45 research outputs found
PCSK6 and Survival in Idiopathic Pulmonary Fibrosis
Rationale: Idiopathic pulmonary fibrosis (IPF) is a devastating disease characterized by limited treatment options and high mortality. A better understanding of the molecular drivers of IPF progression is needed. Objectives: To identify and validate molecular determinants of IPF survival. Methods: A staged genome-wide association study was performed using paired genomic and survival data. Stage I cases were drawn from centers across the United States and Europe and stage II cases from Vanderbilt University. Cox proportional hazards regression was used to identify gene variants associated with differential transplantation-free survival (TFS). Stage I variants with nominal significance (P < 5 x 10(-5)) were advanced for stage II testing and meta-analyzed to identify those reaching genome-wide significance (P < 5 x 10(-8)). Downstream analyses were performed for genes and proteins associated with variants reaching genome-wide significance. Measurements and Main Results: After quality controls, 1,481 stage I cases and 397 stage II cases were included in the analysis. After filtering, 9,075,629 variants were tested in stage I, with 158 meeting advancement criteria. Four variants associated with TFS with consistent effect direction were identified in stage II, including one in an intron of PCSK6 (proprotein convertase subtilisin/kexin type 6) reaching genome-wide significance (hazard ratio, 4.11 [95% confidence interval, 2.54-6.67]; P = 9.45 x 10(-9)). PCSK6 protein was highly expressed in IPF lung parenchyma. PCSK6 lung staining intensity, peripheral blood gene expression, and plasma concentration were associated with reduced TFS. Conclusions: We identified four novel variants associated with IPF survival, including one in PCSK6 that reached genome-wide significance. Downstream analyses suggested that PCSK6 protein plays a potentially important role in IPF progression
Comparison Wage in Trade Union Decision Making
The starting point of this paper is the idea that trade unions and individual workers pay attention to wage settlements in similar sectors of the economy. The foundations of this concept can be found in other social sciences and also in the literature of psychological economics. However, it has not received much attention in connection to union decision making. This comparison or reference wage enters the decision making of the union (i.e. the union utility function). In this paper, we employ a union utility function which incorporates this concept. The analysis is conducted in a bargaining framework and the results show the effects on the optimal wage of important variables like comparison wage, unemployment benefit, union power and of the weight that the union places on the comparison wag
3D finite element analysis of anchorage zones in post-tensioned concrete girder
The anchorage zone of post-tensioned concrete structures is a discontinuity region, where a redistribution of
stress occurs behind the anchor device, as the concentrated prestressing force spreads out over the full
concrete section. This disturbed zone is subjected to a very complex three-dimensional state of stress, with
transverse tensile forces that cause longitudinal cracks which can extend throughout the beam span, thus
causing failure. To prevent excessive cracking, therefore, concrete must be adequately reinforced with
supplementary or ‘’bursting'' reinforcement.
The problem of the stress distribution in the anchorage zone has been well studied in the past decades using
various methods such as linear elastic theory [1-5], experimental investigations [6-7], strut and tie models [7]
and finite element analyses [8-10].
Most efforts in the previous analyses have focused on evaluating the ultimate strength of post-tensioned
beams tested to anchorage failure and only few works have considered the effects of support reaction.
Although ultimate limite states are the most important considerations in the design of prestressed structures,
more in depth study is required at serviceability limit states in order to evaluate the effectiveness of bursting
reinforcement to control maximum crack width. Prediction of this behavior requires advanced analytical
techniques with the ability to simulate the highly nonlinear behaviour of the concrete. To date, most of the
nonlinear finite element analyses have consisted of two-dimensional models of the anchorage zones,
although it is a three-dimensional one even in a rectangular beam. The main reason for this choice is
generally attributed to a lack of a proper description of material properties of concrete.
In this study, three-dimensional non-linear finite element analyses have been carried out using the program
Atena to simulate the behaviour of end zones of rectangular section post-tensioned girders, with the
presence of the support reaction. This program includes an advanced three-dimensional material model
which allows employing it as an effective tool for the investigation of reinforced and prestressed concrete
elements. The validity of the finite element model has been verified through comparisons with tests reported
in literature and it was found good agreement between the experimental and numerical results. The validated
model has been used to investigate the influence of the arrangement of bursting reinforcement on stirrups
strains and crack development at serviceability and ultimate limit state