Extended warranty strategies for online shopping supply chain with competing suppliers considering component reliability

This article presents the issue of extended warranty and management strategies in a three-echelon competing online shopping supply chain with price- and base warranty period-dependent demand. We employ game theory to develop decision models to explore the interactions between component suppliers and the manufacturer, as well as competition between two component suppliers. Products and extended warranty are sold by an online store, which is the leader in the Stackelberg game. Two scenarios are considered: either the manufacturer offers a prepaid extended warranty to customers or doses not. In each scenario, base warranties are assumed to be bundled with products. Our results show that when the manufacturer’s repair costs change in a proper range, providing extended warranty can benefit both the manufacturer and the online store; otherwise, the manufacturer has no incentive to offer the extended warranty. Reducing repair costs, improving component reliability, or shortening the base warranty period allows the manufacturer to realize significantly better value of the extended warranty. High component reliability benefits both the manufacturer and the online store, with the manufacturer reaping more benefit. Extending the length of the base warranty adversely affects profit of the manufacturer and the value of the extended warranty.     

Thermal ecology,activity pattern,habitat, and microhabitats used by the skink Mabuya arajara (Squamata: Scincidae) in the Araripe Plateau,northeastern Brazil

ABSTRACT

We evaluated the activity period, thermal ecology, habitats, and preference for microhabitats of the skink Mabuya arajara in a humid forest environment on the slope of the Araripe Plateau, Brazil. A total of 283 lizards were observed. The lizards were found to be diurnally active (unimodal type pattern), with peak activity during the hottest hours of the day (1100 to 1200). About habitat use, the majority of individuals (73.8% N = 209) were recorded in the narrow transitional area, in the edges of the forest; while 26.4% of individuals were observed in open areas and no observations were made in dense forest. Seven different types of microhabitats were used, with fallen palm leaves (Arecaceae) being the preferred (47.7% N = 135). Considering all lizards, microhabitat niche breadth was 3.27. Males and females presented a high overlap (0.95) in microhabitat use. The average T_c recorded for M. arajara was 32.06 ± 2.72°C. Body size (SVL) did not influence body temperature (F = 0.51, P = > 0.05). Most of the animals were observed with their bodies completely exposed (67.84%, N = 192), 18.37% (N = 52) were semi-exposed and 13.79% (N = 39) were in shelters. Among animals with some degree of sunlight exposure, 57.59% (N = 163) were in shadows, 25.10% (N = 71) were under sunlight filtered by vegetation, and 17.31% (N = 49) were under direct sunlight.A review of the ecology of Mabuya spp. shows that several features appear to be conserved among members of the genus.     

Algal populations in Bottle Hollow Reservoir, Duchesne County, Utah

Bottle Hollow Reservoir contains a diverse algal flora. A total of 289 taxa was observed, 227 of which were diatoms. Both littoral and planktonic communities had high diatom diversity. During summer months filamentous Chlorophvta were diverse and high in biomass in the littoral zone. Phytoplankton collections in Bottle Hollow Reservoir were dominated by four species: Asterionella formosa, Cyclotella comta, Dinobryon divergens, and Fragilaria crotonensis. Plankton samples contained mostly small diatoms in early spring, with larger algae succeeding these as the summer progressed. No blue - green algae were important in this succession. Two peak production periods were observed, one in the fall and one in the spring. Bottle Hollow Reservoir appears to be a healthy mesotrophic system based on the evidences of moderately high algal diversity, insignificance of blue-green algae, and the presence of a suite of diatom species indicative of mesotrophic conditions.     

β-Chitin/Chitosan Obtained from Loligo and Humboldt Squids Effectiveness as Wound Dressing Material

A number of materials are utilized to develop wound care dressing materials with metallic treatments such as ionic silver and zinc. Metallic ions if used for a prolonged time may lead to toxicity. Alternatively chitin,a natural polysaccharide found in nature, is utilized. It is found in fungi, crabs, mushrooms,squids, octopus, and many other living organisms. Chitin has similar structure to cellulose but its deacetylated derivate chitosan has amine groups that provide potential antibacterial properties along with a number of other advantages. Chitin in its natural form is found in three different structural forms,namely α,β,and γ.The β-chitin and chitosan are mostly found in the exoskeleton of squids. Loligo and Humboldt squids were studied. It is anticipated that Humboldt chitin is more effective in serving as antibacterial material and can be utilized for wound care. Differences in steriochemical structure were observed among β-chitin structures obtained and amine group’s presences were found along with ability of materials to swell.     

Palaeontology: spider-web silk from the Early Cretaceous

The use of viscid silk in aerial webs as a means to capture prey was a key innovation of araneoid spiders and has contributed largely to their ecological success. Here I describe a single silk thread from a spider's web that bears glue droplets and has been preserved in Lebanese amber from the Early Cretaceous period for about 130 million years. This specimen not only demonstrates the antiquity of viscid silk and of the spider superfamily Araneoidea, but is also some 90 million years older than the oldest viscid spider thread previously reported in Baltic amber from the Eocene epoch.     

Nucleation and growth of fibres and gel formation in sickle cell haemoglobin

Deoxygenated sickle haemoglobin polymerizes into long 210-A diameter fibres that distort and decrease the deformability of red blood cells, and cause sickle cell disease. The fibres consist of seven intertwined double strands. They can form birefringent nematic liquid crystals (tactoids) and spherulites. Rheologically, the system behaves as a gel. The equilibria show a phase separation and a solubility. The reaction kinetics show a delay time, are then roughly exponential and are highly dependent on concentration and temperature, and accord with the double nucleation model. But these conclusions are derived from macroscopic data, without direct observation of individual fibres. We have now used non-invasive video-enhanced differential interference contrast (DIC) and dark-field microscopy to observe nucleation, growth and interaction of sickle deoxyhaemoglobin fibres in real time. The fibres originate both from centres that produce many radially distributed fibres and on the surface of pre-existing fibres, from which they then branch. The resulting network is cross-linked and dynamic in that it is flexible and continues to grow and cross-link. Our results support most aspects of the double nucleation model.     

云及其他颠覆性技术趋势对商业经济领域的影响

 技术革命带动社会变革,人类社会发展经历的3次浪潮--从农业革命到工业革命再到信息革命,无一不是当时的“颠覆性技术”带来的巨大变革。如今,从云计算到大数据,到人工智能等,这些颠覆性技术每年都给世界经济甚至世界格局带来巨大影响。世界主要国家对技术预见能力都高度重视,颠覆性技术发展核心技术能力成为各国战略布局的重点。本文阐述了颠覆性技术的8个趋势、2个环境和7层技术模型,并介绍了云计算、人工智能对数字化经济的重要变革作用。     

Tetraspanin-enriched microdomains regulate digitation junctions

Tetraspanins co-emerged with multi-cellular organisms during evolution are typically localized at the cell–cell interface, and form tetraspanin-enriched microdomains (TEMs) by associating with each other and other membrane molecules. Tetraspanins affect various biological functions, but how tetraspanins engage in multi-faceted functions at the cellular level is largely unknown. When cells interact, the membrane microextrusions at the cell–cell interfaces form dynamic, digit-like structures between cells, which we term digitation junctions (DJs). We found that (1) tetraspanins CD9, CD81, and CD82 and (2) TEM-associated molecules integrin α3β1, CD44, EWI2/PGRL, and PI-4P are present in DJs of epithelial, endothelial, and cancer cells. Tetraspanins and their associated molecules also regulate the formation and development of DJs. Moreover, (1) actin cytoskeleton, RhoA, and actomyosin activities and (2) growth factor receptor-Src-MAP kinase signaling, but not PI-3 kinase, regulate DJs. Finally, we showed that DJs consist of various forms in different cells. Thus, DJs are common, interactive structures between cells, and likely affect cell adhesion, migration, and communication. TEMs probably modulate various cell functions through DJs. Our findings highlight that DJ morphogenesis reflects the transition between cell–matrix adhesion and cell–cell adhesion and involves both cell–cell and cell–matrix adhesion molecules.