A theoretical analysis of the free vibration of discretely stiffened cylindrical shells with arbitrary end conditions

Theoretical analysis of free vibration of discretely stiffened cylindrical shells with arbitrary end condition

Effect of yeast culture on milk production and metabolic and reproductive performance of early lactation dairy cows

<p>Abstract</p> <p>Background</p> <p>The main objective of this study was to estimate the effect of supplementation with <it>Saccaromyces cerevisiae (SC</it>) (Yea-Sacc^®1026) on milk production, metabolic parameters and the resumption of ovarian activity in early lactation dairy cows.</p> <p>Methods</p> <p>The experiment was conducted during 2005/2006 in a commercial tied-house farm with an average of 200 milking Estonian Holstein Friesian cows. The late pregnant multiparous cows (n = 46) were randomly divided into two groups; one group received 10 g yeast culture from two weeks before to 14 weeks after calving. The groups were fed a total mixed ration with silages and concentrates. Milk recording data and blood samples for plasma metabolites were taken. Resumption of luteal activity was determined using milk progesterone (P₄) measurements. Uterine bacteriology and ovarian ultrasonography (US) were performed and body condition scores (BCS) and clinical disease occurrences were recorded. For analysis, the statistical software Stata 9.2 and R were used to compute Cox proportional hazard and linear mixed models.</p> <p>Results</p> <p>The average milk production per cow did not differ between the groups (32.7 ± 6.4 vs 30.7 ± 5.3 kg/day in the SC and control groups respectively), but the production of milk fat (<it>P </it>< 0.001) and milk protein (<it>P </it>< 0.001) were higher in the SC group. There was no effect of treatment on BCS. The analysis of energy-related metabolites in early lactation showed no significant differences between the groups. In both groups higher levels of β-hydroxybutyrate (BHB) appeared from days 14 to 28 after parturition and the concentration of non-esterfied fatty acid (NEFA) was higher from days 1–7 post partum (PP). According to US and P₄results, all cows in both groups ovulated during the experimental period. The resumption of ovarian activity (first ovulations) and time required for elimination of bacteria from the uterus did not differ between the groups.</p> <p>Conclusion</p> <p>Supplementation with SC had an effect on milk protein and fat production, but did not influence the milk yield. No effects on PP metabolic status, bacterial elimination from the uterus nor the resumption of ovarian activity were found.</p

Poly(A)-Specific Ribonuclease (Parn) Mediates 3 '-End Maturation of the Telomerase Rna Component

Mutations in the PARN gene (encoding poly(A)-specific ribonuclease) cause telomere diseases including familial idiopathic pulmonary fibrosis (IPF) and dyskeratosis congenita(1,2), but how PARN deficiency impairs telomere maintenance is unclear. Here, using somatic cells and induced pluripotent stem cells (iPSCs) from patients with dyskeratosis congenita with PARN mutations, we show that PARN is required for the 3'-end maturation of the telomerase RNA component (TERC). Patient-derived cells as well as immortalized cells in which PARN is disrupted show decreased levels of TERC. Deep sequencing of TERC RNA 3' termini shows that PARN is required for removal of post-transcriptionally acquired oligo(A) tails that target nuclear RNAs for degradation. Diminished TERC levels and the increased proportion of oligo(A) forms of TERC are normalized by restoring PARN, which is limiting for TERC maturation in cells. Our results demonstrate a new role for PARN in the biogenesis of TERC and provide a mechanism linking PARN mutations to telomere diseases.Wo

Managerial challenges of Industry 4.0: an empirically backed research agenda for a nascent field

The increasing intelligence of products and systems, their intra-company cross-linking and their cross-company integration into value creation networks is referred to as Industry 4.0. Academics and practitioners, largely agreeing on the global importance of this proclaimed industrial revolution, have published many contributions on the topic. Research, however, is rather focused on investigating single technologies in quite specific application domains and largely neglects the profound managerial challenges underlying Industry 4.0. Given the recent plea for a more active contribution from the management science community, we strive to establish Industry 4.0 as a challenging but promising field for management research, and aim to assist scholars in engaging with the topic. Therefore, we first gather and analyze extant contributions by means of a systematic literature review and synthesize the information gained into 18 managerial challenges of Industry 4.0 falling into six interrelated clusters: (1) strategy and analysis, (2) planning and implementation, (3) cooperation and networks, (4) business models, (5) human resources and (6) change and leadership. Considering that Industry 4.0 is still an emerging topic and publications may therefore not always be found in highly ranked journals, we aimed to increase the confidence in our findings and triangulated our data by conducting an online survey of industry experts and academics that allows us to qualify the identified challenges in terms of importance and future research need. On this basis, we present an empirically backed research agenda and suggest fruitful avenues for future research in three basic categories: practice-enhancing research, knowledge-enhancing research, and high-impact research