Audio-based classification techniques on body sounds have long been studied to aid in the diagnos... more Audio-based classification techniques on body sounds have long been studied to aid in the diagnosis of respiratory diseases. While most research is centered on the use of cough as the main biomarker, other body sounds also have the potential to detect respiratory diseases. Recent studies on COVID-19 have shown that breath and speech sounds, in addition to cough, correlate with the disease. Our study proposes Fused Audio Instance and Representation (FAIR) as a method for respiratory disease detection. FAIR relies on constructing a joint feature vector from various body sounds represented in waveform and spectrogram form. We conducted experiments on the use case of COVID-19 detection by combining waveform and spectrogram representation of body sounds. Our findings show that the use of self-attention to combine extracted features from cough, breath, and speech sounds leads to the best performance with an Area Under the Receiver Operating Characteristic Curve (AUC) score of 0.8658, a sensitivity of 0.8057, and a specificity of 0.7958. Compared to models trained solely on spectrograms or waveforms, the use of both representations results in an improved AUC score, demonstrating that combining spectrogram and waveform representation helps to enrich the extracted features and outperforms the models that use only one representation.
Transfer learning has become a standard practice to mitigate the lack of labeled data in medical ... more Transfer learning has become a standard practice to mitigate the lack of labeled data in medical classification tasks. Whereas finetuning a downstream task using supervised ImageNet pretrained features is straightforward and extensively investigated in many works, there is little study on the usefulness of self-supervised pretraining. This paper assesses the transferability of the most recent self-supervised Ima-geNet models, including SimCLR, SwAV, and DINO, on selected medical imaging classification tasks. The chosen tasks cover tumor detection in sentinel axillary lymph node images, diabetic retinopathy classification in fundus images, and multiple pathological condition classification in chest X-ray images. We demonstrate that self-supervised pretrained models yield richer embeddings than their supervised counterparts, benefiting downstream tasks for linear evaluation and finetuning. For example, at a critically small subset of the data with linear evaluation, we see an im provement up to 14.79% in Kappa score in the diabetic retinopathy classification task, 5.4% in AUC in the tumor classification task, 7.03% AUC in the pneumonia detection, and 9.4% in AUC in the detection of pathological conditions in chest Xray. In addition, we introduce Dynamic Visual Meta-Embedding (DVME) as an end-toend transfer learning approach that fuses pretrained embeddings from multiple models. We show that the collective representation obtained by DVME leads to a significant improvement in the performance of selected tasks compared to using a single pretrained model approach and can be generalized to any combination of pretrained models.
In this paper, an algebraic decoding method is proposed for the quadratic residue codes that util... more In this paper, an algebraic decoding method is proposed for the quadratic residue codes that utilize the Berlekamp-Massey algorithm. By a modification of the technique developed by He et al., one can express the unknown syndromes as functions of the known syndromes. The unknown syndromes are determined by an efficient algorithm also developed in this paper. With the appearance of unknown syndromes, one obtains the consecutive syndromes that are needed for the application of the Berlekamp-Massey algorithm. The decoding scheme, developed here, is easier to implement than the previous decoding algorithm developed for the Golay code and the (47, 24, 11) QR code. Moreover, it can be extended to decode all codes of the family of binary quadratic residue codes with irreducible generating polynomials.
IEE Proceedings E Computers and Digital Techniques, 1988
Berlekamp 's key equation needed to decode a Reed-Solomon (RS) code. In this article, a simplifie... more Berlekamp 's key equation needed to decode a Reed-Solomon (RS) code. In this article, a simplified procedure is developed and proved. to correct erasures as well as errors by replacing the initial condition of the Euclidean algorithm by the erasure locator polynomial and the Forney syndrome polynomial. By this means, the errata locator polynomial and the errata evaluator polynomial can be obtained, simultaneously and simply, by the Euclidean algorithm only. With this improved technique the complexity of time-domain RS decoders for correcting both errors and erasures is reduced substantially from previous approaches. As a consequence, decoders for correcting both errors and erasures of RS codes can be made more modular, regular, simple, and naturally suitable for both VLSI and software implementation, A n example illustrating this modified decoding procedure is given for a (I 5, 9) RS code. Recently, Eastman' showed that the errata evaluator polynomial can be computed directly by initializing Berlekamp's
IEE Proceedings E Computers and Digital Techniques, 1990
This article considers a Reed-Solomon (RS) code to be a special case of a redundant residue polyn... more This article considers a Reed-Solomon (RS) code to be a special case of a redundant residue polynomial (RRP) code, and presents a fast transform decoding algorithm to correct both errors and erasures, This decoding scheme is an improvement of the decoding algorithm for the RRP code suggested by Shiozaki and Nishida [1], and can be realized readily on VLSI chips.
IEEE Transactions on Acoustics, Speech, and Signal Processing, 1990
In this paper, a new Fourier technique for digital signal processing is developed. This approach ... more In this paper, a new Fourier technique for digital signal processing is developed. This approach to Fourier analysis is based on the number-theoretic method of the Miihius inversion of series. The Fourier transform method developed in this paper is shown also to yield the convolution of two signals. A computer simulation shows that this method to find Fourier coefficients is quite suitable for digital signal processing. Also, it competes with the classical FFT approach in terms of accuracy, complexity, and speed.
Since the pioneering use of autologous rib cartilage for the reconstruction of microtia, there ha... more Since the pioneering use of autologous rib cartilage for the reconstruction of microtia, there have been significant advances in surgical technique that have helped to ameliorate the psychological burden of microtia. To date, the use of rib cartilage for auricular reconstruction is one of the most enduring and ubiquitous techniques for microtia reconstruction as it provides excellent aesthetic results with lasting durability. In this review, the authors outline the most common methods of microtia reconstruction with a comparison of each technique and illustrative case examples.
The frontal bone serves a protective role, representing the transition between the facial skeleto... more The frontal bone serves a protective role, representing the transition between the facial skeleton and the cranium. Within its enclosure, the frontal sinus lies adjacent to many important intracranial structures, and injury to this region has severe complications if not properly managed. Historically, the goals of frontal sinus fracture management have been to best prevent intracranial complications with invasive procedures, but a recent shift favoring conservative management now aims to preserve the form and function of the frontal sinus and its outflow tract. With the advancement of endoscopic techniques and the development of new technologies, many alternatives to aggressive surgical management are available.
Facial fractures are a common source of emergency department consultations for the plastic surgeo... more Facial fractures are a common source of emergency department consultations for the plastic surgeon. A working understanding of evaluation, assessment, management, and prevention of further injury when dealing with these fractures is vital. This two-part series detailing the management of midface fractures serves as a guide for the appropriate workup and management of the wide variety of fracture patterns that are commonly encountered.
Facial fractures are a common source of emergency department consultations for the plastic surgeo... more Facial fractures are a common source of emergency department consultations for the plastic surgeon. A working understanding of the evaluation, the assessment, the management, and the prevention of further injury when dealing with these fractures is vital. This second of a two-part series detailing the management of midfacial fractures serves as a guide for the appropriate workup and management of the wide variety of fracture patterns that are commonly encountered.
The 2004 IEEE Asia-Pacific Conference on Circuits and Systems, 2004. Proceedings.
A new VLSI architecture using free discrepancy Berlekamp-Massey (FDBM) algorithm is proposed for ... more A new VLSI architecture using free discrepancy Berlekamp-Massey (FDBM) algorithm is proposed for wireless applications. Firstly, this project uses the FDBM algorithm to reduce the path delay. A method of module reuse is applied to reduce the overall core size successfully. Using single system clock, it is easy to integrate the core into SoC. As a result, this RS decoder
The 2004 IEEE Asia-Pacific Conference on Circuits and Systems, 2004. Proceedings.
In this paper, a new design of Massey-Omura (MO) multiplier is proposed. This MO multiplier is ve... more In this paper, a new design of Massey-Omura (MO) multiplier is proposed. This MO multiplier is very effective in performing the inverse element or exponentiation of a finite field element on the normal basis. This design focuses on the space reduction and law delay of the previous ones. The delay of this multiplier is fried and independent of m. Due to its regularity and simpliciq, the design and expansion to a high-order finite-field multiplier is much easier to realize. Keyword: Massey-Omura multiplier, Finite field, VLSI, all-one polynomial, optimal normal bases.
The tremendous development of location-based services and mobile devices has led to an increase i... more The tremendous development of location-based services and mobile devices has led to an increase in location databases. Through the data mining process, valuable information can be discovered from such location databases. However, the malicious data miner or attackers may also extract private and sensitive information about the user, and this can create threats against the user location privacy. Therefore, location privacy protection becomes a key factor to the success in privacy protection for the users of location-based services. In this paper, we propose a novel approach as well as an algorithm to guarantee k-anonymity in a location database. The algorithm will maintain the association rules that have significance for the data mining process. Moreover, there may appear new significant association rules created after anonymization, they maybe affect the data mining result. Therefore, the algorithm also considers excluding new significant association rules that are created during the run of the algorithm. Theoretical analyses and experimental results with real-world datasets will confirm the practical value of our newly proposed approach.
NASA's LCRD mission will lay the foundation for future laser communication systems. We show the d... more NASA's LCRD mission will lay the foundation for future laser communication systems. We show the design of the Table Mountain ground station's AO system and time series of predicted coupling efficiency.
International Conference on Communication Technology Proceedings, 2003. ICCT 2003.
In this paper, an algebraic decoding method is proposed for the quadratic residue codes that util... more In this paper, an algebraic decoding method is proposed for the quadratic residue codes that utilize the Berlekamp-Massey (BM) algorithm. By applying a technique developed in He et al. [2001], one can express unknown syndromes as functions of known syndromes. Unknown syndromes are determined by an efficient algorithm also developed in this paper. With the experience of unknown syndromes, one obtains the consecutive syndromes that are needed for the application of the inverse-free BM algorithm. The new decoding scheme, developed here can be used to implement the (71,36,11) QR code which has not been treated so far. It is verified by a computer program that uses the C++ language.
Individual self-assembled quantum dots and quantum posts are studied under the influence of a sur... more Individual self-assembled quantum dots and quantum posts are studied under the influence of a surface acoustic wave. In optical experiments we observe an acoustically induced switching of the occupancy of the nanostructures along with an overall increase of the emission intensity. For quantum posts, switching occurs continuously from predominantly charged excitons (dissimilar number of electrons and holes) to neutral excitons (same number of electrons and holes) and is independent of whether the surface acoustic wave amplitude is increased or decreased. For quantum dots, switching is nonmonotonic and shows a pronounced hysteresis on the amplitude sweep direction. Moreover, emission of positively charged and neutral excitons is observed at high surface acoustic wave amplitudes. These findings are explained by carrier trapping and localization in the thin and disordered two-dimensional wetting layer on top of which quantum dots nucleate. This limitation can be overcome for quantum pos...
Proceedings of the International Astronomical Union, 2013
We present first imaging results from the PALM-3000 adaptive optics system and PHARO camera on th... more We present first imaging results from the PALM-3000 adaptive optics system and PHARO camera on the Hale 5 m telescope. Observations using a vector vortex coronagraph have given us direct detections of the two-ring dusty debris system around the star HD 141569. Our observations reveal the inner clearing in the disk to unprecedentedly small angular separations, and are the most sensitive yet at the H and K bands. We are for the first time able to measure and compare the colors of the scattered light in the inner and outer dust rings, and find that the outer ring is significantly bluer than the inner ring.
Populations of Apis mellifera and Apis cerana in China and Vietnam were surveyed in order to stud... more Populations of Apis mellifera and Apis cerana in China and Vietnam were surveyed in order to study possible pathogen spill-over from European to Asian honeybees. This is the first survey of the prevalence of honeybee pathogens in apiaries in Vietnam, including pathogen prevalence in wild A. cerana colonies never in contact with A. mellifera. The bee samples were assayed for eight honeybee viruses: deformed wing virus (DWV); black queen cell virus (BQCV); sac brood virus (SBV); acute bee paralysis virus (ABPV); Kashmir bee virus (KBV); Israeli acute paralysis virus (IAPV); chronic bee paralysis virus (CBPV); and slow bee paralysis virus (SBPV), for two gut parasites (Nosema ssp.) and for the causative agent for European foulbrood (Melissococcus plutonius). The Vietnamese samples were assayed for Acarapis woodi infestation. No clear evidence of unique inter-specific transmission of virus infections between the two honeybee species was found. However, in wild A. cerana colonies, the only virus infection detected was DWV. With findings of IAPV infections in Chinese samples of A. cerana colonies in contact with A. mellifera , inter-specific transmission of IAPV cannot be ruled out. BQCV was the most prevalent virus in managed colonies irrespective of bee species. We did not detect the causative agent of European foulbrood, M. plutonius in wild or isolated colonies of A. cerana in Vietnam or China; however, low incidence of this pathogen was found in the Asian host species when in contact with its European sister species. No evidence for the presence of A. woodi was found in the Vietnamese samples. Apis mellifera / Apis cerana / virus infections / Nosema ssp / Acarapis woodi / Melissococcus plutonius
Acousto-electric charge conveyance induced by a surface acoustic wave is employed to dissociate p... more Acousto-electric charge conveyance induced by a surface acoustic wave is employed to dissociate photogenerated excitons. Over macroscopic distances, both electrons and holes are injected sequentially into a remotely positioned, isolated and high-quality quantum emitter, a self-assembled quantum post. This process is found to be highly efficient and to exhibit improved stability at high acoustic powers when compared to direct optical pumping at the position of the quantum post. These characteristics are attributed to the wide matrix quantum well in which charge conveyance occurs and to the larger number of carriers available for injection in the remote configuration, respectively. The emission of such pumped quantum posts is dominated by recombination of neutral excitons and fully directional when the propagation direction of the SAW and the position of the quantum post are reversed.
Audio-based classification techniques on body sounds have long been studied to aid in the diagnos... more Audio-based classification techniques on body sounds have long been studied to aid in the diagnosis of respiratory diseases. While most research is centered on the use of cough as the main biomarker, other body sounds also have the potential to detect respiratory diseases. Recent studies on COVID-19 have shown that breath and speech sounds, in addition to cough, correlate with the disease. Our study proposes Fused Audio Instance and Representation (FAIR) as a method for respiratory disease detection. FAIR relies on constructing a joint feature vector from various body sounds represented in waveform and spectrogram form. We conducted experiments on the use case of COVID-19 detection by combining waveform and spectrogram representation of body sounds. Our findings show that the use of self-attention to combine extracted features from cough, breath, and speech sounds leads to the best performance with an Area Under the Receiver Operating Characteristic Curve (AUC) score of 0.8658, a sensitivity of 0.8057, and a specificity of 0.7958. Compared to models trained solely on spectrograms or waveforms, the use of both representations results in an improved AUC score, demonstrating that combining spectrogram and waveform representation helps to enrich the extracted features and outperforms the models that use only one representation.
Transfer learning has become a standard practice to mitigate the lack of labeled data in medical ... more Transfer learning has become a standard practice to mitigate the lack of labeled data in medical classification tasks. Whereas finetuning a downstream task using supervised ImageNet pretrained features is straightforward and extensively investigated in many works, there is little study on the usefulness of self-supervised pretraining. This paper assesses the transferability of the most recent self-supervised Ima-geNet models, including SimCLR, SwAV, and DINO, on selected medical imaging classification tasks. The chosen tasks cover tumor detection in sentinel axillary lymph node images, diabetic retinopathy classification in fundus images, and multiple pathological condition classification in chest X-ray images. We demonstrate that self-supervised pretrained models yield richer embeddings than their supervised counterparts, benefiting downstream tasks for linear evaluation and finetuning. For example, at a critically small subset of the data with linear evaluation, we see an im provement up to 14.79% in Kappa score in the diabetic retinopathy classification task, 5.4% in AUC in the tumor classification task, 7.03% AUC in the pneumonia detection, and 9.4% in AUC in the detection of pathological conditions in chest Xray. In addition, we introduce Dynamic Visual Meta-Embedding (DVME) as an end-toend transfer learning approach that fuses pretrained embeddings from multiple models. We show that the collective representation obtained by DVME leads to a significant improvement in the performance of selected tasks compared to using a single pretrained model approach and can be generalized to any combination of pretrained models.
In this paper, an algebraic decoding method is proposed for the quadratic residue codes that util... more In this paper, an algebraic decoding method is proposed for the quadratic residue codes that utilize the Berlekamp-Massey algorithm. By a modification of the technique developed by He et al., one can express the unknown syndromes as functions of the known syndromes. The unknown syndromes are determined by an efficient algorithm also developed in this paper. With the appearance of unknown syndromes, one obtains the consecutive syndromes that are needed for the application of the Berlekamp-Massey algorithm. The decoding scheme, developed here, is easier to implement than the previous decoding algorithm developed for the Golay code and the (47, 24, 11) QR code. Moreover, it can be extended to decode all codes of the family of binary quadratic residue codes with irreducible generating polynomials.
IEE Proceedings E Computers and Digital Techniques, 1988
Berlekamp 's key equation needed to decode a Reed-Solomon (RS) code. In this article, a simplifie... more Berlekamp 's key equation needed to decode a Reed-Solomon (RS) code. In this article, a simplified procedure is developed and proved. to correct erasures as well as errors by replacing the initial condition of the Euclidean algorithm by the erasure locator polynomial and the Forney syndrome polynomial. By this means, the errata locator polynomial and the errata evaluator polynomial can be obtained, simultaneously and simply, by the Euclidean algorithm only. With this improved technique the complexity of time-domain RS decoders for correcting both errors and erasures is reduced substantially from previous approaches. As a consequence, decoders for correcting both errors and erasures of RS codes can be made more modular, regular, simple, and naturally suitable for both VLSI and software implementation, A n example illustrating this modified decoding procedure is given for a (I 5, 9) RS code. Recently, Eastman' showed that the errata evaluator polynomial can be computed directly by initializing Berlekamp's
IEE Proceedings E Computers and Digital Techniques, 1990
This article considers a Reed-Solomon (RS) code to be a special case of a redundant residue polyn... more This article considers a Reed-Solomon (RS) code to be a special case of a redundant residue polynomial (RRP) code, and presents a fast transform decoding algorithm to correct both errors and erasures, This decoding scheme is an improvement of the decoding algorithm for the RRP code suggested by Shiozaki and Nishida [1], and can be realized readily on VLSI chips.
IEEE Transactions on Acoustics, Speech, and Signal Processing, 1990
In this paper, a new Fourier technique for digital signal processing is developed. This approach ... more In this paper, a new Fourier technique for digital signal processing is developed. This approach to Fourier analysis is based on the number-theoretic method of the Miihius inversion of series. The Fourier transform method developed in this paper is shown also to yield the convolution of two signals. A computer simulation shows that this method to find Fourier coefficients is quite suitable for digital signal processing. Also, it competes with the classical FFT approach in terms of accuracy, complexity, and speed.
Since the pioneering use of autologous rib cartilage for the reconstruction of microtia, there ha... more Since the pioneering use of autologous rib cartilage for the reconstruction of microtia, there have been significant advances in surgical technique that have helped to ameliorate the psychological burden of microtia. To date, the use of rib cartilage for auricular reconstruction is one of the most enduring and ubiquitous techniques for microtia reconstruction as it provides excellent aesthetic results with lasting durability. In this review, the authors outline the most common methods of microtia reconstruction with a comparison of each technique and illustrative case examples.
The frontal bone serves a protective role, representing the transition between the facial skeleto... more The frontal bone serves a protective role, representing the transition between the facial skeleton and the cranium. Within its enclosure, the frontal sinus lies adjacent to many important intracranial structures, and injury to this region has severe complications if not properly managed. Historically, the goals of frontal sinus fracture management have been to best prevent intracranial complications with invasive procedures, but a recent shift favoring conservative management now aims to preserve the form and function of the frontal sinus and its outflow tract. With the advancement of endoscopic techniques and the development of new technologies, many alternatives to aggressive surgical management are available.
Facial fractures are a common source of emergency department consultations for the plastic surgeo... more Facial fractures are a common source of emergency department consultations for the plastic surgeon. A working understanding of evaluation, assessment, management, and prevention of further injury when dealing with these fractures is vital. This two-part series detailing the management of midface fractures serves as a guide for the appropriate workup and management of the wide variety of fracture patterns that are commonly encountered.
Facial fractures are a common source of emergency department consultations for the plastic surgeo... more Facial fractures are a common source of emergency department consultations for the plastic surgeon. A working understanding of the evaluation, the assessment, the management, and the prevention of further injury when dealing with these fractures is vital. This second of a two-part series detailing the management of midfacial fractures serves as a guide for the appropriate workup and management of the wide variety of fracture patterns that are commonly encountered.
The 2004 IEEE Asia-Pacific Conference on Circuits and Systems, 2004. Proceedings.
A new VLSI architecture using free discrepancy Berlekamp-Massey (FDBM) algorithm is proposed for ... more A new VLSI architecture using free discrepancy Berlekamp-Massey (FDBM) algorithm is proposed for wireless applications. Firstly, this project uses the FDBM algorithm to reduce the path delay. A method of module reuse is applied to reduce the overall core size successfully. Using single system clock, it is easy to integrate the core into SoC. As a result, this RS decoder
The 2004 IEEE Asia-Pacific Conference on Circuits and Systems, 2004. Proceedings.
In this paper, a new design of Massey-Omura (MO) multiplier is proposed. This MO multiplier is ve... more In this paper, a new design of Massey-Omura (MO) multiplier is proposed. This MO multiplier is very effective in performing the inverse element or exponentiation of a finite field element on the normal basis. This design focuses on the space reduction and law delay of the previous ones. The delay of this multiplier is fried and independent of m. Due to its regularity and simpliciq, the design and expansion to a high-order finite-field multiplier is much easier to realize. Keyword: Massey-Omura multiplier, Finite field, VLSI, all-one polynomial, optimal normal bases.
The tremendous development of location-based services and mobile devices has led to an increase i... more The tremendous development of location-based services and mobile devices has led to an increase in location databases. Through the data mining process, valuable information can be discovered from such location databases. However, the malicious data miner or attackers may also extract private and sensitive information about the user, and this can create threats against the user location privacy. Therefore, location privacy protection becomes a key factor to the success in privacy protection for the users of location-based services. In this paper, we propose a novel approach as well as an algorithm to guarantee k-anonymity in a location database. The algorithm will maintain the association rules that have significance for the data mining process. Moreover, there may appear new significant association rules created after anonymization, they maybe affect the data mining result. Therefore, the algorithm also considers excluding new significant association rules that are created during the run of the algorithm. Theoretical analyses and experimental results with real-world datasets will confirm the practical value of our newly proposed approach.
NASA's LCRD mission will lay the foundation for future laser communication systems. We show the d... more NASA's LCRD mission will lay the foundation for future laser communication systems. We show the design of the Table Mountain ground station's AO system and time series of predicted coupling efficiency.
International Conference on Communication Technology Proceedings, 2003. ICCT 2003.
In this paper, an algebraic decoding method is proposed for the quadratic residue codes that util... more In this paper, an algebraic decoding method is proposed for the quadratic residue codes that utilize the Berlekamp-Massey (BM) algorithm. By applying a technique developed in He et al. [2001], one can express unknown syndromes as functions of known syndromes. Unknown syndromes are determined by an efficient algorithm also developed in this paper. With the experience of unknown syndromes, one obtains the consecutive syndromes that are needed for the application of the inverse-free BM algorithm. The new decoding scheme, developed here can be used to implement the (71,36,11) QR code which has not been treated so far. It is verified by a computer program that uses the C++ language.
Individual self-assembled quantum dots and quantum posts are studied under the influence of a sur... more Individual self-assembled quantum dots and quantum posts are studied under the influence of a surface acoustic wave. In optical experiments we observe an acoustically induced switching of the occupancy of the nanostructures along with an overall increase of the emission intensity. For quantum posts, switching occurs continuously from predominantly charged excitons (dissimilar number of electrons and holes) to neutral excitons (same number of electrons and holes) and is independent of whether the surface acoustic wave amplitude is increased or decreased. For quantum dots, switching is nonmonotonic and shows a pronounced hysteresis on the amplitude sweep direction. Moreover, emission of positively charged and neutral excitons is observed at high surface acoustic wave amplitudes. These findings are explained by carrier trapping and localization in the thin and disordered two-dimensional wetting layer on top of which quantum dots nucleate. This limitation can be overcome for quantum pos...
Proceedings of the International Astronomical Union, 2013
We present first imaging results from the PALM-3000 adaptive optics system and PHARO camera on th... more We present first imaging results from the PALM-3000 adaptive optics system and PHARO camera on the Hale 5 m telescope. Observations using a vector vortex coronagraph have given us direct detections of the two-ring dusty debris system around the star HD 141569. Our observations reveal the inner clearing in the disk to unprecedentedly small angular separations, and are the most sensitive yet at the H and K bands. We are for the first time able to measure and compare the colors of the scattered light in the inner and outer dust rings, and find that the outer ring is significantly bluer than the inner ring.
Populations of Apis mellifera and Apis cerana in China and Vietnam were surveyed in order to stud... more Populations of Apis mellifera and Apis cerana in China and Vietnam were surveyed in order to study possible pathogen spill-over from European to Asian honeybees. This is the first survey of the prevalence of honeybee pathogens in apiaries in Vietnam, including pathogen prevalence in wild A. cerana colonies never in contact with A. mellifera. The bee samples were assayed for eight honeybee viruses: deformed wing virus (DWV); black queen cell virus (BQCV); sac brood virus (SBV); acute bee paralysis virus (ABPV); Kashmir bee virus (KBV); Israeli acute paralysis virus (IAPV); chronic bee paralysis virus (CBPV); and slow bee paralysis virus (SBPV), for two gut parasites (Nosema ssp.) and for the causative agent for European foulbrood (Melissococcus plutonius). The Vietnamese samples were assayed for Acarapis woodi infestation. No clear evidence of unique inter-specific transmission of virus infections between the two honeybee species was found. However, in wild A. cerana colonies, the only virus infection detected was DWV. With findings of IAPV infections in Chinese samples of A. cerana colonies in contact with A. mellifera , inter-specific transmission of IAPV cannot be ruled out. BQCV was the most prevalent virus in managed colonies irrespective of bee species. We did not detect the causative agent of European foulbrood, M. plutonius in wild or isolated colonies of A. cerana in Vietnam or China; however, low incidence of this pathogen was found in the Asian host species when in contact with its European sister species. No evidence for the presence of A. woodi was found in the Vietnamese samples. Apis mellifera / Apis cerana / virus infections / Nosema ssp / Acarapis woodi / Melissococcus plutonius
Acousto-electric charge conveyance induced by a surface acoustic wave is employed to dissociate p... more Acousto-electric charge conveyance induced by a surface acoustic wave is employed to dissociate photogenerated excitons. Over macroscopic distances, both electrons and holes are injected sequentially into a remotely positioned, isolated and high-quality quantum emitter, a self-assembled quantum post. This process is found to be highly efficient and to exhibit improved stability at high acoustic powers when compared to direct optical pumping at the position of the quantum post. These characteristics are attributed to the wide matrix quantum well in which charge conveyance occurs and to the larger number of carriers available for injection in the remote configuration, respectively. The emission of such pumped quantum posts is dominated by recombination of neutral excitons and fully directional when the propagation direction of the SAW and the position of the quantum post are reversed.
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Papers by Tuan Nha Truong