Despite the widespread assumption that students require scaffolding support for self-regulated learning (SRL) processes in computer-based learning environments (CBLEs), there is little clarity as to which types of scaffolds are most effective. This study offers a literature review covering the various scaffolds that support SRL processes in the domain of science education. Effective scaffolds are categorized and discussed according to the different areas and phases of SRL. The results reveal that most studies on scaffolding processes focus on cognition, whereas few focus on the non-cognitive areas of SRL. In the field of cognition, prompts appear to be the most effective scaffolds, especially for processes during the control phase. This review also shows that studies have paid little attention to scaffold designs, learner characteristics, or various task characteristics, despite the fact that these variables have been found to have a significant influence. We conclude with the implications of our results on future design and research in the field of SRL using CBLEs. © 2012 Wiley Periodicals, Inc.

Several studies have noted a relationship between vegetation type and fire frequency, yet despite the importance of ecosystem processes such as fire the long-term relationships between disturbance, climate and vegetation type are incompletely understood. We analysed pollen, plant macrofossils and sedimentary charcoal from three lakes within the Kenai lowlands to determine postglacial relationships between disturbance, climate and vegetation for the Boreal forest of southwest Alaska. An herb tundra was established in the lowlands following deglaciation by 13 000 cal. BP. Salix, Alnus and probably Betula kenaica, expanded in the area after 10 700 cal. BP, followed by Picea glauca by 8500 cal. BP. Picea mariana became established by 4600 cal. BP. The early Holocene was probably the driest time during the postglacial, as determined by aquatic plant macrofossils and climate models. Lake levels reached near-modern conditions by at least 8000 cal. BP. Mean Fire Intervals (MFI) were longest during the shrub-herb tundra phase (138 +/- 65 yr), decreased after expansion of B. kenaica, Salix and Populus (77 +/- 49 yr) and Picea glauca (81 +/- 41 yr), and increased again with the arrival of P. mariana (130 +/- 66 yr). Unlike previous studies, our data demonstrate the highest fire frequencies during the early to mid-Holocene and less frequent fire during the late Holocene when P. mariana forests dominated the lowlands. Early Holocene forests of P. glauca and B. kenaica existed in summers that were longer and drier than today, while the increasingly wetter and cooler climates of the late Holocene probably hindered forest fire around Paradox Lake, perhaps because of less frequent summer drought.

The purpose of this study was to characterize circulating growth hormone-binding proteins (GHBP) and prolactin-binding proteins (PRLBP) in cattle blood plasma. In particular, the 24-hr profile of these molecules was investigated. The preincubation of bull plasma with iodinated bovine growth hormone (bGH) or bovine prolactin (bPRL), followed by gel filtration chromatography (Superdex 200; 1.6 × 60 cm column), resulted in the formation of essentially two complexes. The majority of [125I]bPRL eluted with the first one (Mr∼600 kDa), whereas [125I]bGH mainly appeared in the second one (Mr ∼70 kDa). The fractions corresponding to these two peaks were analyzed by western ligand blotting (WLB), under reducing conditions. WLB revealed, respectively, 190-, 56-, 52-, and 28-kDa bands for the first peak and only 52- and 28-kDa bands for the second one. The nature of the 600-kDa peak is at present undetermined, but the 70-kDa one was previously identified as high-affinity GHBP. Displacement studies demonstrated that bGH and bPRL were both able to bind to this GHBP, because the bGH- and bPRL-binding activities of this protein could be saturated by an excess of either of these two hormones. This was indirectly confirmed by the close correlation (r = 0.615; P = 0.0001; n = 155) observed between plasma bGH- and bPRL-binding activities, because this correlation could suggest that both ligands are bound to the same proteins. The temporal concentrations of plasma GHBP were measured in samples collected at 20-min intervals for 24 hr from 8 young bulls. The evaluation of GHBP was realized by WLB, followed by densitometric analysis. Some fluctuations were observed, but these were not correlated with bGH release, even with a ±2-hr lag period. In summary, we found that bovine high-affinity GBHP binds not only bGH, but also bPRL. A second type of protein, of higher molecular weight, also binds these two hormones, but further investigations are needed to determine its nature. Finally, GHBP concentrations in cattle blood plasma apparently show fluctuations over a 24-hr period, but no correlation was found between these fluctuations and plasma growth hormone concentrations.

It is well known that sensory deprivations could cause plastic changes in neural populations involved in sensory processing [1-7]. Positron emission tomography (PET) has recently been used for physiological and biochemical measurements in different brain areas [8, 9]. Using PET, Wanet-Defalque [8] has demonstrated a higher glucose metabolism rate in the occipital cortex in human subjects who became blind early in life. It seems interesting to know whether the same high brain activity exists in the auditory cortex of deaf patients. We would like to present the metabolic activity in the brain, as measured by PET, in human subjects with either early or adult loss of hearing compared to controls with normal hearing.

Growth-promoters are banned by the European Community, but different hormonal cocktails are still illegally used. This experiment was therefore conducted to evaluate the effects of one of the most currently used cocktails on some hormonal parameters and spermatogenesis in finishing bulls in an attempt to provide a suitable screening technique for their illegal use. Sixteen double-muscled Belgain White Blue finishing bulls (mean weight: 535 (s.d. 37) kg) were blocked into control (C; no. = 7) and treated (Dex; no. = 9) groups. Animals were treated i.m. with the hormonal preparation (dexamethasone isonicotinate and phosphate, chlormadinone acetate and ethinyl oestradiol) on day 0, day 15 and day 30. Animals were slaughtered on day 45. Three h before each treatment and just prior to slaughter, jugular blood samples were collected to monitor the testosterone (T) response to an i.v. injection of gonadotropin releasing hormone (GnRH) (0.5 mug GnRH per kg body weight). Testicular tissue was also collected at slaughter. Plasma T and insulin-like growth factor-1 (IGF-1) concentrations were measured by radioimmunoassay. IGF-binding proteins (IGFBPs) were evaluated using Western ligand blotting. Daily weight gains were lower in the control group (1.29 (s.d. 0.13) kg for C v. 1.60 (s.d. 0.39) kg for Dex) but the difference was not significant. After treatment, spermatogonia, spermatocytes, spermatids and spermatozoa disappeared from the testis and seminiferous tubules consisted only of Sertoli cells; these observations suggest that treated animals were sterile. Moreover, plasma T concentrations in response to GnRH stimulation were suppressed (P < 0.001) in the Dex group between day 15 and day 45 (mean maximal responses: 5.4 to 7.9 mug/l in C group v. < 0.2 mug/l in Dex group at day 15, 30 and 45). Treatment did not show any prominent effect on plasma IGF-1 levels but increased IGFBP-3 band intensity. In conclusion, treatment with a cocktail containing dexamethasone esters, chlormadinone acetate and ethinyl oestradiol for a short period induced a number of changes in finishing bulls which might be possible to develop as a screening method for the identification of illegally treated animals.

The objectives of the present study were (1) to reveal GH-TaqI RFLPs in different bovine breeds and (2) to look for association between quantitative traits and GH-TaqI RFLPs in bulls highly selected for growth and meat production. Blood was sampled from 269 Holstein heifers, 48 Italian and 45 Hungarian Simmental heifers, 30 Normande heifers and 41 bulls and 13 heifers of the double-muscled Belgian White Blue breed. Bulls were weighed from 7 until 13 months of age and the average daily gain, the feed efficiency, the height and the phenotypic index were determined at the end of the experiment. GH-TaqI RFLPs revealed 4 DNA fragments of 6 (A), 5.2 (B), 4.4 (C) and 4.2 (D) kbp. The distribution of genotypes was different between Normande and the other breeds (P < 0.001) and between Belgian White Blue and Holstein (P < 0.001) or Hungarian Simmental breed (P < 0.005). The Normande heifers were also characterized by a high frequency of the AB genotype (53%) compared with other experimental breeds (range values: 7-24%). In the statistical analysis of the relationships between quantitative traits and GH-TaqI RFLPs in double-muscled Belgian White Blue bulls, the AC genotypic class was not used because of its low distribution. The AA class showed greater records of weight at 7 (P < 0.07) and 13 (P < 0.06) months of age than the AB class. In conclusion, this study has shown a correlation between the GH-TaqI RFLPs and weight at 7 and 13 months of age in Belgian White Blue bulls.(ABSTRACT TRUNCATED AT 250 WORDS)

The presence of GH-binding proteins (GHBPs) in the plasma of adult cattle was investigated using Sephadex G-200 filtration, Western ligand blotting and Western blotting. The changes in the concentration of GHBP in the plasma of dairy half-sister heifers during the first year of life as well as the presence of GHBP in milk were also investigated. When analytical chromatography (on a 1.6 x 100 cm column) was performed, five peaks of recombinant bovine GH (rbGH)-associated radioactivity were revealed in cattle plasma; the first peak, which appeared near the void volume, was presumed to represent aggregates, the second (M(r) 290 kDa) and the third peaks (M(r) 75 kDa) corresponded to specific rbGH-GHBP complexes; the last two peaks representing free 125I-labelled rbGH and Na[125I]. Western ligand blotting revealed multiple GHBPs. Three major bands were observed at approximately 190, 58 and 31 kDa; an excess of unlabelled hormone blocked the binding of 125I-labelled rbGH. Minor non-specific binding bands were also detected in cattle plasma with molecular weights between 40 and 136 kDa. One monoclonal antibody (8H7) produced against synthetic peptide (amino acids 54-63 of the extracellular domain of the bovine GH receptor) specifically interacted with 190 and 58 kDa bands while the 31 kDa band was not recognized. Finally, Western ligand blots were performed to evaluate the changes in plasma GHBP during the first year of life in 55 dairy half-sister heifers and to identify GHBP in milk. In plasma, the intensity of the 31 kDa band varied greatly between animals while the other specific bands remained stable.(ABSTRACT TRUNCATED AT 250 WORDS)

The objectives of this study were to determine the extent of changes in concentrations of testosterone, growth hormone (GH) and insulin-like growth factor I (IGF-I) concentrations in blood plasma and to characterize the respective plasma-binding proteins of these two peptides during the onset of puberty in male calves. The jugular veins of six male Holstein calves (11-weeks-old) were catheterized and blood was collected every 3 days (one sample every 30 min for 8 h). Hormone concentrations in plasma were determined by specific radioimmunoassay. After incubation with [125I]IGF-I, IGF-I-binding proteins (IGFBPs) were separated by gel filtration; radioactivity was determined in each fraction. Western ligand blotting using radiolabelled hormones as ligand was also used to characterize the IGF-I- and GH-binding proteins in plasma. Puberty was characterized by a rapid (in 1 or 2 days) increase in mean concentrations of testosterone in plasma (from 0.5 to > 2 ng ml-1) and a pulsatile release of the hormone. During puberty, IGF-I concentrations also increased rapidly in 8-10 days from +/- 50 ng ml-1 to > 150 ng ml-1, whereas concentrations of GH in plasma remained relatively stable during the experimental period. A significant correlation was observed between IGF-I and testosterone concentrations (r = 0.77; P < 0.001) throughout the experimental period. Three different IGF-I-binding protein fractions with apparent molecular masses of > 200, 150-170 and 45-65 kDa were found in plasma using gel filtration.(ABSTRACT TRUNCATED AT 250 WORDS)

Glucose metabolism has been studied in the auditory cortex of human subjects with deafness of early onset, and compared to normal subjects with ears plugged. The metabolism in the auditory cortex and in the association auditory cortex was higher in deaf subjects than in normal subjects. This result is compared to similar observations that we made previously in the visual cortex of human subjects with blindness of early onset.

Glucose metabolism has been studied in the visual cortex of early blind human subjects. In the forebrain of these subjects, regional glucose utilization was the highest in the striate and prestriate cortical areas. Furthermore, this activity was higher than in blindfolded sighted subjects, whether at rest or during an auditory or tactile task. These observations raise the question of the functionality of the blind's visual cortex.