School of Natural Sciences Faculty Publications

Permanent link for this collectionhttps://hdl.handle.net/2022/27422

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    A tree-ring chronology and paleoclimate record for the Younger Dryas–Early Holocene transition from northeastern North America
    (John Wiley and Sons Ltd, 2017-03-17) Griggs, Carol; Peteet, Dorothy; Kromer, Bernd; Grote, Todd; Southon, John
    Spruce and tamarack logs dating from the Younger Dryas and Early Holocene (YD–EH; ∼12.9–11.3k cal a BP) were found at Bell Creek in the Lake Ontario lowlands of the Great Lakes region, North America. A 211-year tree-ring chronology dates to ∼11 755–11 545 cal a BP, across the YD–EH transition. A 23-year period of higher year-to-year ring-width variability dates to around 11 650 cal a BP, infers strong regional climatic perturbations and may represent the end of the YD. Tamarack and spruce were dominant species throughout the YD–EH interval at the site, indicating that boreal conditions persisted into the EH, in contrast to geographical regions immediately south and east of the lowlands, but consistent with the Great Lakes interior lowlands. This infers that Bell Creek was at the eastern boundary of a boreal ecotone, perhaps a result of its lower elevation and the non-analog dynamics of the Laurentide Ice Sheet. This finding suggests that the ecotone boundary extended farther east during the YD–EH transition than previously thought.
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    Temporal and spatial patterns of hydroclimate variability related to the Pacific Decadal Oscillation in Michigan, USA
    (Taylor and Francis Ltd., 2024-02-15) Grote, Todd; Suriano, Zachary
    Teleconnections play an influential role in driving atmospheric circulation and hydroclimatic variability at regional and global scales. While hydroclimatic conditions are associated with the Pacific Decadal Oscillation (PDO) throughout North America, to date there has been limited study on the influence of the PDO on the hydroclimate of Michigan. Using statistical analyses, this study quantified the mean monthly streamflow, precipitation and temperature characteristics in climate divisions and stream gage stations in both the Upper and Lower Peninsulas of Michigan during the warm (+) and cool (-) phases of the PDO from 1967 to 2018. Streamflow is greater statewide during PDO+ phases compared to during PDO- phases, and most prominent from August to February. During the peak month of streamflow difference by PDO phase, November, there was a streamflow increase of nearly 26% during PDO+ phases compared to the long-term mean. In relation, mean monthly precipitation increased (decreased) statewide from August to November during PDO+ (PDO-) phases, with decreased (increased) monthly precipitation from December to July. This study advances our understanding of the PDO’s influence on hydroclimatic variability in Michigan, presenting novel results at intra-seasonal scales in this highly impactful and populated region.
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    A synoptic climatology of rain-on-snow flooding in Mid-Atlantic region using NCEP/NCAR Re-Analysis
    (Taylor and Francis Ltd., 2020-10-29) Grote, Todd
    Rain-on-snow (ROS) flooding is common throughout the Appalachians and Mid-Atlantic region primarily during late winter and spring. Six recent (2007–2013) widespread snowmelt-related flood events throughout Pennsylvania and other Mid-Atlantic states are used to gain an understanding of synoptic-scale atmospheric conditions that generate annual maximum flows for the region. NCEP/NCAR Re-analysis output for six individual case studies and an all-event composite suggest similar synoptic-scale atmospheric conditions lead to widespread ROS flooding. Snow ablation and subsequent flooding are heavily influenced by the low-level (850 mb Low Level Jet) advection of warm, moist air from the Gulf of Mexico and Atlantic Ocean around an area of high pressure off the Atlantic Coast towards low pressure in the mid-continent. An anomalously deep 500mb trough in the mid-continent aids in steering heat and moisture into the study area. The sustained advection of warm, moist air into the region allows for the snowpack to first ripen and then ablate, thus producing widespread ROS flooding throughout the study area. Although regional snowpack ablation combined with liquid precipitation drive ROS flooding, the impact of antecedent soil moisture or frozen ground should not be overlooked. New information presented herein provides flood forecasters identifiable synoptic-scale features that may precede ROS flooding.
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    Factors contributing to the biodiversity value of an archaeological landscape in Jordan
    (British Herpetological Society, 2022-07) Attum, Omar; Malkawi, Sufian; Hamidan, Nashat
    Archeological landscapes are important places because they protect areas of historical importance, shape cultural and national identity, are recreational spaces, and vital sources of tourism revenue. Archaeological landscapes have the potential to assist in reptile conservation. The objective of this study was to compare the diurnal reptile richness of an archaeological site to the reptile richness of a nature reserve (treatment control for biodiversity value) and a modern olive grove (treatment control for poor biodiversity value). Our results suggest that archaeological landscapes provide valuable reptile habitat, as our archaeological site supported similar reptile richness as the natural site, with both sites having higher species richness than the modern olive tree farm. The high reptile richness and densities were the result of high potential food availability and habitat mosaic of relatively low tree density and open areas with exposed, tall, rocky ruins. Reptile richness had a negative relationship with tree density. The ruins and high food availability of the archaeological site supported higher densities of saxaphilic lizard species as the density of these species increased as mean maximum rock height and percentage of green ground vegetation cover increased. Promoting the reptile richness of archaeological sites provides another justification for the protection and visitor appreciation for archaeological sites as places of historical, cultural and biodiversity importance.
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    Using the 11-point biplane and L 2 ( 11 ) to understand J 1
    (Rocky Mountain Mathematics Consortium, 2022-02) Horine, Thomas
    In this paper, we use the 11-point biplane and its automorphisms in L2(11) to label and study the Livingstone graph (0) and J1, with an aim of using the simplest methods possible. We detail the action of J1 on 0, along with the adjacencies and coadjacencies (vertices at maximum distance) in 0. In the last section, we use this apparatus to describe the generation of subgroups of the form 23 : 7 : 3 and an elegant substructure of 0 fixed by a maximal subgroup of J1 isomorphic to 19 : 6.
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    Revisiting the Least Force Required to Keep a Block from Sliding
    (American Institute of Physics, 2013-03-11) De, Subhranil
    This article pertains to a problem on static friction that concerns a block of mass M resting on a rough inclined plane. The coefficient of static friction is μs and the inclination angle θ is greater than tan−1 μs. This means that some force F must be applied (see Fig. 1)1 to keep the block from sliding down the incline. Familiar textbook versions of this problem ask for the minimum value of F when it is applied in a certain specified direction, for example, parallel to the incline (φ= 0 in Fig. 1) or perpendicular to the incline (φ= 90°). Here, we generalize the problem by allowing the direction of the force to be adjustable and asking what the absolute minimum value of F is in order to keep the block from sliding.
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    Computational study of the propagation of the longitudinal velocity in a polymer melt contained within a cylinder using a scale-bridging method
    (American Physical Society, 2013-11-20) De, Subhranil
    The “constitutive equation”–free scale-bridging method connecting nonequilibrium molecular dynamics and continuum fluid mechanics, that had hitherto been applied only to a parallel-plates geometry, is extended to study the flow of a polymer melt in a cylindrical pipe subject to a velocity in the direction parallel to the cylinder's axis. The system, initially at rest, is given a velocity at the cylinder's surface, and the evolution of the velocity profile within the fluid is studied, along with the time taken for the velocity to propagate toward the cylinder's axis. The said time of propagation is found to increase with the boundary velocity—a fact in contrast with the case of a Newtonian fluid for which the time of propagation is expected to be independent of the boundary velocity. For a fixed value of the boundary velocity, the propagation time is found to increase with the cylinder radius according to a power law with an exponent that is smaller than the corresponding exponent for a Newtonian fluid. For the lower values of the boundary velocity and the lower values of the radius studied, a velocity overshoot is observed at the cylinder's axis—a manifestation of elastic behavior of the fluid.
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    Revisiting the sliding ladder
    (Cambridge University Press, 2015-01-23) De, Subhranil
    A uniform ladder leaning against a wall, or sliding down against a wall, is a familiar theme in introductory mechanics and calculus courses, made popular in recent years by several papers pertaining to its various intriguing aspects and important limitations. This configuration is particularly well-known in the context of static equilibrium where the friction exerted by the floor keeps the ladder from sliding [1]. The situation involving the ladder sliding down instead of being static is a staple topic of calculus courses, although usually only from a geometric point of view. The physics of the sliding ladder was addressed in [2, 3, 4], none of which took friction into consideration. In the present work we study in detail a situation involving a ladder sliding between a rough wall and a frictionless floor. This is a situation where in spite of the presence of friction the ladder is still destined to slide down, no matter how large the friction coefficient between the wall and the ladder is. As we will establish in this paper, in spite of the friction present, the ladder must always be speeding up while sliding down, until it breaks off the wall at some critical angle.
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    On static equilibrium of a hemispheroid
    (Cambridge University Press, 2015-01-23) De, Subhranil
    In the course of a coffee-table conversation with my friends regarding the nature of static equilibrium of different solid objects the situation involving a uniform hemisphere came up. Intuition (and perhaps experience) tells that a uniform hemisphere as shown in Figure 1 resting on a flat surface will be at stable equilibrium, and so will an oblate hemispheroid as shown in Figure 2. Things get complicated when we move to a prolate hemispheroid like the one shown in Figure 3, for the nature of its equilibrium is less obvious. The intuition does come to mind though that if the prolate hemispheroid is made indefinitely taller, keeping its equatorial radius fixed, then the equilibrium should eventually become unstable. Intrigued, we decided to probe into the matter quantitatively.
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    Getting clever with the sliding ladder
    (IOP Publishing Inc., 2014-01-01) De, Subhranil
    The familiar system involving a uniform ladder sliding against a vertical wall and a horizontal floor is considered again. The floor is taken to be smooth and the wall to be possibly rough—a situation where no matter how large the static friction coefficient between the ladder and the wall, the ladder cannot lean at rest and must slide down. Clever arguments that circumvent fully fledged mathematical analyses are presented to establish two more interesting properties: no matter how large the kinetic friction coefficient between the ladder and the wall, (a) the ladder must be speeding up at all times while sliding down, and (b) the ladder must break off the wall at some point during its slide. This work serves as an example of an intuitive rather than a mathematically detailed approach that often provides a shorter route to understanding the properties of a physical system, making it pedagogically valuable. It is also shown how the arguments presented can be easily extended to a non-uniform ladder as well.
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    The magic of the gravity-defying cylinder
    (IOP Publishing Inc., 2016-01-05) De, Subhranil
    The motion of an eccentrically loaded circular hoop is analysed when it rolls without slipping in such a way that its centre of mass stays at the same vertical height, ensuring the conservation of kinetic energy of the hoop. The equation of the required path for such rolling is derived. Although the kinetic energy of the rolling hoop remains constant, its distribution into the rotational mode and the translational mode keeps varying. As a result, it turns out that the hoop's geometric centre actually speeds up while the hoop rolls up its path, and slows down on its way down. This presents the idea of demonstrating an apparently gravity-defying situation where a closed right circular cylinder that is actually eccentrically loaded on the inside is utilised. Since its centre must speed up as it gains vertical height, and vice versa, the cylinder would look as if going against gravity.
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    Weebles Only Wobble But Eggs Fall Down
    (Taylor & Francis, 2017-12-22) De, Subhranil
    Why does a roly-poly toy tend to stand upright on its less pointed end while an egg does not? The answer lies in a simple principle that governs the nature of the mechanical equilibrium of a solid of revolution. A roly-poly toy is at a stable equilibrium on its vertex while an egg is at an unstable equilibrium. The roly-poly toy's center of mass is vertically below the center of curvature of its vertex, while for the egg it is the other way around. Although this simple but powerful principle is known, in this article we present a contrasting analysis that not only verifies this principle, but also provides the answer to another interesting question: Is there another simple principle that governs the nature of the equilibrium in the critical situation where the center of curvature of the vertex happens to coincide with the center of mass?
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    Background, approaches, and resources for teaching energy in environmental studies
    (Springer, 2021-04-19) Forinash, Kyle; Perkins, John; Whitten, Barbara
    Production and use of energy have figured prominently in environmental studies and sciences (ESS) for many years, and it is particularly relevant to enduring themes, such as climate change, environmental justice, ecosystem disruption, and the study of natural resources. Despite its acknowledged centrality, relatively few ESS courses have delved into the intricacies of energy in a broad interdisciplinary framework. This paper encourages the development and improvement of such courses but recognizes that ESS faculty will have to select topics and resources to match their own abilities and interests and the needs of their students. The paper (a) proposes a framework for conceptual content and (b) suggests numerous resources organized in 5 categories and 17 subcategories. Each subcategory has an explanation of its role in the larger picture about energy, and each resource has a brief annotation about its content and utility. Future work on energy in ESS should address pedagogical techniques, different ways of integrating perspectives from different disciplines, and the needs of specific subsets of ESS courses and programs.
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    The use of demographic data to monitor population trends of the Nubian Ibex, Capra nubiana in Jordan
    (Taylor & Francis, 2022-01-07) Attum, Omar; Awaji, Malik; Bender, Louis
    The population status of the IUCN vulnerable Nubian Ibex Capra nubiana is largely unknown in the Middle East because of difficulties conducting intensive surveys. We tested the utility of camera-trapping at permanent water sites to estimate demographics and population trend of the species in the Dana Biosphere Reserve, Jordan. We also studied the relationship between precipitation and the Normalized Difference Vegetation Index NDVI on water site use by the Nubian Ibex, demographics, and population trend. The Nubian Ibex showed a mean annual productivity of 0.81 neonate/female and an adult female survival of 0.87 which is a lower survival rate than found in other ibex species. The mean potential annual rate of increase of this population (λ=1.14) was similar to those reported from other ibex species and indicated a viable population. The capture rate of camera traps (number of photographed animals/camera day) was found not to be a reliable index to monitor population trends because water site use was related to environmental conditions that could not be standardized or predicted a priori. Quantifying population demographic ratios using camera trapping allowed for monitoring the status of key population parameters and growth potential of Nubian Ibex populations in the Dana Reserve, and likely can be used to monitor population status and facilitate informed management of similar populations in the Middle East.