166 research outputs found
Evaluating indicators of job performance: Distributions and types of analyses
Distributions of job performance indicators have historically been assumed to be normally distributed (Aguinis & O\u27Boyle, 2014; Schmidt & Hunter, 1983; Tiffin, 1947). Generally, any evidence to the contrary has been attributed to errors in the measurement of job performance (Murphy, 2008). A few researchers have been skeptical of this assumption (Micceri, 1989; Murphy, 1999; Saal, Downey, & Lahey, 1980); yet, only recently has research demonstrated that in certain specific situations job performance is exponentially distributed (Aguinis, O\u27Boyle, Gonzalez-Mulé, & Joo, 2016; O\u27Boyle & Aguinis, 2012). To date there have been few recommendations in the Industrial-Organizational Psychology literature about how to evaluate distributions of job performance to determine whether they fit an exponential curve. There also has not been substantial justification in the literature as to why distributions of job performance would be expected to be normally distributed versus exponentially distributed. Furthermore, recent research about job performance distributions has narrowly focused only on a few specific types of work and on a few specific indicators of performance. Thus, research concerning distributions of job performance indicators is, to date, of limited generalizability.
The current research attempts to close the gaps in the literature by identifying high fidelity methods and applying them to classify distributions of various indicators of job performance on a continuous spectrum from normal to exponential. In this research, multiple types of indicators of performance (and indices computed from combinations of indicators) were found to produce exponential distributions. More specifically, managerial indicators of job performance were found to best fit a normal distribution whereas objective measures, as well as composite measures of performance consisting of objective and subjective indicators, were found to best fit an exponential distribution. This study provides researchers and practitioners with new suggestions for classifying job performance distributions as well as new techniques for better differentiating between top and bottom performers
Self-Assembly Mechanisms of Organosilanes and Porphyrins Investigated with Scanning Probe Microscopy
This dissertation details the development of new fabrication strategies for the preparation of spatially selective surfaces by combining techniques of particle lithography and scanning probe microscopy (SPM). This combination of lithography and nanoscale surface characterization was applied to study the mechanisms of molecular level surface-assembly of organosilanes and porphyrin on surfaces of Si(111). Particle lithography was used to investigate the surface assembly of 4-chloromethylphenyltrichlorosilane (CMPS) within exposed sites of nanoholes in selected solvents and at selected temperatures to gain insight into the details of self-polymerization. Nanopillars of CMPS were generated under selected conditions of solvent and temperature and characterized with atomic force microscopy (AFM). CMPS nanopillars were shown to grow taller with more layers at higher reactions temperatures. It was also observed that CMPS nanopillars grown in toluene formed more fractured pillars with multiple domains from a single nanoholes, compared to nanopillars grown in bicyclohexane that were observed to have more structured growth and less diverse morphology. The self-assembly of CMPS was strictly confined to nanoholes with the surrounding matrix showing very little evidence of non-specific adsorption. Surface platforms of nanopatterned CMPS nanopillars were fabricated within a resistive thin film of octadecyltrichlorosilane (OTS) to spatially direct and pattern the addition of 5,10,15,20-Tetra(4-pyridyl)porphyrin. The generation of CMPS-porphyrin heterostructures was studied ex-situ and confirmed by statistically significant changes in nanostructure height before and after the porphyrin addition. The fabrication of CMPS-porphyrin heterostructures from morphologically diverse CMPS nanopillar foundations was studied to provide insight into the mechanisms of CMPS nanopillar self-assembly. The morphology of final stage heterostructures closely resembled the original morphology of the CMPs nanopillars with little evidence of non-specific adsorption across the OTS thin film resist. Particle lithography was used to fabricate silicon porphyrin nanostructures on surfaces of Si(111) via a porphyrin-silane coupling reaction. Previous steps for nanopatterning porphyrin on a surface included an additional step to of an organosilane linker molecular that the porphyrin molecules could bind and assembly from. This new protocol coordinates a silane to each porphyrin macrocycle though a simple single vessel reaction system developed by Kurihara et al.1 Through this coupling reaction porphyrins can be directly assembled on surfaces of silicon and glass. Porphyrin nanostructures of nanoholes, nanorings and nanopillars as well as porphyrin thin films were generated using this technique
The obsolescence of patent proxies as country and firm innovation measures
Strategic practitioners and business scholars continuously analyze and study competitive advantage through innovation, seeking measurements that provide evidence of cause and effect. As a policy matter and academic matter, the impact of intellectual property rights on innovation is still debated. Despite the argument from authority via some bureaus, institutions and vested interests, who do emphasize some empirical studies, the matter remains unsettled. This would appear perplexing considering the volumes of scholarship surrounding this topic. This dissertation encourages a stepping back and, via refreshed considerations of classical and contemporary international business literature, a baselining of the analysis. A means to balance the holistic with the detailed is necessary; innovation proxies, such as R&D spending or patent activity, are suspect given the fluid nature of innovation. Offering an enhancement to the value chain paradigm, a means to assess innovation as comparative advantage demands respect to the holistic activities of firms and country institutions. Property rights are often employed to show economic growth and innovation; however, property rights require parsing to determine if physical property rights alone are an impetus to innovation without reliance on intellectual property rights. The usage of patent as innovation proxy is challenged in this thesis. Thus, the argument is constructed by viewing multiple, theoretical drivers that effect the firm as well as country-specific institutions. The results indicate that patent protection is not correlated with macro-level views of innovation, and it is not an appropriate proxy for innovation unless confined in the narrowest of scenarios. (Author abstract)Chambers, J.G. (2016). The obsolescence of patent proxies as country and firm innovation measures. Retrieved from http://academicarchive.snhu.eduDoctor of Philosophy (Ph.D.)International BusinessSchool of Busines
A Mid-Infrared Census of Star Formation Activity in Bolocam Galactic Plane Survey Sources
We present the results of a search for mid-infrared signs of star formation
activity in the 1.1 mm sources in the Bolocam Galactic Plane Survey (BGPS). We
have correlated the BGPS catalog with available mid-IR Galactic plane catalogs
based on the Spitzer Space Telescope GLIMPSE legacy survey and the Midcourse
Space Experiment (MSX) Galactic plane survey. We find that 44% (3,712 of 8,358)
of the BGPS sources contain at least one mid-IR source, including 2,457 of
5,067 (49%) within the area where all surveys overlap (10 deg < l < 65 deg).
Accounting for chance alignments between the BGPS and mid-IR sources, we
conservatively estimate that 20% of the BPGS sources within the area where all
surveys overlap show signs of active star formation. We separate the BGPS
sources into four groups based on their probability of star formation activity.
Extended Green Objects (EGOs) and Red MSX Sources (RMS) make up the highest
probability group, while the lowest probability group is comprised of
"starless" BGPS sources which were not matched to any mid-IR sources. The mean
1.1 mm flux of each group increases with increasing probability of active star
formation. We also find that the "starless" BGPS sources are the most compact,
while the sources with the highest probability of star formation activity are
on average more extended with large skirts of emission. A subsample of 280 BGPS
sources with known distances demonstrates that mass and mean H_2 column density
also increase with probability of star formation activity.Comment: 20 pages, 12 figures, 3 tables. Accepted for publication in ApJ. Full
Table 2 will be available online through Ap
Student Composers Concert
Kennesaw State University School of Music presents the 2013 Student Composers Concert featuring Premieres of Newly Composed Works.https://digitalcommons.kennesaw.edu/musicprograms/1348/thumbnail.jp
The Role of MMP7 and Its Cross-Talk with the FAS/FASL System during the Acquisition of Chemoresistance to Oxaliplatin
Background: The efficacy of oxaliplatin in cancer chemotherapy is limited by the development of drug resistance. MMP7 has been related to the loss of tumor cell response to cytotoxic agents although the exact mechanism is not fully understood. Moreover, MMP7 is an independent prognosis factor for survival in patients with colorectal cancer. The aim of the present study was to analyze the role of MMP7 and its cross-talk with the Fas/FasL system during the acquisition of oxaliplatin resistance in colon cancer cells. Principal Findings: For this purpose we have developed three different oxaliplatin-resistant cell lines (RHT29, RHCT116 p53+/+, RHCT116 p53−/−) from the parental HT29, HCT116 p53+/+ and HCT116 p53−/− colon cancer cells. MMP7 basal expression was higher in the resistant compared to the parental cell lines. MMP7 was also upregulated by oxaliplatin in both HT29 (p53 mutant) and RHCT116 p53−/− but not in the RHCT116 p53+/+. Inhibition of MMP by 1,10-phenantroline monohydrate or siRNA of MMP7 restores cell sensitivity to oxaliplatin-induced apoptosis in both HT29 and RHCT116 p53−/− but not in the RHCT116 p53+/+. Some of these effects are caused by alterations in Fas receptor. Fas is upregulated by oxaliplatin in colon cancer cells, however the RHT29 cells treated with oxaliplatin showed a 3.8-fold lower Fas expression at the cell surface than the HT29 cells. Decrease of Fas at the plasma membrane seems to be caused by MMP7 since its inhibition restores Fas levels. Moreover, functional analysis of Fas demonstrates that this receptor was less potent in inducing apoptosis in RHT29 cells and that its activation induces MAPK signaling in resistant cells. Conclusions: Taking together, these results suggest that MMP7 is related to the acquisition of oxaliplatin-resistance and that its inhibition restores drug sensitivity by increasing Fas receptor. Furthermore, Fas undergoes a change in its functionality in oxaliplatin-resistant cells inducing survival pathways instead of apoptotic signals
Editorial for the special issue: vulnerability to natural hazards—the challenge of integration
Cancer Cell Invasion Is Enhanced by Applied Mechanical Stimulation
Metastatic cells migrate from the site of the primary tumor, through the stroma, into the blood and lymphatic vessels, finally colonizing various other tissues to form secondary tumors. Numerous studies have been done to identify the stimuli that drive the metastatic cascade. This has led to the identification of multiple biochemical signals that promote metastasis. However, information on the role of mechanical factors in cancer metastasis has been limited to the affect of compliance. Interestingly, the tumor microenvironment is rich in many cell types including highly contractile cells that are responsible for extensive remodeling and production of the dense extracellular matrix surrounding the cancerous tissue. We hypothesize that the mechanical forces produced by remodeling activities of cells in the tumor microenvironment contribute to the invasion efficiency of metastatic cells. We have discovered a significant difference in the extent of invasion in mechanically stimulated verses non-stimulated cell culture environments. Furthermore, this mechanically enhanced invasion is dependent upon substrate protein composition, and influenced by topography. Finally, we have found that the protein cofilin is needed to sense the mechanical stimuli that enhances invasion. We conclude that other types of mechanical signals in the tumor microenvironment, besides the rigidity, can enhance the invasive abilities of cancer cells in vitro. We further propose that in vivo, non-cancerous cells located within the tumor micro-environment may be capable of providing the necessary mechanical stimulus during the remodeling of the extracellular matrix surrounding the tumor
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