RC Baja: DriveTrain

The American Society of Mechanical Engineers (ASME) annually hosts an RC Baja challenge, testing a RC car in three events: slalom, acceleration and Baja. Although ASME will not be holding an event this year, CWU will be holding an event with three RC Baja car teams from CWU as well as other teams from local colleges. The RC car that is tested in these events is designed and manufactured typically in teams of two. The RC car that each team submits must be able to complete these events to score points. One part of great importance for the RC car is the drivetrain. The drivetrain of the RC car will need to operate continuously through each event and without interfering with the remaining components of the RC car, namely the suspension and steering designed by Hunter Jacobson. The RC car for this year features a 540 DC electric motor cradled in a 3D printed mount. A gear reduction of 5.14:1 is accomplished with a 14 tooth pinion and 72 tooth gear. The gear is on a shaft with a timing belt sheave. This belt then drives the rear axle. The design of the drivetrain incorporates a simple and effective design that can be repaired easily if necessary and fulfils the design specifications outlined by ASME. The design of the RC cars drivetrain has been tested to verify the requirement that it will reach a top speed of 25 mph

DNA Barcoding: Error Rates Based on Comprehensive Sampling

DNA barcoding has attracted attention with promises to aid in species identification and discovery; however, few well-sampled datasets are available to test its performance. We provide the first examination of barcoding performance in a comprehensively sampled, diverse group (cypraeid marine gastropods, or cowries). We utilize previous methods for testing performance and employ a novel phylogenetic approach to calculate intraspecific variation and interspecific divergence. Error rates are estimated for (1) identifying samples against a well-characterized phylogeny, and (2) assisting in species discovery for partially known groups. We find that the lowest overall error for species identification is 4%. In contrast, barcoding performs poorly in incompletely sampled groups. Here, species delineation relies on the use of thresholds, set to differentiate between intraspecific variation and interspecific divergence. Whereas proponents envision a “barcoding gap” between the two, we find substantial overlap, leading to minimal error rates of ~17% in cowries. Moreover, error rates double if only traditionally recognized species are analyzed. Thus, DNA barcoding holds promise for identification in taxonomically well-understood and thoroughly sampled clades. However, the use of thresholds does not bode well for delineating closely related species in taxonomically understudied groups. The promise of barcoding will be realized only if based on solid taxonomic foundations

Evaluation and suggestions for improvement of seismic design procedures for R/C walls in dual systems

This paper aims to shed some further light on the seismic behaviour and design of reinforced concrete (R/C) walls which form part of dual (frame + wall) structures. The significance of post-elastic dynamic effects is recognized by most seismic codes in the definition of the design action effects on walls, i.e. bending moments and shear forces. However, the resulting envelopes are not always fully satisfactory, particularly in the case of medium-to-high-rise buildings. The relevant provisions of modern seismic codes are first summarized and their limitations discussed. Then an extensive parametric study is presented which involves typical multi-storey dual systems that include walls with unequal lengths, designed according to the provisions of Eurocode 8 for two different ductility classes (M and H) and two effective peak ground acceleration levels (0.16 and 0.24g). The walls of these structures are also designed according to other methods, such as those used in New Zealand and Greece. The resulting different designs are then assessed by subjecting the structures to a suite of records from strong ground motions, carrying out inelastic time history analysis, and comparing the results with the design action effects. It is found that for (at least) the design earthquake intensity, the first two modes of vibration suffice for describing the seismic response of the walls. The bending moment envelope, as well as the base shear of each wall, is found to be strongly dependent on the second mode effect. As far as the code-prescribed design action effects are concerned, only the NZ Code was found to be consistently conservative, whereas this was not always the case with EC8. A new method is then proposed which focuses on quantifying in a simple way the second mode effects in the inelastic response of the walls. This procedure seems to work better than the others evaluated herein

Depression Symptoms of College Students During COVID-10 and the Universities’ Response

In early spring 2020, universities worldwide shut down their campuses in response to a global pandemic. The present study examines the potential effect of the shutdown and other pandemic-related stresses on student well-being at Western Washington University. It assesses students’ depression symptoms using the IDAS-II General Depression Scale. The study also considers two campus resources (the Counseling Center, and Prevention and Wellness Services) that students can turn to for help with mental health issues, and gauges students’ awareness and utilization of these resources. The study subjects were Western undergraduates (N = 252), who answered a survey that included the IDAS-II questions as well as questions about awareness, perceptions, use, and barriers to use, of campus resources. The average IDAS-II score of respondents was 56.20, indicating significantly greater depression symptoms than the widely cited average score for college students of 42.21. Participants were more aware of the Counseling Center than of Prevention and Wellness Services. Their attitudes toward both resources were more positive than negative, but they cited numerous barriers to utilizing the resources, including bad experiences and schedule conflicts. The results suggest that a greater effort should be made to increase awareness of Prevention and Wellness Services, which are especially appropriate for help with mild depression symptoms, as well as other resources (e.g. My SSP) that are minimally advertised. One approach would be to enact a mandatory resource training for students and faculty. This paper highlights Western students’ mental health and discusses ways that the university could make improvements to combat the negative effects of COVID-19

An Estimate of the Yield Displacement of Coupled Walls for Seismic Design

A formula to estimate the yield displacement observed in the pushover analysis of coupled wall lateral force-resisting systems is presented. The estimate is based on the results of an analytical study of coupled walls ranging from 8 to 20 stories in height, with varied amounts of reinforcement in the reinforced concrete coupling beams and walls, subjected to first-mode pushover analysis. An example illustrates the application of these estimates to the performance-based seismic design of coupled walls

In situ observation of sexual reproduction of Holothuria tubulosa Gmelin 1788 (Echinodermata: Holothuroidea) in the Azores (NE Atlantic)

Copyright © SPC 2010.[...]. In the Azores, H. tubulosa spawning occurs in the summer months (so far observed in July and August) during the afternoon, which may follow the annual pattern, during warm sea temperatures (22–26°C) and being synchronous in both sexes, as stated by Despalotovic et al. (2004) in the Adriatic Sea. [...

Diversification and distribution of gall crabs (Brachyura: Cryptochiridae: <i>Opecarcinus</i>) associated with Agariciidae corals

Coral reefs are home to the greatest diversity of marine life, and many species on reefs live in symbiotic associations. Studying the historical biogeography of symbiotic species is key to unravelling (potential) coevolutionary processes and explaining species richness patterns. Coral-dwelling gall crabs (Cryptochiridae) live in obligate symbiosis with a scleractinian host, and are ideally suited to study the evolutionary history between heterogeneous taxa involved in a symbiotic relationship. The genus Opecarcinus Kropp and Manning, 1987, like its host coral family Agariciidae, occurs in both Indo-Pacific and Caribbean seas, and is the only cryptochirid genus with a circumtropical distribution. Here, we use mitochondrial and nuclear DNA gene fragments of Opecarcinus specimens sampled from 21 Indo-Pacific localities and one Atlantic (Caribbean) locality. We applied several species delimitation tests to characterise species diversity, inferred a Bayesian molecular-clock time-calibrated phylogeny to estimate divergence times and performed an ancestral area reconstruction. Time to the most recent common ancestor (tMRCA) of Opecarcinus is estimated at 15−6 Mya (middle Miocene—late Miocene). The genus harbours ~ 15 undescribed species as well as several potential species complexes. There are indications of strict host-specificity patterns in certain Opecarcinus species in the Indo-Pacific and Atlantic, however, a robust phylogeny reconstruction of Agariciidae corals—needed to test this further—is currently lacking. The Indo-West Pacific was inferred to be the most probable ancestral area, from where the Opecarcinus lineage colonised the Western Atlantic and subsequently speciated into O. hypostegus. Opecarcinus likely invaded from the Indo-West Pacific across the East Pacific Barrier to the Atlantic, before the full closure of the Isthmus of Panama. The subsequent speciation of O. hypostegus, is possibly associated with newly available niches in the Caribbean, in combination with genetic isolation following the closure of the Panama Isthmus

Envisioning a Marine Biodiversity Observation Network

Humans depend on diverse ocean ecosystems for food, jobs, and sustained well-being, yet many stressors threaten marine life. Extensive research has demonstrated that maintaining biodiversity promotes ocean health and service provision; therefore, monitoring the status and trends of marine biodiversity is important for effective ecosystem management. However, there is no systematic sustained program for evaluating ocean biodiversity. Coordinating existing monitoring and building a proactive marine biodiversity observation network will support efficient, economical resource management and conservation and should be a high priority. A synthesis of expert opinions suggests that, to be most effective, a marine biodiversity observation network should integrate biological levels, from genes to habitats; link biodiversity observations to abiotic environmental variables; site projects to incorporate environmental forcing and biogeography; and monitor adaptively to address emerging issues. We summarize examples illustrating how to leverage existing data and infrastructure to meet these goals

Short-Lived Aggregations of Filograna/Salmacina Tube Worms in the Gulf of Oman

Dense aggregations of serpulid worms were encountered in the Daymaniyat Islands (Gulf of Oman) from 10 to 20 m depth, over the period January–March, 2021. The species responsible for these aggregations belongs to the Filograna/Salmacina-complex (Annelida: Serpulidae). This species has been present in the area and observed along the Oman coastline, but high-density aggregates like this have not been reported before. The most probable cause of the aggregations, supported by field observations and Aqua-MODIS satellite data, was natural eutrophication with a subsequent algal bloom linked to the local winter monsoon. This observation emphasises the importance of documenting biodiversity and dynamics of reef communities along the Oman coastline

Cyclic Behavior of HPFRCC Coupling Beams with Bundled Diagonal Bars

Coupled shear walls are efficient in resisting lateral forces induced by winds and earthquakes. However, it is difficult to construct coupled shear walls particularly because current design codes require complex reinforcing details within coupling beams. The objective of this study was to develop simple reinforcement details for diagonally reinforced coupling beams; reducing transverse steel by use of high-performance fiber-reinforced cementitious composites (HPFRCCs) and bundling diagonal bars are explored. Four coupling beam specimens with length-to-depth aspect ratios of 2.0 or 3.5 were fabricated and tested under cyclic lateral displacements. The test results revealed that HPFRCC coupling beams with bundled diagonal bars and widely spaced transverse reinforcement (one-half the amount of reinforcement required by current seismic codes) exhibited excellent seismic performance compared with ordinary concrete coupling beams having code-required distributed diagonal reinforcement and transverse reinforcement