4,010 research outputs found
Factors Influencing Auction Outcomes: Bidder Turnout, Auction Houses and Market Conditions
This study provides new evidence on the outcomes of auctions of residential real estate, focusing on the effects of bidder turnout, pricing, market conditions and auction houses. Our analysis of properties offered for sale by auction in Singapore from 1995 to 2000 shows that several variables are significant in explaining why an auction results in a sale or not. These variables included the state of the market, the timing of the auction (year), the number of bidders at the auction and the auction house. We also find that the probability of a sale is higher for distress sales, for more homogenous properties and for those located in the central region. Finally, we provide a sensitivity analysis of how market conditions and the choice of auction house influence the probability of a sale.
The development of abdominal aortic aneurysms in mice is enhanced by benzo(a)pyrene
Cigarette smoking has been strongly associated with abdominal aortic aneurysm (AAA), but the components of tobacco smoke involved in AAA have not been identified. Benzo(a)pyrene (BaP) is an important constituent in cigarette smoke capable of induction of alterations strikingly similar to the pathological changes seen during AAA development. We therefore hypothesized that BaP exposure contributes to the development of AAA. In this study, C57/B6J mice were treated with vehicle, angiotensin II (AngII) (0.72 mg/kg/day), BaP (10 mg/kg/week), or the combination of AngII and BaP, for 5 weeks, and then examined for incidence of AAA and pathological changes of the aortic wall. Results showed that incidence of AAA formation in C57/B6J mice treated with BaP and AngII was significantly higher than that in AngII-treated mice (7 of 12 compared to 2 of 12). Further, five mice in the group treated with AngII/BaP and one in the group treated with AngII exhibited AAA rupture and hematoma. BaP caused macrophage infiltration, disarray of elastic lamella, and loss of vascular smooth muscle cells (VSMCs). We conclude that BaP aggravates AAA formation and rupture in C57/B6J mice by promoting macrophage infiltration, degeneration of elastic lamella, and loss of VSMCs in the aortic wall
An Overview of Principles and Designs of Hydraulic Fracturing Experiments and an Inquiry into the Influence of Rock Permeability and Strength on Failure Mode
The relevance of hydraulic fracturing experiments in the analysis of subsurface flow mechanisms and interactions during fracking operations underpins past and current efforts towards designing and implementing more representative physical models. An overview has been presented that comprehensively discusses the key elements and design requirements for successful experimentations. In setting up a hydraulic fracturing experiment, it is imperative that, in line with the research objective, the physical model that includes the initial and boundary conditions, wellbore configuration, type of fracturing fluid and injection rate be a true representative of actual reservoir/underground flow environments. This investigation recognises the main elements that form the framework for effective laboratory scale experiments, which comprise the specimen, in‐situ stresses, pore pressure, fluid injection, duration, and visualisation and monitoring. Furthermore, an examination of the influence of rock properties on the characteristics of fracturing and failure of rocks subjected to wellbore conditions indicates a trend highly dependent on rock strength and permeability. Soft and highly permeable rocks tend to cause an inward collapse of the wellbore cavity. Cavity size is also shown to have a considerable effect on the failure process. Wellbore stability is inversely related to cavity size; larger cavities are found to be less stable
New Paleomagnetic, Rock Magnetic, and Petrographic Results from the Valle Group, Baja California, Mexico: Exploring the Causes of Anomalously Shallow Paleomagnetic Inclinations
[1] A detailed paleomagnetic, rock magnetic, and sedimentologic study was conducted on Cenomanian‐age strata of the Valle Group at El Campito, Baja California, to examine the burial compaction effects on the paleomagnetic inclination of marine sedimentary rocks. Alternating field and thermal demagnetization isolated a characteristic remanence at 16 of 18 sites with a mean of Dec = 342.6°, Inc = 19.1°, and α95 = 3.4°. The inclination is 38.7° shallower than that predicted by the reference paleopole for North America. Laboratory experiments indicate that compaction could account for only 7.5° of the inclination shallowing. Fold tests at different scales yield both positive and negative results, making a tight constraint on the remanence\u27s age impossible. A primary postdepositional remanence is supported by bedding‐parallel foliations in the anisotropy of anhysteretic remanence fabric. Although primary anomalously shallow inclinations could indicate significant southerly, then northerly, paleolatitudinal offset, a more likely scenario is a late Cenozoic low‐temperature remagnetization, which is suggested by alteration along the edges of some detrital silicate grains and a bimodal magnetic grain size distribution revealed by isothermal remanence data. The synthesis of the data indicates that the Vizcaino terrane was contiguous with the Cordillera margin during remagnetization and underwent a subsequent 13.5 ± 5.4° clockwise rotation. We tentatively interpret that the remagnetization resulted from burial and/or Miocene volcanism, which caused an acquisition of thermochemical remanent magnetization (TCRM). This study reveals a complicated remanence that resists easy interpretation and suggests caution in studies of similar rocks
The Sensitivity of Micro—Macro Mechanical Behaviour of Sand to the Inter-Particle Properties
Sand is a particulate material but is treated as a continuum solid in some engineeringanalyses. This approach is proven to be acceptable when dealing with geotechnical structures,provided an adequate factor of safety is applied so that there is no risk of failure. However, thecontinuum approach does not account for the effect of interparticle forces on the micro–macrobehaviour of sand. Sand could be modelled as a particulate material using the discrete elementmethod (DEM), taking into account its discrete nature. This paper shows how the microscopiccontact properties between the idealised sand particles influence the macro-mechanical behaviour,highlighting the development of the fabric as the soil approaches failure. Thirty DEM biaxial testswere performed to study the sensitivity of the macro–micro mechanical properties of sand to theinter-particle properties of an idealised sand particle. The conditions of these simulations were thesame (e.g., particle size distribution, number of particles, porosity after radius enlargement, boundaryconditions, and rate of loading). The sensitivity of the pre-peak, peak, and post-peak behaviour ofthese simulations to the inter-particle properties of an idealised sand particle was studied. Two extraDEM biaxial tests under different confining pressures were performed to verify the cohesionlessnature of the synthetic material used for this study. Since a two-dimensional DEM is used for thisstudy, a detailed approach to interpret the results assuming either a plane strain or a plane stresssituation was discussed. This study highlighted the critical inter-particle properties and the rangeover which these influence macro-mechanical behaviour. The results show that Young’s modulus ismainly dependent on the normal contact stiffness, and peak stress and the angle of internal frictionare greatly dependent on the inter-particle coefficient of friction, while Poisson’s ratio and volumetricbehaviour of particulate sand are dictated mainly by shear contact stiffness. A set of relationshipswere established between inter-particle properties and macro-machinal parameters such as Young’smodulus, Poisson’s ratio, and angle of internal friction. The elastoplastic parameters obtained fromthese tests are qualitatively in agreement with the typical medium and dense sand behaviour
Click to Success? The Temporal Effects of Facebook Likes on Crowdfunding
Small and medium-sized businesses as well as individuals are increasingly using online crowdfunding platforms to raise funds in the fintech world. Creators of crowdfunding projects depend heavily on social networks like Facebook to publicize their projects. Social media activities such as “liking” on Facebook bring massive traffic to crowdfunding projects and attract contributions. Using data collected from Facebook and Kickstarter, our empirical tests demonstrate that social media activities significantly and positively impact the likely success of crowdfunding. Our duration model analysis reveals that the impact of social media activities on crowdfunding outcomes follows a J-curve in the temporal space. We explain the J-curve by identifying two important effects of social media activities throughout the crowdfunding process: a quality-signaling effect in the opening period and a herding effect in the closing period. Especially in the “last mile,” there is a strong herding effect that helps crowdfunding projects reach their respective fundraising goals. Our results offer useful contributions to the literature and suggestions for practitioners
Acute Kidney Injury: Controversies Revisited
This paper addresses the epidemiology of AKI specifically in relation to recent changes in AKI classification and revisits the controversies regarding the timing of initiation of dialysis and the use of peritoneal dialysis as a renal replacement therapy for AKI. In summary, the new RIFLE/AKIN classifications of AKI have facilitated more uniform diagnosis of AKI and clinically significant risk stratification. Regardless, the issue of timing of dialysis initiation still remains unanswered and warrants further examination. Furthermore, peritoneal dialysis as a treatment modality for AKI remains underutilised in spite of potential beneficial effects. Future research should be directed at identifying early reliable biomarkers of AKI, which in conjunction with RIFLE/AKIN classifications of AKI could facilitate well-designed large randomised controlled trials of early versus late initiation of dialysis in AKI. In addition, further studies of peritoneal dialysis in AKI addressing dialysis dose and associated complications are required for this therapy to be accepted more widely by clinicians
Characterization and modeling of strain assisted diffusion in an epoxy adhesive layer
AbstractIn this paper a coupled model for strain-assisted diffusion is derived from the basic principles of continuum mechanics and thermodynamics, and material properties characterized using diffusion experiments. The proposed methodology constitutes a significant step toward modeling the synergistic bond degradation mechanism at the bonded interface between a Fiber Reinforced Polymer (FRP) and a substrate, and for predicting debond initiation and propagation along the interface in the presence of a diffusing penetrant at the crack tip and at elevated temperatures. It is now well-known that Fick’s law is frequently inadequate for describing moisture diffusion in polymers and polymer composites. Non-Fickian or anomalous diffusion is likely to occur when a polymer is subjected to external stresses and strains, as well as elevated temperatures and humidity. In this paper, a modeling methodology based on the basic principles of continuum mechanics and thermodynamics is developed which allows characterization of the combined effects of temperature, humidity, and strain on diffusion coefficients as well as on moisture saturation level, from moisture weight gain data. For tractability, the diffusion governing equations are simplified for the special case of 1-D diffusion subjected to uniaxial strain and a uniform strain gradient. A novel test specimen that introduces a uniform strain gradient is developed, and diffusion test data for an epoxy-based primer/adhesive are presented and employed for complete characterization of material constants used in the model
Genetic Identification and Mass Propagation of Economically Important Seaweeds
Seaweeds are a primary source of hydrocolloids, which can be processed into various food additives, cosmetics, and pharmaceuticals. The inability of current commercial seaweed farming projects to meet industrial demands is underscored by a plethora of challenges, which include the lack of high-quality germplasm with the desired cultural characteristics. This chapter describes the current trends in commercial seaweed production and the potential technological advances in production methods and genetic selection strategies, which can be applied to raise the productivity of seaweed farms. Molecular markers have become increasingly relevant to the selection of a diverse range of wild varieties for domestication, and this augurs well for strain identification. The development of high-density linkage maps based on molecular markers offers an avenue for the implementation of molecular breeding strategies based on quantitative trait loci (QTLs). Concurrently, productivity of existing varieties can be enhanced by the analysis of exogenous factors known to affect the growth and survival of tissue-cultured seedlings. The application of photobioreactors for tissue culture is another important development, which will be digressed upon. In addition to this, quality control which focuses on the comparison of chemical and physical qualities of the tissue-cultured and conventional cultivated seaweeds will become increasingly relevant to the development of industry standards for sustainable seaweed production to fulfill the increasing demands of seaweed-related industries
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