Multiage Classrooms: A New Way to Learn Math

Recent research supports Vygotsky\u27s zone of proximal development theory; children receiving peer assistance can stretch their learning beyond their individual accomplishment. A study of a multiage classroom revealed three strategies used by children working together to solve math problems--modeling, tutoring, and pairing/sharing activities. The multiage setting invites collaboration and sharing, while helping students meet mathematics learning standards. (MLH

Impact des terrils houillers sur la qualité des eaux souterraines (bassin minier Nord-Pas-de-Calais, France) : approche géochimique et isotopique

L'exploitation du charbon dans le Nord-Pas-de-Calais (France) a engendré le dépôt d'importantes quantités de résidus miniers sous forme de terrils, essentiellement constitués de schistes houillers. Le lessivage de ces stériles par les eaux météoriques et l'oxydation des sulfures de fer contenus sont susceptibles de contribuer à l'enrichissement en sulfates et métaux associés de l'aquifère de la craie, principale ressource en eau de la région. Des analyses chimiques et isotopiques (S & C) ont été effectuées sur des prélèvements d'eau en amont et en aval hydraulique des sites d'étude ainsi que sur la fraction minérale des terrils. Afin de déterminer les modalités d'infiltration des eaux météoriques au sein des terrils, des prospections radio-magnétotelluriques, couplées à des mesures de perméabilité et de granularité ont été effectuées. Les analyses ont permis de mettre en évidence que le lessivage des terrils entraîne un flux d'ions sulfate et de carbone vers l'aquifère de la craie. L'approche géophysique a permis de mettre en évidence un phénomène d'infiltration des eaux météoriques. Elle a montré en outre l'existence de barrières de perméabilité en profondeur. Il apparaît donc que les eaux météoriques, lorsqu'elles s'infiltrent dans le terril, ne peuvent pénétrer à plus de quelques mètres de profondeur. L'existence de zones imperméables, en limitant l'infiltration des eaux en profondeur, limite également la quantité de sulfure potentiellement oxydable et donc la quantité de sulfates entraînée vers l'aquifère de la craie.In the Nord-Pas-de-Calais region (France), coal mining activity has induced a build-up of many mine tips. The tip materials are dominantly composed of siltstones, locally rich in iron sulfide. Weathering of pyrite might be expected to release sulfate ions and associated metals within the run-off waters down to the underlying aquifer, which is composed of a thick Cretaceous chalk formation. The objectives of this study were twofold: (1) to determine the possible role of the mine tips in the sulfate mineralization of the chalk aquifer and; (2) to assess the amount of waste material that can be leached and may supply sulfate ions to the water table.Two sites were selected for this study. Site 1 rests directly on the Senonian-Turonian chalk, whereas site 2 lies on sandy-clayey Cenozoic formations overlying the chalk formations (Figs. 1-2). Water samples were collected within the chalk aquifer (Fig. 3), which represents a free water table except for where the almost impermeable Cenozoic formations confine this table (site 2). Rock samples were collected at the surface and at a depth of <12 m at both sites. Various analyses were performed on these samples including mineralogical analyses carried out on both the bulk fraction and the clayey fraction, as well as elementary analyses of total carbon, total sulfur and CaCO3 contents. Elemental analyses were carried out by Inductively Coupled Plasma-Atomic Emission Spectroscopy (ICP-AES: major and minor elements) or Inductively Coupled Plasma-Mass Spectrometry (ICP-MS: trace elements). Chemical and isotopic (C, S) analyses were performed on water sampled from upstream and downstream of the mine tips. In situ measurements were also carried out during sampling. Finally, to assess the degree of rainwater seeping through the coal mine tips, two radio-magnetotelluric surveys were carried out in September and November, 1999 following rainy periods. Permeability measurements and grain-size analyses of subsurface samples were also performed at site 2.The carbon and sulfur contents showed superficial leaching on the mine tips (Fig. 4). The use of sulfur isotopes as tracers of the sulfate origin allowed identification of two sources for the two sites: a "mine tip" source with a slightly negative d34 S (-2.8‰ to -3.9‰), which corresponds to the oxidation of sulfides contained by the Carboniferous shales, and another source (d34 S=-20‰) corresponding to the gypsum of the Cenozoic formations, which was only present at site 2 (Figs. 5 & 6).This study outlined different behavior for the tips of the two sites. At site 1, where there is a free water-table zone, the mine tip leachates carry sulfate ions directly to the water table, whereas in the case of a confined aquifer zone such as the one present at site 2, a proportion of the sulfate was reduced once exported to the water table (the redox potential showed negative values; Table 1). This suggestion of bacterially-mediated reduction is supported by the d34 S of the sulfate content in the water table. The bacterial activity was fueled by the organic carbon release that accompanies the sulfur leaching on the mine tips. This carbon contribution was confirmed by the 14C activity that characterized the chalk aquifer waters at the upstream region of the mine tip and noticeably decreased downstream. The decrease is a result of the supply of "dead carbon" from the mine tips (Fig. 7).The oxidation of pyrite also results in H+ production. However, the pH decrease observed downstream from the sites was very slight. Waters derived from leaching of the mine tip seeped through the buffered environment of the chalk aquifer. The distribution of metal content showed no surface to depth gradient for samples taken from both sites. The only evidence of "neutral acid mining drainage" (NAMD) was the sulfate amounts exported, and the increase in Mg, Ca, HCO3- and Sr contents observed downstream from the sites (Table 2a-b).The decrease in the apparent resistivity of radio-magnetotelluric profiles demonstrated that rain waters could deeply penetrate in some parts of the tip at site 2 (Fig. 9). Considering the constant nature of the waste material (grain size and porosity), a decrease in resistivity accompanied by an increase in conductivity between the two surveys indicated water seepage. Permeability measurements showed the occurrence of deep permeability barriers (Fig. 10), limiting not only rainwater seepage, but also the amount of mobilizable sulfide and consequently the amount of sulfates exported to the chalk aquifer. Grain size is not the only reason for the permeable or impermeable nature of waste material - the grain ordering and the compaction of levels at depth also have a role

Differing roles of autophagy in HIV-associated neurocognitive impairment and encephalitis with implications for morphine co-exposure

We investigated the role of autophagy in HIV-infected subjects with neurocognitive impairment (NCI) ± HIV encephalitis (HIVE), many of which had a history of polysubstance abuse/dependence, using post-mortem brain tissues to determine whether differences in autophagy related factors may be more associated with NCI or NCI-encephalitis. Using qRT-PCR, we detected significant differences in gene expression levels with SQSTM1, LAMP1 higher in HIV-infected subjects without NCI while ATG5, SQSTM1 were then lower in HIV infection/NCI and ATG7, SQSTM1 being higher in NCI-HIVE. Immunohistochemical labeling of these autophagy associated proteins (also including Beclin 1 and LC3B) in Iba1-positive microglial cells showed generally higher immunoreactivity in the NCI and NCI-HIVE groups with more focal vs. diffuse patterns of expression in the NCI-HIVE group. Furthermore, analysis of microarray data from these same subjects found significantly higher levels of LAMP1 in NCI-HIVE compared to uninfected subjects in the basal ganglia. Finally, we tested the effect of supernatant from HIV-1-infected microglia and HIV-1 Tat protein in combination with morphine on neurons in vitro and found opposing events with both significant inhibition of autophagic flux and reduced dendrite length for morphine and supernatant treatment while Tat and morphine exposure resulted in lower autophagic activity at an earlier time point and higher levels in the later. These results suggest autophagy genes and their corresponding proteins may be differentially regulated at the transcriptional, translational, and post-translational levels in the brain during various stages of the HIV disease and that infected individuals exposed to morphine can experience mixed signaling of autophagic activity which could lead to more severe NCI than those without opioid use

Load Magnitude and Locomotion Strategy Alters Knee Mechanics in Recruit-Aged Women

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The starch-deficient plastidic <em>PHOSPHOGLUCOMUTASE </em>mutant of the constitutive crassulacean acid metabolism (CAM) species <em>Kalancho\ueb fedtschenkoi</em> impacts diel regulation and timing of stomatal CO₂ responsiveness

\ua9 The Author(s) 2023.• Background and Aims Crassulacean acid metabolism (CAM) is a specialized type of photosynthesis characterized by a diel pattern of stomatal opening at night and closure during the day, which increases water-use efficiency. Starch degradation is a key regulator of CAM, providing phosphoenolpyruvate as a substrate in the mesophyll for nocturnal assimilation of CO2. Growing recognition of a key role for starch degradation in C3 photosynthesis guard cells for mediating daytime stomatal opening presents the possibility that starch degradation might also impact CAM by regulating the provision of energy and osmolytes to increase guard cell turgor and drive stomatal opening at night. In this study, we tested the hypothesis that the timing of diel starch turnover in CAM guard cells has been reprogrammed during evolution to enable nocturnal stomatal opening and daytime closure. • Methods Biochemical and genetic characterization of wild-type and starch-deficient RNAi lines of Kalancho\ueb fedtschenkoi with reduced activity of plastidic phosphoglucomutase (PGM) constituted a preliminary approach for the understanding of starch metabolism and its implications for stomatal regulation in CAM plants. • Key Results Starch deficiency reduced nocturnal net CO2 uptake but had negligible impact on nocturnal stomatal opening. In contrast, daytime stomatal closure was reduced in magnitude and duration in the starch-deficient rPGM RNAi lines, and their stomata were unable to remain closed in response to elevated concentrations of atmospheric CO2 administered during the day. Curtailed daytime stomatal closure was linked to higher soluble sugar contents in the epidermis and mesophyll. • Conclusions Nocturnal stomatal opening is not reliant upon starch degradation, but starch biosynthesis is an important sink for carbohydrates, ensuring daytime stomatal closure in this CAM species

Subtidal inner-shelf circulation near Point Conception, California

We discuss connections between inner‐shelf and mid‐shelf circulation near Point Conception, California, as well as the wind forcing of inner‐shelf circulation. Point Conception marks the southern edge of a major upwelling zone that extends from Oregon to central California. The coastline makes a sharp eastward turn at Point Conception, and the Santa Barbara Channel to the east is generally assumed to be an upwelling shadow. Consistent with this regional division, inner‐shelf currents are strongly correlated with wind north of Point Conception, but not in the Santa Barbara Channel. One exception to this generalization is a location in the Santa Barbara Channel, near a pass that cuts through the coastal mountains, where local winds have a dominant cross‐shore component and directly drive cross‐shore currents over the inner shelf. Inner‐shelf currents in the Santa Barbara Channel, when compared with mid‐shelf currents in that area, are weaker, but strongly correlated. By contrast, inner‐shelf currents north of Point Conception show a far greater incidence of poleward flow than is seen over the mid‐shelf in that area. Poleward flow events, lasting 1–5 days, transport warm water from the Santa Barbara Channel around Point Conception to the central California coast. These events are associated with relaxation of the generally equatorward wind, but not always with mid‐shelf flow reversals

Solar Effects on Tensile and Optical Properties of Hubble Space Telescope Silver-Teflon(Registered Trademark) Insulation

A section of the retrieved Hubble Space Telescope (HST) solar array drive arm (SADA) multilayer insulation (MLI), which experienced 8.25 years of space exposure, was analyzed for environmental durability of the top layer of silver-Teflon (DuPont) fluorinated ethylene propylene (Ag-FEP). Because the SADA MLI had solar and anti-solar facing surfaces and was exposed to the space environment for a long duration, it provided a unique opportunity to study solar effects on the environmental degradation of Ag-FEP, a commonly used spacecraft thermal control material. Data obtained included tensile properties, solar absorptance, surface morphology and chemistry. The solar facing surface was found to be extremely embrittled and contained numerous through-thickness cracks. Tensile testing indicated that the solar facing surface lost 60% of its mechanical strength and 90% of its elasticity while the anti-solar facing surface had ductility similar to pristine FEP. The solar absorptance of both the solar facing surface (0.155 plus or minus 0.032) and the anti-solar facing surface (0.208 plus or minus 0.012) were found to be greater than pristine Ag-FEP (0.074). Solar facing and anti-solar facing surfaces were microscopically textured, and locations of isolated contamination were present on the anti-solar surface resulting in increased localized texturing. Yet, the overall texture was significantly more pronounced on the solar facing surface indicating a synergistic effect of combined solar exposure and increased heating with atomic oxygen erosion. The results indicate a very strong dependence of degradation, particularly embrittlement, upon solar exposure with orbital thermal cycling having a significant effect

“Never Say Never?”: Heterosexual, bisexual, and lesbian women’s accounts of being childfree

Feminist scholars have identified a “motherhood imperative” in Western cultures, where heterosexual women are understood to both want, and have, children. However, social shifts have resulted in a decrease in pronatalism as well as an increase in social recognition of the parenting desires of same-sex parents. Despite a resurgence of interest in childfree identities, research to date has predominantly focused on heterosexual women’s explanations for being childfree and their experiences of marginalisation. Our aim in the current study was to explore how childfree heterosexual, lesbian, bisexual, and queer women negotiate their childfree lives and identities in the context of their personal and social relationships within changing cultural contexts. Data from 23 interviews with women in the United Kingdom, who responded to a call for childfree participants, were thematically analysed. We constructed two themes: 1) Never say never? Negotiating being childfree as ever precarious, shows how women constructed being childfree as requiring constant revisiting and renegotiating to maintain; 2) An ordinary life: Constructing being childfree as rational and reasonable, in which we identify the rhetorical efforts of participants to establish their being childfree as an ordinary, reasonable, and rational position. We conclude that for these women, childfreedom was constantly in flux and that maintaining a positive childfree identity required considerable identity work in order to manage intimate personal relationships and wider friendships

Three interacting freshwater plumes in the northern California Current System

The northern California Current System is impacted by two primary freshwater sources: the Strait of Juan de Fuca and the Columbia River. The Columbia is frequently bidirectional in summer, with branches both north and south of the river mouth simultaneously. We describe the interaction of these two warm Columbia plumes with each other and with the colder plume originating from the strait. The interactions occurred when a period of strong downwelling-favorable winds and high Columbia River discharge was followed by persistent and strong upwelling-favorable winds. The northward plume that developed under the downwelling winds extended over 200 km along the coast to the Strait of Juan de Fuca and into the strait. The plume subsequently wrapped around Juan de Fuca Strait water in the counterclockwise seasonal eddy just offshore of the strait. Inspection for similar wind and outflow conditions (>0.15 N m¯² and 10⁴ m³ s¯¹, respectively) suggest that these events might have occurred in roughly half the years since 1994. Surface drifters deployed in the Columbia plume near its origin tracked this plume water northward along the coast, then reversed direction at the onset of upwelling-favorable winds, tracking plume water southward past the river mouth once again. ‘‘Recent’’ (~1–2 day old) and ‘‘Aged’’ (>14 day old) plume water folded around the newly emerging southwest tending Columbia plume, forming a distinctive ‘‘sock’’ shaped plume. This plume was a mixture of ~10% ‘‘New’’ (<1 day old) water and ~90% Recent and Aged water from prior north tending plumes