Ten Years of Research on Corrective Reading Programs: A Review of the Literature

The purpose of this paper is to survey the research of the past ten years on corrective or remedial reading programs. In the literature, various definitions are given to corrective reading and remedial reading programs, but in this paper no distinction will be made between the two terms. Both terms refer to a plan of corrective instruction and treatment for the disabled reader, generally outside of the regular classroom setting

Copepods in Fram Strait in summer: Distribution, feeding and metabolism

A summer study of zooplankton in the Fram Strait area of the Greenland Sea showed elevated abundances of herbivorous copepods in the marginal ice zone or ice-edge compared with copepod communities under the pack ice cover. Several physical factors contributed to this, including the large-scale current systems which deliver both North Atlantic and Arctic plankton to the ice-edge and the effect of melting ice and eddies in increasing primary productivity and standing stocks of phytoplankton. The potential importance of the ice-edge in secondary production was observed directly as increased numbers of juvenile copepods. Indirectly, it can be inferred from observations that copepods under ice-cover were ingesting only enough to meet daily metabolic demands, were metabolizing protein, and were not storing lipid. Copepods were not undertaking diel vertical migration. Abundances of female copepods at the ice-edge were largely a function of currents, while growth of juveniles was dependent on food supply which even at the ice-edge fell short of the calculated requirements of the dominant copepods

Spatial and temporal effects of salinity, temperature and chlorophyll on the communities of zooplankton in the southeastern Bering Sea

Analyses of 402 samples collected from late March through early June in 1980 have shown that the two communities of zooplankton over the southeastern shelf of the Bering Sea are kept separate spatially by the lack of advection and frontal characteristics of the salinity distributions. The abundance of copepods over the middle shelf, between 50 and 100 m isobaths approximately, was highly correlated with seasonal warming of the surface layer, while abundances of copepods over the outer shelf and slope were not. The spring bloom of phytoplankton influenced abundances over the middle shelf more profoundly than the outer shelf; of the twelve taxa which composed most of the biomass of copepods over the middle shelf, eleven were significantly more abundant during the bloom than they were prior to the bloom. Over the outer shelf, only six of eighteen taxa were significantly more abundant during the bloom, and over the slope, three of eighteen. Differences in abundance of copepods between domains and among stations within each domain were greatest early in the study. During the study, stations of each domain became more similar in the abundance of their characteristic taxa

Androhermaphrodites of Lychnis Alba

Lychnis alba was found to produce four categories of flowers; i.e. pistillate, staminate, gynohermaphrodite and androhermaphrodite. Hermaphrodites are formed when a rudimentary pistil (pistillodium) or stamens (staminodea) develop into mature organs on the ovaries of otherwise pistillate or staminate flowers. Androhermaphrodites, in particular, were studied and their structure and behavior found to be essentially similar to corresponding parts of regular staminate and pistillate flowers. Ovaries of androhermaphrodite flowers exhibited variations in style number ranging from one to five. Ovaries with two to five styles were self- or cross-fertile with any good Lychnis alba pollen. One-styled ovaries of androhermaphrodite flowers were of unusual interest because they occurred so commonly, showed a range of development from a pistillodium to a mature ovary, and because they were characteristically self- and cross-sterile

Biological observations in the marginal ice zone of the East Greenland Sea

The distribution of nutrients, phytoplankton and zooplankton was investigated during summer, 1983 in the marginal ice zone of the East Greenland Sea. Nutrient levels, especially inorganic nitrogen, were extremely low, and probably limited the growth of phytoplankton during this period. An ammonium maximum at the base of the euphotic zone, generally around 50 m, was found repeatedly and appeared to be controlled by active nitrogen regeneration and decreased ammonium uptake at low light levels. Chlorophyll a levels were elevated at the ice-edge, but were even higher in an area influenced by an eddy. Species of zooplankton were accurate indicators of the origin of the two major water masses in this area, and zooplanktonic biomass was similar to other polar regions. Calculations of their impact on phytoplankton distributions indicated that grazing losses resulting from ingestion by large copepads may have been small. The dynamics associated with mesoscale eddies appear to be important in introducing new nitrogen into the euphotic zone and structuring the distribution of plant biomass at the ice-edge of the East Greenland Sea

Simulating Active Layer Thaw in a Boreal Environment

A large part of the boreal zone of the western Canadian Arctic is underlain by ice-rich discontinuous permafrost which when thawed, can lead to settlement of the ground surface that has implications for the integrity of northern infrastructure, including oil and gas pipelines. A simple yet physically-based model is desired to simulate thawing of the active layer in different materials commonly found along the Mackenzie Valley pipeline corridor. Stefan’s algorithm determines the phase change of soil moisture using ground surface temperature as the upper boundary condition and conduction to transfer heat to the freeze-thaw front. It is tested on a permafrost site near Wrigley, Northwest Territories, where the computed thaw penetration compares satisfactorily with field data. To further explore the effects of climate and soil types on active layer depth, three representative sites in the Mackenzie valley where ground surface temperatures are available were selected for simulation of ground thaw, under two summer conditions. Results of the simulation demonstrate the sensitivity of active layer thaw to (1) soil materials due to differential thermal properties, (2) moisture content, which largely controls the latent heat requirement for phase change, and (3) inter-annual variations in ground surface temperature. Given the strong potential for environmental changes in the vast boreal region, the model allows the active layer thaw responses to be easily assessed.Simulation de la couche active de dégel d’un environnement boréal. Une vaste partie de la zone boréale de l’Arctique canadien occidental repose sur un pergélisol discontinu riche en glace qui, en dégelant, peut causer des problèmes de surface du sol pouvant compromettre l’intégrité des structures nordiques, dont les pipelines de pétrole et de gaz. Un modèle physique simple est nécessaire pour la simulation du dégel de la couche active des divers dépôts meubles trouvés le long du corridor du pipeline de la vallée du Mackenzie. L’algorithme de Stefan détermine la phase du changement d’humidité du sol en utilisant la température de surface comme la condition limite supérieure, et la conduction au transfert de la chaleur jusqu’au front de gel-dégel. Cet algorithme est appliqué à un site de pergélisol près de Wrigley, Territoires-du-Nord-Ouest, où la simulation de la profondeur de dégel se compare bien aux données de terrain. Afin d’explorer plus encore les effets du climat et du type de sol sur la profondeur de la couche active, trois sites représentatifs de la vallée du Mackenzie, où les températures de la surface du sol sont disponibles, ont été sélectionnés pour une simulation de dégel du sol, selon deux conditions estivales. Les résultats de la simulation montrent la sensibilité de la couche active de dégel (1) aux propriétés thermiques différentielles des matériaux du sol, (2) au contenu en humidité, qui contrôle la chaleur latente provoquant le changement de phase, et (3) aux variations interannuelles des températures de la surface du sol. En raison du fort potentiel de changements environnementaux dans la vaste région boréale, le modèle permet d’évaluer aisément le dégel de la couche active qui en constitue une réaction

The impacts of oil palm on recent deforestation and biodiversity loss

Palm oil is the most widely traded vegetable oil globally, with demand projected to increase substantially in the future. Almost all oil palm grows in areas that were once tropical moist forests, some of them quite recently. The conversion to date, and future expansion, threatens biodiversity and increases greenhouse gas emissions. Today, consumer pressure is pushing companies toward deforestation-free sources of palm oil. To guide interventions aimed at reducing tropical deforestation due to oil palm, we analysed recent expansions and modelled likely future ones. We assessed sample areas to find where oil palm plantations have recently replaced forests in 20 countries, using a combination of high-resolution imagery from Google Earth and Landsat. We then compared these trends to countrywide trends in FAO data for oil palm planted area. Finally, we assessed which forests have high agricultural suitability for future oil palm development, which we refer to as vulnerable forests, and identified critical areas for biodiversity that oil palm expansion threatens. Our analysis reveals regional trends in deforestation associated with oil palm agriculture. In Southeast Asia, 45% of sampled oil palm plantations came from areas that were forests in 1989. For South America, the percentage was 31%. By contrast, in Mesoamerica and Africa, we observed only 2% and 7% of oil palm plantations coming from areas that were forest in 1989. The largest areas of vulnerable forest are in Africa and South America. Vulnerable forests in all four regions of production contain globally high concentrations of mammal and bird species at risk of extinction. However, priority areas for biodiversity conservation differ based on taxa and criteria used. Government regulation and voluntary market interventions can help incentivize the expansion of oil palm plantations in ways that protect biodiversity-rich ecosystems

Substrate Stiffness Controls Osteoblastic and Chondrocytic Differentiation of Mesenchymal Stem Cells without Exogenous Stimuli

Stem cell fate has been linked to the mechanical properties of their underlying substrate, affecting mechanoreceptors and ultimately leading to downstream biological response. Studies have used polymers to mimic the stiffness of extracellular matrix as well as of individual tissues and shown mesenchymal stem cells (MSCs) could be directed along specific lineages. In this study, we examined the role of stiffness in MSC differentiation to two closely related cell phenotypes: osteoblast and chondrocyte. We prepared four methyl acrylate/methyl methacrylate (MA/MMA) polymer surfaces with elastic moduli ranging from 0.1 MPa to 310 MPa by altering monomer concentration. MSCs were cultured in media without exogenous growth factors and their biological responses were compared to committed chondrocytes and osteoblasts. Both chondrogenic and osteogenic markers were elevated when MSCs were grown on substrates with stiffnesschondrocytes, MSCs on lower stiffness substrates showed elevated expression of ACAN, SOX9, and COL2 and proteoglycan content; COMP was elevated in MSCs but reduced in chondrocytes. Substrate stiffness altered levels of RUNX2 mRNA, alkaline phosphatase specific activity, osteocalcin, and osteoprotegerin in osteoblasts, decreasing levels on the least stiff substrate. Expression of integrin subunits α1, α2, α5, αv, β1, and β3 changed in a stiffness- and cell type-dependent manner. Silencing of integrin subunit beta 1 (ITGB1) in MSCs abolished both osteoblastic and chondrogenic differentiation in response to substrate stiffness. Our results suggest that substrate stiffness is an important mediator of osteoblastic and chondrogenic differentiation, and integrin β1 plays a pivotal role in this process

Compromised vertebral structural and mechanical properties associated with progressive kidney disease and the effects of traditional pharmacological interventions

BACKGROUND/AIMS: Patients with chronic kidney disease mineral and bone disorder (CKD-MBD) have a significantly higher vertebral and non-vertebral fracture risk than the general population. Several preclinical models have documented altered skeletal properties in long bones, but few data exist for vertebral bone. The goal of this study was to examine the effects of progressive CKD on vertebral bone structure and mechanics and to determine the effects of treatment with either bisphosphonates or anti-sclerostin antibody in groups of animals with high or low PTH. METHODS: Animals with progressive kidney disease were left untreated, treated with calcium to lower PTH, zoledronic acid to lower remodeling without affecting PTH, anti-sclerostin antibody, or anti-sclerostin antibody plus calcium. Non-diseased, untreated littermates served as controls. Vertebral bone morphology (trabecular and cortical) and mechanical properties (structural and material-level) were assessed at 35 weeks of age by microCT and mechanical testing, respectively. RESULTS: CKD with high PTH resulted in 6-fold higher bone formation rate, significant reductions in the amount of trabecular and cortical bone, and compromised whole bone mechanical properties in the vertebra compared to normal animals. Treatments that reduced bone remodeling were effective in normalizing vertebral structure and mechanical properties only if the treatment reduced serum PTH. Similarly, treatment with anti-sclerostin antibody was effective in enhancing bone mass and mechanical properties but only if combined with PTH-suppressive treatment. CONCLUSIONS: CKD significantly altered both cortical and trabecular bone properties in the vertebra resulting in compromised mechanical properties and these changes can be normalized by interventions that involve reductions in PTH levels