Some biophysical parameters of the skin of the electric fishTorpedo marmorata

The transverse electrical resistance and DC potentials of the electric fishTorpedo marmorata have been measured. The resistance is lower in the skin covering the electric organ than in skin taken from other parts of the body. The external skin surface is electropositive relative to the internal one. On the basis of the results obtained it is probable that electrical discharges are channelled from the body through low resistant pathways; the skin covering the electric organ does not seem to play any specific role in ionic transport occurring in connection with, or as a consequence of, electrical discharges of the fish.     

Social competition masculinizes the communication signals of female electric fish

Male intrasexual competition and female choice explain the evolution of male ornaments. Except in sex-role-reversed taxa, female ornaments have been regarded as an epiphenomenon of genetic correlation, with no female-specific function or independently selected basis. Females from species with conventional sex roles may still experience some degree of female–female competition and male choice that could explain the persistence of female ornaments. We studied the effect of female competition on the expression of a sexually dimorphic communication signal. In the electric fish Brachyhypopomus gauderio, both sexes produce an electric signal pulse for communication and electrolocation. Male electric pulses are longer in duration and greater in amplitude than those of females. As competition increases, males further enhance their signals in response to elevated androgen levels. We explored whether females respond to social competition as males do, by enhancing their communication signals and increasing androgen levels. We measured amplitude and duration of the electric signal pulse, and testosterone levels in female B. gauderio in their natural habitat in Uruguay and estimated social competition by calculating population density and adult sex ratio (ASR). In the lab, we manipulated ASR and population density independently to separate these factors and eliminate seasonal confounds. Under both field and lab conditions, signal pulse amplitude increased with population density, while pulse duration increased with female bias in ASR. In the field, but not the lab, androgen levels increased when ASR was female biased. Our findings indicate that the socially mediated mechanism of signal regulation is shared by the sexes, although whether androgens regulate this signal plasticity in females remains unclear.     

Feeding and associated electrical behavior of the Pacific electric ray Torpedo californica in the field

The predatory behavior of 74 Pacific electric rays (Torpedo californica), studied between August and December during 1988 through 1991 in situ off the Palos Verdes Peninsula, southern California, consisted of two feeding modes: an ambush from the substratum during the day and a more vigorous attack from the water column at night. Predatory motor patterns and electric organ discharges (EODs) were recorded on the video and audio channels of a housed camcorder. Predatory motor patterns included four phases: (1) jump (simultaneous with EOD initiation), (2) pectoral-fin cupping, (3) orientation to prey, and (4) ingestion. The initial electrical activity of the rays was a train of 46 to 414 5-ms monophasic EODs that lasted 0.45 to 7.06 s; the maximum number of EODs produced during an attack was >1200. Maximum output, measured on only one ray, was 45 V. Fifty-five rays were presented one of four types of prey stimuli: live fish (LF), freshly-speared fish (FSF), frozen fish (FF), or a simulated bioelectric field (SBF). The percent frequency of attacks for the LF, FSF, and FF treatments ranged from 70 to >90%, but was <30% for the SBF. The interval between prey presentation and attack was 30 s for the LF, FSF, and FF and over five times longer for the SBF; intervals averaged <4 s for the three rays tested at night. Attacks by rays on energized electrodes provide the first evidence that electric rays use electroreceptors to detect their prey. However, the lack of clear differences among the four prey treatments in five characteristics of the initial pulse train suggests that a suite of sensory stimuli cooperate in triggering an attack and regulating the electrical output during the attack.     

Providing the Spark: Impact of financial incentives on battery electric vehicle adoption

To overcome adoption barriers and promote battery electric vehicles (BEVs) as an energy efficient consumer transportation option, a number of states offer subsidies to consumers for BEVs. We use a national data set of vehicle registrations and state-level financial incentives to assess the impact of vehicle purchase subsidies on adoption using both difference-in-differences and synthetic controls methods. We find that incentives offered as direct purchase rebates generate increased levels of new BEV registrations at a rate of approximately 8 percent per thousand dollars of incentive offered. Between 2011 and 2015, vehicle rebate incentives are associated with an increase in overall BEV registrations of approximately 11 percent. Our findings indicate incentives offered as state income tax credits do not have a statistically significant effect on BEV adoptions, though we caution this may be a result of limited temporal variation in BEV incentives across our sample. Responses to rebate incentives do not differ significantly by the make of the vehicle purchased (i.e., Tesla and non-Tesla vehicles). We combine our results with recent assessments of marginal environmental costs of electric vehicle charging and measure net welfare effects of BEV subsidy programs. Our analysis indicates these programs are not welfare-improving if only considering benefits associated with avoided emissions. Additional benefits associated with long-term market growth, production cost savings, network externalities, or accelerated innovation could substantially impact the net welfare outcomes.     

车载锂离子动力电池组环境特性分析

虽然电动汽车在行驶阶段不直接排放温室气体,但是车载锂离子动力电池组在生产阶段的环境影响不容忽视.本研究以11个不同的车载锂离子电池组作为研究对象,将环境特性指标引入动力电池组的综合环境评价领域.结合生命周期评价框架,总结出包含足迹家族类指标、资源耗竭类指标和毒性损害类指标的评价体系.采取灰色关联和熵权组合赋权法计算权重.详细分析了锂离子电池不同成分在生产阶段的综合环境影响.结果表明,对于综合环境评价中的足迹家族指标,FeS2SS电池组在碳足迹和生态足迹的环境潜值最小;对于资源耗竭指标,FeS2SS在酸化潜势、富营养化潜势和光化学氧化方面的环境潜值最小,而在非生物性耗竭和臭氧层损耗方面的潜值也较小;对于毒性损害指标,FeS2SS在人类非致癌毒性和生态毒性方面的潜值最小,其人类致癌毒性仅高于Li-S电池.对于环境特性指标,FeS2SS电池组得分最高,表明其在生产阶段更为绿色环保.     

Patterns of the electric organ discharge during courtship and spawning in the mormyrid fish,Pollimyrus isidori

Summary Pollimyrus isidori's electric organ discharge (EOD) is of the pulse type. Patterns of EOD intervals were investigated prior to, during and following spawning behaviors as related with overt behaviors, and with the sound production by the nestbuilding male. Prior to the time of reproduction, isolated and socially interacting fish (n=15) showed characteristic discharge interval patterns for resting, swimming, probing, hovering and hiding activities. Males (n=8) and females (n=6) did not differ in their mean EOD repetition rates during resting (11.6±2.5 Hz), nor Short Bursts/min (less than 20 intervals of 8–13 ms). In interacting fish Long Bursts (greater than 20 intervals of 8–13 ms, lasting for more than 300 ms) were observed only during the attack and bite sequence. A pursuing fish displayed a rapid alternation of Long Bursts with Discharge Breaks (300–1000 ms silence) during the chase behavior. Avoidance behavior which followed from several attacks was correlated with a Medium Uniform Rate (8–12 Hz) normally lasting for 20 to 60 s, or a Discharge Arrest (silence greater than 1 s) in the submissive fish. The nocturnal courtship behavior began soon after dark (1900 h). Spawning typically started 2 to 5 h after dark, continuing for 2 to 6 h until about 0200 h. During courtship and spawning the female's brief visits (15–25 s) to the male's territory recurred every 30–60 s. At all other times the female was aggressively excluded from the nest region. Courtship and spawning behaviors are described along with the electrical displays identified from 19 spawnings in three fish pairs (from a total of 37 spawnings in 4 males and 4 females). Just prior to the onset of courtship behavior, with male territorial aggression beginning to decline, females switched from a Medium Sporadic Rate pattern (resting and hiding patterns; 13 Hz) to a Medium Uniform Rate pattern (6–8 Hz) while still in their hiding area. Females continued to display this uniform rate throughout the courship and spawning period, including the courtship and spawning bouts when Discharge Breaks or Arrests also occurred. This persistance distinguishes the courtship pattern from the similar avoidance pattern (see above). The male courtship and spawning EOD pattern was similar to the female's and unique for a territorial male. He switched from a High Sporadic Rate (swimming EOD pattern; about 18 Hz) to a regularized Medium Uniform Rate (about 9 to 11 Hz) only during courtship and spawning bouts, including 1–3 EOD Breaks during Vent-to-Vent coupling (average interval: 272±71 ms, n=37). No sooner had the female left the spawning site than he resumed displaying a High Sporadic Rate. This temporal correlation of reproductive behaviors with electrical displays suggests their instrumental role in mutual acceptance of mates. Males showed their sex-specific type of EOD phase-locking, the Preferred Latency Response, only during the first few hours of entry of a fish in their tank. Two females with EOD waveform features more typical of males also spawned repeatedly; waveform does not appear to be critical. Males stopped their nocturnal sound production for the later part of courtship and the whole spawning period. Except for infrequent attacks on the female between spawning bouts, the male did not resume singing until the end of spawning when all eggs were shed (around 0200 h); from this time on the male sang until dawn. The sequencing of the three acoustic elements (moans, grunts, growls) are described. A catalogue of discharge patterns correlated with overt behaviors (Tables 1, 2), and an integrated summary time table of P. isidori's complex reproductive behavior are presented.     

潮间带土壤盐度与电导率的关系

以5：1的水土质量比浸提潮间带土壤，质量法测定的土壤盐度(质量分数)，与电导法测定的稀释了5倍的土壤浸提液(5：1水土质量比)的电导率值之间有极显著的相关性。质量法实测的土壤盐度与电导率计算的土壤盐度之间的相对误差多在5％以下。因此，用电导法测定潮间带土壤盐度不失为一种简便、快速的方法，尤其是样品数较多时更可节约时间。     

Influence of low temperature on the discharge mechanism of the electric fish Torpedo marmorata and T. ocellata

The influence of low temperature on the discharge of a part of the electric organ, evoked by electrical stimulation of the nerve leading to it, has been studied on in vitro nerve-electric tissue preparations of the fishes Torpedo marmorata or T. ocellata placed into sea water of different temperatures. It has been found that the amplitude of the discharge of the electric tissue made up from serially organized electroplaques sharply decreases at temperatures below 15 °C. The latent period of discharges increases most markedly at lower temperatures (about 10 °C). Experiments have been performed during July and August on fish caught in the Kotor bay of the Southern Adriatic. Questions related to the dissociation of different aspects of the intrinsic mechanism of the discharge generation by temperature, and to the possible significance of this finding with respect to the ecology of this fish, as well as possible adaptation mechanisms involved, are discussed.     

External secretion of tetrodotoxin from puffer fishes stimulated by electric shock

Four toxic species of puffers (Takifugu pardalis, T. poecilonotus, T. vermicularis and T. niphobles) secreted large amounts of tetrodotoxin into the surrounding water immediately after being stimulated by electric shock. The total amount of toxin secreted ranged from 2 000 to 50 000 MU depending upon the specimen. The amount of toxin secreted seemed to be related to the toxicity of individuals. Non-toxic specimens of T. rubripes did not secrete any toxin. The stimulation always caused inflation of puffers, and this is generally accepted as a repelling behavior of these species. The secreted tetrodotoxin may act as a repellent to predators.     

Locally enhanced electric field treatment (LEEFT) for water disinfection

• Nanowire-assisted LEEFT is applied for water disinfection with low voltages. • LEEFT inactivates bacteria by disrupting cell membrane through electroporation. • Multiple electrodes and device configurations have been developed for LEEFT. • The LEEFT is low-cost, highly efficient, and produces no DBPs. • The LEEFT can potentially be applicable for water disinfection at all scales. Water disinfection is a critical step in water and wastewater treatment. The most widely used chlorination suffers from the formation of carcinogenic disinfection by-products (DBPs) while alternative methods (e.g., UV, O₃, and membrane filtration) are limited by microbial regrowth, no residual disinfectant, and high operation cost. Here, a nanowire-enabled disinfection method, locally enhanced electric field treatment (LEEFT), is introduced with advantages of no chemical addition, no DBP formation, low energy consumption, and efficient microbial inactivation. Attributed to the lightning rod effect, the electric field near the tip area of the nanowires on the electrode is significantly enhanced to inactivate microbes, even though a small external voltage (usually<5 V) is applied. In this review, after emphasizing the significance of water disinfection, the theory of the LEEFT is explained. Subsequently, the recent development of the LEEFT technology on electrode materials and device configurations are summarized. The disinfection performance is analyzed, with respect to the operating parameters, universality against different microorganisms, electrode durability, and energy consumption. The studies on the inactivation mechanisms during the LEEFT are also reviewed. Lastly, the challenges and future research of LEEFT disinfection are discussed.     

Liver lesions produced by hydatid-like cysts in an elasmobranch,the electric ray (Torpedo californica)

Large masses composed of multiple sand-filled cysts were present in the liver of an electric ray, Torpedo californica. There was much inflammation and necrosis of pericystic parenchyma, but remarkably little fibrosis. Other organs were not involved. No evidence of microorganisms or neoplastic transformation was observed. The cysts are hydatid-like and are the first to be reported in a lower vertebrate. They possibly represent larval cestodes, for which elasmobranchs have not been known to be hosts.     

Sustainability measurement of product-service systems: Brazilian case studies about electric car-sharing

Modifying the traditional production system and the culture of consumption is necessary to achieve a sustainable society. The product-service system (PSS) business model allows companies to progressively add services to physical products, thus promoting more pro-sustainable business outcomes. The purpose of this work is to verify how a PSS model can contribute to sustainability by analyzing two electric car-sharing projects using a set of five factors. As a methodological strategy, a Systematic Literature Review and a case study of the two projects (VAMO and EMOTIVE) were performed. Findings show benefits generated by both projects as to environmental aspects, mainly related to gases emission. It was also possible to observe social benefits due to income development and environmental awareness. This paper thus contributes to the discussion of the potential of the PSS models and how they can leverage business models toward a more sustainable society. Although the results are applicable only in this case, this article can motivate new projects and contribute to enriching the debate about sustainable solutions, as the literature in this field still provides few case studies showing these types of applications.     

Influence of weak electric and magnetic fields on turning behavior in elvers of the American eel Anguilla rostrata

The turning behavior of elvers of the American eel Anguilla rostrata was studied in an arena in which a horizontal electric or a vertical magnetic field could be manipulated. The objectives were to determine if the strength and polarity of a weak direct-current (dc) electric field influenced elver orientation, and to determine if any such influence was due to electric fields generated by the elvers' own swimming movements. As electric current density increased from 10^-2 A cm^-2 to 10² A cm^-2, elvers turned increasingly more toward the anode, regardless of whether the anode was on the left or right side of the arena. Elvers in the lowest field turned more toward the cathode than control elvers, and elvers in the highest field turned more toward the anode than controls. There were no differences in mean turning angles of groups of elvers swimming in four different vertical magnetic field conditions (0.54 gauss, <0.02 gauss, 0.52 gauss reversed direction, and 2.00 gauss), suggesting that elvers were not influenced by internally generated electric fields. However, swimming speeds were such that the generated fields would have been of the order of 10^-4 A cm^-2 or less. Elver orientation apparently could be influenced by electric fields of the magnitude generated in major ocean current systems, but probably are not influenced by electric fields generated by their own swimming in the geomagnetic field.     

The ecology,discharge diversity and predatory behaviour of gymnotiforme electric fish in the coastal streams of French Guiana

Summary 1. A survey of the species distribution, discharge characteristics, ecology and behaviour of South American Gymnotiforme electric fish was carried out during two field trips to sites in the vicinity of Kourou, French Guiana, in 1983 and 1985. 2. Measurements of water conditions, collected over a twelve month period, highlight the strong ecological pressure on species exploiting the rapidly fluctuating and often temporary coastal streams. Adaptation of the reproductive cycle to the rainy seasons is particularly marked and the possible zeitgebers are considered. Given the almost invariant water conductivity, its suggested use as an environmental trigger is rejected in favour of acoustic or mechanical cues. 3. The two main study areas were inhabited principally by pulse gymnotoids of the genera Gymnotus and Hypopomus. A new Hypopomus species was discovered as well as specimens of G. pantherinus, previously undescribed in French Guiana. Larvae of H. beevei were found prior to the start of the 1985 rainy season. Developmental data for this species are presented which support the view that, as in other weakly electric gymnotoids, a primitive larval electric organ probably precedes the adult structure. The larval discharge also strongly resembles that of the adult electric eel, lending weight to published theories of an Electrophorus-like ancestor to the wekly electric fish. 4. The predatory behaviour of the strongly electric eel was recorded in detail. The field results indicated that this species preyed on weakly electric fish whose responses to the foraging eel are also reported. The probable use of electrical cues by hunting eels was further investigated in a laboratory experiment in which predatory responses were compared in the presence of non-electric and electric live prey, and models mimicking electric prey. It is concluded that electrical cues are probably of paramount importance in the eel's normal prey capture behaviour.