Implementing Tactile Learning to Aid Students Understanding of the Bohr Model

It is essential for introductory level chemistry students to understand atomic models and how atoms interact to form chemical bonds. The tactile model in this article utilizes marbles to represent subatomic particles, a cup to represent the nucleus and wooden rings to simulate the electron orbitals. These inexpensive items can be combined to construct models in which students can build foundational knowledge of atomic structure and how subatomic particles interact. Students were asked to provide feedback comparing the use of this tactile model to atomic computer simulations, videos and their textbook regarding the method they felt was most useful to learn atomic structure

Livestock depredation by large carnivores in northern Botswana

Often, however, conservation agencies and governments do not have a proper understanding of conflicts prior to establishing mitigation programs or are unable to collect the appropriate data to verify claims of livestock loss. We investigated livestock depredation events in the Eastern Panhandle of the Okavango Delta, Botswana between October 2014 and December 2016 and compared these investigations with concurrent Problem Animal Control (PAC) information from the Botswana Department of Wildlife and National Parks (DWNP) compensation program. Only animals killed in livestock enclosures or while being herded qualify for reimbursement through the compensation program, but DWNP is typically unable to verify claims. We identified wildlife sign at the depredation event location and collected information from the livestock owner to determine the species responsible for the attack, time of the attack, the livestock lost, and the husbandry methods employed. In total, 116 livestock were killed and 13 more injured in 102 confirmed wild carnivore attacks. Most (90%) attacks occurred while livestock were unattended and freely grazing in multi-use, communal areas. Cows, oxen (castrated male cows) and calves (Bos taurus and B. t. indicus) were killed most often and African lions (Panthera leo) were responsible for 74% of investigated attacks, while African wild dogs (Lycaon pictus) accounted for 13%, leopard (Panthera pardus) 8%, and spotted hyena (Crocuta crocuta) 5%. Valuation of verified losses totaled ∼$30,000 over the study period. There were 50% more events reported to DWNP for compensation than we confirmed through independent investigations. In its current form, the compensation program does not seem sustainable, nor does it enable the verification of claims. While compensation programs should not be abandoned, programs designed to provide monetary reimbursement for losses caused by predators should require timely reporting and in-depth investigation of depredation events. Additional conflict mitigation strategies should target increasing livestock husbandry methods in the area, with a specific focus on herding

Strontium Isotopic Variations of Neoproterozoic Seawater: Implications for Crustal Evolution

We report high precision Sr isotopic data on carbonates from the Neoproterozoic Shaler Group, Victoria Island, Northwest Territories, Canada. Lithostratigraphic correlations with the relatively well-dated Mackenzie Mountains Supergroup constrain Shaler deposition to approximately 770-880 Ma, a range corroborated by 723 +/- 3 Ma lavas that disconformably overlie Shaler carbonates and by Late Riphean microfossils within the section. Samples with low Rb-87/Sr-86 ratios (< 0.01) were selected for Sr isotopic analysis. delta-O-18, Mn, Ca, Mg, and Sr data were used to recognize altered samples. The altered samples are characterized by high Mn/Sr (greater-than-or-equal-to 2) and variable delta-O-18; most are dolomites. The data indicate that between ca. 790-850 Ma the Sr-87/Sr-86 ratio of seawater varued between 0.70676 and 0.70561. The samples show smooth and systematic variation, with the lowest Sr-87/Sr-86 value of 0.70561 at ca. 830 Ma. The low Sr-87/Sr-86 ratio of carbonates from the lower parts of our section is similar to a value reported for one sample from the Adrar of Mauritania (almost-equal-to 900 Ma), West African Craton. Isotopic ratios from the upper part of the Shaler section are identical to values from the lower part of the Neoproterozoic Akademikerbreen Group, Spitsbergen. Although a paucity of absolute age determinations hinders attempts at the precise correlation of Neoproterozoic successions, it is possible to draw a broad outline of the Sr isotopic composition of seawater for this period. Indeed, the Sr isotope data themselves provide a stratigraphic tool of considerable potential. Data from this study and the literature are used to construct a curve of the Sr-87/Sr-86 ratio of Neoproterozoic seawater. The new data reported in this study substantially improve the isotopic record of Sr in seawater for the period 790-850 Ma. The Sr isotope composition of seawater reflects primarily the balance between continental Sr input through river input and mantle input via hydrothermal circulation of seawater through mid-ocean ridges. Coupling of Nd and Sr isotopic systems allows us to model changes in seafloor spreading rates (or hydrothermal flux) and continental erosion. The Sr hydrothermal flux and the erosion rate (relative to present-day value) are modeled for the period 500-900 Ma. The results indicate that the hydrothermal flux reached a maximum value at ca. 830 Ma. In contrast, a large peak in erosion rate is indicated at ca. 570 Ma. The peaks in hydrothermal flux and erosion rate are most likely related to developments in the Pan-African and related orogenic events, whose initial development is characterized by production of juvenile crust during supercontinental break up and rifting. The time ca. 570 Ma is characterized by continent-continent collision and production of recycled crust. Sr isotope data from Proterozoic carbonates offer a valuable resource for understanding large-scale crust dynamics.Earth and Planetary SciencesOrganismic and Evolutionary Biolog

The validity and reliability characteristics of the M-BACK Questionnaire to assess the barriers, attitudes, confidence, and knowledge of mental health staff regarding metabolic health of mental health service users

Background: Addressing the burden of poor physical health and the subsequent gap in life expectancy experienced by people with mental illness is a major priority in mental health services. To equip mental health staff with the competence to deliver evidence-based interventions, targeted staff training regarding metabolic health is required. In order to evaluate the effectiveness of staff training regarding metabolic health, we aimed to develop a succinct measure to determine the barriers, attitudes, confidence, and knowledge of health practitioners through the development and test–retest reliability of the Metabolic-Barriers, Attitudes, Confidence, and Knowledge Questionnaire (M-BACK). Methods: The M-BACK questionnaire was developed to evaluate the impact of special-ized training in metabolic health care for mental health nurses. Content of the M-BACK was developed from a literature review and refined by an expert review panel and validated via a piloting process. To determine the test–retest reliability of the M-BACK, 31 nursing students recruited from the University of Notre Dame, Sydney completed the questionnaire on two separate occasions, 7 days apart. Intraclass correlation coefficients (ICCs) were calculated for the total score, as well as each of the four domains. Results: Pilot testing was undertaken with a sample of 106 mental health nurses with a mean age 48.2, ranging from 24 to 63 years of age, who participated in six training courses. Questionnaire development resulted in a 16-item instrument, with each item is scored on a five-point Likert scale ranging from “strongly disagree” to “strongly agree.” Test–retest reliability of the M-BACK was completed by 30 of 31 nursing students recruited, ICCs ranged from 0.62 to 0.96. Conclusion: The M-BACK is a reliable measure of the key elements of practitioner perceptions of barriers, and their knowledge, attitudes, and confidence regarding metabolic monitoring in people with mental illness. It can be used to assess the effectiveness of interventions aimed at increasing uptake of metabolic monitoring, a key component of programs to reduce the life expectancy gap in people living with severe mental illness

Integrated chronostratigraphy of Proterozoic-Cambrian boundary beds in the western Anabar region, northern Siberia

Carbonate-rich sedimentary rocks of the western Anabar region, northern Siberia, preserve an exceptional record of evolutionary and biogeochemical events near the Proterozoic/Cambrian boundary. Sedimentologically, the boundary succession can be divided into three sequences representing successive episodes of late transgressive to early highstand deposition; four parasequences are recognized in the sequence corresponding lithostratigraphically to the Manykai Formation. Small shelly fossils are abundant and include many taxa that also occur in standard sections of southeastern Siberia. Despite this coincidence of faunal elements, biostratigraphic correlations between the two regions have been controversial because numerous species that first appear at or immediately above the basal Tommotian boundary in southeastern sections have first appearances scattered through more than thirty metres of section in the western Anabar. Carbon- and Sr-isotopic data on petrographically and geochemically screened samples collected at one- to two-metre intervals in a section along the Kotuikan River, favour correlation of the Staraya Reckha Formation and most of the overlying Manykai Formation with sub-Tommotian carbonates in southeastern Siberia. In contrast, isotopic data suggest that the uppermost Manykai Formation and the basal 26 m of the unconformably overlying Medvezhya Formation may have no equivalent in the southeast; they appear to provide a sedimentary and palaeontological record of an evolutionarily significant time interval represented in southeastern Siberia only by the sub-Tommotian unconformity. Correlations with radiometrically dated horizons in the Olenek and Kharaulakh regions of northern Siberia suggest that this interval lasted approximately three to six million years, during which essentially all 'basal Tommotian' small shelly fossils evolved

The cell cycle regulator p27kip1 contributes to growth and differentiation of osteoblasts

The cyclin-dependent kinase (cdk) inhibitors are key regulators of cell cycle progression. p27 and p21 are members of the Cip/Kip family of cdk inhibitors and regulate cell growth by inactivating cell cycle stage-specific CDK-cyclin complexes. Because down-regulation of osteoprogenitor proliferation is a critical step for osteoblast differentiation, we investigated expression of p27 and p21 during development of the osteoblast phenotype in rat calvarial osteoblasts and in proliferating and growth-inhibited osteosarcoma ROS 17/2.8 cells. Expression of these proteins indicates that p21, which predominates in the growth period, is related to proliferation control. p27 levels are maximal postproliferatively, suggesting a role in the transition from cell proliferation to osteoblast differentiation. We directly examined the role of p27 during differentiation of osteoprogenitor cells derived from the bone marrow (BM) of p27-/- mice. BM cells from p27 null mice exhibited increased proliferative activity compared with BM cells from wild-type mice and formed an increased number and larger size of osteoblastic colonies, which further differentiated to the mineralization stage. Although p27-/- adherent marrow cells proliferate faster, they retain competency for differentiation, which may result, in part, from observed higher p21 levels compared with wild type. Histological studies of p27-/- bones also showed an increased cellularity in the marrow cavity compared with the p27+/+. The increased proliferation in bone does not lead to tumorigenesis, in contrast to observed adenomas in the null mice. Taken together, these findings indicate that p27 plays a key role in regulating osteoblast differentiation by controlling proliferation-related events in bone cells