297 research outputs found
Invertebrate Egg and Plant Seed Banks in Natural, Restored, and Drained Wetlands in the Prairie Pothole Region (USA) and Potential Effects of Sedimentation On Recolonization of Hydrophytes and Aquatic Invertebrates
Sediment is the major pollutant of wetlands, lakes, rivers, and estuaries in the United States and it poses unique threats to wetlands of the Prairie Pothole Region (PPR). Sediment may impact the success of wetland restorations because burial of invertebrate and plant propagules may impact hatching and germination success, and hence, may hamper successional changes throughout interannual climate cycles. Sedimentation also reduces the pool depth and volume, further exacerbating the recovery of hydrophyte communities in restored wetlands. I evaluated the potential impacts of sedimentation on prairie wetlands from several perspectives. First, I evaluated the effects of sedimentation on loss of wetland pool depth and volume, and secondly, I examined the effect of sediment load on emergence of plants and invertebrates from seed and invertebrate egg banks. Additionally, I compared the seed and invertebrate egg bank composition of high quality reference wetlands (i.e., having no history of cultivation) to previously farmed nondrained, restored, and drained seasonal and semipermanent wetlands in the Missouri and Prairie Coteau, and Glaciated Plain physiographic regions of the PPR. My results demonstrated that previously farmed wetlands of all categories had greater mean (± SE) accretion (0.26 ± 0.02 cm yr·1) and mass accumulation (0.268 ± 0.027 g cm·2 yr·1) rates of sediments than non-farmed reference wetlands (0.08 ± 0.03 cm yr·1, 0.068 ± 0.034 g cm·2 yr-1). Projected over the next 200 years, I estimated that cultivated and reference wetlands would accrete significant quantities of sediment, resulting in a 57% and 18% loss, respectively, in the number of wetlands capable of attaining water depths ≥ 1 m. Wetland pool depths ≥ 1 m are important for the establishment of vegetative zones during seasonal and interannual wet and dry periods. Also, over the next 200 years, I estimated that 50% and 20% of the wetland volume (203 hectare-meters) would be lost based on my estimated accretion rates for cultivated and reference wetlands, respectively. Egg bank hatching success in seasonal wetlands was lowest in drained wetlands. Drained and restored semipermanent wetlands in the Glaciated Plain and Missouri Coteau also had poorer hatching success than reference and nondrained wetlands. More restored seasonal wetlands in the Coteau regions attained taxon richness similar to reference and nondrained wetlands than in the Glaciated Plain. Within 5 years after restoration, most restored seasonal wetlands contained viable invertebrate egg banks, but I was unable to detect a significant increase in taxon richness and invertebrate abundance with restoration age. Hatching success and abundance of invertebrate egg banks in restored semipermanent wetlands were lower than in seasonal wetlands. Trends indicated that for all regions and wetland classes, reference wetlands had greater perennial-native seed density, tax on richness, floristic quality, and fewer annual species than nondrained, restored, and drained wetlands. However, most comparisons of perennial-native response variables were found to be similar among nondrained, restored,and drained wetlands. I found no increase in the floristic quality of seed banks as restored wetlands aged. Sediment load experiments showed burial of seed and egg banks with sediment depths as little as 0.5 cm virtually halted invertebrate and seedling emergence. My results show that intensive agriculture has negatively impacted seed and invertebrate egg banks in both restored and nondrained wetlands, and that active planting or donor material will be needed to restore certain wetland communities. Results of my burial experiments on seedling emergence corroborated prior research; however, my research also demonstrated that invertebrate emergence is equally impacted by sediment burial. Agricultural activities in the PPR appear to have caused significant loss in wetland volume and depth that have potential to alter the success of wetland restorations. Agricultural conservation strategies need to be implemented to reverse this trend and keep valuable topsoil in place for agricultural production
University Distance Learning Program Promotion
With the rapid development of online programs, there have been few studies in the marketing literature focusing on the promotion of distance learning (DL) programs. This study chooses a university’s master level DL program exploring how the current students initially found the program. The results of the study can be used to aid in determining the most effective way to reach and attract potential students to the program. A survey method with 138 respondents is use
Regulation of genes affecting body size and innate immunity by the DBL-1/BMP-like pathway in Caenorhabditis elegans
<p>Abstract</p> <p>Background</p> <p>Bone morphogenetic proteins (BMPs) are members of the conserved transforming growth factor β (TGFβ superfamily, and play many developmental and homeostatic roles. In <it>C. elegans</it>, a BMP-like pathway, the DBL-1 pathway, controls body size and is involved in innate immunity. How these functions are carried out, though, and what most of the downstream targets of this pathway are, remain unknown.</p> <p>Results</p> <p>We performed a microarray analysis and compared expression profiles of animals lacking the SMA-6 DBL-1 receptor, which decreases pathway signaling, with animals that overexpress DBL-1 ligand, which increases pathway signaling. Consistent with a role for DBL-1 in control of body size, we find positive regulation by DBL-1 of genes involved in physical structure, protein synthesis and degradation, and metabolism. However, cell cycle genes were mostly absent from our results. We also identified genes in a <it>hedgehog</it>-related pathway, which may comprise a secondary signaling pathway downstream of DBL-1 that controls body size. In addition, DBL-1 signaling up-regulates pro-innate immunity genes. We identified a reporter for DBL-1 signaling, which is normally repressed but is up-regulated when DBL-1 signaling is reduced.</p> <p>Conclusions</p> <p>Our results indicate that body size in <it>C. elegans </it>is controlled in part by regulation of metabolic processes as well as protein synthesis and degradation. This supports the growing body of evidence that suggests cell size is linked to metabolism. Furthermore, this study discovered a possible role for <it>hedgehog</it>-related pathways in transmitting the BMP-like signal from the hypodermis, where the core DBL-1 pathway components are required, to other tissues in the animal. We also identified the up-regulation of genes involved in innate immunity, clarifying the role of DBL-1 in innate immunity. One of the highly regulated genes is expressed at very low levels in wild-type animals, but is strongly up-regulated in Sma/Mab mutants, making it a useful reporter for DBL-1/BMP-like signaling in <it>C. elegans</it>.</p
Optic Nerve Sheath Mechanics in VIIP Syndrome
Visual Impairment and Intracranial Pressure (VIIP) syndrome results in a loss of visual function and occurs in astronauts following long-duration spaceflight. Understanding the mechanisms that lead to the ocular changes involved in VIIP is of critical importance for space medicine research. Although the exact mechanisms of VIIP are not yet known, it is hypothesized that microgravity-induced increases in intracranial pressures (ICP) drive the remodeling of the optic nerve sheath, leading to compression of the optic nerve which in turn may reduce visual acuity. Some astronauts present with a kink in the optic nerve after return to earth, suggesting that tissue remodeling in response to ICP increases may be taking place. The goal of this work is to characterize the mechanical properties of the optic nerve sheath (dura mater) to better understand its biomechanical response to increased ICP
2006 SQ372: A Likely Long-Period Comet from the Inner Oort Cloud
We report the discovery of a minor planet (2006 SQ372) on an orbit with a
perihelion of 24 AU and a semimajor axis of 796 AU. Dynamical simulations show
that this is a transient orbit and is unstable on a timescale of 200 Myrs.
Falling near the upper semimajor axis range of the scattered disk and the lower
semimajor axis range of the Oort Cloud, previous membership in either class is
possible. By modeling the production of similar orbits from the Oort Cloud as
well as from the scattered disk, we find that the Oort Cloud produces 16 times
as many objects on SQ372-like orbits as the scattered disk. Given this result,
we believe this to be the most distant long-period comet ever discovered.
Furthermore, our simulation results also indicate that 2000 OO67 has had a
similar dynamical history. Unaffected by the "Jupiter-Saturn Barrier," these
two objects are most likely long-period comets from the inner Oort Cloud
Finite Element Modeling of the Posterior Eye in Microgravity
Microgravity experienced during spaceflight affects astronauts in various ways, including weakened muscles and loss of bone density. Recently, visual impairment and intracranial pressure (VIIP) syndrome has become a major concern for space missions lasting longer than 30 days. Astronauts suffering from VIIP syndrome have changes in ocular anatomical and visual impairment that persist after returning to earth. It is hypothesized that a cephalad fluid shift in microgravity may increase the intracranial pressure (ICP), which leads to an altered biomechanical environment of the posterior globe and optic nerve sheath (ONS).Currently, there is a lack of knowledge of how elevated ICP may lead to vision impairment and connective tissue changes in VIIP. Our goal was to develop a finite element model to simulate the acute effects of elevated ICP on the posterior eye and optic nerve sheath. We used a finite element (FE) analysis approach to understand the response of the lamina cribrosa and optic nerve to the elevations in ICP thought to occur in microgravity and to identify which tissue components have the greatest impact on strain experienced by optic nerve head tissues
Effects of resistance training on depression and cardiovascular disease risk in black men: Protocol for a randomized controlled trial
Background
Depression is severely undertreated in Black men. This is primarily because Black men are less likely to seek traditional psychiatric treatment, have less access and more barriers to treatment, and perceive more stigma associated with treatment. Depression contributes to cardiovascular disease (CVD), and Black men have the highest rate of mortality from CVD. Resistance training (RT) can have beneficial effects on both depression and CVD. This study will be the first randomized controlled trial to test the effects of RT on depression and cardiovascular health in a sample of depressed Black men.
Method
Fifty Black men with clinically significant symptoms of depression will be randomized to either (a) a 12-week RT or (b) an attention control group. Behavioral Activation techniques will be used to support adherence to home-based RT goals. Both groups will meet on-site twice/week during the 12-week program, and follow-up assessments will occur at the end-of-treatment and 3 months post-treatment. Qualitative interviews will be conducted after the 3-month follow-up. The objectives of this study are (1) to assess the feasibility and acceptability of recruitment, retention, and intervention procedures, (2) to obtain preliminary evidence of efficacy, and (3) to explore potential mediators of the effects of RT on depression.
Discussion
This study will advance the field of minority men\u27s health by producing new data on the effects of RT for depression, the potential mechanisms of action that may support its use, and its effects on markers of CVD risk in Black men
Quantum advantage by relational queries about physically realizable equivalence classes
Relational quantum queries are sometimes capable to effectively decide
between collections of mutually exclusive elementary cases without completely
resolving and determining those individual instances. Thereby the set of
mutually exclusive elementary cases is effectively partitioned into equivalence
classes pertinent to the respective query. In the second part of the paper, we
review recent progress in theoretical certifications (relative to the
assumptions made) of quantum value indeterminacy as a means to build quantum
oracles for randomness.Comment: 8 Pages, one figure, invited contribution to TopHPC2019, Tehran,
Iran, April 22-25, 201
The Cold Peace: Russo-Western Relations as a Mimetic Cold War
In 1989–1991 the geo-ideological contestation between two blocs was swept away, together with the ideology of civil war and its concomitant Cold War played out on the larger stage. Paradoxically, while the domestic sources of Cold War confrontation have been transcended, its external manifestations remain in the form of a ‘legacy’ geopolitical contest between the dominant hegemonic power (the United States) and a number of potential rising great powers, of which Russia is one. The post-revolutionary era is thus one of a ‘cold peace’. A cold peace is a mimetic cold war. In other words, while a cold war accepts the logic of conflict in the international system and between certain protagonists in particular, a cold peace reproduces the behavioural patterns of a cold war but suppresses acceptance of the logic of behaviour. A cold peace is accompanied by a singular stress on notions of victimhood for some and undigested and bitter victory for others. The perceived victim status of one set of actors provides the seedbed for renewed conflict, while the ‘victory’ of the others cannot be consolidated in some sort of relatively unchallenged post-conflict order. The ‘universalism’ of the victors is now challenged by Russia's neo-revisionist policy, including not so much the defence of Westphalian notions of sovereignty but the espousal of an international system with room for multiple systems (the Schmittean pluriverse)
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