State of the Art of Structural Engineering

Abstract: The objective of this paper is to provide an overview of the developments in structural engineering that took place during the past century. This overview includes ͑1͒ some of the major structural accomplishments as selected by the writers, ͑2͒ the advances in mechanics as the basis of structural analysis, ͑3͒ the development of new materials, ͑4͒ new fields of research and practice, and ͑5͒ the changes in the way design projects are performed. In addition, the writers' personal predictions for future developments during the 21st century are also presented. One of the main features affecting the evolution of structural engineering over the last part of the 20th century has been the advent and rapid development of digital computers as engineering tools. Computers can be used to perform complex and cumbersome computations and to enhance worldwide communications, both with great speed and reliability. This has already had an important effect on the way we design structures and educate civil engineers, but the impact on structural analysis and design as well as on construction planning and management is still in progress. We believe that this impact will be fully felt in the 21st century. Computers will liberate engineers from tedious and routine computations, allowing them to concentrate on more creative and important endeavors. They will facilitate the design of constructed facilities as complete systems rather than by considering each subsystem ͑such as structure and foundation͒ separately. They will lead finally to the needed integration of the design and construction processes

Near-field intensity pattern at the output of silica-based graded-index multimode fibers under selective excitation with a single-mode fiber

Abstract: Selective excitation of graded-index multimode fibers (GIMMFs) with a single-mode fiber (SMF) has gained increased interest for telecommunication applications. It has been proposed as a way to enhance the transmission bandwidth of GI-MMF links and/or create parallel communication channels over the same GI-MMF. Although the effect of SMF excitation on the transmission bandwidth has been investigated, its impact on the near-field intensity pattern at the output face of the GI-MMF has not been systematically addressed. We have carried out an analysis of the near-field intensity pattern at the output face of silica-based GI-MMFs excited by a radially offset SMF. Simulation results exhibit all of the features displayed by experimental ones. It turns out that differential mode attenuation and delay, full intra-group mode mixing, and small deviations in the refractive index profile of the GI-MMF do not affect the overall shape of the near-field intensity, which is determined by the radial offset of the input SMF. This can be exploited in mode group diversity multiplexing links. The effect of defects in the refractive index profile, such as a central dip or peak, is also examined

Acoustic oscillations and dynamo action in the G8 sub-giant EK Eri

We present further evidence of the presence of acoustic oscillations on the slowly-rotating, over-active G8 sub-giant EK Eri. This star was observed with the 1-m Hertzsprung SONG telescope, at the Observatorio del Teide for two different runs of 8 and 13 nights, respectively, and separated by about a year. We determined a significant excess of power around $\nu_\mathrm{max} = 253 \pm 3\,\mu$Hz in the first observing run and we were able to determine the large separation $\Delta\nu = 16.43 \pm 0.22\,\mu$Hz. No significant excess of power was instead detected in a subsequent SONG observing season, as also supported by our analysis of the simultaneous TESS photometric observations. We propose a new amplitude-luminosity relation in order to account for the missing power in the power spectrum. Based on the evolutionary stage of this object we argue that standard $\alpha^2\Omega$ dynamo cannot be excluded as a possible origin for the observed magnetic field.Comment: 8 pages, 8 figures, accepted for publication in A&

Optoacoustic solitons in Bragg gratings

Optical gap solitons, which exist due to a balance of nonlinearity and dispersion due to a Bragg grating, can couple to acoustic waves through electrostriction. This gives rise to a new species of ``gap-acoustic'' solitons (GASs), for which we find exact analytic solutions. The GAS consists of an optical pulse similar to the optical gap soliton, dressed by an accompanying phonon pulse. Close to the speed of sound, the phonon component is large. In subsonic (supersonic) solitons, the phonon pulse is a positive (negative) density variation. Coupling to the acoustic field damps the solitons' oscillatory instability, and gives rise to a distinct instability for supersonic solitons, which may make the GAS decelerate and change direction, ultimately making the soliton subsonic.Comment: 5 pages, 3 figure

Reconstructing complex regions of genomes using long-read sequencing technology

Cataloged from PDF version of article.Obtaining high-quality sequence continuity of complex regions of recent segmental duplication remains one of the major challenges of finishing genome assemblies. In the human and mouse genomes, this was achieved by targeting large-insert clones using costly and laborious capillary-based sequencing approaches. Sanger shotgun sequencing of clone inserts, however, has now been largely abandoned, leaving most of these regions unresolved in newer genome assemblies generated primarily by next-generation sequencing hybrid approaches. Here we show that it is possible to resolve regions that are complex in a genome-wide context but simple in isolation for a fraction of the time and cost of traditional methods using long-read single molecule, real-time (SMRT) sequencing and assembly technology from Pacific Biosciences (PacBio). We sequenced and assembled BAC clones corresponding to a 1.3-Mbp complex region of chromosome 17q21.31, demonstrating 99.994% identity to Sanger assemblies of the same clones. We targeted 44 differences using Illumina sequencing and find that PacBio and Sanger assemblies share a comparable number of validated variants, albeit with different sequence context biases. Finally, we targeted a poorly assembled 766-kbp duplicated region of the chimpanzee genome and resolved the structure and organization for a fraction of the cost and time of traditional finishing approaches. Our data suggest a straightforward path for upgrading genomes to a higher quality finished state

The p110 delta structure: mechanisms for selectivity and potency of new PI(3)K inhibitors.

Deregulation of the phosphoinositide-3-OH kinase (PI(3)K) pathway has been implicated in numerous pathologies including cancer, diabetes, thrombosis, rheumatoid arthritis and asthma. Recently, small-molecule and ATP-competitive PI(3)K inhibitors with a wide range of selectivities have entered clinical development. In order to understand the mechanisms underlying the isoform selectivity of these inhibitors, we developed a new expression strategy that enabled us to determine to our knowledge the first crystal structure of the catalytic subunit of the class IA PI(3)K p110 delta. Structures of this enzyme in complex with a broad panel of isoform- and pan-selective class I PI(3)K inhibitors reveal that selectivity toward p110 delta can be achieved by exploiting its conformational flexibility and the sequence diversity of active site residues that do not contact ATP. We have used these observations to rationalize and synthesize highly selective inhibitors for p110 delta with greatly improved potencies

Association between dental and periodontal conditions with chronic kidney disease: A cross-sectional analysis of urban South Africans

Oral diseases are preventable causes of poor health outcomes in people with chronic kidney disease (CKD). Investigate the association between dental and periodontal conditions with kidney function and determine whether inflammation mediate the association between periodontitis and CKD. Cross-sectional analysis of 1551 South African adults of mixed ancestry. CKD was classified as estimated glomerular filtration rate (eGFR) <60mL/min/1.73m2. Oral profile was captured by decayed, missing, filled teeth index (DMFTi), bleeding on probing (BOP), pocket depth (PD), clinical attachment loss (CAL), and periodontitis classified as PD ≥4 mm.Overall, 6% had CKD, with 93% and 66% of participants with and without CKD, respectively having a high DMFTi (p<0.0001). Further, 84% (CKD) and 43% (without CKD) were edentulous (p<0.0001). A great proportion of the dentate sub-sample (n=846) had periodontitis, however, BOP, PD ≥4mm and CAL ≥4mm were similar between the groups. DMFTi was associated with eGFR and prevalent CKD (p<0.023), with this association driven by the Missing component. Periodontitis was not associated with eGFR nor CKD (p>0.282). In routine care of people with CKD, attention should be given to oral health

Short-term and medium-term health effects of 9/11

The New York City terrorist attacks on Sept 11, 2001 (9/11), killed nearly 2800 people and thousands more had subsequent health problems. In this Review of health effects in the short and medium terms, strong evidence is provided for associations between experiencing or witnessing events related to 9/11 and post-traumatic stress disorder and respiratory illness, with a correlation between prolonged, intense exposure and increased overall illness and disability. Rescue and recovery workers, especially those who arrived early at the World Trade Center site or worked for longer periods, were more likely to develop respiratory illness than were other exposed groups. Risk factors for post-traumatic stress disorder included proximity to the site on 9/11, living or working in lower Manhattan, rescue or recovery work at the World Trade Center site, event-related loss of spouse, and low social support. Investigators note associations between 9/11 exposures and additional disorders, such as depression and substance use; however, for some health problems association with exposures related to 9/11 is unclear

Sceptical Employees as CSR Ambassadors in Times of Financial Uncertainty

This chapter offers new insights into the understanding of internal (employee) perceptions of organizational corporate social responsibility (CSR) policies and strategies. This study explores the significance of employees’ involvement and scepticism upon CSR initiatives and focuses on the effects it may have upon word of mouth (WOM) and the development of employee–organisation relationships. Desk research introduces the research questions. Data for the research questions were gathered through a self-completion questionnaire distributed in a hardcopy form to the sample. An individual’s level of scepticism and involvement appears to affect the development of a positive effect on employees’ WOM. Involvement with the domain of the investment may be a central factor affecting relationship building within the organization, and upon generation of positive WOM. The chapter offers a conceptual framework to public relations (PR) and corporate communications practitioners, which may enrich their views and understanding of the use and value of CSR for communication strategies and practices. For-profit organisations are major institutions in today’s society. CSR is proffered as presenting advantages for (at macro level) society and (micro level) the organization and its employees. Concepts, such as involvement and scepticism, which have not been rigorously examined in PR and corporate communication literature, are addressed. By examining employee perceptions, managers and academic researchers gain insights into the acceptance, appreciation and effectiveness of CSR policies and activities upon the employee stakeholder group. This will affect current and future CSR communication strategies. The knowledge acquired from this chapter may be transferable outside the for-profit sector

Effects of broadening and electron overheating in tunnel structures based on metallic clusters

We study the influence of energy levels broadening and electron subsystem overheating in island electrode (cluster) on current-voltage characteristics of three-electrode structure. A calculation scheme for broadening effect in one-dimensional case is suggested. Estimation of broadening is performed for electron levels in disc-like and spherical gold clusters. Within the two-temperature model of metallic cluster and by using a size dependence of the Debye frequency the effective electron temperature as a function of bias voltage is found approximately. We suggest that the effects of broadening and electron overheating are responsible for the strong smoothing of current-voltage curves, which is observed experimentally at low temperatures in structures based on clusters consisting of accountable number of atoms.Comment: 8 pages, 5 figure