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Understanding customer behavior in retail stores plays a crucial role in improving customer satisfaction by adding personalized value to services. Behavior analysis reveals both general and detailed patterns in the interaction of customers with a store items and other people, providing store managers with insight into customer preferences. Several solutions aim to utilize this data by recognizing specific behaviors through statistical visualization. However, current approaches are limited to the analysis of small customer behavior sets, utilizing conventional methods to detect behaviors. They do not use deep learning techniques such as deep neural networks, which are powerful methods in the field of computer vision. Furthermore, these methods provide limited figures when visualizing the behavioral data acquired by the system. In this study, we propose a framework that includes three primary parts: mathematical modeling of customer behaviors, behavior analysis using an efficient deep learning based system, and individual and group behavior visualization. Each module and the entire system were validated using data from actual situations in a retail store.

Developing sustainably and becoming a smart city is a long-term and strategic orientation of Hanoi. Shophouses, which are multi-function urban houses, converge many factors that strongly support sustainable development of Hanoi such as providing high quality residential areas; helping create diverse and lively communities, touristic attractiveness, conditions for sustainable management of resources and energy efficiency, etc. With various economic activities, shophouses also have lots of potentials in development towards smart cities such as lively and safe pedestrian zones, abilities to transform, local and supra-local accessibility, reasonable density of construction and population, etc. Analyses and studies show that in order to sustainably develop shophouses in new urban areas of Hanoi, it is necessary to solve existing problems of the constitutional system, the socio-economy, living space quality and management of the shophouse neighbourhoods. Notably, the criteria for smart city development are closely related to the above-mentioned issues. Proposals have been made based on studying the core values of shophouses and historical research of architecture in the Southeast Asia region. In addition to the proposals on improving the constitution and urban design solutions, the proposals on digitization of shophouse projects are submitted for the sustainable development towards smart cities development

People today are exposed to a greater technological burden than in the past. Numerous information and communication technologies (ICTs) have penetrated everyday life. The smartphone usage particularly continues to increase. This change leads to problematic developments, such as technostress and internet addiction. This study employs William Stephenson’s Q-methodology and investigates 28 personal viewpoints of smartphone users. The research analyzes their smartphone use and coping behavior. With the employment of Q-methodological approach this study examines the shared viewpoints among individuals. Based on the personal views and evaluation of these, four different smartphone user types are identified: Bystanders, Addicts, Moderates, and Struggling integrators. These types have different characteristics in smartphone use, handling of smartphone and coping behavior. This study shows that internet addiction has three determinants: impulsiveness, anxiety, and habit. Different levels of impulsiveness personality traits are decisive when it comes to internet addiction. In addition, the level of impulsiveness regulates anxiety, as low impulsiveness leads to higher levels of control. Anxiety is also a contributing factor to internet addiction. Furthermore, anxiety results in higher levels of stress resistance. The last determinant, habit, in combination with technology use, promotes internet addiction and less interest in harms. Thus, high levels of internet addiction, lead to negative consequences that affect one’s effectiveness, health, happiness, and relationships. This study provides a link between different research areas by creating a framework that combines technostress, internet addiction and coping theory., Masterarbeit Universität Innsbruck 2022

People today are exposed to a greater technological burden than in the past. Numerous information and communication technologies (ICTs) have penetrated everyday life. The smartphone usage particularly continues to increase. This change leads to problematic developments, such as technostress and internet addiction. This study employs William Stephenson’s Q-methodology and investigates 28 personal viewpoints of smartphone users. The research analyzes their smartphone use and coping behavior. With the employment of Q-methodological approach this study examines the shared viewpoints among individuals. Based on the personal views and evaluation of these, four different smartphone user types are identified: Bystanders, Addicts, Moderates, and Struggling integrators. These types have different characteristics in smartphone use, handling of smartphone and coping behavior. This study shows that internet addiction has three determinants: impulsiveness, anxiety, and habit. Different levels of impulsiveness personality traits are decisive when it comes to internet addiction. In addition, the level of impulsiveness regulates anxiety, as low impulsiveness leads to higher levels of control. Anxiety is also a contributing factor to internet addiction. Furthermore, anxiety results in higher levels of stress resistance. The last determinant, habit, in combination with technology use, promotes internet addiction and less interest in harms. Thus, high levels of internet addiction, lead to negative consequences that affect one’s effectiveness, health, happiness, and relationships. This study provides a link between different research areas by creating a framework that combines technostress, internet addiction and coping theory., Author Hoang Tung Dinh, Masterarbeit Universität Innsbruck 2022

The lack of large-scale datasets has been impeding the advance of deep learning approaches to the problem of F-formation detection. Moreover, most research works on this problem rely on input sensor signals of object location and orientation rather than image signals. To address this, we develop a new, large-scale dataset of simulated images for F-formation detection, called F-formation Simulation Dataset (F2SD). F2SD contains nearly 60,000 images simulated from GTA-5, with bounding boxes and orientation information on images, making it useful for a wide variety of modelling approaches. It is also closer to practical scenarios, where three-dimensional location and orientation information are costly to record. It is challenging to construct such a large-scale simulated dataset while keeping it realistic. Furthermore, the available research utilizes conventional methods to detect groups. They do not detect groups directly from the image. In this work, we propose (1) a large-scale simulation dataset F2SD and a pipeline for F-formation simulation, (2) a first-ever end-to-end baseline model for the task, and experiments on our simulation dataset., Comment: Accepted at ICMV 2022

Most of the current task-oriented dialogue systems (ToD), despite having interesting results, are designed for a handful of languages like Chinese and English. Therefore, their performance in low-resource languages is still a significant problem due to the absence of a standard dataset and evaluation policy. To address this problem, we proposed ViWOZ, a fully-annotated Vietnamese task-oriented dialogue dataset. ViWOZ is the first multi-turn, multi-domain tasked oriented dataset in Vietnamese, a low-resource language. The dataset consists of a total of 5,000 dialogues, including 60,946 fully annotated utterances. Furthermore, we provide a comprehensive benchmark of both modular and end-to-end models in low-resource language scenarios. With those characteristics, the ViWOZ dataset enables future studies on creating a multilingual task-oriented dialogue system.

Developing sustainably and becoming a smart city is a long-term and strategic orientation of Hanoi. Shophouses, which are multi-function urban houses, converge many factors that strongly support sustainable development of Hanoi such as providing high quality residential areas; helping create diverse and lively communities, touristic attractiveness, conditions for sustainable management of resources and energy efficiency, etc. With various economic activities, shophouses also have lots of potentials in development towards smart cities such as lively and safe pedestrian zones, abilities to transform, local and supra-local accessibility, reasonable density of construction and population, etc. Analyses and studies show that in order to sustainably develop shophouses in new urban areas of Hanoi, it is necessary to solve existing problems of the constitutional system, the socio-economy, living space quality and management of the shophouse neighbourhoods. Notably, the criteria for smart city development are closely related to the above-mentioned issues. Proposals have been made based on studying the core values of shophouses and historical research of architecture in the Southeast Asia region. In addition to the proposals on improving the constitution and urban design solutions, the proposals on digitization of shophouse projects are submitted for the sustainable development towards smart cities development

Developing sustainably and becoming a smart city is a long-term and strategic orientation of Hanoi. Shophouses, which are multi-function urban houses, converge many factors that strongly support sustainable development of Hanoi such as providing high quality residential areas; helping create diverse and lively communities, touristic attractiveness, conditions for sustainable management of resources and energy efficiency, etc. With various economic activities, shophouses also have lots of potentials in development towards smart cities such as lively and safe pedestrian zones, abilities to transform, local and supra-local accessibility, reasonable density of construction and population, etc. Analyses and studies show that in order to sustainably develop shophouses in new urban areas of Hanoi, it is necessary to solve existing problems of the constitutional system, the socio-economy, living space quality and management of the shophouse neighbourhoods. Notably, the criteria for smart city development are closely related to the above-mentioned issues. Proposals have been made based on studying the core values of shophouses and historical research of architecture in the Southeast Asia region. In addition to the proposals on improving the constitution and urban design solutions, the proposals on digitization of shophouse projects are submitted for the sustainable development towards smart cities development

Developing sustainably and becoming a smart city is a long-term and strategic orientation of Hanoi. Shophouses, which are multi-function urban houses, converge many factors that strongly support sustainable development of Hanoi such as providing high quality residential areas; helping create diverse and lively communities, touristic attractiveness, conditions for sustainable management of resources and energy efficiency, etc. With various economic activities, shophouses also have lots of potentials in development towards smart cities such as lively and safe pedestrian zones, abilities to transform, local and supra-local accessibility, reasonable density of construction and population, etc. Analyses and studies show that in order to sustainably develop shophouses in new urban areas of Hanoi, it is necessary to solve existing problems of the constitutional system, the socio-economy, living space quality and management of the shophouse neighbourhoods. Notably, the criteria for smart city development are closely related to the above-mentioned issues. Proposals have been made based on studying the core values of shophouses and historical research of architecture in the Southeast Asia region. In addition to the proposals on improving the constitution and urban design solutions, the proposals on digitization of shophouse projects are submitted for the sustainable development towards smart cities development

Autonomous vehicles (AVs) must always have a safe motion to guarantee that they are not causing any accidents. In an AV system, the motion of the vehicle is represented as a trajectory. A trajectory planning component is responsible to compute such a trajectory at run-time, taking into account the perception information about the environment, the dynamics of the vehicles, the predicted future states of other road users and a number of safety aspects. Due to the enormous amount of information to be considered, trajectory planning algorithms are complex, which makes it non-trivial to guarantee the safety of all planned trajectories. In this way, it is necessary to have an extra component to assess the safety of the planned trajectories at run-time. Such trajectory safety assessment component gives a diverse observation on the safety of AV trajectories and ensures that the AV only follows safe trajectories. We use the term trajectory checker to refer to the trajectory safety assessment component. The trajectory checker must evaluate planned trajectories against various safety rules, taking into account a large number of possibilities, including the worst-case behavior of other traffic participants. This must be done while guaranteeing hard real-time performance since the safety assessment is carried out while the vehicle is moving and in constant interaction with the environment. In this paper, we present a prototype of the trajectory checker we have developed at IVEX. We show how our approach works smoothly and accomplishes real-time constraints embedded in an Infineon Aurix TC397B automotive platform. Finally, we measure the performance of our trajectory checker prototype against a set of NCAPS-inspired scenarios.

Methylmercury (MeHg) is one of the most potent neurotoxins. It is produced in nature through the methylation of inorganic divalent mercury (HgII) by phylogenetically diverse anaerobic microbes. The mechanistic understanding of the processes that govern the extent of bacterial export of MeHg, its bioaccumulation, and bio-toxicity depends on accurate quantification of its species, especially its complexation with low molecular mass thiols; organometallic complexes that are difficult to detect and measure in natural conditions. Here, we report the development of a novel analytical method based on liquid chromatography tandem mass spectrometry (LC-MS/MS) to determine 13 MeHg complexes with important thiol compounds which have been observed in the environment and in biological systems. By using online preconcentration via solid phase extraction (SPE), the method offers picomolar (12–530 pM) detection limits, the lowest reported so far for the determination of MeHg compounds. Among three different SPE materials, a weak cation exchange phase showed the best efficiency at a low pH of 2.5. We further report the presence of MeHg-cysteine, MeHg-cysteamine, MeHg-penicillamine, MeHg-cysteinylglycine, and MeHg-glutamylcysteine as the predominant MeHg–thiol complexes in the extracellular milieu of an important HgII methylating bacterium, Geobacter sulfurreducens PCA, exposed to 100 nM of HgII.

Methylmercury (MeHg) is one of the most potent neurotoxins. It is produced in nature through the methylation of inorganic divalent mercury (HgII) by phylogenetically diverse anaerobic microbes. The mechanistic understanding of the processes that govern the extent of bacterial export of MeHg, its bioaccumulation, and bio-toxicity depends on accurate quantification of its species, especially its complexation with low molecular mass thiols; organometallic complexes that are difficult to detect and measure in natural conditions. Here, we report the development of a novel analytical method based on liquid chromatography tandem mass spectrometry (LC-MS/MS) to determine 13 MeHg complexes with important thiol compounds which have been observed in the environment and in biological systems. By using online preconcentration via solid phase extraction (SPE), the method offers picomolar (12–530 pM) detection limits, the lowest reported so far for the determination of MeHg compounds. Among three different SPE materials, a weak cation exchange phase showed the best efficiency at a low pH of 2.5. We further report the presence of MeHg-cysteine, MeHg-cysteamine, MeHg-penicillamine, MeHg-cysteinylglycine, and MeHg-glutamylcysteine as the predominant MeHg–thiol complexes in the extracellular milieu of an important HgII methylating bacterium, Geobacter sulfurreducens PCA, exposed to 100 nM of HgII.

Methylmercury (MeHg) is one of the most potent neurotoxins. It is produced in nature through the methylation of inorganic divalent mercury (HgII) by phylogenetically diverse anaerobic microbes. The mechanistic understanding of the processes that govern the extent of bacterial export of MeHg, its bioaccumulation, and bio-toxicity depends on accurate quantification of its species, especially its complexation with low molecular mass thiols; organometallic complexes that are difficult to detect and measure in natural conditions. Here, we report the development of a novel analytical method based on liquid chromatography tandem mass spectrometry (LC-MS/MS) to determine 13 MeHg complexes with important thiol compounds which have been observed in the environment and in biological systems. By using online preconcentration via solid phase extraction (SPE), the method offers picomolar (12–530 pM) detection limits, the lowest reported so far for the determination of MeHg compounds. Among three different SPE materials, a weak cation exchange phase showed the best efficiency at a low pH of 2.5. We further report the presence of MeHg-cysteine, MeHg-cysteamine, MeHg-penicillamine, MeHg-cysteinylglycine, and MeHg-glutamylcysteine as the predominant MeHg–thiol complexes in the extracellular milieu of an important HgII methylating bacterium, Geobacter sulfurreducens PCA, exposed to 100 nM of HgII.

Methylmercury (MeHg) is one of the most potent neurotoxins. It is produced in nature through the methylation of inorganic divalent mercury (HgII) by phylogenetically diverse anaerobic microbes. The mechanistic understanding of the processes that govern the extent of bacterial export of MeHg, its bioaccumulation, and bio-toxicity depends on accurate quantification of its species, especially its complexation with low molecular mass thiols; organometallic complexes that are difficult to detect and measure in natural conditions. Here, we report the development of a novel analytical method based on liquid chromatography tandem mass spectrometry (LC-MS/MS) to determine 13 MeHg complexes with important thiol compounds which have been observed in the environment and in biological systems. By using online preconcentration via solid phase extraction (SPE), the method offers picomolar (12–530 pM) detection limits, the lowest reported so far for the determination of MeHg compounds. Among three different SPE materials, a weak cation exchange phase showed the best efficiency at a low pH of 2.5. We further report the presence of MeHg-cysteine, MeHg-cysteamine, MeHg-penicillamine, MeHg-cysteinylglycine, and MeHg-glutamylcysteine as the predominant MeHg–thiol complexes in the extracellular milieu of an important HgII methylating bacterium, Geobacter sulfurreducens PCA, exposed to 100 nM of HgII.

Methylmercury (MeHg) is one of the most potent neurotoxins. It is produced in nature through the methylation of inorganic divalent mercury (HgII) by phylogenetically diverse anaerobic microbes. The mechanistic understanding of the processes that govern the extent of bacterial export of MeHg, its bioaccumulation, and bio-toxicity depends on accurate quantification of its species, especially its complexation with low molecular mass thiols; organometallic complexes that are difficult to detect and measure in natural conditions. Here, we report the development of a novel analytical method based on liquid chromatography tandem mass spectrometry (LC-MS/MS) to determine 13 MeHg complexes with important thiol compounds which have been observed in the environment and in biological systems. By using online preconcentration via solid phase extraction (SPE), the method offers picomolar (12–530 pM) detection limits, the lowest reported so far for the determination of MeHg compounds. Among three different SPE materials, a weak cation exchange phase showed the best efficiency at a low pH of 2.5. We further report the presence of MeHg-cysteine, MeHg-cysteamine, MeHg-penicillamine, MeHg-cysteinylglycine, and MeHg-glutamylcysteine as the predominant MeHg–thiol complexes in the extracellular milieu of an important HgII methylating bacterium, Geobacter sulfurreducens PCA, exposed to 100 nM of HgII.

Scaling often leads to a series of technical and economical problems in industrial plants and equipments by blocking water flow in pipes or limiting heat transfer in heat exchangers. While most contemporary studies are focusing on crystallization at heat-exchanger surfaces and scaling on nanofilters in desalination plants,very little work has been done investigating scale formation on pipe and vessel walls. A comprehensive investigation of the effects of various process parameters in controlling the formation of calcium sulfate scale in pipes was undertaken. Supersaturation ratio, run time, and operational hydrodynamics were altered systematically to determine their influence on the scale growth rate. The results confirmed that the deposition of gypsum on pipe walls was significantly affected by these process parameters.

Gypsum is widely known as one of the major components of scale in many industrial processes and domestic applications. The scale formation of gypsum is a persistent problem encountered by several hydrometallurgical processes in Australia. It is a complicated phenomenon which causes a series of operational problems such as a reduction in production capacity, an increase in energy requirement, and an increase in downtime for maintenance and replacement of parts. Ultimately, these technical difficulties lead to substantial economic consequences.Early researchers on gypsum scaling mainly focused on the kinetics of scale formation, while later studies put the emphasis on the effects of external factors such as hydrodynamics. To date, very little work has been done to investigate gypsum scale formation pertinent to hydrometallurgical processes such as those found in Australia, namely gypsum scaling on pipes, vessel walls and cooling systems.This paper presents a thorough and systematic investigation on the effects of various process parameters and the efficacy of both inorganic and organic additives in controlling the formation of gypsum scale in pipe flow systems. These process parameters included flow rate, temperature, supersaturation and surface materials. The effects of three inorganic and twelve organic additives, mainly the derivatives of carboxylic and phosphonic acids, on the scale formation were also investigated. © 2011 by Nova Science Publishers, Inc. All rights reserved.

Calcium sulphate scaling is a serious problem encountered in many industrial and domestic applications. Supersaturation has been proven to be the major driving force of scale formation, but the solubility of calcium sulphate changes with temperature. The main purpose of this work is toinvestigate the effects of temperature on the formation of calcium sulphate scales in pipes, using a pipe flow system. Various levels of supersaturation of the calcium sulphate solution have been employed at different temperatures. Results indicated that higher temperature produced a large increase of scale amounts and a significant decrease of induction periods. Many forms of hydrated calcium sulphate were created at high temperature. The relationship between deposited scale mass and temperature was deduced from experimental data. From the relationship between induction period and temperature activation energies of the surface nucleation were estimated to be in the range of 42 to 48 kJ mol-1.

Communication is often limited in a disaster area and other emergency situations where no infrastructure exists or existing infrastructure has been destroyed. This makes its difficult for relief workers in the field to communicate with one another and with their home head office. Ericsson Response has developed a Wireless LAN in Disaster and Emergency Response (WIDER) solution. WIDER is based on broadband Wireless LAN internetworking to satellite and GSMnetworks. The WIDER solution has identified ways for organizations to share their communication infrastructure, and information in a secure and cost effective manner during an emergency response operation. Data over WIDER needs to be secured to prevent from unauthorized access to sensitive information of relief organizations. VoIP calls should be protected against eavesdropping. The thesis investigated how to enhance security solution in WIDER and implement a secure VoIP client. Measurements of the performance of WIDER and the total delay of VoIP over satellite were used to estimate the capability of WIDER before deployment in the field., Kommunikation är ofta begränsad i katastrofområden och andra nödsituationer där infrastruktur saknas eller har blivit förstörd. Det gör det svårt för fältarbetande personal att kommunicera, både med varandra och centraliserade kontor. Ericsson Response har utvecklat en lösning kallad "Wireless LAN in Disaster and Emergency Response" (WIDER). WIDER använder trådlöst LAN och är en bredbandsbaserad internetteknik mot satelit- och GSM-nätverk. WIDER har identifierat lösningar för organisationer att dela deras infrastruktur för kommunikation och information på ett säkert och kostnatseffektivt sätt vid nödsituationer. Informationen som skickas via WIDER behöver bli skyddad för att förhindra oaktorisierad tillgång till känslig information. VoIP förhindrar obehöriga att avlyssna trafiken. Examensarbetet har undersökt den utökade säkerhetslösningen för WIDER och har implementerat en säker VoIP-klient. Mätningar av prestanda hos WIDER och den fördröjning som sker med VoIP över satelitlänk användes för att estimera WIDERs kapacitet innan systemet används i fält.

Communication is often limited in a disaster area and other emergency situations where no infrastructure exists or existing infrastructure has been destroyed. This makes its difficult for relief workers in the field to communicate with one another and with their home head office. Ericsson Response has developed a Wireless LAN in Disaster and Emergency Response (WIDER) solution. WIDER is based on broadband Wireless LAN internetworking to satellite and GSMnetworks. The WIDER solution has identified ways for organizations to share their communication infrastructure, and information in a secure and cost effective manner during an emergency response operation. Data over WIDER needs to be secured to prevent from unauthorized access to sensitive information of relief organizations. VoIP calls should be protected against eavesdropping. The thesis investigated how to enhance security solution in WIDER and implement a secure VoIP client. Measurements of the performance of WIDER and the total delay of VoIP over satellite were used to estimate the capability of WIDER before deployment in the field., Kommunikation är ofta begränsad i katastrofområden och andra nödsituationer där infrastruktur saknas eller har blivit förstörd. Det gör det svårt för fältarbetande personal att kommunicera, både med varandra och centraliserade kontor. Ericsson Response har utvecklat en lösning kallad "Wireless LAN in Disaster and Emergency Response" (WIDER). WIDER använder trådlöst LAN och är en bredbandsbaserad internetteknik mot satelit- och GSM-nätverk. WIDER har identifierat lösningar för organisationer att dela deras infrastruktur för kommunikation och information på ett säkert och kostnatseffektivt sätt vid nödsituationer. Informationen som skickas via WIDER behöver bli skyddad för att förhindra oaktorisierad tillgång till känslig information. VoIP förhindrar obehöriga att avlyssna trafiken. Examensarbetet har undersökt den utökade säkerhetslösningen för WIDER och har implementerat en säker VoIP-klient. Mätningar av prestanda hos WIDER och den fördröjning som sker med VoIP över satelitlänk användes för att estimera WIDERs kapacitet innan systemet används i fält.

The effects of light intensity (I, 750 and 75 lx) and photoperiod (P, 12L/12D and 7L/5D) on moulting and growth of Penaeus merguiensis were investigated over 12 weeks under laboratory conditions. Both light intensity and photoperiod significantly (P<0.05) influenced the percentage weight gain (PWG), but did not influence moult frequency or moult interval. Mean PWG of prawns cultured at 750 lx was 198.4%, significantly (P<0.01) higher than those cultured at 75 lx (168.1%). Imposing two light/dark cycles (7L/5D) in 24 h resulted in a significantly higher growth of prawns (P<0.05) than the normal photoperiod (12L/12D). Prawns cultured at 750 lx had a lower food conversion ratio (FCR, 1.485) than those cultured at 75 lx (1.590, P<0.05). The effect of light intensity on prawn growth was found to be stronger and more immediate than that of photoperiod. There was no interaction between light intensity and photoperiod. Although not significantly different (P>0.05), prawns cultured at 750 lx tended to moult more frequently. Sexual dimorphism was not observed within the range of tested prawns.

The effects of light intensity (I, 750 and 75 lx) and photoperiod (P, 12L/12D and 7L/5D) on moulting and growth of Penaeus merguiensis were investigated over 12 weeks under laboratory conditions. Both light intensity and photoperiod significantly (P<0.05) influenced the percentage weight gain (PWG), but did not influence moult frequency or moult interval. Mean PWG of prawns cultured at 750 lx was 198.4%, significantly (P<0.01) higher than those cultured at 75 lx (168.1%). Imposing two light/dark cycles (7L/5D) in 24 h resulted in a significantly higher growth of prawns (P<0.05) than the normal photoperiod (12L/12D). Prawns cultured at 750 lx had a lower food conversion ratio (FCR, 1.485) than those cultured at 75 lx (1.590, P<0.05). The effect of light intensity on prawn growth was found to be stronger and more immediate than that of photoperiod. There was no interaction between light intensity and photoperiod. Although not significantly different (P>0.05), prawns cultured at 750 lx tended to moult more frequently. Sexual dimorphism was not observed within the range of tested prawns.

The effect of three levels of light intensity (BRIGHT: 1100 lux; DIM: 2 lux; and DARK: 0 lux) on ovarian maturation and spawning of Penaeus merguiensis was investigated. The proportion of spawners, latency period, spawning rate, fecundity, spawning interval and number of days spent at stage IV per spawn were not significantly different (P>0.05) among the three light intensity treatments. Compared to dim light, bright light did not adversely affect the maturation and reproductive performance of ablated prawns. However, the percentage of spawning at stage III (31.6%) and mortality (26.7%) were significantly higher in the DARK treatment (P<0.05). A trend of increasing fecundity with an increase in light intensity was observed. Also, the hypothesis of whether the prawn eye is the only light receptor involved in ovarian maturation and spawning was tested by covering the remaining eye of ablated prawns with prepared caps made from black heat-shrinkable tubing (polyolefin). These prawns were held under 1100 lux (BRI-COV treatment) and 2 lux (DIM-COV) with the DARK treatment as the control group. The proportion of spawners was lowest in the BRI-COV treatment and highest in the DARK treatment (P<0.05), whereas there was no significant difference between these two treatments and the DIM-COV treatment. The DARK treatment, however, had a significantly higher spawning rate (P<0.05). The significantly higher percentage of spawning at stage III and less time spent at stage IV per spawn of prawns in the DARK treatment (P<0.05) compared with the DIM-COV and BRI-COV treatments suggest that the prawn eye may not be the only light receptor involving in ovarian maturation and spawning in P. merguiensis.

The effect of light intensity on ovarian maturation and spawning of unablated female Penaeus merguiensis was investigated in a 4 week experiment. The experiment had two different light intensity treatments: BRIGHT (1100 lx) and DIM (2 lx). At starting time, there were four groups of broodstock with four different ovarian maturation stages (II, III, IV and V) in each treatment. Results showed that light intensity plays an important role in controlling ovarian maturation of prawns, especially at the later stages (stages III and IV). Bright light showed an inhibitory effect, whereas dim light favoured ovarian maturation and spawning. Ovarian regression occurred in most stage III and stage IV prawns kept under bright light, while prawns at the same stages developed their ovaries further and spawned under dim light. Proportion of spawners (12.5%), mean number of spawns per prawn (0.12) and mean fecundity (87,300) of prawns were significantly lower (P<0.05) in the BRIGHT treatment, compared to the DIM treatment. Under light intensity of 2 lx, 41.7% of prawns spawned, producing 0.5 spawn per prawn on average with a mean fecundity of 117,300. The results also suggest that the sensitivity of broodstock to light increased from stages II to IV of ovarian maturation, while there were some evidence of light adaptation in stage V broodstock. This study confirmed multiple spawning of unablated P. merguiensis for the first time. Rematuration period was short (6–7 days).

This 12-month preliminary study investigated the development of sexual characters, primary sexual maturity, ovarian maturity and spawning performance of pond-reared Penaeus merguiensis in relation to culture conditions in south-east Queensland, Australia. Post-larvae of P. merguiensis were produced and cultured in two 60-m3 tanks during the first 14 weeks. Before winter, they were harvested and stocked in three different overwintering facilities: a 200-m2 covered pond, two 60-m3 outdoor tanks and a 15-m3 indoor, recirculated tank at a stocking density of 10 individuals m−2. The development of sexual characters was found to be similar to that reported previously in wild P. merguiensis. Males matured at younger ages and smaller sizes than females. Overall, the average size at primary sexual maturity of pond-reared P. merguiensis was 23.1 mm carapace length for males (possessed spermatophores) and 29.3 mm for females (being impregnated). Water temperature and the availability of natural food strongly influenced prawn growth, maturity rate and their subsequent spawning performance. Growth, maturity rate and spawning performance of prawns in the covered pond were significantly higher than in the other overwintering facilities. Prawns started mating at 6–7 months, reached full ovarian maturation and spawned as early as about 8 (peaked at 9–11) months from hatching, producing high fecundity and viable larvae. There was a strong relationship (P < 0.001) between prawn size and fecundity. The results of this study suggest a potential for using pond-reared broodstock P. merguiensis for hatchery production and for domestication or selective breeding programmes.

Critical thermal minima (CTMin) were determined for subadults of Penaeus merguiensis acclimated at 15, 18, 21 and 24 °C for 3 weeks. The effect of cooling rate on CTMin was also investigated. The CTMin of prawns from these respective acclimation groups were 5.3, 6.0, 7.4, 9.0 and 4.7, 5.4, 6.0, 7.3 °C at the cooling rate of 1 °C h−1 and 3 °C h−1 respectively. Both acclimation temperature and cooling rate had a significant effect (P < 0.01) on the CTMin. Observation during the acclimation period showed that the growth rate of prawns acclimated at 24 °C was much higher than those acclimated at 21, 18 and 15 °C. The results indicate that P. merguiensis can overwinter in aquaculture ponds in south-east Queensland, Australia, or other subtropical areas and attain good growth if simple overwintering facilities are available.

An experiment was conducted to investigate the effect of light intensity just prior to and during spawning of Penaeus (Fenneropenaeus) merguiensis de Man in the laboratory. Neither the presence of light nor light intensity (0, 10 and 1100 lux) had a significant effect on the spawning process or hatching rate in P. merguiensis. Difference in the percentage of spawners, percentage of incomplete spawning, fecundity and hatching rate were all insignificant (P > 0.05) among the three light treatments. However, spawning was delayed (up to 21 min on average) under 1100 lux with a high percentage of incomplete spawning, compared with the Control (0 lux). For the first time, spawning behaviour of P. merguiensis was observed and fully described. The spawning process can be divided into four phases: dormant, pre-spawning, spawning and post-spawning by distinct behaviour of prawn broodstock. The dormant phase was characterized by a quiescent and non-feeding period, whereas movement of prawn broodstock was active during the pre-spawning and post-spawning phases. Depending on the individual, spawning was completed within 3–5 min. Prawns often stayed still on the water surface during spawning with occasional manoeuvres to change the position. After a short rest at the termination of the spawning phase, prawn broodstock re-exhibited active movement as in the pre-spawning phase, but showing conspicuous care to the deposited eggs. The role of light in controlling ovarian development and spawning, and the behaviour of prawn broodstock in relation to maximizing fertilization rate are discussed.

The effects of prawn age, size, and light intensity on spawning performance of pond-reared Penaeus merguiensis were studied by inducing spawning of prawn broodstock by eyestalk ablation under two different light intensities (bright, 1100 lx and dim, 2 lx) at three different known ages (7, 10, and 13 months old). For each age group (except the 13-month-old group), two distinguished size classes (large and small) were established to reveal the effect of prawn size. Results showed that light intensity did not affect spawning performance of prawns of different ages and sizes (P>0.05). In contrast, age had a significant effect on spawning performance of prawns (P<0.01). The overall spawning performance of the prawns increased from 7 to 10 months old and started to decline at 13 months old. Within the 7- and 10-month-old groups, larger prawns produced a superior overall spawning performance compared with smaller ones (P<0.01). Comparison across the size range of the experimental prawns showed that spawning performance improved with the increase of body size. However, the 13-month-old prawns, although having a similar size as large 10-month-old prawns, had an inferior spawning performance (P<0.01). Survival and growth of ablated prawns significantly decreased with the increase of prawn size and age (P<0.01). It is suggested that spawning performance of pond-reared P. merguiensis peaked between 10 and 12 months old, and broodstock should be bred during this period for hatchery production.

The maturation rate and spawning performance of ablated Penaeus merguiensis were significantly (P<0.05) higher at 27°C than at 23°C. Increasing the temperature from 23°C to 27°C further improved spawning performance (P<0.05), whereas reducing the temperature from 27°C to 23°C impaired spawning. The effect of temperature during the inducing period was more critical than during the holding period. Prawn growth (% of weight gain), however, was not different between 23°C and 27°C over the 60-day experimental period (P>0.05).

Joint Research on Environmental Science and Technology for the Earth

Joint Research on Environmental Science and Technology for the Earth