOXO. Unexpectedly, we showed that the odor of diacetyl decreased longevity independently of two established diacetyl receptors, ODR-10 and SRI-14, in sensory neurons. Thus, diacetyl, a food-derived odorant, may shorten food deprivation-induced longevity via decreasing the activity of DAF-16/FOXO through binding to unidentified receptors. © 2020 The Authors. Aging Cell published by the Anatomical Society and John Wiley &amp; Sons Ltd.1