Search

Interpreting the paleomagnetic records of altered rocks, especially those from Earth's earliest history, is complicated by metamorphic overprints and recrystallization of ferromagnetic minerals. However, these records may be as valuable as a primary signal if the timing and mechanism of alteration‐related remagnetizations can be ascertained. We illustrate the success of this approach in the case of seafloor hydrothermal alteration by integrating simple rock magnetic and magnetic microscopy data with petrography, hyperspectral imagery, aeromagnetic surveys, field mapping, and geochronology of Paleoarchean basalts from North Pole Dome located in the East Pilbara Craton, Western Australia. We identify 12 hydrothermal episodes during the deposition of the stratigraphy between ∼3490 and 3350 Ma. These episodes produced stratabound zones of hydrothermal alteration with predictable facies successions of mineral assemblages reflecting sub‐seafloor gradients in fluid temperature, pH, composition, and water/rock ratios. Rock magnetic data and magnetic microscopy pinpoint the secondary ferromagnetic minerals within each alteration assemblage, revealing a specific single‐domain magnetite population within leucoxenes (titanite and anatase after primary titanomagnetites) that always accompanies low‐water/rock alteration in fluids buffered to pH equilibrium with the host basalts. Highly uniform magnetic properties indicate that once formed, these magnetites remain unchanged upon further exposure to rock buffered fluids, stabilizing them against later alteration events and making them durable paleofield recorders. The altered basalts hosting this magnetite have unique and consistent appearances, mineralogy, IR absorption features, aeromagnetic signatures, and magnetic properties across all hydrothermal systems studied here, highlighting how integrating these data sets can identify and interpret this alteration style in future paleomagnetic investigations. Plain Language Summary: Paleomagnetists interpret the magnetic signals preserved in rocks to understand plate tectonics and the Earth's magnetic field in the deep past. However, rocks can get altered via heat, pressure, or chemical reactions, which also alter these magnetic signals. The aim of this study is to demonstrate that one type of alteration—chemical alteration of rocks as they marinate in circulating hot water within seafloor hydrothermal systems—modifies the magnetic signals of rocks in order to use them for future paleomagnetic studies. Using airborne infrared imaging, magnetic field mapping, field observations, and radiometric dating, we demonstrate that an area of Western Australia called North Pole Dome experienced a dozen seafloor hydrothermal alteration events over 3 billion years ago. We then use magnetic measurements and mineralogical observations to document how these hydrothermal systems altered the magnetic signals in their host rocks. These analyses reveal a recognizable population of altered rocks that can preserve paleomagnetic signals related to hydrothermal alteration. This is because the alteration results in the growth of very fine‐grained magnetite with all the necessary characteristics to reliably and durably hold onto magnetic signals over geologic time. Key Points: Field mapping, remote sensing, and petrographic data identify 12 seafloor hydrothermal episodes in an Archean volcanic successionMagnetic and mineralogical characteristics of the basalts predictably co‐vary with alteration facies across all hydrothermal systemsWe establish a geologic, chronological, and petrographic framework for identifying seafloor hydrothermal remagnetization in basalts [ABSTRACT FROM AUTHOR]

In situ geologic context mapping based on rover and helicopter observations provides documentation of a nearly continuous record of geology and exposed surface structure over a 120 m‐wide corridor along the traverse of the Mars 2020/Perseverance rover. The results record the geologic context of Mars 2020 campaign sites and sample sites, including the local extent of bedrock outcrops, stratigraphy, attitude, and structure from imaging and rover‐based remote sensing, and outcrop lithology based on in situ proximity science. Mapping identifies a sequence of igneous lithologies including (a) early mafic, possibly intrusive, rocks; (b) pervasively fractured and deeply altered massive bedrock of undetermined protolith; (c) buried and exhumed lava flows with pahoehoe and aa textures; (d) several varieties of regolith; and (e) small impact craters. Plain Language Summary: Reconnaissance‐type geologic mapping along the traverse of Perseverance on the Jezero Crater floor is adapted from field geologic methods used on Earth and modified to account for the geometry of rover‐based imaging. The final field geologic map records bedrock and surficial geology, contacts, and structures over a 120‐m wide strip along the traverse. Most of the lithologies are igneous, including possible intrusive mafic rocks, deeply weathered massive rocks of unknown original lithology, and lava flows. Stratigraphy determined from mapping together with the observed inclination of layers identifies either uplift or draping of the section centered in the elevated older terrain. The final map information provides ground‐truth geologic context for the first eight samples collected for return to Earth. Key Points: In situ mapping from the rover observations on Mars uses field geologic mapping methodsDocuments the geologic context of samples and the crater floor traverse of PerseveranceDevelops methods applicable to future robotic and human traverses on planetary surfaces [ABSTRACT FROM AUTHOR]

We present a combined geomorphologic, multispectral, and geochemical analysis of crater floor rocks in Jezero crater based on data obtained by the Mast Camera Zoom and SuperCam instruments onboard the NASA Mars 2020 Perseverance rover. The combined data from this analysis together with the results of a comparative study with geologic sites on Earth allows us to interpret the origins of rocks exposed along the Artuby ridge, a ∼900 m long scarp of lower Máaz formation rocks. The ridge exposes rocks belonging to two morphologically distinct members, Artuby and Rochette, both of which have basaltic composition and are spectrally indistinguishable in our analysis. Artuby rocks consist of morphologically distinct units that alternate over the ridge, bulbous, hummocky, layers with varying thicknesses that in places appear to have flowed over underlying strata, and sub‐planar thinner laterally continuous layers with variable friability. The Rochette member has a massive appearance with pronounced pitting and sub‐horizontal partings. Our findings are most consistent with a primary igneous emplacement as lava flows, through multiple eruptions, and we propose that the thin layers result either from preferential weathering, interbedded ash/tephra layers, ʻaʻā clinker layers, or aeolian deposition. Our analyses provide essential geologic context for the Máaz formation samples that will be returned to Earth and highlight the diversity and complexity of geologic processes on Mars not visible from orbit. Plain Language Summary: Characterization of the landing site for the Mars 2020 Perseverance rover mission yields insight into early solar system processes and provides essential context for Mars Sample Return. Here we have investigated crater floor rocks in Jezero crater that are exposed along a scarp called Artuby ridge with the Mast Camera Zoom (Mastcam‐Z) and SuperCam instruments onboard the Perseverance rover. The Artuby ridge displays a characteristically layered set of rocks with a basaltic composition that are spectrally and chemically indistinguishable in our investigation. We compare our observations from Jezero with well‐understood geologic deposits on Earth, from Hawaiʻi and New Mexico. We find that terrestrial lava flows can have complex interiors that replicate many features that we see in Mastcam‐Z images of the Artuby ridge, and thus, that the series of rocks exposed along the Artuby ridge are dominated by lava flows originating through multiple eruptions. There are a number of layers and textures of the rocks in our investigation that may not have originated as lava flows, that instead may be products of weathering, interbedding of lava and volcanic ash/tephra, or wind‐borne sediment deposition. Our results highlight the diversity of geologic units on Mars not visible from orbit. Key Points: We investigated Artuby and Rochette member rocks of the Máaz formation in Jezero crater using Perseverance's Mast Camera Zoom and SuperCam dataComplex knobbly, foliated, vesicular, and layered lithologies are most consistent with lava flows originating through multiple eruptionsThe Máaz formation in Jezero crater could be unrelated to the regional Circum–Isidis capping unit [ABSTRACT FROM AUTHOR]

Let p be a prime and let ℂ be the complex field. We explicitly classify the finite solvable irreducible monomial subgroups of GL (p , ℂ) up to conjugacy. That is, we give a complete and irredundant list of GL (p , ℂ) -conjugacy class representatives as generating sets of monomial matrices. Copious structural information about non-solvable finite irreducible monomial subgroups of GL (p , ℂ) is also proved, enabling a classification of all such groups bar one family. We explain the obstacles in that exceptional case. For p ≤ 3 , we classify all finite irreducible subgroups of GL (p , ℂ). Our classifications are available publicly in MAGMA. [ABSTRACT FROM AUTHOR]

Carbonate minerals have been detected in Jezero crater, an ancient lake basin that is the landing site of the Mars 2020 Perseverance rover, and within the regional olivine‐bearing (ROB) unit in the Nili Fossae region surrounding this crater. It has been suggested that some carbonates in the margin fractured unit, a rock unit within Jezero crater, formed in a fluviolacustrine environment, which would be conducive to preservation of biosignatures from paleolake‐inhabiting lifeforms. Here, we show that carbonate‐bearing rocks within and outside of Jezero crater have the same range of visible‐to‐near‐infrared carbonate absorption strengths, carbonate absorption band positions, thermal inertias, and morphologies. Thicknesses of exposed carbonate‐bearing rock cross‐sections in Jezero crater are ∼75–90 m thicker than typical ROB unit cross‐sections in the Nili Fossae region, but have similar thicknesses to ROB unit exposures in Libya Montes. These similarities in carbonate properties within and outside of Jezero crater is consistent with a shared origin for all of the carbonates in the Nili Fossae region. Carbonate absorption minima positions indicate that both Mg‐ and more Fe‐rich carbonates are present in the Nili Fossae region, consistent with the expected products of olivine carbonation. These estimated carbonate chemistries are similar to those in martian meteorites and the Comanche carbonates investigated by the Spirit rover in Columbia Hills. Our results indicate that hydrothermal alteration is the most likely formation mechanism for non‐deltaic carbonates within and outside of Jezero crater. Plain Language Summary: Spacecraft orbiting Mars can measure the composition of rocks that make up its surface. Understanding rock composition allows us to interpret past environmental conditions on Mars, including their likelihood to be habitable. Using data acquired from orbit, researchers have found carbonate minerals in Jezero crater and the surrounding region—called the Nili Fossae region. Jezero crater is the landing site of NASA's Mars 2020 Perseverance rover and once contained a lake. The discovery of carbonates is exciting because on Earth they sometimes form in habitable environments and preserve fossils. In this study, we used all available high resolution orbital datasets to look at similarities and differences between carbonate‐bearing rocks within and outside of Jezero crater. We found that carbonate‐bearing rocks within and outside of Jezero crater have similar orbital properties, implying that they formed by the same processes. We found that the range in chemistries (magnesium‐rich vs. iron‐rich) for carbonates within and outside of Jezero crater is similar to carbonate chemistries found in martian meteorites and by other rovers on Mars. The carbonates within and outside of Jezero crater could have formed by the same water‐rock interactions that formed carbonates discovered in martian meteorites and by other rovers on Mars. Key Points: Carbonates within and outside of Jezero crater have similar spectra, thermal inertias, morphologies, and thicknessesCarbonates within and outside of Jezero crater likely formed via the same processesHydrothermal alteration and evaporation are the most likely processes for carbonate formation within and outside of Jezero crater [ABSTRACT FROM AUTHOR]

Abstract Understanding the long‐term effects of population and GDP changes requires a multisectoral and regional understanding of the coupled human‐Earth system, as the long‐term evolution of this coupled system is influenced by human decisions and the Earth system. This study investigates the impact of compounding economic and population growth uncertainties on long‐term multisectoral outcomes. We use the Global Change Analysis Model (GCAM) to explore the influence of compounding and feedback between future GDP and population growth on four key sectors: final energy consumption, water withdrawal, staple food prices, and CO2 emissions. The results show that uncertainties in GDP and population compound, resulting in a magnification of tail risks for outcomes across sectors and regions. Compounding uncertainties significantly impact metrics such as CO2 emissions and final energy consumption, particularly at the upper tail at both global and regional levels. However, the impact of staple food prices and water withdrawal depends on regional factors. Additionally, an alternative low‐carbon transition scenario could compound uncertainties and increase tail risk, particularly in staple food prices, highlighting the influence of emergent constraints on land availability and food‐energy competition for land use. The findings underscore the importance of considering and adequately accounting for compounding uncertainties in key drivers of multisectoral systems to enhance our comprehensive understanding of the complex nature of multisectoral systems. The paper provides valuable insights into the potential implications of compounding uncertainties.

Abstract: We introduce the notion of quasi‐orthogonal cocycle. This is motivated in part by the maximal determinant problem for square { ± 1 }‐matrices of size congruent to 2 modulo 4. Quasi‐orthogonal cocycles are analogous to the orthogonal cocycles of algebraic design theory. Equivalences with new and known combinatorial objects afforded by this analogy, such as quasi‐Hadamard groups, relative quasi‐difference sets, and certain partially balanced incomplete block designs, are proved. [ABSTRACT FROM AUTHOR]

Calibration of the prototype Planetary Instrument for X-ray Lithochemistry (PIXL) selected for Mars 2020 has commenced with an empirical derivation of the X-ray optic transmission profile. Through a straightforward method of dividing a measured “blank” spectrum over one calculated assuming no optic influence, a rudimentary profile was formed. A simple boxcar-smoothing algorithm was implemented to approximate the complete profile that was incorporated into PIQUANT. Use of this form of smoothing differs from the more conventional approach of using a parameter-based function to complete the profile. Comparison of element-specific correction factors, taken from a measurement of NIST SRM 610, was used to assess the accuracy of the new profile. Improvement in the low- to mid-energy portion of the data was apparent though the high-energy region diverged from unity, and thus, requires further refinement. [ABSTRACT FROM AUTHOR]

The impacts of water scarcity depend on physical basin characteristics and global economic dynamics. Here, the authors show scenario assumptions can yield either highly positive or negative economic impacts due to water scarcity, and the drivers of these impacts are basin-specific and cannot be determined a priori.

Abstract Future water scarcity is a global concern with impacts across the energy, water, and land (EWL) sectors. Countries in Latin America and the Caribbean (LAC) are significant producers of agricultural goods, so disruptions resulting from water scarcity in LAC have global importance. Understanding where water scarcity in LAC could occur and what could exacerbate it is critical for strategic resource management and planning, both regionally and globally. Assessing future water scarcity in LAC is challenging given the complex interactions among the EWL sectors and the multiple uncertainties acting across spatial scales. To illuminate these dynamics, we use scenario discovery on a large ensemble representing diverse futures simulated using an integrated human‐environmental systems model. We quantify future water scarcity and its economic impacts across several physical and economic metrics. We find that future levels of reservoir storage expansion could be a significant driver of physical and economic water scarcity, highlighting the importance of strategic water infrastructure development in maintaining future water availability. Changes in crop profit are driven by both water supply and demand, emphasizing the complexity of EWL multisector dynamics. While most of LAC is poised to have abundant land and water resources available for future development, basins in Mexico and along the Pacific coast of South America experience high exposure to severe outcomes and uncertainty across outcomes for at least one metric. We find that drivers of severe scarcity vary spatially and across metrics, highlighting the region's heterogeneity and the importance of considering multiple metrics to assess water scarcity.

Abstract Land scarcity is increasing over time, driven by complex multisector dynamics. The impacts of land scarcity on the economy and environment are multi‐faceted and regional, so any action to convert land will contain inherent tradeoffs. These impacts are complicated by the deeply uncertain evolution of the various sectors influencing land scarcity. A need therefore exists to provide multi‐metric and multi‐sector assessments that are robust to myriad uncertainties. Land conservation effectively limits the supply of productive land, while biofuel consumption increases the demand and competition for that land, and how these dynamics individually and jointly propagate to economic and environmental impacts is an important open question. To address this, we adopt the Global Change Analysis Model (GCAM) that has representations of various important systems including the climate, macroeconomic, energy, agriculture and land, and water resources systems. Various scenarios of increased land demand (from biofuels) and decreased land supply (from conservation) under various socioeconomic scenarios drawn from the SSPs were simulated using GCAM. We find that while biofuel consumption and land conservation reduce carbon emissions, this comes at the cost of higher food prices, reduced crop production, and increased water withdrawals. Additionally, some regions experience these tradeoffs more severely than others and are more heavily impacted from the same biofuel mandate or by an additional percent of protected land. These and other findings highlight the importance of multisector modeling frameworks that capture many cross‐sector linkages, and acknowledge the important uncertainties confronting the human‐Earth system when making any analysis of land scarcity impacts.

We survey the legacy of L. G. Kovács in linear group theory, with a particular focus on classification questions. [ABSTRACT FROM PUBLISHER]

The hydrocarbons preserved in an Archean rock were extracted, and their composition and distribution in consecutive slices from the outside to the inside of the rock were examined. The 2.7 Ga rock was collected from the Fortescue Group in the Pilbara region, Western Australia. The bitumen I (solvent-extracted rock) and bitumen II (solvent-extracted hydrochloric acid-treated rock) fractions have different hydrocarbon compositions. Bitumen I contains only trace amounts of aliphatic hydrocarbons and virtually no aromatic hydrocarbons. In contrast, bitumen II contains abundant aliphatic and aromatic hydrocarbons. The difference seems to reflect the weathering history and preservational environment of the investigated rock. Aliphatic hydrocarbons in bitumen I are considered to be mainly from later hydrocarbon inputs, after initial deposition and burial, and are therefore not indigenous. The lack of aromatic hydrocarbons in bitumen I suggests a severe weathering environment since uplift and exposure of the rock at the Earth's surface in the Cenozoic. On the other hand, the high abundance of aromatic hydrocarbons in bitumen II suggests that bitumen II hydrocarbons have been physically isolated from removal by their encapsulation within carbonate minerals. The richness of aromatic hydrocarbons and the relative scarcity of aliphatic hydrocarbons may reflect the original compositions of organic materials biosynthesised in ancient organisms in the Archean era, or the high thermal maturity of the rock. Cyanobacterial biomarkers were observed in the surficial slices of the rock, which may indicate that endolithic cyanobacteria inhabited the surface outcrop. The distribution of aliphatic and aromatic hydrocarbons implies a high thermal maturity, which is consistent with the lack of any specific biomarkers, such as hopanes and steranes, and the prehnite-pumpellyite facies metamorphic grade. [ABSTRACT FROM AUTHOR]

The northern part of the Fortescue Group consists of interbedded flood basalts and sedimentary rocks that were deposited on the southern margin of the Pilbara Craton, Western Australia, during one or more periods of continental rifting betweenca2.78 andca2.63 Ga. Well-preserved sedimentary intervals within the group have yielded stable carbon and sulfur isotope data that have been used to infer changes in geobiological processes in the Neoarchean. However, the Fortescue Group is notable for being a predominantly subaerial succession, and it remains unclear whether data obtained from these intervals should be interpreted in the context of deposition in marine environments, possibly recording changes in the global ocean/atmosphere system, or in local and restricted lacustrine settings. Here, we describe the sedimentology, stratigraphy, stromatolites and stable carbon isotope geochemistry of theca2.74 Ga Mopoke Member, Kylena Formation, the oldest stromatolitic horizon in the Fortescue Group. This unit differs in terms of internal stratigraphic relationships, sedimentology, carbonate mineralogy and stable isotope geochemistry when compared with intervals of probable lacustrine origin in the overlying Tumbiana and Maddina formations. In contrast, we suggest that parts of the Mopoke Member may have been deposited under open marine conditions, or alternatively, in a lacustrine environment characterised by differing water chemistry and basement topography. Stromatolitic microfabrics of the Mopoke Member are dominated by spar, dolospar and vertically aligned calcitic crusts, rather than the micritic microfabrics described from other Fortescue Group stromatolites. Mud-draped ripples are common sedimentary features in the Mopoke Member, suggesting a tidal influence. Mopoke Member δ13Ccarbvalues are generally slightly positive, but also include some significantly depleted values, which may relate to the reoxidation of13C-depleted organic matter. δ13Corgvalues average –36.7‰, consistent with Neoarchean marine units reported from elsewhere, but significantly less13C-depleted than values reported from overlying lacustrine intervals in the Fortescue Group. We conclude that some features of Fortescue Group datasets relevant to the field of geobiology may be facies dependent, and that more work focusing on the overall depositional environments of the Fortescue Group is needed in order to appropriately interpret geobiological data reported from that group. [ABSTRACT FROM AUTHOR]

This article considers the impact of geographic accessibility and social class on school leavers when making decisions relating to higher education institution (HEI) type, degree level and field of study. Using a novel and comprehensive Irish data set, we consider a number of joint decisions facing school leavers in relation to where and what to study and employ a range of bivariate choice models which allows us to control for correlations in these decisions. We find that geographic accessibility and social class play an important role in determining outcomes relating to HEI type, degree level and field of study. We argue that these decisions are important in terms of future labour market and other outcomes for school leavers and that current policy in Ireland does not go far enough in mitigating the impact of distance and socio-economic barriers on these outcomes. [ABSTRACT FROM PUBLISHER]

Background Cardiac resynchronisation therapy ( CRT) is established in the management of cardiac failure in patients with systolic dysfunction. Clinical response to CRT is not uniform, and response has been difficult to predict. Aim Patient management within a high volume, multidisciplinary service focused on optimal delivery of CRT would improve response rates. Methods Four hundred and thirty-five consecutive patients who underwent CRT under a multidisciplinary heart failure service were enrolled prospectively over a 5-year period. Medically optimised, symptomatic patients with an ejection fraction ( EF) <35%, widened QRS or abnormal dyssynchrony index were included. Left ventricular lead position was targeted anatomically to the segment of latest mechanical activation, and electrically to a site with maximal intrinsic intracardiac electrogram separation. Routine device and clinical follow up, as well as CRT optimisations, were performed at baseline and at 3-monthly intervals. Responders were defined as having an absolute reduction in left ventricular end-diastolic diameter >10% and an improvement in EF >5%. Results With a mean follow up of 53 ± 11 months, response rate to CRT was 81%. Mean EF improved from 26 ± 10% to 37 ± 11%, and mean left ventricular end-diastolic diameter reduced from 68.6 ± 9.2 mm to 57.8 ± 9.3 mm. Predictors of response were sinus rhythm, high dyssynchrony index and intrinsic electrical dyssynchrony >80ms. Successful LV lead implantation at initial procedure was achieved in 99.1%, and at latest follow up 94.6% of initial LV leads were still active. Conclusion CRT undertaken with a unit focus on optimal LV lead positioning and device optimisation, along with a multidisciplinary follow-up model, results in an excellent response rate to CRT. [ABSTRACT FROM AUTHOR]

Research on disclosure among heterosexual adult person(s) living with HIV (PLH) was reviewed, omitting disclosure of parental HIV to children. Disclosure has been studied within five additional relational contexts: with partners, family members, friends, healthcare professionals and in work settings. Disclosure is higher among women than men, among Latino and white compared to African-American families, and among younger compared to older HIV-positive adults. Most PLH disclose to their sexual partners and family members, yet there is a significant minority who do not disclose. Similarly, rates of disclosure to employers range from 27-68%, suggesting broad variability in perceived consequences of employment disclosures. Of concern, 40% of PLH do not consistently disclose to their healthcare professionals. Rather than examine HIV disclosures in the context of relationships, it is possible to understand disclosures around personal identity. Disclosure decisions are often made to tell everyone (making HIV status a central attribute of one's identity), no one (requiring strategies for securing social support while remaining anonymous) or some people (requiring strategic decisions based on context). Given that disclosure decisions are central to personal identity, future data on disclosure and interventions designed to increase disclosure or comfort with disclosure must focus on communication strategies adopted by PLH to present a coherent identity. [ABSTRACT FROM AUTHOR]

For n = 2,3 and finite field 피 of characteristic greater than n, we provide a complete and irredundant list of soluble irreducible subgroups of GL(n,피). The insoluble irreducible subgroups of GL(2,피) are similarly determined. Each group is given explicitly by a generating set of matrices. The lists are available electronically. [ABSTRACT FROM AUTHOR]

We describe an algorithm for explicitly listing the irreducible monomial subgroups of GL(n,q), given a suitable list of finite irreducible monomial subgroups of ${\rm GL}(n,{\mathbb C})$, where n is 4 or a prime, and q is a prime power. Particular attention is paid to the case n=4, and the algorithm is illustrated for n=4 and q=5. Certain primitive permutation groups can be constructed from a list of irreducible monomial subgroups of GL(n,q). The paper's final section shows that the computation of automorphisms of such permutation groups reduces mainly to computation of irreducible monomial subgroups of GL(n,q), q prime. [ABSTRACT FROM AUTHOR]

OBJECTIVE: To determine trends and sexual risk behaviors associated with anal intercourse among college women over an 8-year period. METHODS: A sexual activity questionnaire was used to collect data from 813 students enrolled in a women's health course. RESULTS: Thirty-two percent of the women had engaged in anal intercourse, and this measure was consistent across time. Women who had engaged in anal intercourse were significantly younger at first intercourse and had a greater lifetime number of partners and more reported STIs. CONCLUSION: This study underscores the importance of expanding our understanding of sexual behaviors of college women and openly addressing anal intercourse as a part of the sexual repertoire of college women. [ABSTRACT FROM AUTHOR]

Avian leukosis virus of subgroup J (ALV-J), isolated in the late 1980s, predominantly causes myelocytic myeloid leukosis in meat-type chickens. In the past few years, we have observed the occurrence of lesions indicative of erythroblastosis in ALV-J-infected flocks and, in this paper, we report the isolation of ALV-J strains from such flocks. Three of these isolates were acutely transforming viruses, as shown by their ability to transform bone marrow cell cultures. The bone marrow cultures transformed by these virus isolates were very similar to the myeloid cells transformed by the ALV-J strain 966. However, the infection of meat-type chickens with these isolates either as embryos or as 1-day-old chicks resulted in the induction of erythroblastosis as well as myelocytomatosis. Other histopathological changes observed in the inoculated birds included neoplastic lesions such as cholangioma and testicular cell tumour, and non-neoplastic lesions such as lymphomyeloid hyperplasia. This report demonstrates that highly oncogenic ALV-J, capable of inducing a different spectrum of disease other than the widely reported myelocytomatosis, could be established in naturally infected flocks. [ABSTRACT FROM AUTHOR]

Avian leukosis virus subgroup J (ALV-J), isolated in the late 1980s, predominantly causes myelocytic myeloid leukosis in meat-type chickens. In the past 10 years, ALV-J infection has become very widespread, causing serious problems to the chicken meat industry. Previously, we have shown that turkey cells can be infected in vitro with Rous sarcoma virus pseudotypes of ALV-J. In this paper, we extend those observations to show that turkey monocyte cultures can be transformed in vitro with acutely transforming ALV-J strain 966. We also show that turkeys are experimentally susceptible to infection with ALV-J prototype strain HPRS–103. However, neoplastic lesions were not observed in these birds, probably due to the short experimental period of 10 weeks. When inoculated into 1-day-old turkey poults, acutely transforming ALV-J strain 966 induced tumours between 3 and 4 weeks after infection. Most of the birds showed tumours involving the liver, with histopathological lesions of myelocytomatosis. The demonstration of the spread of HPRS–103 by contact among turkeys, although observed only at low levels in the present study, stresses the importance of segregation of turkey and chicken breeding operations to avoid the spread of ALV-J infection. [ABSTRACT FROM AUTHOR]

Objective: To discuss the connections between multicultural education, service learning, and the development of professional competencies. Methods: Qualitative data were collected from reflective papers, classroom observations, and pamphlets of students (n=125) involved in communitybased learning. Results: The findings of the study revealed three major themes related to service learning and cultural competence: (1) the development of 'ethnic consciousness' (2) the importance of both personal and intellectual development for cultural competence with regard to health issues and (3) the role of service learning in empowering students to be contributing citizens to their community. Conclusion: Community-based service learning moves students beyond cultural awareness toward the development of cultural competence that is grounded in both health education and in the realities and complexities of a multicultural community. [ABSTRACT FROM AUTHOR]