528 research outputs found
Supporting induction: relationships count
This article examines the structural changes to the induction of teachers in Scotland using the perceptions of a group of final year student teachers. This group would be the first probationer teachers to experience revised arrangements for new teacher induction in 37 years. Their preferences and concerns are highlighted, as the new procedures roll out in schools nationwide, in an attempt to stress the importance of relationships to the success of the induction scheme. The argument put forward in this article is based on the notion that personal intelligence is central to effective relationships and therefore crucially important in the context of this mentoring relationship. The views of our sample provide evidence to suggest that the quality of interactions between the mentor and the probationer teacher are paramount in providing a good induction experience. These views are substantiated by experiences in England and in induction literature elsewhere. A synthesis of this evidence is used to make recommendations for those involved in supporting induction in schools, local authorities or teacher education institutions
Measuring Galaxy Star Formation Rates From Integrated Photometry: Insights from Color-Magnitude Diagrams of Resolved Stars
We use empirical star formation histories (SFHs), measured from HST-based
resolved star color-magnitude diagrams, as input into population synthesis
codes to model the broadband spectral energy distributions (SEDs) of ~50 nearby
dwarf galaxies (6.5 < log M/M_* < 8.5, with metallicities ~10% solar). In the
presence of realistic SFHs, we compare the modeled and observed SEDs from the
ultraviolet (UV) through near-infrared (NIR) and assess the reliability of
widely used UV-based star formation rate (SFR) indicators. In the FUV through i
bands, we find that the observed and modeled SEDs are in excellent agreement.
In the Spitzer 3.6micron and 4.5micron bands, we find that modeled SEDs
systematically over-predict observed luminosities by up to ~0.2 dex, depending
on treatment of the TP-AGB stars in the synthesis models. We assess the
reliability of UV luminosity as a SFR indicator, in light of independently
constrained SFHs. We find that fluctuations in the SFHs alone can cause factor
of ~2 variations in the UV luminosities relative to the assumption of a
constant SFH over the past 100 Myr. These variations are not strongly
correlated with UV-optical colors, implying that correcting UV-based SFRs for
the effects of realistic SFHs is difficult using only the broadband SED.
Additionally, for this diverse sample of galaxies, we find that stars older
than 100 Myr can contribute from <5% to100% of the present day UV luminosity,
highlighting the challenges in defining a characteristic star formation
timescale associated with UV emission. We do find a relationship between UV
emission timescale and broadband UV-optical color, though it is different than
predictions based on exponentially declining SFH models. Our findings have
significant implications for the comparison of UV-based SFRs across
low-metallicity populations with diverse SFHs.Comment: 22 pages, 15 figures, ApJ accepte
Rac and Cdc42 GTPases control hematopoietic stem cell shape, adhesion, migration, and mobilization
Critical to homeostasis of blood cell production by hematopoietic stem/progenitor (HSC/P) cells is the regulation of HSC/P retention within the bone marrow microenvironment and migration between the bone marrow and the blood. Key extracellular regulatory elements for this process have been defined (cell–cell adhesion, growth factors, chemokines), but the mechanism by which HSC/P cells reconcile multiple external signals has not been elucidated. Rac and related small GTPases are candidates for this role and were studied in HSC/P deficient in Rac2, a hematopoietic cell-specific family member. Rac2 appears to be critical for HSC/P adhesion both in vitro and in vivo, whereas a compensatory increase in Cdc42 activation regulates HSC/P migration. This genetic analysis provides physiological evidence of cross-talk between GTPase proteins and suggests that a balance of these two GTPases controls HSC/P adhesion and mobilization in vivo
Protocol for Monitoring Aquatic Invertebrates of Small Streams in the Heartland Inventory & Monitoring Network, Version 2.1
Executive Summary
The Heartland Inventory and Monitoring Network (HTLN) is a component of the National Park Service’s (NPS) strategy to improve park management through greater reliance on scientific information. The purposes of this program are to design and implement long-term ecological monitoring and provide information for park managers to evaluate the integrity of park ecosystems and better understand ecosystem processes. Concerns over declining surface water quality have led to the development of various monitoring approaches to assess stream water quality. Freshwater streams in network parks are threatened by numerous stressors, most of which originate outside park boundaries. Stream condition and ecosystem health are dependent on processes occurring in the entire watershed as well as riparian and floodplain areas; therefore, they cannot be manipulated independently of this interrelationship. Land use activities—such as timber management, landfills, grazing, confined animal feeding operations, urbanization, stream channelization, removal of riparian vegetation and gravel, and mineral and metals mining—threaten stream quality. Accordingly, the framework for this aquatic monitoring is directed towards maintaining the ecological integrity of the streams in those parks.
Invertebrates are an important tool for understanding and detecting changes in ecosystem integrity, and they can be used to reflect cumulative impacts that cannot otherwise be detected through traditional water quality monitoring. The broad diversity of invertebrate species occurring in aquatic systems similarly demonstrates a broad range of responses to different environmental stressors. Benthic invertebrates are sensitive to the wide variety of impacts that influence Ozark streams. Benthic invertebrate community structure can be quantified to reflect stream integrity in several ways, including the absence of pollution sensitive taxa, dominance by a particular taxon combined with low overall taxa richness, or appreciable shifts in community composition relative to reference condition. Furthermore, changes in the diversity and community structure of benthic invertebrates are relatively simple to communicate to resource managers and the public. To assess the natural and anthropogenic processes influencing invertebrate communities, this protocol has been designed to incorporate the spatial relationship of benthic invertebrates with their local habitat including substrate size and embeddedness, and water quality parameters (temperature, dissolved oxygen, pH, specific conductance, and turbidity). Rigid quality control and quality assurance are used to ensure maximum data integrity. Detailed standard operating procedures (SOPs) and supporting information are associated with this protocol
Protocol for Monitoring Fish Communities in Small Streams in the Heartland Inventory and Monitoring Network, Version 2.0
Executive Summary
Fish communities are an important component of aquatic systems and are good bioindicators of ecosystem health. Land use changes in the Midwest have caused sedimentation, erosion, and nutrient loading that degrades and fragments habitat and impairs water quality. Because most small wadeable streams in the Heartland Inventory and Monitoring Network (HTLN) have a relatively small area of their watersheds located within park boundaries, these streams are at risk of degradation due to adjacent land use practices and other anthropogenic disturbances. Shifts in the physical and chemical properties of aquatic systems have a dramatic effect on the biotic community. The federally endangered Topeka shiner (Notropis topeka) and other native fishes have declined in population size due to habitat degradation and fragmentation in Midwest streams. By protecting portions of streams on publicly owned lands, national parks may offer refuges for threatened or endangered species and species of conservation concern, as well as other native species.
This protocol describes the background, history, justification, methodology, data analysis and data management for long-term fish community monitoring of wadeable streams within nine HTLN parks: Effigy Mounds National Monument (EFMO), George Washington Carver National Monument (GWCA), Herbert Hoover National Historic Site (HEHO), Homestead National Monument of America (HOME), Hot Springs National Park (HOSP), Pea Ridge National Military Park (PERI), Pipestone National Monument (PIPE), Tallgrass Prairie National Preserve (TAPR), and Wilson\u27s Creek National Battlefield (WICR). The objectives of this protocol are to determine the status and long-term trends in fish richness, diversity, abundance, and community composition in small wadeable streams within these nine parks and correlate the long-term community data to overall water quality and habitat condition (DeBacker et al. 2005)
Experimental transmission of chronic wasting disease agent from mule deer to cattle by the intracerebral route
This communication reports final observations on experimental transmission of chronic wasting disease (CWD) from mule deer to cattle by the intracerebral route. Thirteen calves were inoculated intracerebrally with brain suspension from mule deer naturally affected with CWD. Three other calves were kept as uninoculated controls. The experiment was terminated 6 years after inoculation. During that time, abnormal prion protein (PrPres) was demonstrated in the central nervous system (CNS) of 5 cattle by both immunohistochemistry and Western blot. However, microscopic lesions suggestive of spongiform encephalopathy (SE) in the brains of these PrPres-positive animals were subtle in 3 cases and absent in 2 cases. Analysis of the gene encoding bovine PRNP revealed homozygosity for alleles encoding 6 octapeptide repeats, serine (S) at codon 46, and S at codon 146 in all samples. Findings of this study show that although PrPres amplification occurred after direct inoculation into the brain, none of the affected animals had classic histopathologic lesions of SE. Furthermore, only 38% of the inoculated cattle demonstrated amplification of PrPres. Although intracerebral inoculation is an unnatural route of exposure, this experiment shows that CWD transmission in cattle could have long incubation periods (up to 5 years). This finding suggests that oral exposure of cattle to CWD agent, a more natural potential route of exposure, would require not only a much larger dose of inoculum but also may not result in amplification of PrPres within CNS tissues during the normal lifespan of cattle
Experimental transmission of chronic wasting disease agent from mule deer to cattle by the intracerebral route
This communication reports final observations on experimental transmission of chronic wasting disease (CWD) from mule deer to cattle by the intracerebral route. Thirteen calves were inoculated intracerebrally with brain suspension from mule deer naturally affected with CWD. Three other calves were kept as uninoculated controls. The experiment was terminated 6 years after inoculation. During that time, abnormal prion protein (PrPres) was demonstrated in the central nervous system (CNS) of 5 cattle by both immunohistochemistry and Western blot. However, microscopic lesions suggestive of spongiform encephalopathy (SE) in the brains of these PrPres-positive animals were subtle in 3 cases and absent in 2 cases. Analysis of the gene encoding bovine PRNP revealed homozygosity for alleles encoding 6 octapeptide repeats, serine (S) at codon 46, and S at codon 146 in all samples. Findings of this study show that although PrPres amplification occurred after direct inoculation into the brain, none of the affected animals had classic histopathologic lesions of SE. Furthermore, only 38% of the inoculated cattle demonstrated amplification of PrPres. Although intracerebral inoculation is an unnatural route of exposure, this experiment shows that CWD transmission in cattle could have long incubation periods (up to 5 years). This finding suggests that oral exposure of cattle to CWD agent, a more natural potential route of exposure, would require not only a much larger dose of inoculum but also may not result in amplification of PrPres within CNS tissues during the normal lifespan of cattle
Modeling the Effects of Star Formation Histories on Halpha and Ultra-Violet Fluxes in Nearby Dwarf Galaxies
We consider the effects of non-constant star formation histories (SFHs) on
Halpha and GALEX far ultra-violet (FUV) star formation rate (SFR) indicators.
Under the assumption of a fully populated Chabrier IMF, we compare the
distribution of Halpha-to-FUV flux ratios from ~ 1500 simple, periodic model
SFHs with observations of 185 galaxies from the Spitzer Local Volume Legacy
survey. We find a set of SFH models that are well matched to the data, such
that more massive galaxies are best characterized by nearly constant SFHs,
while low mass systems experience bursts amplitudes of ~ 30 (i.e., an increase
in the SFR by a factor of 30 over the SFR during the inter-burst period), burst
durations of tens of Myr, and periods of ~ 250 Myr; these SFHs are broadly
consistent with the increased stochastic star formation expected in systems
with lower SFRs. We analyze the predicted temporal evolution of galaxy stellar
mass, R-band surface brightness, Halpha-derived SFR, and blue luminosity, and
find that they provide a reasonable match to observed flux distributions. We
find that our model SFHs are generally able to reproduce both the observed
systematic decline and increased scatter in Halpha-to-FUV ratios toward low
mass systems, without invoking other physical mechanisms. We also compare our
predictions with those from the Integrated Galactic IMF theory with a constant
SFR. We find that while both predict a systematic decline in the observed
ratios, only the time variable SFH models are capable of producing the observed
population of low mass galaxies ( < 10 Msun) with normal
Halpha-to-FUV ratios. These results demonstrate that a variable IMF alone has
difficulty explaining the observed scatter in the Halpha-to-FUV ratios. We
conclude by considering the limitations of the model SFHs, and discuss the use
of additional empirical constraints to improve future SFH modeling efforts.Comment: 15 pages, 11 Figures. Accepted for publication in Ap
Teacher induction: personal intelligence and the mentoring relationship
This article is aimed at probationer teachers in Scotland, their induction supporters, and all those with a responsibility for their support and professional development. It argues that the induction process is not merely a mechanistic one, supported only by systems in schools, local authorities and the General Teaching Council for Scotland (GTCS), but a more complex process where the relationship between the new teacher and the supporter is central to its success. In particular, the characteristics and skills of the induction supporter in relation to giving feedback are influential. This applies to feedback in all its forms – formative and summative, formal and informal. The ability of the probationer to handle that feedback and to be proactive in the process is also important
- …