590 research outputs found
Assessment: Insights Into Teachers\u27 Beliefs and Practices
It is well established that instruction in process writing is important from the primary grades through the high school years. The work of Graves (1983) and Calkins (1986) provides teachers with a theoretical framework for implementing process writing instruction. However, wide variation in translating theory into practice is evident among teachers (Mangano and Allen, 1986; Bridge, Hiebert and Chesky, 1983). Research reveals that teachers seem to maintain their preset notions about writing conventions such as correct spelling, proper grammar and neatness while attempting to incorporate process writing into the curriculum (Ray, Lee and Stansell, 1986). Thus, teachers\u27 conceptualizations seem to affect the way writing is taught (Bridge, Hiebert and Chesky, 1983)
Assessment: Insights into Children\u27s Beliefs and Perceptions About Process Writing
How do children acquire knowledge about written language? Investigations of emergent literacy have shown that children\u27s written language knowledge reflects their cultural environment (Clay, 1982; Kastler, Roser, and Hoffman, 1987). At home, children observe their parents writing grocery lists, letters to friends and relatives, and telephone messages, thereby learning the functions of written language as they are used in daily life (Morgan, 1987; Purcell-Gates, 1986). Independently, children experiment with their own messages, incorporating scribble, pictures and random letters. Often their written products mirror the functional writing their parents modeled (Rowe, 1989). In school, additional opportunities to learn about written language are presented. Some tasks are inherent to the school setting, such as reports and labels, while others resemble those practices at home (Dyson, 1984). Children in classrooms where traditional writing instruction prevails find constraints placed upon their writing by their teacher, such as topic, length and purpose
Intensive Family Reunification Services: A Conceptual Framework and Case Example
Recent federal mandates require child welfare agencies to make reasonable efforts to reunify families after out-of-home placement. Consistent with those mandates, agencies are increasingly employing techniques from family preservation services intended initially to prevent out-of-home placement. The purpose of this article is to articulate a conceptual framework and practice guidelines for family reunification services and to describe an experimental reunification program based on a family preservation model. A case example illustrates the way in which the services affected one family that participated in the experiment
Working with simple machines
A set of examples is provided that illustrate the use of work as applied to
simple machines. The ramp, pulley, lever and hydraulic press are common
experiences in the life of a student and their theoretical analysis therefore
makes the abstract concept of work more real. The mechanical advantage of each
of these systems is also discussed so that students can evaluate their
usefulness as machines.Comment: 9 pages, 4 figure
Structure of Be probed via secondary beam reactions
The low-lying level structure of the unbound neutron-rich nucleus Be
has been investigated via breakup on a carbon target of secondary beams of
B at 35 MeV/nucleon. The coincident detection of the beam velocity
Be fragments and neutrons permitted the invariant mass of the
Be+ and Be++ systems to be reconstructed. In the case of
the breakup of B, a very narrow structure at threshold was observed in
the Be+ channel. Contrary to earlier stable beam fragmentation
studies which identified this as a strongly interacting -wave virtual state
in Be, analysis here of the Be++ events demonstrated that
this was an artifact resulting from the sequential-decay of the
Be(2) state. Single-proton removal from B was found to
populate a broad low-lying structure some 0.70 MeV above the neutron-decay
threshold in addition to a less prominent feature at around 2.4 MeV. Based on
the selectivity of the reaction and a comparison with (0-3)
shell-model calculations, the low-lying structure is concluded to most probably
arise from closely spaced J=1/2 and 5/2 resonances
(E=0.400.03 and 0.85 MeV), whilst the broad
higher-lying feature is a second 5/2 level (E=2.350.14 MeV). Taken
in conjunction with earlier studies, it would appear that the lowest 1/2
and 1/2 levels lie relatively close together below 1 MeV.Comment: 14 pages, 13 figures, 2 tables. Accepted for publication in Physical
Review
Biodegradable nanomats produced by electrospinning : expanding multifunctionality and potential for tissue engineering
With increasing interest in nanotechnology, development of nanofibers (n-fibers) by using the
technique of electrospinning is gaining new momentum. Among important potential applications of
n-fiber-based structures, scaffolds for tissue-engineering represent an advancing front. Nanoscaffolds
(n-scaffolds) are closer to natural extracellular matrix (ECM) and its nanoscale fibrous structure.
Although the technique of electrospinning is relatively old, various improvements have been
made in the last decades to explore the spinning of submicron fibers from biodegradable polymers
and to develop also multifunctional drug-releasing and bioactive scaffolds. Various factors can
affect the properties of resulting nanostructures that can be classified into three main categories,
namely: (1) Substrate related, (2) Apparatus related, and (3) Environment related factors. Developed
n-scaffolds were tested for their cytocompatibility using different cell models and were seeded
with cells for to develop tissue engineering constructs. Most importantly, studies have looked at the
potential of using n-scaffolds for the development of blood vessels. There is a large area ahead
for further applications and development of the field. For instance, multifunctional scaffolds that
can be used as controlled delivery system do have a potential and have yet to be investigated for
engineering of various tissues. So far, in vivo data on n-scaffolds are scarce, but in future reports
are expected to emerge. With the convergence of the fields of nanotechnology, drug release and
tissue engineering, new solutions could be found for the current limitations of tissue engineering
scaffolds, which may enhance their functionality upon in vivo implantation. In this paper electrospinning
process, factors affecting it, used polymers, developed n-scaffolds and their characterization
are reviewed with focus on application in tissue engineering
PAK6 Phosphorylates 14-3-3 gamma to Regulate Steady State Phosphorylation of LRRK2
Mutations in Leucine-rich repeat kinase 2 (LRRK2) are associated with Parkinson’s
disease (PD) and, as such, LRRK2 is considered a promising therapeutic target for
age-related neurodegeneration. Although the cellular functions of LRRK2 in health and
disease are incompletely understood, robust evidence indicates that PD-associated
mutations alter LRRK2 kinase and GTPase activities with consequent deregulation of
the downstream signaling pathways. We have previously demonstrated that one LRRK2
binding partner is P21 (RAC1) Activated Kinase 6 (PAK6). Here, we interrogate the
PAK6 interactome and find that PAK6 binds a subset of 14-3-3 proteins in a kinase
dependent manner. Furthermore, PAK6 efficiently phosphorylates 14-3-3γ at Ser59 and
this phosphorylation serves as a switch to dissociate the chaperone from client proteins
including LRRK2, a well-established 14-3-3 binding partner. We found that 14-3-3γ
phosphorylated by PAK6 is no longer competent to bind LRRK2 at phospho-Ser935,
causing LRRK2 dephosphorylation. To address whether these interactions are relevant in
a neuronal context, we demonstrate that a constitutively active form of PAK6 rescues the
G2019S LRRK2-associated neurite shortening through phosphorylation of 14-3-3γ. Our
results identify PAK6 as the kinase for 14-3-3γ and reveal a novel regulatory mechanism
of 14-3-3/LRRK2 complex in the brain
<i>C-elegans</i> model identifies genetic modifiers of alpha-synuclein inclusion formation during aging
Inclusions in the brain containing alpha-synuclein are the pathological hallmark of Parkinson's disease, but how these inclusions are formed and how this links to disease is poorly understood. We have developed a <i>C-elegans</i> model that makes it possible to monitor, in living animals, the formation of alpha-synuclein inclusions. In worms of old age, inclusions contain aggregated alpha-synuclein, resembling a critical pathological feature. We used genome-wide RNA interference to identify processes involved in inclusion formation, and identified 80 genes that, when knocked down, resulted in a premature increase in the number of inclusions. Quality control and vesicle-trafficking genes expressed in the ER/Golgi complex and vesicular compartments were overrepresented, indicating a specific role for these processes in alpha-synuclein inclusion formation. Suppressors include aging-associated genes, such as sir-2.1/SIRT1 and lagr-1/LASS2. Altogether, our data suggest a link between alpha-synuclein inclusion formation and cellular aging, likely through an endomembrane-related mechanism. The processes and genes identified here present a framework for further study of the disease mechanism and provide candidate susceptibility genes and drug targets for Parkinson's disease and other alpha-synuclein related disorders
The Roc domain of LRRK2 as a hub for protein-protein interactions:a focus on PAK6 and its impact on RAB phosphorylation
Leucine-rich repeat kinase 2 (LRRK2) has taken center stage in Parkinson's disease (PD) research as mutations cause familial PD and more common variants increase lifetime risk for disease. One unique feature in LRRK2 is the coexistence of GTPase/Roc (Ras of complex) and kinase catalytic functions, bridged by a COR (C-terminal Of Roc) platform for dimerization. Multiple PD mutations are located within the Roc/GTPase domain and concomitantly lead to defective GTPase activity and augmented kinase activity in cells, supporting a crosstalk between GTPase and kinase domains. In addition, biochemical and structural data highlight the importance of Roc as a molecular switch modulating LRRK2 monomer-to-dimer equilibrium and building the interface for interaction with binding partners. Here we review the effects of PD Roc mutations on LRRK2 function and discuss the importance of Roc as a hub for multiple molecular interactions relevant for the regulation of cytoskeletal dynamics and intracellular trafficking pathways. Among the well-characterized Roc interactors, we focused on the cytoskeletal-related kinase p21-activated kinase 6 (PAK6). We report the affinity between LRRK2-Roc and PAK6 measured by microscale thermophoresis (MST). We further show that PAK6 can modulate LRRK2-mediated phosphorylation of RAB substrates in the presence of LRRK2 wild-type (WT) or the PD G2019S kinase mutant but not when the PD Roc mutation R1441G is expressed. These findings support a mechanism whereby mutations in Roc might affect LRRK2 activity through impaired protein-protein interaction in the cell
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