Withdrawal Properties of Self-Tapping Screws in Japanese larch (Larix kaempferi (Lamb.) Carr.) Cross Laminated Timber

With the increasing popularity of cross-laminated timber (CLT) constructions around the world, there have been attempts to produce CLT using local wood species in different countries, such as Japanese larch (Larix kaempferi (Lamb.) Carr.) in China. Thus, the need to investigate the connection performance also increases to support the design and construction of CLT buildings using local wood species. In this study, the withdrawal properties of three different types of self-tapping screws (STS), with a diameter of 6 mm, 8 mm, and 11 mm, were tested with Japanese larch CLT. The results revealed that the withdrawal strength of STS increased with increasing density and effective length, but decreased with an increasing diameter. With a density increment of 0.05 g/cm3, the withdrawal strength increased by an average of 9.4%. With an effective length increment of 24 mm, the withdrawal strength increased by an average of 1.4%. An empirical regression model was adopted to predict the withdrawal strength of Japanese larch CLT based on the results, which can be used for potential engineering design of CLT connections using STS.

Insulin-like growth factor-1 and growth in infants 0-6 months of age

Background During infancy, growth is affected by many factors, including hormones. Insulin-like growth factor-1 (IGF-1) is a hormone with an important role in regulating somatic growth and organ development. Objective To analyze for possible correlations between IGF-1 levels and infant growth from 0-6 months of age. Methods A prospective study was conducted on 38 infants from birth to 6 months of age. Inclusion criteria were full-term newborns with normal birth weight and singleton birth. Serum IGF-1 was measured twice, from umbilical cord blood at birth and at 6 months of age. Anthropometric measurements were made every three months. Paired T-test was used to analyze mean IGF-1 among time points, and Pearson’s correlation test was used to analyze IGF-1 levels and growth. Results Mean IGF-1 level decreased from birth to 6 months of age (89.6 ng/mL vs. 48.3 ng/mL, respectively; P<0.001). Delta IGF-1 had positive significant correlations with delta weight at 3 months (r=0.347; P=0.033) and 6 months (r=0.386; P=0.017), as well as delta head circumference at 3 months (r= 0.356; P=0.028) and 6 months (r=0.357; P=0.028). However, there were significant negative correlations between umbilical cord IGF-1 with delta body weight (r= −0.459; P=0.004) and delta length at 6 months (r= −0.414; P=0.010). Conclusions. There iss a decrease in IGF-1 levels at the first 6 months of life. Umbilical cord IGF-1 level has negative correlations with the weight and length increment at the age of 6 months.

Age Structure and Growth in the Lataste’s Toad, Bufotes latastii (Anura: Bufonidae)

The paper provided the first data about age structure and growth of the Lataste’s toad, Bufotes latastii (Boulenger, 1882), from the Jammu and Kashmir State (India). The study of age structure of toads was carried out using skeletochronology. The minimal and maximal ages in males of B. latastii were 3 and 10 years, respectively, with mean age of 6.0 years. The majority of males (70%) were 5 or 6 years old. The age in females ranged from 4 to 10 years with mean value of 5.9 years. The majority of females (71%) were 4 – 6 years old. Males of B. latastii can reach maturation after three winterings and females after four winterings. The body length increment in males is 3.6 times, whereas in females is 3.7 – 4.0 times. After maturation, the growth rate is retarded and the individuals of different ages did not differ in its body length. In spite of maximal age of 10 years in both sexes, the largest male was 5 years old and the largest female was 4 years old.

Influence of two management systems on the growth performance of adult African giant land snails (Archachatina marginata)

African gaint land snails are important as means of alleviating acute protein shortage in Nigeria livestock Industries. The present study aimed to study the influence of intensive and extensive management systems on the growth Performance of adult African Giant Land Snails (Archachatina marginata) was carried out in the wildlife domestication unit of the Department of Forest Resources and Wildlife Management, University of Benin, Benin City, Nigeria. Ninety African giant land snails (A. marginata) of average body weight 160.31g ± 0.38g were used for the study. The snails were grouped into two- Group A and Group B. 45 snails in group A were raised in an intensive system of management while 45 snails in group B were raised in an extensive system of management. The data collected on weight gain, shell length increment and shell width increment during the experiment were subjected to student t-Test at 5% significant level. Results showed that there was a significant difference at (p<0.05) in the weight gain. The intensive management system had a higher weight gain of 128.96g with mean value of 4.96 while the extensive management system had a weight gain of 88.37g with mean value of 3.40. There was no significant difference at (p>0.05) in the shell length increment. The snails in the extensive management system had the higher shell length increment of 5.32cm with mean value of 0.20 while the snails in the intensive management system had a shell length increment of 2.43cm with mean value of 0.09. There was a significant difference at (p<0.05) in the shell width increment. The snails in the extensive management system had the higher shell width increment of 9.31cm with mean value of 0.36 while the snails in the intensive management system had a shell width increment of 4.30cm with mean value of 0.17. The snails in the intensive system had a Feed Conversion Ratio of 5.03. For better growth performance of A. marginata in terms of weight gain, snail farmers should raise their snails in an intensive system of management and formulated diet should be used in feeding the snails along side with natural feed such as leaves and fruits.

Peeling of an Extensible Soft Microbeam to Solid: Large Deformation Analysis

Adhesion and peeling of slender structures at micro and nanoscale have attracted great attention of scientists and engineers, which hold great implications in a number of domains. In this study, we present the model formulation on the peeling of a soft beam under a concentrated force, by considering its large deformation and axis extensibility. The governing equation group and the transversality condition are then derived, according to the variation on the energy functional with movable boundary conditions. We find that the key parameters in peeling, such as the adhered segment length, applied force and length increment of the beam, are correlated with two dimensionless variables, i.e., the non-dimensional maximum displacement of the beam and non-dimensional work of adhesion. The calculated results are in excellent agreement with the experimental data, which are also compared with the infinitesimal deformation model and large deformation model with inextensible axis. These findings shed light on the design of elementary structures in micro and nanodevices, fabrication of nanofiber materials, and better application of micro/nanoprinting technique, etc.

Impact Suboptimal Signal Degradation Handoff (SDH) Properties to Handoff Parameters

Study on mobile handoff is aim at avoiding inefficient mobile station transfer from a base station to other base station. Efficient handoff leads to smooth communication and seamless mobile station migration. This paper studies impact of cost and window length properties of the suboptimal signal degradation handoff (SDH) to handoff performance parameters such as received signal level, delay and number of handoff. Simulation results show that cost and average length increment cause signal degradation and delay increment. However, number of handoff decreases. The suggested optimal cost (c) for average window length (dr) 0 and 10 are 0.65 and 0.25. However, dr = 20 and 30 experience poor signal for any cost values.

Calendar and thermal time-based growth models for common carp and pikeperch, and the influence of stocking strategy in Lake Balaton, Hungary

Common carp Cyprinus carpio and pikeperch Sander lucioperca are widely distributed and economically important freshwater fishes. Because these species are extensively stocked both within and outside of their native ranges, it is important to assess the effect of these actions. We aimed to analyse growth rate and its variability related to stocking strategy (season × lake area × habitat × fish size) in common carp and pikeperch in Lake Balaton (Hungary), based on cooperative tagging experiments with anglers. In both species, length increment was more closely associated with thermal time (degree-day sum) over 8 °C threshold water temperature than calendar time. Except a marked decrease with increasing fish size, stocking parameters had little effect on length increment. Growth models based on the GROTAG method and the von Bertalanffy's asymptotic length (L∞) and growth rate (K) are provided. Compared to other habitats, estimated growth rate proved to be high in common carp (128 mm year−1 at 300 mm standard length) and modest in pikeperch (61 mm year−1 at 250 mm standard length). We concluded that stocking rate even might be increased in common carp, while management of the pikeperch population should rather be based on catch restriction measures than intensified stockings.

A New Dynamic Model of Coupled Axial–Torsional Vibration of a Drill String for Investigation on the Length Increment Effect on Stick–Slip Instability

In this paper, a new model is proposed to study the coupled axial–torsional vibration of the drill string. It is assumed that rotary table angular speed is constant and equals to the nominal angular speed of the drill string. In addition, axial displacement of any point on the drill string is considered to be as the sum of rigid-body motion and elastic vibrations. The depth of cut is defined using instantaneous dynamic states instead of using the delayed model as presented in previous researches. A velocity-weakening function is introduced for modeling the behavior of the frictional component of the torque-on-bit (TOB) with respect to the bit angular speed. After discretizing vibration equations, stability analysis of the system is investigated by linearizing the nonlinear system around its steady-state response point. Considering nominal weight-on-bit (WOB) (W0) and nominal rotational speed (Ω) as the input parameters of the drilling, variation of maximum allowable value of (W0) is presented with respect to variation of Ω . It is shown that the maximum allowable value of W0 has an increasing–decreasing behavior with respect to Ω. The effect of drill string upper and lower part lengths is studied on the stability of the system, and practical results are presented both in the condition that W0 is constant and in the condition that the hook upward force is constant. It is shown that by increasing the drill string length, the system is more exposed to instability, and this must be considered in regulating the input parameters of drilling.