From Stem Cells to Bone-Forming Cells

Bone formation starts near the end of the embryonic stage of development and continues throughout life during bone modeling and growth, remodeling, and when needed, regeneration. Bone-forming cells, traditionally termed osteoblasts, produce, assemble, and control the mineralization of the type I collagen-enriched bone matrix while participating in the regulation of other cell processes, such as osteoclastogenesis, and metabolic activities, such as phosphate homeostasis. Osteoblasts are generated by different cohorts of skeletal stem cells that arise from different embryonic specifications, which operate in the pre-natal and/or adult skeleton under the control of multiple regulators. In this review, we briefly define the cellular identity and function of osteoblasts and discuss the main populations of osteoprogenitor cells identified to date. We also provide examples of long-known and recently recognized regulatory pathways and mechanisms involved in the specification of the osteogenic lineage, as assessed by studies on mice models and human genetic skeletal diseases.     

Preface to the Special Issue on “Heterogeneous Photocatalysts: From Fundamentals to Innovative Applications”

Topics in Catalysis -     

Using context to improve the effectiveness of segmentation and targeting in e-commerce

In e-commerce, where competition is tough and customers’ preferences can change quickly, it is crucial for companies to segment customers and target marketing actions effectively. The process of segmentation and targeting is effective if the customers grouped into the same segment show the same behavior and reaction to marketing campaigns. However, the link between segmentation and targeting is often missing. Some research contributions have recently addressed this issue, by proposing approaches to build customer behavior models in each segment. However customers’ behavior can change with the context, such as in many e-commerce business applications. In these cases, building contextual models of behavior would provide better predictive performance and, in turn, better targeting. However, the problem of including context in a segmentation model and building predictive behavior model of each segment consistently is still an open issue. This research aims at providing an answer to the following research issue: how to include context in a segmentation model in order to build an effective predictive model of customer behavior of each segment. To this aim we identified three different approaches and compared them by a set of experiments across several settings. The first result is that one of the three approaches dominates the others in certain conditions in our experiments. Another important result is that the most accurate approach is not always the most efficient from a managerial perspective.     

Guidelines and recommendations for indoor use of fuel cells and hydrogen systems

Hydrogen energy applications often require that systems are used indoors (e.g., industrial trucks for materials handling in a warehouse facility, fuel cells located in a room, or hydrogen stored and distributed from a gas cabinet). It may also be necessary or desirable to locate some hydrogen system components/equipment inside indoor or outdoor enclosures for security or safety reasons, to isolate them from the end-user and the public, or from weather conditions.Using of hydrogen in confined environments requires detailed assessments of hazards and associated risks, including potential risk prevention and mitigation features. The release of hydrogen can potentially lead to the accumulation of hydrogen and the formation of a flammable hydrogen-air mixture, or can result in jet-fires. Within Hyindoor European Project, carried out for the EU Fuel Cells and Hydrogen Joint Undertaking safety design guidelines and engineering tools have been developed to prevent and mitigate hazardous consequences of hydrogen release in confined environments. Three main areas are considered: Hydrogen release conditions and accumulation, vented deflagrations, jet fires and including under-ventilated flame regimes (e.g., extinguishment or oscillating flames and steady burns). Potential RCS recommendations are also identified.     

New Insights into the Decisional Use of Process Capability Indices via Hypothesis Testing

Process capability indices C_p, C_pk, and C_pm are still nowadays widely used in industry—thanks to their easy formulation and implementation. This paper aims to give new mathematical insights in order to support their use in decision‐making via hypothesis testing. The minimum sample size usually needed in the applications to achieve fixed significance level and power is reported in light of the new mathematical aspects for C_pk and C_pm, which avoid misleading conclusions and the use of extensive numerical experiments. In addition, power curves for C_pk and C_pm, which have not previously appeared in the literature before, are also presented. Lastly, easy‐to‐follow diagrams for hypothesis testing with C_pk and C_pm and two critical scenarios for C_pm are included in the paper to facilitate the applicative use and the comprehension of the novel inferential aspects. Copyright © 2014 John Wiley & Sons, Ltd.     

Tract‐tracing study of the extrabulbar Olfactory projections in the brain of some teleosts

The extrabulbar olfactory projections (EBOP) is a collection of nerve fibers that originate from primary olfactory receptor neurons. These fibers penetrate into the brain, bypassing the olfactory bulbs (OBs). While the presence of an EBOP has been well established in teleosts, here we morphologically characterize the EBOP structure in four species each with a different morphological relationship of OB with the ventral telencephalic area. Tract‐tracing methods (carbocyanine DiI/DIA and biocytin) were used. FMRFamide immunoreactive nervus terminalis (NT) components were also visualized to define any neuroanatomical relationship between the NT and EBOP. Unilateral DiI/DiA application to the olfactory chamber stained the entire olfactory epithelium, olfactory nerve fibers, and ipsilateral olfactory bulb. Labeled primary olfactory fibers running ventromedially as extrabulbar primary olfactory projections reached various regions of the secondary prosencephalon. Only in Moenkhausia sanctaefilomenae (no olfactory peduncle) did lipophilic tracer‐labeled fibers reach the ipsilateral mesencephalon. The combination of tracing techniques and FMRFamide immunohistochemistry revealed a substantial overlap of the label along the olfactory pathways as well as in the anterior secondary prosencephalon. However, FMRFamide immunoreactivity was never colocalized in the same cellular or fiber component as visualized using tracer molecules. Our results showed a certain uniformity in the neuroanatomy and extension of EBOP in all four species, independent of the pedunculate feature of the OBs. The present study also provided additional evidence to support the view that EBOP and FMRFamide immunoreactive components of the NT are separate anatomical entities. Microsc. Res. Tech. 78:268–276, 2015. © 2015 Wiley Periodicals, Inc.     

Approximate Analytic Estimate of Axial Fluid Conduction in Laminar Forced Convection Tube Flows with Zero-to-Uniform Step Wall Heat Fluxes

The influence of axial fluid conduction on low Péclet number flows in the thermal entrance region of long circular tubes is investigated in this theoretical study. The convective heat transport of viscous fluids relates to a specific condition under which the first part of the tube ( x h 0) is insulated and the second part of the tube ( x > 0) receives a heat flux of uniform intensity. A conjugate one-dimensional lumped model produces a solution of compressed algebraic form that is able to deliver dependable mean bulk temperatures that are in perfect agreement with those obtained numerically by the formal conjugate two-dimensional distributed model. As a by-product of the succession of algebraic calculations within the platform of the lumped model, the critical Péclet number Pe cr has been easily quantified. This number is a figure-of-merit of remarkable importance in the modeling of forced heat convection in tubes because it establishes the threshold between two contrasting situations: one embracing axial fluid conduction (finite Pe) and the other implicating negligible axial fluid conduction (Pe M X ). In addition, the local wall temperatures were calculated with an approximate engineering procedure, showing good agreement with those determined numerically by the formal conjugate two-dimensional distributed model.     

Waste‐Free Electrochemical Oxidation of Alcohols in Water

We describe a new sol‐gel molecular electrode made of a thin layer of organosilica doped with the nitroxyl radical TEMPO (2,2,6,6‐tetramethylpiperidine‐1‐oxyl) electrodeposited on the surface of an ITO‐coated glass and its employment as a selective and versatile oxidation catalyst in the electrochemical conversion of different alcohols to carbonyl compounds. Environmentally friendly water or a water/acetonitrile mixture buffered with bicarbonate is used as solvent. The electrode is highly stable and it can be reused for a prolonged period of time allowing easy separation from the products.     

Effects of scenery, lighting, glideslope, and experience on timing the landing flare.

This study examined three visual strategies for timing the initiation of the landing flare based on perceptions of either: (a) a critical height above ground level; (b) a critical runway width angle (Ψ); or (c) a critical time-to-contact (TTC) with the runway. Visual displays simulated landing approaches with trial-to-trial variations in glideslope, lighting, and scene detail. Twenty-four participants (8 private pilots, 8 student pilots, and 8 nonpilots) were instructed to initiate the flare when they perceived that their TTC with the runway (30 m wide by 840 m long) had reached a critical value of 2 seconds. Our results demonstrated a significant effect of flight experience on flare timing accuracy and dominance of the height-based strategy over the runway-width-angle and TTC-based strategies. (PsycINFO Database Record (c) 2010 APA, all rights reserved)