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This paper presents the design of a novel multi-beam Luneburg lens antenna with specific dielectric structure and proposes a new solution for downsizing planar lens antennas. The quasi-conformal transformation optics (QCTO) principle is applied to achieve an equivalent transformation relation between the spatial coordinate and the electromagnetic properties of material, effectively preserving the behavior of electromagnetic waves while achieving a significant reduction in antenna size. The antenna comprises a deformed Luneburg lens with a radius equivalent to 3.75lambda , metal plates flanking the lens, and a linear array of seven microstrip antennas operating at 10 GHz. By selectively activating antenna elements within the array, the antenna can generate seven distinct beams, enabling a scanning range of ±30° in the azimuth plane. Each beam achieves a gain exceeding 15 dBi. In comparison to traditional planar lens antennas, this antenna boasts a reduction in size of more than 30% and has the flexibility of being fed using a linear array.

This paper presents the design of a novel multi-beam Luneburg lens antenna with specific dielectric structure and proposes a new solution for downsizing planar lens antennas. The quasi-conformal transformation optics (QCTO) principle is applied to achieve an equivalent transformation relation between the spatial coordinate and the electromagnetic properties of material, effectively preserving the behavior of electromagnetic waves while achieving a significant reduction in antenna size. The antenna comprises a deformed Luneburg lens with a radius equivalent to 3.75lambda , metal plates flanking the lens, and a linear array of seven microstrip antennas operating at 10 GHz. By selectively activating antenna elements within the array, the antenna can generate seven distinct beams, enabling a scanning range of ±30° in the azimuth plane. Each beam achieves a gain exceeding 15 dBi. In comparison to traditional planar lens antennas, this antenna boasts a reduction in size of more than 30% and has the flexibility of being fed using a linear array.

Water quality degradation of urban rivers has become a serious constraint to the sustainable development of big cities in sub-Saharan Africa, and few systematic quantitative studies have been conducted on this issue. Here, we studied three main urban rivers: Mzinga River, Kizinga River, and Msimbazi River in Dar es Salaam, the largest port city on the west coast of the Indian Ocean. The spatial and temporal changes of the physicochemical parameters including DO, pH, oxidation–reduction potential (ORP), electrical conductivity (EC), total dissolved solids (TDS), turbidity, total nitrogen (TN), total dissolved nitrogen (TDN), dissolved inorganic nitrogen (DIN), chemical oxygen demand (CODMn), total phosphorus (TP), total dissolved phosphorus (TDP), soluble reactive phosphate (SRP), and water quality index (WQI) were investigated. The results showed that the middle and lower reaches of the three rivers were severely polluted with N (nitrogen) and P (phosphorus) with pollution increasing from the upstream to the downstream. WQI results showed that the water quality of Msimbazi River was in the “poor” category and fluctuated temporally and spatially. Principal component analyses (PCA) implied that redox status and N were the main factors affecting the water quality of the rivers. Unregulated discharges of untreated municipal and industrial wastewaters were the main drivers of water quality degradation in the rivers. Rapid urbanization characterized by population explosion and the small handicraft industry aggravated the situation. Source control and end treatment are urgently needed to prevent the water quality of the urban rivers in Dar es Salaam from deteriorating further.

The Square Kilometre Array Observatory (SKAO) will explore the radio sky to new depths in order to conduct transformational science. SKAO data products made available to astronomers will be correspondingly large and complex, requiring the application of advanced analysis techniques to extract key science findings. To this end, SKAO is conducting a series of Science Data Challenges, each designed to familiarise the scientific community with SKAO data and to drive the development of new analysis techniques. We present the results from Science Data Challenge 2 (SDC2), which invited participants to find and characterise 233245 neutral hydrogen (Hi) sources in a simulated data product representing a 2000~h SKA MID spectral line observation from redshifts 0.25 to 0.5. Through the generous support of eight international supercomputing facilities, participants were able to undertake the Challenge using dedicated computational resources. Alongside the main challenge, `reproducibility awards' were made in recognition of those pipelines which demonstrated Open Science best practice. The Challenge saw over 100 participants develop a range of new and existing techniques, with results that highlight the strengths of multidisciplinary and collaborative effort. The winning strategy -- which combined predictions from two independent machine learning techniques to yield a 20 percent improvement in overall performance -- underscores one of the main Challenge outcomes: that of method complementarity. It is likely that the combination of methods in a so-called ensemble approach will be key to exploiting very large astronomical datasets., Comment: Under review by MNRAS; 28 pages, 16 figures

Antibiotics in wastewater can affect the structures and functions of bacterial communities, subsequently influencing how well a biological process performs. Therefore, the characteristics of bacterial community were investigated in a hybrid moving bed biofilm reactor-membrane bioreactor system when treating domestic wastewater containing sulfadiazine (SDZ). Results indicated total nitrogen removal reduced by 10.2%, 9.1%, 2.7% and 2.9%, respectively, with increasing carbon to nitrogen (C/N) ratios (2.5, 4, 6 and 9) when SDZ was present (0.5 mg/L). The microbial communities' analysis revealed that the abundance of nitrogen removal-related bacteria increased with C/N. Specifically, the abundance of ammonia-oxidizing bacteria (0.46%-0.90%) was low, and the nitrite-oxidizing bacteria (2.16%-7.13%) and denitrifying bacteria showed a significant increase (Hyphomicrobium: 0.57%-3.54%) when C/N ratio increased. The abundance of denitrifying bacterial declined by 4.82-8.56% at different C/N ratios, while nitrifying bacterial rose by 0.70-5.67%. Interestingly, the denitrifying bacteria Enterobacter, Sphingomonas and Gemmatimonas acted as mutualistic bacteria that stabilized denitrification.

During flexible gastroscopy, physicians have extreme difficulties to self-localize. Camera tracking method such as simultaneous localization and mapping (SLAM) has become a research hotspot in recent years, allowing tracking of the endoscope. However, most of the existing solutions have focused on tasks in which sufficient texture information is available, such as laparoscope tracking, and cannot be applied to gastroscope tracking since gastroscopic images have fewer textures than laparoscopic images. This paper proposes a new monocular SLAM framework based on scale-invariant feature transform (SIFT) and narrow-band imaging (NBI), which extracts SIFT features instead of oriented features from accelerated segment test (FAST) and rotated binary robust independent elementary features (BRIEF) features from gastroscopic NBI images, and performs feature retention based on the response sorting strategy for achieving more matches. Experimental results show that the root mean squared error of the proposed algorithm can reach a minimum of 2.074 mm, and the pose accuracy can be improved by up to 25.73% compared with oriented FAST and rotated BRIEF (ORB)-SLAM. SIFT features and response sorting strategy can achieve more accurate matching in gastroscopic NBI images than other features and homogenization strategy, and the proposed algorithm can also run successfully on real clinical gastroscopic data. The proposed algorithm has the potential clinical value to assist physicians in locating the gastroscope during gastroscopy.

Usably secure ad-hoc device pairing fosters connectivity with hardware which is difficult to access (e.g., implanted) and grants convenience for ad-hoc short-term on-off pairing patterns (e.g. shared public domain). Examples are medical devices or fitness equipment. We present CardioID, an approach to extract features from heart rate variability for secure pairing keys that change with the randomness inherited in heart operation. Our processing chain is compatible with electrocardiogram (ECG, voltage), as well as ballistocardiogram (BCG, acceleration) type signals. Dissimilarities in locally generated sequences are accounted for using fuzzy cryptography exploiting Bose–Chaudhuri–Hocquenghem (BCH) codes. We propose a quantization to derive secure keys for cross BCG-ECG device pairing from heart-rate variability and analyze the performance in (inter- and intra-subject) BCG-to-ECG pairing. A secure communication protocol for Body Area Networks (BAN) is discussed. The attack surface of the protocol is analyzed, and we conduct a video-based attack study. In addition, two case studies with 5 (laboratory) and 20 (controlled in-field) subjects were conducted.

PurposeThis study explored how teachers change, what teachers learn and how they learn during the implementation of project-based learning through lesson study.Design/methodology/approachIn this study, three university researchers, one doctoral student and six mathematics school teachers formed a lesson study team. Using a qualitative research method, this study employed a locally integrating networking strategy to combine the modified Interconnected Model of Teacher Professional Growth (IMTPG) and Bannister's framework to describe the teachers' knowledge change when participating in a lesson study on project-based learning.FindingsThe research revealed that the school teachers' knowledge about authenticity and assessment in the context of project-based learning was changed after the lesson study and how the changes were triggered.Originality/valueThe study demonstrates how the networking of two different theories—modified IMTPG and Bannister's framework—contributes to a better understanding of the process of teachers' collective practice, as well as the knowledge change in PjBL. This networking was done by combining the two theories, which were superimposed at the domain of practice.

PurposeThis study explored how teachers change, what teachers learn and how they learn during the implementation of project-based learning through lesson study.Design/methodology/approachIn this study, three university researchers, one doctoral student and six mathematics school teachers formed a lesson study team. Using a qualitative research method, this study employed a locally integrating networking strategy to combine the modified Interconnected Model of Teacher Professional Growth (IMTPG) and Bannister's framework to describe the teachers' knowledge change when participating in a lesson study on project-based learning.FindingsThe research revealed that the school teachers' knowledge about authenticity and assessment in the context of project-based learning was changed after the lesson study and how the changes were triggered.Originality/valueThe study demonstrates how the networking of two different theories—modified IMTPG and Bannister's framework—contributes to a better understanding of the process of teachers' collective practice, as well as the knowledge change in PjBL. This networking was done by combining the two theories, which were superimposed at the domain of practice.

Transformers have demonstrated impressive expressiveness and transfer capability in computer vision fields. Dense prediction is a fundamental problem in computer vision that is more challenging to solve than general image-level prediction tasks. The inherent properties of transformers enable them to process feature representations with stable and relatively high resolution, which precisely satisfies the demands of dense prediction tasks for finer-grained and more globally coherent predictions. Furthermore, compared to convolutional networks, transformer methods require minimal inductive bias and permit long-range information interaction. These strengths have contributed to exciting advancements in dense prediction tasks that apply transformer networks. This survey aims to provide a comprehensive overview of transformer models with a specific focus on dense prediction. In this survey, we provide a well-rounded view of state-of-the-art transformer-based approaches, explicitly emphasizing pixel-level prediction tasks. We generally consider transformer variants from the network architecture perspective. We further propose a novel taxonomy to organize these models according to their constructions. Subsequently, we examine various specific optimization strategies to tackle certain bottleneck problems in dense prediction tasks. We explore the commonalities and differences among these works and provide multiple horizontal comparisons from the experimental point of view. Finally, we summarize several stubborn problems that continue to impact visual transformers and outline some possible development directions.

Circular cam-roller (CCR) quasi-zero stiffness (QZS) vibration isolators have been extensively studied. As the CCR isolator can only achieve low stiffness in a very small range and cannot withstand excitation with large amplitude, study on other cam profiles has become interests. This paper investigates a parabolic cam-roller (PCR) QZS vibration isolator. Theoretical formulations of the PCR QZS isolator are derived in detail and the condition of PCR isolator outperforming CCR one is obtained. Design parameters are analyzed and then the optimal design is presented. A prototype of the PCR QZS vibration isolator is fabricated and tested; the corresponding CCR QZS and linear isolators are also experimentally evaluated. In comparison with CCR QZS isolators, the proposed PCR QZS isolators can withstand force and displacement excitations with larger amplitudes in the QZS region. The experimental results validate the present formulation and show that vibration isolation performance of the proposed PCR QZS isolator is much better than that of the CCR QZS isolator and that of the corresponding linear isolator. In comparison with the CCR QZS isolator, the present PCR QZS isolator can have lower stiffness in a wider region around the equilibrium position and lower transmissibility.

© 2020 Elsevier B.V. The Tianlai project is a 21 cm intensity mapping experiment aimed at detecting dark energy by measuring the baryon acoustic oscillation (BAO) features in the large scale structure power spectrum. This experiment provides an opportunity to test the data processing methods for cosmological 21 cm signal extraction, which is still a great challenge in current radio astronomy research. The 21 cm signal is much weaker than the foregrounds and easily affected by the imperfections in the instrumental responses. Furthermore, processing the large volumes of interferometer data poses a practical challenge. We have developed a data processing pipeline software called tlpipe to process the drift scan survey data from the Tianlai experiment. It performs offline data processing tasks such as radio frequency interference (RFI) flagging, array calibration, binning, and map-making, etc. It also includes utility functions needed for the data analysis, such as data selection, transformation, visualization and others. A number of new algorithms are implemented, for example the eigenvector decomposition method for array calibration and the Tikhonov regularization for m-mode analysis. In this paper we describe the design and implementation of the tlpipe and illustrate its functions with some analysis of real data. Finally, we outline directions for future development of this publicly code.

© 2020 Wiley-VCH GmbH Vanadium-based materials are fascinating potential cathodes for high energy density Zn-ion batteries (ZIBs), due to their high capacity arising from multi-electron redox chemistry. Most vanadium-based materials suffer from poor rate capability, however, owing to their low conductivity and large dimension. Here, we propose the application of V2C MXene (V2CTx), a conductive 2D nanomaterial, for achieving high energy density ZIBs with superior rate capability. Through an initial charging activation, the valence of surface vanadium in V2CTx cathode is raised significantly from V2+/V3+ to V4+/V5+, forming a nanoscale vanadium oxide (VOx) coating that effectively undergoes multi-electron reactions, whereas the inner V-C-V 2D multi-layers of V2CTx are intentionally preserved, providing abundant nanochannels with intrinsic high conductivity. Owing to the synergistic effects between the outer high-valence VOx and inner conductive V-C-V, the activated V2CTx presents an ultrahigh rate performance, reaching 358 mAh g−1 at 30 A g−1, together with remarkable energy and power density (318 Wh kg−1/22.5 kW kg−1). The structural advantages of activated V2CTx are maintained after 2000 cycles, offering excellent stability with nearly 100% Coulombic efficiency. This work provides key insights into the design of high-performance cathode materials for advanced ZIBs.

The authors present a wideband circularly polarised antenna array consisting of a 10-element ellipse dipole antenna and a feed network. A metal pillar is vertically loaded at the end of each ellipse dipole arm to extend the current path, thereby reducing the lateral dimension of the antenna element. For uniform coverage over the Earth's surface, antenna with an isoflux pattern is required due to its uniform power density over a wide coverage area. To obtain wideband and isoflux characteristics, the amplitude and phase distributions along the network are optimised by applying the hybrid of the genetic algorithm and particle swarm optimisation. Particularly, the feed network with broadband phase shifting performance is designed to attain a broad bandwidth requirement. The proposed antenna can achieve excellent impedance matching and axial ratio characteristics from 1.1 to 1.6 GHz. In addition, the isoflux radiation pattern is obtained with the beamwidth of ±21° where the gain is higher than 0 dBi in the elevation plane (xoz-Plane). The realised gain is better than 10.2 dBi and the side lobes are below −14.2dB across the operating frequency. Finally, the antenna array is manufactured and measured, and good agreement is achieved between the simulation and measurement results.

To accurately and quickly predict the open-circuit air-gap magnetic field in interior permanent magnet synchronous machines (IPMSMs), an analytical model based on magnetic equivalent circuit (MEC) method is proposed. The analytical model can provide radial and tangential components of open-circuit magnetic field in the slotless air gap. The radial component is obtained from the MEC model, and the tangential component is obtained from boundary conditions of macroscopic equations. Then, a complex relative air-gap permeance is applied to take the effect of slots into account. As a result, an accurate solution of both radial and tangential components of the flux density in the slotted air gap is obtained. Additionally, the no-load back electromotive force (EMF) and cogging torque are calculated based on the open-circuit air-gap magnetic field. All the analytical results are verified by the finite element (FE) analysis and they are well matched. In the end, a direct measurement experiment of open-circuit air-gap magnetic field is proposed to verify the validity of both radial and tangential open-circuit air-gap magnetic fields.

To accurately and quickly predict the open-circuit air-gap magnetic field in interior permanent magnet synchronous machines (IPMSMs), an analytical model based on magnetic equivalent circuit (MEC) method is proposed. The analytical model can provide radial and tangential components of open-circuit magnetic field in the slotless air gap. The radial component is obtained from the MEC model, and the tangential component is obtained from boundary conditions of macroscopic equations. Then, a complex relative air-gap permeance is applied to take the effect of slots into account. As a result, an accurate solution of both radial and tangential components of the flux density in the slotted air gap is obtained. Additionally, the no-load back electromotive force (EMF) and cogging torque are calculated based on the open-circuit air-gap magnetic field. All the analytical results are verified by the finite element (FE) analysis and they are well matched. In the end, a direct measurement experiment of open-circuit air-gap magnetic field is proposed to verify the validity of both radial and tangential open-circuit air-gap magnetic fields.

© 2020 Wiley-VCH GmbH Vanadium-based materials are fascinating potential cathodes for high energy density Zn-ion batteries (ZIBs), due to their high capacity arising from multi-electron redox chemistry. Most vanadium-based materials suffer from poor rate capability, however, owing to their low conductivity and large dimension. Here, we propose the application of V2C MXene (V2CTx), a conductive 2D nanomaterial, for achieving high energy density ZIBs with superior rate capability. Through an initial charging activation, the valence of surface vanadium in V2CTx cathode is raised significantly from V2+/V3+ to V4+/V5+, forming a nanoscale vanadium oxide (VOx) coating that effectively undergoes multi-electron reactions, whereas the inner V-C-V 2D multi-layers of V2CTx are intentionally preserved, providing abundant nanochannels with intrinsic high conductivity. Owing to the synergistic effects between the outer high-valence VOx and inner conductive V-C-V, the activated V2CTx presents an ultrahigh rate performance, reaching 358 mAh g−1 at 30 A g−1, together with remarkable energy and power density (318 Wh kg−1/22.5 kW kg−1). The structural advantages of activated V2CTx are maintained after 2000 cycles, offering excellent stability with nearly 100% Coulombic efficiency. This work provides key insights into the design of high-performance cathode materials for advanced ZIBs.

The parasitic ciliate Ichthyophthirius multifiliis has a low host specificity eliciting white spot disease (WSD) in a wide range of freshwater fishes worldwide. The parasite multiplies rapidly whereby the infection may reach problematic levels in a host population within a few days. The parasite targets both wild and cultured fish but the huge economic impact of the protozoan is associated with mortality, morbidity and treatment in aquacultural enterprises. We have investigated the potential for genetic selection of WSD-resistant strains of rainbow trout. Applying the DNA typing system Affymetrix® and characterizing the genome of the individual fish by use of 57,501 single nucleotide polymorphisms (SNP) and their location on the rainbow trout chromosomes, we have genetically characterized rainbow trout with different levels of natural resistance towards WSD. Quantitative trait loci (QTL) used for the selection of breeders with specific markers for resistance are reported. We found a significant association between resistance towards I. multifiliis infection and SNP markers located on the two specific rainbow trout chromosomes Omy 16 and Omy 17. Comparing the expression of immune-related genes in fish-with and without clinical signs-we recorded no significant difference. However, trout surviving the infection showed high expression levels of genes encoding IgT, T-cell receptor TCRβ, C3, cathelicidins 1 and 2 and SAA, suggesting these genes to be associated with protection.

The main fish host reaction to an infection with third stage anisakid nematode larvae is a response in which host immune cells (macrophages, granulocytes, lymphocytes) in affected internal organs initially are attracted to the parasite whereafter fibroblasts may enclose the parasite forming granuloma. Generally, the reaction is non-lethal to the parasite which may survive for years in the fish host retaining infectivity to the final host. This may also apply for the anisakid nematode Contracaecum rudolphii (having the adult stage in cormorants, using copepods as first intermediate/paratenic host and zooplankton feeding fish as paratenic hosts). The present study has shown that most Contracaecum rudolphii larvae survive in bream (Abramis brama) (from Lake Balaton, Hungary) whereas the majority of the nematode larvae die in Cyprinus carpio (from Lake Hévíz, directly connected to Lake Balaton). Both cyprinid host species interacted with the nematode larvae through establishing a marked cellular encapsulation around them but with different effects. The differential survival in common carp and bream may theoretically be explained by ecological factors, such as the environmental temperature which either directly or indirectly affect the development of nematode larvae, and/or intrinsic host factors, such as differential immune responses and host genetics.

The main fish host reaction to an infection with third stage anisakid nematode larvae is a response in which host immune cells (macrophages, granulocytes, lymphocytes) in affected internal organs initially are attracted to the parasite whereafter fibroblasts may enclose the parasite forming granuloma. Generally, the reaction is non-lethal to the parasite which may survive for years in the fish host retaining infectivity to the final host. This may also apply for the anisakid nematode Contracaecum rudolphii (having the adult stage in cormorants, using copepods as first intermediate/paratenic host and zooplankton feeding fish as paratenic hosts). The present study has shown that most Contracaecum rudolphii larvae survive in bream (Abramis brama) (from Lake Balaton, Hungary) whereas the majority of the nematode larvae die in Cyprinus carpio (from Lake Hévíz, directly connected to Lake Balaton). Both cyprinid host species interacted with the nematode larvae through establishing a marked cellular encapsulation around them but with different effects. The differential survival in common carp and bream may theoretically be explained by ecological factors, such as the environmental temperature which either directly or indirectly affect the development of nematode larvae, and/or intrinsic host factors, such as differential immune responses and host genetics.

Populations of grey seals (Halichoerus grypus), sprats (Sprattus sprattus) and cod (Gadus morhua) in the Baltic Sea are relatively stationary. The present work, applying classical and molecular helminthological techniques, documents that seals and cod also share a common parasite, the anisakid nematode Contracaecum osculatum, which uses seals as the final host and fish as transport hosts. Sequencing mitochondrial genes (COX1 and COX2) in adult worms from seals and third-stage larvae from livers of Baltic fish (sprats and cod), showed that all gene variants occur in both seals and fish. Other anisakid nematodes Pseudoterranova decipiens and Anisakis simplex are also found in both seals and cod in the Baltic Sea, but at much lower rates. The Baltic grey seal population was left at a critically low level (comprising a few hundred individuals) during the latter part of the 20th century, but since the year 2000 a marked increase in the population has been observed, reaching more than 40,000 individuals at present. Ecological consequences of the increased seal abundance may result from increased predation on fish stocks, but recent evidence also points to the influence of elevated parasitism on fish performance. Contracaecum osculatum larvae preferentially infect the liver of Baltic cod, considered a vital organ of the host. Whereas low prevalences and intensities in cod were reported during the 1980s and 1990s, the present study documents 100% prevalence and a mean intensity of above 80 worms per fish. Recent studies have also indicated the zoonotic potential of C. osculatum larvae in fish, following the consumption of raw or under-cooked fish. Therefore the present work discusses the impact of parasitism on the cod stock and the increasing risk for consumer health, and lists possible solutions for control.

Populations of grey seals (Halichoerus grypus), sprats (Sprattus sprattus) and cod (Gadus morhua) in the Baltic Sea are relatively stationary. The present work, applying classical and molecular helminthological techniques, documents that seals and cod also share a common parasite, the anisakid nematode Contracaecum osculatum, which uses seals as the final host and fish as transport hosts. Sequencing mitochondrial genes (COX1 and COX2) in adult worms from seals and third-stage larvae from livers of Baltic fish (sprats and cod), showed that all gene variants occur in both seals and fish. Other anisakid nematodes Pseudoterranova decipiens and Anisakis simplex are also found in both seals and cod in the Baltic Sea, but at much lower rates. The Baltic grey seal population was left at a critically low level (comprising a few hundred individuals) during the latter part of the 20th century, but since the year 2000 a marked increase in the population has been observed, reaching more than 40,000 individuals at present. Ecological consequences of the increased seal abundance may result from increased predation on fish stocks, but recent evidence also points to the influence of elevated parasitism on fish performance. Contracaecum osculatum larvae preferentially infect the liver of Baltic cod, considered a vital organ of the host. Whereas low prevalences and intensities in cod were reported during the 1980s and 1990s, the present study documents 100% prevalence and a mean intensity of above 80 worms per fish. Recent studies have also indicated the zoonotic potential of C. osculatum larvae in fish, following the consumption of raw or under-cooked fish. Therefore the present work discusses the impact of parasitism on the cod stock and the increasing risk for consumer health, and lists possible solutions for control.

Baltic cod livers have during recent years been found increasingly and heavily infected with third-stage larvae of Contracaecum osculatum. The infections are associated with an increasing population of grey seals which are final hosts for the parasite. Heavy worm burdens challenge utilization and safety of the fish liver products, and technological solutions for removal of worms are highly needed. We investigated the attachment of the worm larvae in liver tissue by use of histochemical techniques and found that the cod host encapsulates the worm larvae in layers of host cells (macrophages, fibroblasts) supported by enclosures of collagen and calcium. A series of incubation techniques, applying compounds targeting molecules in the capsule, were then tested for their effect to induce worm escape/release reactions. Full digestion solutions comprising pepsin, NaCl, HCl and water induced a fast escape of more than 60% of the worm larvae within 20 min and gave full release within 65 min but the liver tissue became highly dispersed. HCl alone, in concentrations of 48 and 72 mM, triggered a corresponding release of worm larvae with minor effect on liver integrity. A lower HCl concentration of 24 mM resulted in 80% release within 35 min. Water and physiological saline had no effect on worm release, and 1% pepsin in water elicited merely a weak escape reaction. In addition to the direct effect of acid on worm behaviour it is hypothesised that the acid effect on calcium carbonate in the encapsulation, with subsequent release of reaction products, may contribute to activation of C. osculatum larvae and induce escape reactions. Short-term pretreatment of infected cod liver and possibly other infected fish products, using low acid concentrations is suggested as part of a technological solution for worm clearance as low acid concentrations had limited macroscopic effect on liver integrity within 35 min.

Baltic cod livers have during recent years been found increasingly and heavily infected with third-stage larvae of Contracaecum osculatum. The infections are associated with an increasing population of grey seals which are final hosts for the parasite. Heavy worm burdens challenge utilization and safety of the fish liver products, and technological solutions for removal of worms are highly needed. We investigated the attachment of the worm larvae in liver tissue by use of histochemical techniques and found that the cod host encapsulates the worm larvae in layers of host cells (macrophages, fibroblasts) supported by enclosures of collagen and calcium. A series of incubation techniques, applying compounds targeting molecules in the capsule, were then tested for their effect to induce worm escape/release reactions. Full digestion solutions comprising pepsin, NaCl, HCl and water induced a fast escape of more than 60% of the worm larvae within 20 min and gave full release within 65 min but the liver tissue became highly dispersed. HCl alone, in concentrations of 48 and 72 mM, triggered a corresponding release of worm larvae with minor effect on liver integrity. A lower HCl concentration of 24 mM resulted in 80% release within 35 min. Water and physiological saline had no effect on worm release, and 1% pepsin in water elicited merely a weak escape reaction. In addition to the direct effect of acid on worm behaviour it is hypothesised that the acid effect on calcium carbonate in the encapsulation, with subsequent release of reaction products, may contribute to activation of C. osculatum larvae and induce escape reactions. Short-term pretreatment of infected cod liver and possibly other infected fish products, using low acid concentrations is suggested as part of a technological solution for worm clearance as low acid concentrations had limited macroscopic effect on liver integrity within 35 min.

Ichthyophonus (Plehn & Mulsow) is a protistan fish parasite with a broad host range (Ragan et al. 1996). It infects marine and freshwater fish species worldwide and produces a granulomatous systemic disease in vascularized organs such as heart, liver and kidney (Spanggaard et al. 1994; McVicar 1999). The susceptibility of various fish species is considerably variable. Atlantic herring (Clupea harengus L.) are highly susceptible (Rahimian & Thulin 1996), while rainbow trout Oncorhynchus mykiss (Walbaum) show a medium level of susceptibility and catfish (Ameiurus nebulosus Lesueur) are relatively resistant to this parasite (McVicar 1982, 1999). The main characteristics of the infection are multinucleated spherical parasite cells with a double wall and the tissue around the parasite contains inflammatory cells early in the infection, whereas fibrous tissue dominates late in the infection (McVicar & Maclay 1985; Franco‐Sierra & Alvarez‐Pellitero 1999; McVicar 1999). Despite the numerous histopathological studies conducted, we have no information about specific lymphocytes involved with Ichthyophonus in rainbow trout. In teleost fish, different B lymphocyte subsets can be found defined by their expression of immunoglobulin types (Igs) present in fish.

Hemorrhagic fever with renal syndrome (HFRS) caused by hantaviruses and transmitted by rodents is a significant public health problem in China, and occurs more frequently in selenium-deficient regions. To study the role of selenium concentration in HFRS incidence we used a multidisciplinary approach combining ecological analysis with preliminary experimental data. The incidence of HFRS in humans was about six times higher in severe selenium-deficient and double in moderate deficient areas compared to non-deficient areas. This association became statistically stronger after correction for other significant environment-related factors (low elevation, few grasslands, or an abundance of forests) and was independent of geographical scale by separate analyses for different climate regions. A case-control study of HFRS patients admitted to the hospital revealed increased activity and plasma levels of selenium binding proteins while selenium supplementation in vitro decreased viral replication in an endothelial cell model after infection with a low multiplicity of infection (MOI). Viral replication with a higher MOI was not affected by selenium supplementation. Our findings indicate that selenium deficiency may contribute to an increased prevalence of hantavirus infections in both humans and rodents. Future studies are needed to further examine the exact mechanism behind this observation before selenium supplementation in deficient areas could be implemented for HFRS prevention.

The rice XA21 immune receptor kinase and the structurally related XA3 receptor confer immunity to Xanthomonas oryzae pv. oryzae (Xoo), the causal agent of bacterial leaf blight. Here we report the isolation of OsSERK2 (rice somatic embryogenesis receptor kinase 2) and demonstrate that OsSERK2 positively regulates immunity mediated by XA21 and XA3 as well as the rice immune receptor FLS2 (OsFLS2). Rice plants silenced for OsSerk2 display altered morphology and reduced sensitivity to the hormone brassinolide. OsSERK2 interacts with the intracellular domains of each immune receptor in the yeast two-hybrid system in a kinase activity-dependent manner. OsSERK2 undergoes bidirectional transphosphorylation with XA21 in vitro and forms a constitutive complex with XA21 in vivo. These results demonstrate an essential role for OsSERK2 in the function of three rice immune receptors and suggest that direct interaction with the rice immune receptors is critical for their function. Taken together, our findings suggest that the mechanism of OsSERK2-meditated regulation of rice XA21, XA3, and FLS2 differs from that of AtSERK3/BAK1-mediated regulation of Arabidopsis FLS2 and EFR.

A total of 705 rodents from 6 provinces and autonomous regions of mainland People's Republic of China were tested by PCRs for tick-borne agents (Anaplasma phagocytophilum, Borrelia burgdorferi sensu lato, spotted fever grou