Bolted Timber Connections. Part I. a Wafer Technique to Model Wood Deformation Around Bolts

An experimental technique to model wood material behavior in the plane perpendicular to the axes of bolts in joint members is described. In this technique, 0.8-mm-thick wood wafers sandwiched between glass plates, with a steel pin representing a bolt passing through them, are loaded in tension. Wood deformation and failure around the pin, visible through the glass plates as loading proceeds, are photographed, and load-slip curves are also recorded. Reported tests were limited to steel pins of 12.5-mm diameter; preliminary findings suggest that information can be gained that sheds light on the effects of growth-ring orientation, wood defects, bolt end-distance, and multiple-bolt positions. The technique may be used directly, to indicate the sensitivity of joints to design factors such as those above, or indirectly, when results are combined with bolt bending data obtained with X-ray scanning

Bolted Timber Connections: Part II. Bolt Bending and Associated Wood Deformation

Complete double-shear joints with a single bolt were tested in tension. Approximately 10 X-ray scans were made of each joint as it was progressively loaded to failure; in this way, bending and overall displacement of the bolts within the members could be quantified. Combining the above data with measured joint-slip values enables the penetration of the bolt into the surrounding wood to be calculated for all positions along the length of the bolt. In a preceding related study, the authors observed the mechanisms of deformation that occur in thin wood wafers around a round steel pin of a diameter identical to that of the bolts used in the present work. By combining this information on behavior mechanisms in the plane at right angles to the pin axis with the X-ray data for whole joints, wood behavior throughout the joint and reactions against the bolt along its length can be estimated. The above analysis is applied principally to joints with 75- x 75-mm wood main members, 75- x 37.5-mm wood side members, and a single 12.5-mm diameter bolt an an end-distance of seven diameters. Representative X-ray scans of joints manufactured with a range of steel side-member thicknesses and bolt diameters are also included. The techniques presented complement theoretical model predictions and thus may be used to aid in optimizing joint design

NEW SEISMIC SOURCE ZONE MODEL FOR PORTUGAL AND AZORES

The development of seismogenic source models is one of the first steps in seismic hazard assessment. In seismic hazard terminology, seismic source zones (SSZ) are polygons (or volumes) that delineate areas with homogeneous characteristics of seismicity. The importance of using knowledge on geology, seismicity and tectonics in the definition of source zones has been recognized for a long time [1]. However, the definition of SSZ tends to be subjective and controversial. Using SSZ based on broad geology, by spreading the seismicity clusters throughout the areal extent of a zone, provides a way to account for possible long-term non-stationary seismicity behavior [2,3]. This approach effectively increases seismicity rates in regions with no significant historical or instrumental seismicity, while decreasing seismicity rates in regions that display higher rates of seismicity. In contrast, the use of SSZ based on concentrations of seismicity or spatial smoothing results in stationary behavior [4]. In the FP7 Project SHARE (Seismic Hazard Harmonization in Europe), seismic hazard will be assessed with a logic tree approach that allows for three types of branches for seismicity models: a) smoothed seismicity, b) SSZ, c) SSZ and faults. In this context, a large-scale zonation model for use in the smoothed seismicity branch, and a new consensus SSZ model for Portugal and Azores have been developed. The new models were achieved with the participation of regional experts by combining and adapting existing models and incorporating new regional knowledge of the earthquake potential. The main criteria used for delineating the SSZ include distribution of seismicity, broad geological architecture, crustal characteristics (oceanic versus continental, tectonically active versus stable, etc.), historical catalogue completeness, and the characteristics of active or potentially-active faults. This model will be integrated into an Iberian model of SSZ to be used in the Project SHARE seismic hazard assessment

Type Ia supernova Hubble diagram with near-infrared and optical observations

We main goal of this paper is to test whether the NIR peak magnitudes of SNe Ia could be accurately estimated with only a single observation obtained close to maximum light, provided the time of B band maximum and the optical stretch parameter are known. We obtained multi-epoch UBVRI and single-epoch J and H photometric observations of 16 SNe Ia in the redshift range z=0.037-0.183, doubling the leverage of the current SN Ia NIR Hubble diagram and the number of SNe beyond redshift 0.04. This sample was analyzed together with 102 NIR and 458 optical light curves (LCs) of normal SNe Ia from the literature. The analysis of 45 well-sampled NIR LCs shows that a single template accurately describes them if its time axis is stretched with the optical stretch parameter. This allows us to estimate the NIR peak magnitudes even with one observation obtained within 10 days from B-band maximum. We find that the NIR Hubble residuals show weak correlation with DM_15 and E(B-V), and for the first time we report a possible dependence on the J_max-H_max color. The intrinsic NIR luminosity scatter of SNe Ia is estimated to be around 0.10 mag, which is smaller than what can be derived for a similarly heterogeneous sample at optical wavelengths. In conclusion, we find that SNe Ia are at least as good standard candles in the NIR as in the optical. We showed that it is feasible to extended the NIR SN Ia Hubble diagram to z=0.2 with very modest sampling of the NIR LCs, if complemented by well-sampled optical LCs. Our results suggest that the most efficient way to extend the NIR Hubble diagram to high redshift would be to obtain a single observation close to the NIR maximum. (abridged)Comment: 39 pages, 15 figures, accepted by A&

COMPILATION OF ACTIVE FAULT DATA IN PORTUGAL FOR USE IN SEISMIC HAZARD ANALYSIS

To estimate where future earthquakes are likely to occur, it is essential to combine information about past earthquakes with knowledge about the location and seismogenic properties of active faults. For this reason, robust probabilistic seismic hazard analysis (PSHA) integrates seismicity and active fault data. Existing seismic hazard assessments for Portugal rely exclusively on seismicity data and do not incorporate data on active faults. Project SHARE (Seismic Hazard Harmonization in Europe) is an EC-funded initiative (FP7) that aims to evaluate European seismic hazards using an integrated, standardized approach. In the context of SHARE, we are developing a fully-parameterized active fault database for Portugal that incorporates existing compilations, updated according to the most recent publications. The seismogenic source model derived for SHARE will be the first model for Portugal to include fault data and follow an internationally standardized approach. This model can be used to improve both seismic hazard and risk analyses and will be combined with the Spanish database for use in Iberian- and European-scale assessments

Increasing body mass index at diagnosis of diabetes in young adult people during 1983-1999 in the Diabetes Incidence Study in Sweden (DISS).

Objective. To study trends in body mass index (BMI) at diagnosis of diabetes in all young Swedish adults in the age range of 15-34 years registered in a nation-based registry. Design. The BMI was assessed at diagnosis in diabetic patients 15-34 years of age at diagnosis, for a period of 17 years (1983-1999). Islet cell antibodies (ICA) were measured during three periods (1987-1988, 1992-1993 and 1998-1999). Setting. A nationwide study (Diabetes Incidence Study in Sweden). Subjects. A total of 4727 type 1 and 1083 type 2 diabetic patients. Main outcome measures. Incidence-year specific BMI adjusted for age, gender and time of diagnosis (month). Results. Body mass index at diagnosis increased significantly both in type 1 (21.4 ± 3.6 to 22.5 ± 4.0; P < 0.0001) and in type 2 (27.4 ± 6.8 to 32.0 ± 6.0; P < 0.0001) diabetic patients, also when adjusted for age, gender and month of diagnosis. A similar significant increase in BMI was found in type 1 diabetic patients and in type 2 diabetic patients in the periods 1987-1988, 1992-1993 and 1998-1999; years when ICA were assessed and considered in the classification of diabetes. Despite this increase in BMI, there was no increase in the incidence of diabetes in young-adult people in Sweden. Conclusion. Body mass index at diagnosis of diabetes in subjects 15-34 years of age has substantially increased during 1983-1999 in Sweden when adjusted for age, gender and month of diagnosis

Signatures of photon and axion-like particle mixing in the gamma-ray burst jet

Photons couple to Axion-Like Particles (ALPs) or more generally to any pseudo Nambu-Goldstone boson in the presence of an external electromagnetic field. Mixing between photons and ALPs in the strong magnetic field of a Gamma-Ray Burst (GRB) jet during the prompt emission phase can leave observable imprints on the gamma-ray polarization and spectrum. Mixing in the intergalactic medium is not expected to modify these signatures for ALP mass > 10^(-14) eV and/or for < nG magnetic field. We show that the depletion of photons due to conversion to ALPs changes the linear degree of polarization from the values predicted by the synchrotron model of gamma ray emission. We also show that when the magnetic field orientation in the propagation region is perpendicular to the field orientation in the production region, the observed synchrotron spectrum becomes steeper than the theoretical prediction and as detected in a sizable fraction of GRB sample. Detection of the correlated polarization and spectral signatures from these steep-spectrum GRBs by gamma-ray polarimeters can be a very powerful probe to discover ALPs. Measurement of gamma-ray polarization from GRBs in general, with high statistics, can also be useful to search for ALPs.Comment: 17 pages, 3 figures. Accepted for publication in JCAP with minor change

Compilation of parameterized seismogenic sources in Iberia for the SHARE European-scale seismic source model.

Abstract: SHARE (Seismic Hazard Harmonization in Europe) is an EC-funded project (FP7) that aims to evaluate European seismic hazards using an integrated, standardized approach. In the context of SHARE, we are compiling a fully-parameterized active fault database for Iberia and the nearby offshore region. The principal goal of this initiative is for fault sources in the Iberian region to be represented in SHARE and incorporated into the source model that will be used to produce seismic hazard maps at the European scale. The SHARE project relies heavily on input from many regional experts throughout the Euro-Mediterranean region. At the SHARE regional meeting for Iberia, the 2010 Working Group on Iberian Seismogenic Sources (WGISS) was established; these researchers are contributing to this large effort by providing their data to the Iberian regional integrators in a standardized format. The development of the SHARE Iberian active fault database is occurring in parallel with IBERFAULT, another ongoing effort to compile a database of active faults in the Iberian region. The SHARE Iberian active fault database synthesizes a wide range of geological and geophysical observations on active seismogenic sources, and incorporates existing compilations (e.g., Cabral, 1995; Silva et al., 2008), original data contributed directly from researchers, data compiled from the literature, parameters estimated using empirical and analytical relationships, and, where necessary, parameters derived using expert judgment. The Iberian seismogenic source model derived for SHARE will be the first regional-scale source model for Iberia that includes fault data and follows an internationally standardized approach (Basili et al., 2008; 2009). This model can be used in both seismic hazard and risk analyses and will be appropriate for use in Iberian- and European-scale assessments

Incorporating Descriptive Metadata into Seismic Source Zone Models for Seismic Hazard Assessment: A case study of the Azores-West Iberian region

In probabilistic seismic-hazard analysis (PSHA), seismic source zone (SSZ) models are widely used to account for the contribution to the hazard from earth- quakes not directly correlated with geological structures. Notwithstanding the impact of SSZ models in PSHA, the theoretical framework underlying SSZ models and the criteria used to delineate the SSZs are seldom explicitly stated and suitably docu- mented. In this paper, we propose a methodological framework to develop and docu- ment SSZ models, which includes (1) an assessment of the appropriate scale and degree of stationarity, (2) an assessment of seismicity catalog completeness-related issues, and (3) an evaluation and credibility ranking of physical criteria used to delin- eate the boundaries of the SSZs. We also emphasize the need for SSZ models to be supported by a comprehensive set of metadata documenting both the unique character- istics of each SSZ and the criteria used to delineate its boundaries. This procedure ensures that the uncertainties in the model can be properly addressed in the PSHA and that the model can be easily updated whenever new data are available. The pro- posed methodology is illustrated using the SSZ model developed for the Azores–West Iberian region in the context of the Seismic Hazard Harmonization in Europe project (project SHARE) and some of the most relevant SSZs are discussed in detail