EFFECTS OF RECEIVER MISALIGNMENT ON THE INTERCEPT FACTOR OF PARABOLIC TROUGH COLLECTORS

This study developed a methodology for determining the intercept factor (γ) and reports the effects of varying the design parameters, within realistic ranges, on the optical performance of parabolic trough collectors (PTC). The design equations account for the aperture width of the concentrator, the geometric concentration ratio, rim-angle and misalignment of the receiver, characterized by the radial and angular offsets. The Latin Hypercube Sampling (LHS) based ray-tracing method was used. Validation of the method was performed by comparing the results obtained by tracing a single ray with measurements obtained in a 2D drafting program. Then, parametric analyses were performed to determine the effects of changing the radial and angular offset, geometric concentration ratio and rim-angle on the percentage change in intercept factor (γΔ) with respect to the γ of a PTC with a perfectly aligned receiver. Finally, contour plots depicting the γ of various standard troughs over the range of radial and angular offsets were plotted, compared and discussed. An online tool is also presented to help designers and researchers analyze these effects quickly by providing the design parameters.

Shell morphometric ratios as a tool for taxonomic determination in gastropods: a case study in Nerita (Gastropoda, Neritidae)

In the study, we compare the shell shape morphometrics in four species of neritid gastropods (Nerita fulgurans, Nerita tessellata, Nerita peloronta and Nerita versicolor), collected in Accra Beach (Barbados Island). We tested the hypothesis that the morphometric ratios can be used as a tool in the taxonomic determination among these four species of neritids. For this we determine the morphometric ratios from the external (length, height, width) and internal (shell aperture length, shell aperture width) measures. A principal component analysis (PCA) was used to determine which ratios were significant, and subsequently the proposed hypothesis was tested using the Kruskal–Wallis test. The morphometric ratios AW/H and AL/L were decisive in distinguishing the four species of neritids studied. In this study, the hypothesis of the efficacy of the use of shell morphometric ratios as an instrument in taxonomic studies was corroborated for the four species. Due to its low cost, this methodology can be applied in the recognition of species that have lost their external characteristics such as operculum, spire or colour and also in the identification of fossil specimens.

Analisis Penyebab Tundaan dan Panjang Antrian Kendaraan Pada Pergerakan U-Turn di Ruas Jalan Perkotaan Kota Balikpapan

Congestion is a problem in transportation that most occurs on urban roads. The increase in the number of vehicle that are not matched by an increase in road capacity makes the volume of vehicle that cross the road exceeds the existing road capacity causing congestion. Besides increasing the number of vehicle, one of the causes of congestion was the existence of U-Turns. The poor design and management of U-Turns will cause drivers to be disorganized when turn around and causing congestion. Factors that cause congestion on the U-Turns include delay and length of queue. This research was conducted with multiple linear regression methods with data in the form of traffic surveys and road geometry. The results of multiple linear regression analysis mentioned that the vehicle delay time on the U-Turn movement was caused by the turning volume and the median aperture width with the dominant factor is the median aperture width. Then, the length of queue on the U-Turn movement is caused by the delay time and the turning time with the dominant factor is the turning time. Keywords : congestion, length of queue, delay time, U-Turn AbstrakKemacetan merupakan suatu permasalahan dalam transportasi yang sering terjadi di jalan perkotaan. Peningkatan jumlah kendaraan yang tidak diimbangi dengan peningkatan kapasitas jalan membuat volume kendaraan yang melintasi ruas jalan tersebut melebihi kapasitas jalan yang ada sehingga menyebabkan kemacetan. Selain peningkatan jumlah kendaraan, salah satu penyebab kemacetan adalah adanya U-Turn. Desain dan pengelolaan U-Turn yang kurang baik akan menyebabkan tidak teraturnya pengendara yang akan memutar arah sehingga menimbulkan kemacetan. Faktor yang menyebabkan kemacetan pada U-Turn diantaranya adalah tundaan dan panjang antrian. Penelitian ini dilakukan dengan metode analisis regresi linier berganda dengan data berupa survei lalu lintas dan geometrik jalan. Hasil analisis regresi linier berganda menyebutkan bahwa waktu Tundaan kendaraan pada pergerakan U-Turn dipengaruhi oleh adanya Volume Putar Balik kendaraan dan Lebar Bukaan Median dengan faktor dominan berupa Lebar Bukaan Median. Kemudian Panjang Antrian pada pergerakan U-Turn dipengaruhi oleh waktu Tundaan dan Waktu Putar Balik dengan faktor dominan berupa waktu Putar Balik. Kata Kunci: kemacetan, panjang antrian, tundaan, U-Turn.

A molecular phylogeny of Geotrochus and Trochomorpha species (Gastropoda: Trochomorphidae) in Sabah, Malaysia reveals convergent evolution of shell morphology driven by environmental influences

There are currently eleven Geotrochus and four Trochomorpha species in Sabah. The primary diagnostic character that separates the two genera is the intensity of sculpture on the shell upper surface. All Trochomorpha species have a coarse nodular sculpture while Geotrochus species has a non-nodular sculpture or smooth shell. However, it is known that shell characters are often evolutionary labile with high plasticity in response to environmental factors. Hence, identifying the phylogenetic and ecological determinants for the shell characters will shed light on the shell-based taxonomy. This study aims to estimate the phylogenetic relationship between Geotrochus and Trochomorpha species in Sabah based in two mitochondrial genes (COI, 16S) and one nuclear gene (ITS) and also to examine the influence of temperature, elevation and annual precipitation on the coarseness of shell upper surface sculpture and shell sizes of the species of both genera. Additionally, we also investigated the phylogenetic signal of the shell characters. The phylogenetic analysis showed that Geotrochus and Trochomorpha species are not reciprocally monophyletic. The phylogenetic signal test suggested that shell size and upper surface sculpture are homoplastic, and these shell traits are strongly influenced by elevation and annual precipitation, particularly at the cloud zone of Mount Kinabalu. The highland species of both genera have a coarser shell surface than lowland species. The shell and aperture width decrease with increasing elevation and annual precipitation. In the view of finding above, the current taxonomy of Geotrochus and Trochmorpha in this region and elsewhere that based on shell characters need to be revised with sufficient specimens throughout the distribution range of the two genera.

Influence of breeds and number of whorls on phenotypic traits and correlations among giant African land snails in Nigeria

Six hundred adult mature black-skinned snails with four and five whorls on the shellcomprising of 200 each of the breeds; Archachatina marginata, Achatina achatina and Achatina fulica were used for the study. Phenotypic traits measured from the snails included body weight (BDW), shell length (SHL), shell width (SHW), aperture length (APL), aperture width (APW), spiral length (SPL), spiral width (SPW), diagonal length (DAL), length between the aperture and first spiral (LAS). The data obtained were used to estimate simple statistics (mean, standard error and coefficient of variations) and correlation oefficients. The results showed high significant (p<0.01) breed effects on phenotypic traits as A.nmarginata snails with four (288.700g) and 5(394.500g) whorls were phenotypically and genotypically heavier, larger and wider than A. achatina (127.0g and 182.000g) and A. fulica (48.850g and 65.050g) with four and five whorls respectively. There were also high significant (p<0.01) disparity number of whorls effects on body weight and other phenotypic traits studied. There was only one strong, negative and significant (p<0.01) phenotypic correlation (r ) between SHL and LAS (r = – 0.650) recorded for A. achatina snails with four whorls while A. achatina snails with five whorls recorded few strong, negative and significant(P<0.01) phenotypic correlations between BDW and SHW (r = – 0.613), SHL and LAS (r = –0.641), SHW and APW (r = – 0.602). Similarly, A. fulica snails with four whorls recorded few strong, negative and significant (p<0.01) phenotypic correlations between BDW and SHW (r = – 0.627), SHL and APL (r = – 0.639), SHW and APW (r = – 0.657) and only one strong, negative and significant (p<0.01) phenotypic correlation between SHL and LAS (r = – 0.605) for A. fulica snails with five whorls. Again, Am snails with four whorls had only one strong, negative and significant(p<0.01) phenotypic correlation between BDW and SHL (r = – 0.720). The only two low, positive and significant (p<0.05) phenotypic correlations recorded in this study were between APL and APW ((r = 0.544) and between SPL and DAL (r = 0.583) for A. marginata snails with four and five whorls respectively. Thus, the breed type and number of whorls on snail shells strongly influenced estimates of phenotypic traits and correlation coefficients of giant African land snails in Nigeria. Also, that estimates of correlation coefficients of mature giant African land snails with higher whorls were (4 and 5) are scarcely strong, positive and significant. The study revealed and confirmed that A. marginata snails are phenotypically and genotypically heavier, larger and wider than A. achatina and A. fulica snails with 4 and 5 whorls. These estimates are recommended as strong and efficient tools for selection and up grading or improvement of giant African land snails genetic traits in Nigeria.

Plasticity in shell selection behaviour by the endemic hermit crab Diogenes alias (Anomura, Diogenidae) from the northeastern Arabian Sea, India

Selection of gastropod shells as shelter by hermit crabs in controlled experiments would provide useful information on the utility of these shells in nature. In this study, shell size and species preferences of Diogenes alias from the northeastern Arabian Sea were quantified by free choice experiments. Males of D. alias, prefer Indothais lacera and Tibia curta, when choice was given; no differences were found for other demographic groups. All hermit crabs occupied larger shells than the shells they occupied in nature. The best correlation was observed between internal volume, weight, and aperture width of the shell with the size of the hermit crab. This pattern has also been reported for other species (i.e., Clibanarius albidigitus, Calcinus tibicen, and C. obscurus). Furthermore, the present study highlights the importance of optimal resources in a scarce environment.

Computed Tomography Evaluation of Nasal Dimensions among Different Singaporean Ethnicities

Osteotomies in rhinoplasty are performed to correct deformities in nasal contour. The size of osteotome used is dictated by the thickness of the bony nasal pyramid along the osteotomy route. The aim of this study is to determine whether nasal bony dimensions differ between different ethnic groups in Singapore. Randomly selected patients' computed tomography (CT) scans of the face performed between the years 2010 to 2013 in our institution (Khoo Teck Puat Hospital) were evaluated. The setting was a tertiary government hospital. CT images of 309 patients (233 Chinese [147 males, 86 females], 32 Malays [16 males, 16 females], and 44 Indians [33 males, 11 females]) were evaluated. Anthropomorphic measurements of the nasal bone along the track of the lateral, medial, and intermediate osteotomies, as well as the nasal bone length and pyriform aperture width were measured on the CT images by two independent observers. Statistical analysis was performed using Student's t-test and two-way analysis of variance (ANOVA) test. There was no significant difference between the nasal pyramid bone thickness between different ethnicities along the osteotomy tracks (p > 0.05; degrees of freedom [df] = 2). However, there was a significant difference between males and females of the same ethnicity at the low level of the lateral osteotomy (p = 0.003) and the midlevel (p = 0.002) and high-level (p = 0.004) of the intermediate osteotomy. There was a statistically significant difference in nasal pyramid length (p < 0.05, df = 2) and pyriform aperture width (p < 0.05, df = 2) among the races and between the genders (p < 0.05). The mean difference in nasal pyramid length of 2.54 mm and pyriform aperture width of 1.89 mm was particularly significant between the Chinese and the Indians. Gender and ethnic differences in nasal bony dimensions should be considered in surgical planning for rhinoplasty.

Facial Reconstruction: Anthropometric Studies Regarding the Morphology of the Nose for Romanian Adult Population I: Nose Width

Craniofacial reconstruction often represents a final step in medico-legal identification and is dependent on facial tissue thickness measurements and feature shape estimation. This study’s aim is to create a reliable and readily reproductible method of predicting the maximum nose width (MNW) based on the maximum nasal aperture width (MAW) for a Romanian adult population. A sample of 55 computer tomography (CT) scans consisting of Romanian adult subjects was selected from the database of a neurosurgery hospital. The craniometrics measured consisted of a first measure of MAW and second one of the MNW using 3D systems Freeform Modelling Plus Software. Correlation analysis indicated a moderate link between the MAW and the MNW. Regression analysis showed that MAW and sex form a statistically significant regression pattern (R2 = 0.340, SEE (Standard Error of Estimate) = 3.801). The preliminary results obtained provide reliable predictions of MNW for facial reconstruction based on MAW measured on the skull.

Comparison of Acorn and Fluted Reamers on Tibial Tunnel Outer Aperture Dimensions in Anterior Cruciate Ligament Reconstruction

The aim of this study was to determine if the type of reamer used in tibial tunnel creation during anterior cruciate ligament (ACL) reconstruction influences the dimensions of the tunnel's outer aperture. Tibial tunnels were created in tibial saw bones by reaming over a guidewire using an 8 mm acorn or fluted reamer in an antegrade manner. Reaming was aimed either in line with the guidewire, or with 10-degree inferior/superior deviation in relation to the wire. The shape and size of the outer aperture of the tibial tunnel were compared between the two reamers. When using the acorn reamer, a 10-degree deviation in relation to the guidewire resulted in minimal change in outer aperture length (mean 13.6 vs. 15.6 mm, p = 0.11) and width (11.6 vs. 11.1 mm, p = 0.51). However, when using the fluted reamer, although the aperture width showed no substantial change with reamer/guidewire deviation (11.4 vs. 11.2 mm, p = 0.71), the mean length almost doubled (14.7 vs. 28.1 mm, p = 0.002). The use of a fluted reamer when reaming the tibial tunnel creates a distal aperture which is inconsistently sized, larger, and of oblong shape compared with an acorn-shaped reamer. This should be taken in consideration when using a fluted reamer for creating the tibial tunnel in ACL reconstruction.