13251 research outputs found
Sort by
Modeling of groundwater level changes in an urban area
No full textGroundwater level changes, mostly depletion, are widespread around the world due to the high population and industrial growth. Numerical models can provide relevant information in a data scares location and thus could be great means to save both money and time. In this study, an attempt was made to analyze changes in the groundwater level using the widely accepted MODFLOW-2005 model. This study covered 22 wards among the 41 wards of Chittagong city in Bangladesh and the simulation was run for the year 2009–2016. Compare to the observed water heads, the simulated model could reasonably predict water heads with a residual of less than 10%. From 2009 to 2016, the model outcome showed a depletion rate of about 4.75 m/year in the central part of the city. Finally, the model was run for the year 2020 to predict the future condition of the water head. From this, there are five wards in the central part facing a serious groundwater lowering problem. Thus, to save this natural resource more comprehensive strategies as well as ground extraction regulations should be made. And in this context, this study will provide an overview of this urgent issue in this city. Graphic abstract: [Figure not available: see fulltext.
EPIC 216747137: A new HW Vir eclipsing binary with a massive sdOB primary and a low-mass M-dwarf companion
No full textEPIC 216747137 is a new HW Virginis system discovered by the Kepler spacecraft during its K2 \u27second life\u27. Like the other HW Vir systems, EPIC 216747137 is a post-common-envelope eclipsing binary consisting of a hot subluminous star and a cool low-mass companion. The short orbital period of 3.87 h produces a strong reflection effect from the secondary (∼9 per cent in the R band). Together with AA Dor and V1828 Aql, EPIC 216747137 belongs to a small subgroup of HW Vir systems with a hot evolved sdOB primary. We find the following atmospheric parameters for the hot component: Teff = 40400 ± 1000 K, log g = 5.56 ± 0.06, and log(N(He)/N(H)) =-2.59 ± 0.05. The sdOB rotational velocity v sin i = 51 ± 10 km s-1 implies that the stellar rotation is slower than the orbital revolution and the system is not synchronized. When we combine photometric and spectroscopic results with the Gaia parallax, the best solution for the system corresponds to a primary with a mass of about 0.62 M close to, and likely beyond, the central helium exhaustion, while the cool M-dwarf companion has a mass of about 0.11 M
Do darters (Etheostoma sp.) in streams with introduced trout exhibit increased wariness?
No full textIntroduced predators can negatively affect native prey species via either direct predation or through indirect effects such as behavioral changes or habitat shifts that lead to declines in growth, condition, and reproductive success. In freshwater habitats, salmonid fishes are one of the most common introduced predators worldwide. Most studies of effects of salmonids on native prey species have focused on direct predation, with fewer studies examining how behavior of prey is affected. We used a snorkeling protocol to examine whether introduction of rainbow (Oncorhyuchus mykiss) and brown (Salmo trutta) trout in streams was associated with increased wariness in two small prey fishes, darters in the genus Etheostoma. Wariness was measured as flight initiation distance (FID), the distance at which individuals flee from an approaching threat (snorkeler), for darters in four rivers with and four rivers without introduced trout. Darters in rivers with trout had longer FIDs, indicating that they were less tolerant of risk than darters in control rivers. Increased wariness could lead to darters decreasing activities associated with foraging and reproduction, which could have long-term negative effects on populations of these prey fishes
Identification of Chemical Structures and Substructures via Deep Q-Learning and Supervised Learning of FTIR Spectra
No full textFourier-transform infrared (FTIR) spectra of organic compounds can be used to compare and identify compounds. A mid-FTIR spectrum gives absorbance values of a compound over the 400-4000 cm-1 range. Spectral matching is the process of comparing the spectral signature of two or more compounds and returning a value for the similarity of the compounds based on how closely their spectra match. This process is commonly used to identify an unknown compound by searching for its spectrum’s closes match in a database of known spectra. A major limitation of this process is that it can only be used to identify substances already in the database. An unknown compound not found in the database will likely match to a similar yet structurally different compound. Alternatively, FTIR has been used to identify characteristics, substructures, or functional groups of a compound based on the compounds IR spectral features. However, most works have only attempted to predict a limited set of substructures and there has only been limited success in predicting the full structure of an unknown compound based purely on its FTIR spectrum. For this thesis, I investigated the possibility of identifying compounds and identifying substructures present in the compound’s structure by analyzing the compound’s FTIR spectrum. This was dependent on the property that the infrared (IR) absorbances of a compound are the result of the physical interactions between bonded sets of atoms in the compound’s structure. I hypothesized that different instances of the same substructures will either give similar spectral signatures or some pattern of spectral signatures that could be learned using machine learning. In this thesis I show that it is possible to use convolutional neural networks (CNN) to predict the presence or absence of substructures within a compound. Finally, I demonstrate a method of making predictions for the full structure of these compounds based on the substructure predictions and the compound’s FTIR spectrum
Neuronal Migration in Developmental Hyperserotonmia: Assessment of Vesicular Glutamate in the Raphe Nuclei
No full textThe neurotransmitter serotonin is involved in the early development of the central nervous system and the organization of neurons throughout the cerebral cortex and cerebellum. It is proposed that serotonin indirectly interacts with cells in the marginal zone of the cerebral cortex known as Cajal-Retizus (CR) cells. These cells secrete the extracellular matrix protein reelin, which is known for its role in neuronal organization and migration during early neural development. It has been observed that low levels of serotonin are associated with similarly low levels of reelin during development and have been reported to result in disorganization of neurons in the cortical layers. Similarly, neuronal disorganization of the cortex has also been reported in response to increased levels of developmental serotonin which in-turn can lower serotonin levels in the developed brain due to activation of an autoregulatory negative feedback mechanisms. For reelin to be secreted by the CR cells, the neurotransmitter γ-aminobutyric acid (GABA) needs to be available to interact with the GABAA receptor on the CR cells themselves. However, GABA is associated with the Glutamate/GABA excitatory and inhibitory feedback system where high levels of glutamate will stimulate release of GABA and vice versa. These neurotransmitters regulate the activity of many key processes such as overall excitation of the brain and is proposed to have a role in the organization and migration of neurons during development. It is known that serotonin is the early regulator of glutamate release in the cell which in turn activates the release of GABA. However, it is thought that in conditions where excess serotonin is released during development (hyperserotonemia) that serotonin will inhibit glutamate release instead of activation. This study proposes to investigate the methodological processes necessary to analyze the correlation of excess developmental serotonin on the neurotransmitter glutamate. This was conducted by identifying the dorsal raphe nuclei via cresyl violet staining on control Sprague-Dawley rat brain tissues while investigation of glutamate release levels in development was performed via immunohistochemical labeling of vesicular glutamate transporters in the dorsal raphe nuclei
Rapid Diagnostic Framework for Assessing Bridge and Culvert Sensitivity to Hydraulic Forcing
No full textFlooding, intense scour, and bank erosion often contribute to the failure of bridges and culverts. While geomorphic assessment techniques have been devised to evaluate whether structures are vulnerable to the effects of high-magnitude flooding, they generally require prolonged onsite appraisals. Because of financial constraints, however, many state transportation agencies cannot hire staff dedicated solely to geomorphic assessments. As such, agencies can benefit enormously from having access to a simple, holistic, and robust method for quickly evaluating the sensitivity of bridges and culverts to severe hydraulic forcings - one that leverages data gathered during existing inspection routines and accounts for the condition of structures and their criticality. This paper outlines the development and application of the Bridge and Culvert Sensitivity Index (BCSI), which was originally created on behalf of the Kentucky Transportation Cabinet. Using information from the National Bridge Inventory and Cabinet-specific inspection data points, the BCSI (when combined with geostatistical methods and dynamic mapping) facilitates a multilevel hierarchical analysis of bridge and culvert inventories, allowing agency personnel to quickly appraise the performance of structures from the district level down to the level of individual structures. Applying the BCSI in Kentucky identified clusters of bridges and culverts in the western, eastern, and north-central parts of the state that exhibit heightened sensitivity to hydraulic forcings
Importance of costs in target date fund selection using three morningstar ratings
No full textAlthough target date mutual funds (TDFs) have only been around since the mid-1990s, they are now common vehicles for retirement investing. Sixty percent of US companies now automatically funnel employees\u27 non-directed retirement funds into TDFs, which account for nearly one-quarter of all savings US workers have in 401(k)s. Helping investors pick among TDFs, Morningstar rates past risk-adjusted performance using a star system and provides forward-looking evaluations of more than 2,500 TDFs using either Analyst Ratings or a newly implemented machine-learning-based Quantitative Ratings. Morningstar assigns Analyst Ratings to a smaller subset of TDFs that tend to have been in existence the longest and have the largest size. We find that TDFs with lower fees have significantly higher star ratings than their higher expense counterparts. No-load TDFs have significantly higher star ratings than their load-charging counterparts. In assessing future fund prospects, TDFs with low expense ratios are favored by both analysts and artificial intelligence. TDFs without load charges have significantly better Quantitative Ratings than their load charging counterparts. TDFs with Quantitative Ratings tend to be smaller, younger, and have poorer prior performance than TDFs with Analyst Ratings
Motivational Factors Affecting Recruitment and Retention in the Clever Band Program
No full textStudent participation in band has many educational, social, and life benefits for students; however, high attrition rates reflect that many students are not motivated to join and continue in band. This study surveyed sixth, eighth, and tenth grade students in the Clever R-V School District to examine the factors that the students self-identify when deciding to enroll in and persist with band in school. The survey data were analyzed to identify key factors that affect students’ recruitment and retention in school band. Students answered forty multiple choice questions that addressed areas of motivation including parental support, teacher-student relationship, intrinsic motivation, peer involvement, extrinsic motivation, financial aspects, competition versus ego, and the approach success/avoid failure component of goal orientation theory. The participants also answered seven or eight short answer questions that examined each student’s specific perception and experience regarding band recruitment and retention. The survey results indicated that some of the motivational factors that affect students’ decisions the most are peer involvement, teacher-student relationships, intrinsic motivation, and extrinsic motivation. Two larger motivational themes that the students identified through their short answer responses were band being fun and band offering social opportunities. This survey could help music educators in any school to recognize how some students perceive the band experience and could also help teachers to better inform their recruiting processes and teaching practices in order to make participation in band accessible for as many students as possible
Centrosymmetric or Noncentrosymmetric? Transition Metals Talking in K\u3csub\u3e2\u3c/sub\u3eTGe\u3csub\u3e3\u3c/sub\u3eS\u3csub\u3e8\u3c/sub\u3e(T = Co, Fe)
No full textTwo new quaternary sulfides K2TGe3S8(T = Co, Fe) have been synthesized by a high-temperature solid-state routine and flux growth method. The crystal growth process of K2TGe3S8(T = Co, Fe) was elucidated by in situ powder X-ray diffraction and DSC thermal analysis. The millimeter-sized crystals of K2TGe3S8(T = Co, Fe) were grown. K2CoGe3S8 crystallizes in a new structure type in centrosymmetric space group P1 (no. 2) with unit cell parameters of a = 7.016(1) Å, b= 7.770(1) Å, c = 14.342(1) Å, α = 93.80(1)°, β = 92.65(1)°, γ= 114.04(1)°. K2FeGe3S8 crystallizes in the K2FeGe3Se8 structure type and the noncentrosymmetric space group P21 (no. 4) with unit cell parameters of a = 7.1089(5)Å, b = 11.8823(8) Å, c = 16.7588(11) Å, β = 96.604(2)°. There is a high structural similarity between K2CoGe3S8 and K2FeGe3S8. The larger volume coupled with higher degrees of distortion of the [FeS4] tetrahedra compared to the [CoS4] tetrahedra accounts for the structure\u27s shift from centrosymmetric to noncentrosymmetric. The theory simulation confirms that [TS4]T= Co or Fe tetrahedra play a crucial role in controlling the structure and properties of K2TGe3S8(T = Co, Fe). The measured optical bandgaps of K2CoGe3S8 and K2FeGe3S8 are 2.1(1) eV and 2.6(1) eV, respectively. K2FeGe3S8 shows antiferromagnetic ordering at 24 K while no magnetic ordering was detected in K2CoGe3S8. The magnetic measurements also demonstrate the divalent nature of transition metals in K2TGe3S8(T = Co, Fe)