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This study examined the distribution of 495 Asian elephants (Elephas maximus) and 336 African elephants (Loxodonta africana) in 194 zoos, most of which were located in Europe (49.1%) and North America (32.6%). Cows outnumbered bulls 4 to 1 (Loxodonta) and 3 to 1 (Elephas). Groups contained 7 or fewer: mean, 4.28 (σ = 5.73). One fifth of elephants lived alone or with one conspecific. Forty-six elephants (5.5%) had no conspecific. Many zoos ignore minimum group sizes of regional zoo association guidelines. The American Zoo and Aquarium Association recommends that breeding facilities keep herds of 6 to 12 elephants. The British and Irish Association of Zoos and Aquariums recommends keeping together at least 4 cows over 2 years old. Over 69% Asian and 80% African cow groups—including those under 2 years—consisted of fewer than 4 individuals. Recently, Europe and North America have made progress with some zoos no longer keeping elephants and with others investing in improved facilities and forming larger herds. The welfare of individual elephants should outweigh all other considerations; zoos should urgently seek to integrate small groups into larger herds.  相似文献   

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African elephants and other indigenous megaherbivores have a major impact on local vegetation structure, including aquatic communities, as their big feet and large mass pound the fringes of water bodies. This disturbance is likely to have a profound influence on the structure and composition of insect assemblages in these habitats. We investigated which dragonfly (Odonata) species were tolerant of trampling by elephants and other game. Assemblage composition differed according to extremely high, very high or high disturbance levels. Dragonfly abundance was greatest where impact was high, and decreasing when disturbance became very high or extremely high. Several odonate species are well-adapted to fairly high levels of disturbance, although too much is impoverishing. Medium and low impact sites were geographically separated, and this, combined with much lower disturbance levels, had a considerable influence on promoting regional dragonfly diversity. Several regional specialist species only occurred in the geographically separated, low-impact sites. The full complement of dragonflies is present only when there is a combination of various disturbance levels combined with spatial variation. Elephant impact is similar to that of humans, with too much of either or both, leading to a species-poor, habitat-generalist dragonfly assemblage.  相似文献   

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《人与生物圈》2004,(6):20-29
听说处在人象之争最前沿的.是中国老挝边境附近一个叫做南坪的村寨,几年来它屡屡遭受野象的袭击,老百姓苦不堪言。我们换上了善跑山路的越野吉普,在保护区杨副局长的陪同下直奔南坪……  相似文献   

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Purpose

To assess the clinical outcomes of femtosecond laser-assisted keratoplasty (FLAK) using the VisuMax femtosecond laser system, and to compare them with those of conventional penetrating keratoplasty (PK).

Methods

We retrospectively examined 20 eyes of 20 consecutive patients undergoing FLAK and 20 eyes of 20 age- and diagnosis-matched patients undergoing conventional PK. We quantitatively assessed corneal astigmatism, refractive astigmatism, and corrected visual acuity, 1, 3, and 6 months postoperatively, and endothelial cell density 6 months postoperatively.

Results

Corneal and refractive astigmatism after FLAK were significantly lower after FLAK than that after conventional PK at 3 and 6 months postoperatively (p = 0.04 and p = 0.03, respectively, Mann-Whitney U test). FLAK provided significantly faster visual recovery than conventional PK at 1 month postoperatively (p = 0.02), but not at 3 and 6 months postoperatively (p = 0.52 and p = 0.80, respectively). We found no significant differences in the change in endothelial cell density between the two groups (p = 0.30).

Conclusions

FLAK using the VisuMax femtosecond laser system induces significantly less corneal and refractive astigmatism than conventional PK, and provides significantly faster visual recovery in the early postoperative period, possibly because the geometry of the donor-recipient matching is more physiological and requires less tight sutures. It is suggested that FLAK has advantages over conventional PK, in terms of astigmatism and fast visual recovery.  相似文献   

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Prolactin was isolated from anterior lobes of elephant pituitary glands. It consisted of 199 amino acids with three disulfide bridges and two tryptophan residues as found in prolactin from other species. The sequence of the NH2-terminal 28 amino acids was determined and shown homologous with the ovine hormone. In comparison with ovine prolactin, a marked difference was seen in the methionine content; the elephant hormone possessed only 18-34% lactogenic potency. The conformation of elephant prolactin was examined by zero order, second order and circular dichroism spectroscopy. The alpha helical content was estimated to be about 60%. In comparison with prolactins from other species, the second order spectra of elephant prolactin suggest that the local microenvironment for one or both tryptophan residues is somewhat different.  相似文献   

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走进野象谷     
我们的西双版纳之行是从2001年8月19日开始的。22日,我们出发去向往已久的勐养,途中,我们参观了绿石林森林公园。这可是真正的原始森林,进林前还是阳光明媚,一进森林就如进入阴暗潮湿的地下室,无一丝阳光射入,很少能见到鸟类,通常是只闻其声不见其影。但是昆虫却非常多,30厘米长的马陆、樱桃大小的西瓜虫、小孩拳头大小的蜗牛、各式各样的毛毛虫随处可见,数不胜数。下午,我们来到了野象谷。野象谷,顾名思义就是  相似文献   

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《Plains anthropologist》2013,58(97):217-224
Abstract

One aspect of the Denver Elephant Project, the experimental use of thrusting spears, is presented. A recentlydeceased elephant was made available for archaeological experimentation, and as a part of this work the author manufactured and, with the aid of others, employed a series of thrusting spears tipped with Clovis fluted point replicas. It was found that the use of composite thrusting spears permitted penetration of the elephant carcass, but also revealed problems in spear design. The types of projectile point breakage which occurred were found to compare favorably with archaeological specimens. Other implications of the work for the understanding of Clovis elephant procurement strategy and weaponry are presented, and suggestions are made for future experiments.  相似文献   

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During business collaboration, partners may benefit through sharing data. People may use data mining tools to discover useful relationships from shared data. However, some relationships are sensitive to the data owners and they hope to conceal them before sharing. In this paper, we address this problem in forms of association rule hiding. A hiding method based on evolutionary multi-objective optimization (EMO) is proposed, which performs the hiding task by selectively inserting items into the database to decrease the confidence of sensitive rules below specified thresholds. The side effects generated during the hiding process are taken as optimization goals to be minimized. HypE, a recently proposed EMO algorithm, is utilized to identify promising transactions for modification to minimize side effects. Results on real datasets demonstrate that the proposed method can effectively perform sanitization with fewer damages to the non-sensitive knowledge in most cases.  相似文献   

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Apidaecin peptides from Apis mellifera hemolymph are believed to attack intracellular bacterial targets. Our in vivo results for apidaecins 1a and 1b confirm that bacterial activity is non-lytic, however, the manner in which these peptides pass through the cell membrane to exert this activity is unknown. These data are combined with fluorescence (dye leakage) and quartz crystal microbalance studies to investigate the membrane interaction for these two wildtype peptides. It was found that the peptides penetrate the membrane in a trans-membrane manner. The amount of peptide uptake by the membrane is proportional to the concentration of the peptide, however, this appears to be a dynamic equilibrium which can be almost completely reversed by addition of buffer medium. Interestingly, a small residual mass remains within the membrane and the amount of peptide remaining in the membrane is a function of the buffer-salt concentration viz. in high salt, the residual peptide mass remaining is small whereas at low salt concentration, a larger mass of peptide remains bound. These results support a direct membrane penetration mechanism by the wild type apidaecins 1a and 1b. In both cases the peptide–membrane interaction has a negligible effect on the membrane, although, in high salt a permanent change in the membrane does occur at the highest peptide concentration which does not recover following peptide removal. Stefania Piantavigna and Patricia Czihal contributed equally to this article.  相似文献   

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Ocak  Bugra 《Food biophysics》2021,16(3):381-394

One of the long-standing problems of the leather manufacturing industry is that tons of solid leather waste generated during production meet environmental standards. Among all these solid wastes, untanned trimming wastes are of primary interest because of their relative collagen content, and therefore, in this research, hide trimming wastes from tanneries were used to prepare biodegradable films. The SDS-PAGE results suggested that obtained collagen hydrolysate (CH) was in its natural molecular form. Chitosan nanoparticles (CSNPs) were synthesized by ionotropic gelation technique with chitosan (CS) and tripolyphosphate anions and used in the preparation of CS/CH/CSNPs films containing different concentrations of CSNPs. The incorporation of CSNPs in CS/CH films has positively improved the films' remarkable physical properties. The DSC result showed that CS/CH films incorporated with CSNPs had higher glass transition and melting temperature. As a result, it was determined that CS/CH/CSNPs nanocomposite films have a high potential in biodegradable film systems.

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