Tuan Tran - Academia.edu (original) (raw)

Papers by Tuan Tran

Research paper thumbnail of Approximating the level probabilities in order restricted inference: The simple tree ordering

Biometrika, 1985

... biomet.oxfordjournals.org Downloaded from Page 4. 432 FT WRIGHT AND TUAN TRAN ... In (2) and ... more ... biomet.oxfordjournals.org Downloaded from Page 4. 432 FT WRIGHT AND TUAN TRAN ... In (2) and (4) the x2 an d beta distributions decrease with I and so upper bounds for these tail probabilities are obtained by finding lower stochastic bounds for Pk(w) and vice versa. ...

Research paper thumbnail of Wireless Broadcast Using Network Coding

IEEE Transactions on Vehicular Technology, 2009

Traditional approaches to transmit information reliably over an error-prone network employ either... more Traditional approaches to transmit information reliably over an error-prone network employ either Forward Error Correction (FEC) or retransmission techniques. In this paper we propose some network coding schemes to reduce the number of broadcast transmissions from one sender to multiple receivers. The main idea is to allow the sender to combine and retransmit the lost packets in a certain way, so that with one transmission, multiple receivers are able to recover their own lost packets. For comparison, we derive a few theoretical results on the bandwidth efficiencies of the proposed network coding and traditional Automatic Repeat-reQuest (ARQ) schemes. Both simulations and theoretical analysis confirm the advantages of the proposed network coding schemes over the Automatic Repeat-reQuest (ARQ) ones.

Research paper thumbnail of Pain-related magnetic fields evoked by intra-epidermal electrical stimulation in humans

Clinical Neurophysiology, 2002

We recently developed a new method for the preferential stimulation of Ad fibers in humans. The a... more We recently developed a new method for the preferential stimulation of Ad fibers in humans. The aim of the present study was to examine whether this method can serve as an appropriate stimulus in a magnetoencephalographic study.

Research paper thumbnail of A new method for measuring the conduction velocities of Aβ-, Aδ- and C-fibers following electric and CO 2 laser stimulation in humans

Neuroscience Letters, 2001

The conduction velocities of Ab-, Ad-and C-®bers of a peripheral nerve of the upper limb in norma... more The conduction velocities of Ab-, Ad-and C-®bers of a peripheral nerve of the upper limb in normal subjects were measured by a combination of conventional electric stimulation, painful CO 2 laser stimulation and non-painful CO 2 laser stimulation of a tiny skin surface area, respectively. The values obtained were 69.1^7.4 m/s, 10.6^2.1 and 1.2^0.2 m/s, respectively. These ®ndings demonstrated that the combined methods are useful for experimental and clinical exploration of the physiological function and pathophysiological role of Ab-, Ad-and C-®bers of a given peripheral nerve. q

Research paper thumbnail of A Joint Network-Channel Coding Technique for Single-Hop Wireless Networks

Reliable transmission over an error-prone channel is typically accomplished via channel coding or... more Reliable transmission over an error-prone channel is typically accomplished via channel coding or retransmission of the lost information. In this paper, we investigate a joint network-channel coding technique to increase the bandwidth efficiency of wireless networks. In particular, we show that the proposed joint network-channel coding approach which combines the recent Network Coding (NC) concept with the traditional Forward Error Correction (FEC) technique, can increase the bandwidth efficiency in single-hop wireless networks such as WLAN or WiMAX networks. We present some analytical results on the bandwidth efficiency for both broadcast and unicast scenarios. Based on these theoretical results, we provide a heuristic algorithm that dynamically selects the optimal level of FEC to be used with network coding technique for given channel conditions. For typical channel characteristics, both simulations and theoretical results confirm that the proposed joint networkchannel coding approach can reduce the bandwidth usage up to five times over the Automatic Repeat reQuest (ARQ) technique and up to two times over the HARQ technique.

Research paper thumbnail of Conduction velocity of the spinothalamic tract in humans as assessed by CO 2 laser stimulation of C-fibers

Neuroscience Letters, 2001

We measured the conduction velocity (CV) of C-fibers in the spinothalamic tract (STT) following s... more We measured the conduction velocity (CV) of C-fibers in the spinothalamic tract (STT) following stimulation with a CO 2 laser using a new method. We delivered non-painful laser pulses to tiny areas of the skin overlying the vertebral spinous processes at different levels from the 7 th cervical (C7) to the 12 th thoracic (T12), and recorded cerebral evoked potentials in 11 healthy men. We used the term 'ultra-late laser evoked potentials' (ultra-late LEPs), since the peak latency was much longer than that for conventional LEPs related to Ad-fibers following painful laser stimulation (late LEPs). The mean CV of C-fibers in the STT was 2.2^0.6 m/s, which was significantly lower than the CV of the Ad-fibers (10.0^4.5 m/s). This technique is novel and simple, and should be useful as a diagnostic tool for assessing the level of spinal cord lesions. q

Research paper thumbnail of Cerebral responses following stimulation of unmyelinated C-fibers in humans: electro- and magneto-encephalographic study

Neuroscience Research, 2003

There are two kinds of pain, a sharp pain ascending through Ad fibers (first pain) and a second b... more There are two kinds of pain, a sharp pain ascending through Ad fibers (first pain) and a second burning pain ascending though C fibers (second pain). By using a novel method, the application of a low intensity CO 2 laser beam to a tiny area of skin using a very thin aluminum plate with numerous tiny holes as a spatial filter, we succeeded in selectively stimulating unmyelinated C fibers of the skin in humans, and could record consistent and clear brain responses using electroencephalography (EEG) and magnetoencephalography (MEG). The conduction velocity (CV) of the C fibers of the peripheral nerve and spinal cord, probably spinothalamic tract (STT), is approximately 1 Á/4 m/s, which is significantly slower than that of Ad (approximately 10 Á/15 m/s) and Ab fibers (approximately 50 Á/70 m/s). This method should be very useful for clinical application. Following C fiber stimulation, primary and secondary somatosensory cortices (SI and SII) are simultaneously activated in the cerebral hemisphere contralateral to the stimulation, and then, SII in the hemisphere ipsilateral to the stimulation is activated. These early responses are easily detected by MEG. Then, probably limbic systems such as insula and cingulate cortex are activated, and those activities reflected in EEG components. Investigations of the cortical processing in pain perception including both first and second pain should provide a better understanding of pain perception and, therefore, contribute to pain relief in clinical medicine. #

Research paper thumbnail of Preferential stimulation of Aδ fibers by intra-epidermal needle electrode in humans

Pain, 2002

We recorded evoked potentials (EPs) induced by conventional transcutaneous electrical stimulation... more We recorded evoked potentials (EPs) induced by conventional transcutaneous electrical stimulation (TS), laser stimulation (LS) and epidermal electrical stimulation (ES) using a specially made needle electrode. We evaluated the activated fibers by epidermal stimulation by assessing the conduction velocity (CV) of the peripheral nerves. The EPs were recorded from Cz electrode (vertex) of the International 10-20 system in 12 healthy subjects. For the ES, the tip of a stainless steel needle electrode was inserted in the epidermis of the skin (0.2 mm in depth). Distal and proximal sites of the upper limb were stimulated by the LS and ES with an intensity which induced a definite pain sensation. Similar sites were stimulated by TS with an intensity of two times the sensory threshold. A major EP positive response (P1) was obtained by stimulation by all three types of stimuli. The P1 latency for the TS (245^22 ms) was significantly shorter than that for the ES (302^17 ms, P , 0:0001) and LS (341^21 ms, P , 0:0001) and the peak latency P1 by the LS was also significantly longer, approximately 40 ms, than that by the ES ðP , 0:0001Þ. The CVs were 15.1, 15.3 and 44.1 m/s obtained by ES, LS and TS, respectively. The CV indicated that the fibers activated by the ES were mainly Ad fibers, which corresponded to the fibers stimulated by the LS. We considered that the ES with our newly developed needle electrode was a very convenient method for the selective stimulation of the Ad fibers, since it was very simple, not requiring any special apparatus, did not cause bleeding or burns and caused minimum uncomfortable feeling.

Research paper thumbnail of Supergravity duals of gauge theories from F(4) gauged supergravity in six dimensions

Journal of High Energy Physics, 2001

We construct supergravity solutions dual to twisted field theories that are the worldvolume theor... more We construct supergravity solutions dual to twisted field theories that are the worldvolume theories of D4-branes wrapped on 2, 3-cycles, and NS-fivebranes on 3-cycles. We first obtain the solutions for the Romans' six-dimensional gauged supergravity theories and then up-lift them to ten dimensions. In particular, we find solutions for field configurations with either non-Abelian fields or B-fields being excited. One of these solutions, in the massless case, is up-lifted to the massless type IIA string theory. This is the first example of such a kind. The cases studied provide new examples of the AdS/CFT duality involving twisted field theories.

Research paper thumbnail of Supergravity duals of gauge field theories from SU(2) × U(1) gauged supergravity in five dimensions

Journal of High Energy Physics, 2001

]. This solution contains purely magnetic non-Abelian and electric Abelian fields. It can be inte... more ]. This solution contains purely magnetic non-Abelian and electric Abelian fields. It can be interpreted as a reduction of seven-dimensional gauged supergravity on a torus, which comes from type IIB supergravity on S^3. We also show how to obtain that solution from six-dimensional Romans' theory on a circle. We then up-lift the solution to massless type IIA supergravity. The dual gauge field theory is twisted and is defined on the worldvolume of a NS-fivebrane wrapped on S^3. Two other spatial directions of the NS-fivebrane are on a torus. In the IR limit it corresponds to a three-dimensional gauge field theory with two supercharges.

Research paper thumbnail of Settings Vray ngoại thất, Vray Camera, Vray Sun

Chào các bạn, thể theo nguyện vọng của nhiều bạn mới học 3D và Vray, hôm nay tôi xin mạn phép viế... more Chào các bạn, thể theo nguyện vọng của nhiều bạn mới học 3D và Vray, hôm nay tôi xin mạn phép viết bài viết này hướng dẫ cơ bản về các Settings, ánh sáng Vray Sun, đặt Vray Camera và các thông số của nó. Các bạn sau khi xem xong bài viết này, nếu có thắc mắc, xin liên hệ với tôi theo các thông tin sau: Trương Tuấn Kiên Email: tuankien1311@gmail.com Skype: truongtuankien Yahoo: tk_46kd2 Mobile: 0904 664 662 Phone: 04 665 84 662 Tôi sẽ cố gắng giải đáp giúp các bạn. Nếu bài viết của tôi có sai sót, các bạn có thể đóng góp với tôi qua các địa chỉ trên để tôi có thể bổ sung, hoàn thiện nhằm giúp đỡ các bạn khác một cách tốt nhất. Xin cảm ơn! MỤC LỤC: SETTINGS: page 1 VRAY CAMERA: page 15 VRAY SUN: page 19

Research paper thumbnail of Approximating the level probabilities in order restricted inference: The simple tree ordering

Biometrika, 1985

... biomet.oxfordjournals.org Downloaded from Page 4. 432 FT WRIGHT AND TUAN TRAN ... In (2) and ... more ... biomet.oxfordjournals.org Downloaded from Page 4. 432 FT WRIGHT AND TUAN TRAN ... In (2) and (4) the x2 an d beta distributions decrease with I and so upper bounds for these tail probabilities are obtained by finding lower stochastic bounds for Pk(w) and vice versa. ...

Research paper thumbnail of Wireless Broadcast Using Network Coding

IEEE Transactions on Vehicular Technology, 2009

Traditional approaches to transmit information reliably over an error-prone network employ either... more Traditional approaches to transmit information reliably over an error-prone network employ either Forward Error Correction (FEC) or retransmission techniques. In this paper we propose some network coding schemes to reduce the number of broadcast transmissions from one sender to multiple receivers. The main idea is to allow the sender to combine and retransmit the lost packets in a certain way, so that with one transmission, multiple receivers are able to recover their own lost packets. For comparison, we derive a few theoretical results on the bandwidth efficiencies of the proposed network coding and traditional Automatic Repeat-reQuest (ARQ) schemes. Both simulations and theoretical analysis confirm the advantages of the proposed network coding schemes over the Automatic Repeat-reQuest (ARQ) ones.

Research paper thumbnail of Pain-related magnetic fields evoked by intra-epidermal electrical stimulation in humans

Clinical Neurophysiology, 2002

We recently developed a new method for the preferential stimulation of Ad fibers in humans. The a... more We recently developed a new method for the preferential stimulation of Ad fibers in humans. The aim of the present study was to examine whether this method can serve as an appropriate stimulus in a magnetoencephalographic study.

Research paper thumbnail of A new method for measuring the conduction velocities of Aβ-, Aδ- and C-fibers following electric and CO 2 laser stimulation in humans

Neuroscience Letters, 2001

The conduction velocities of Ab-, Ad-and C-®bers of a peripheral nerve of the upper limb in norma... more The conduction velocities of Ab-, Ad-and C-®bers of a peripheral nerve of the upper limb in normal subjects were measured by a combination of conventional electric stimulation, painful CO 2 laser stimulation and non-painful CO 2 laser stimulation of a tiny skin surface area, respectively. The values obtained were 69.1^7.4 m/s, 10.6^2.1 and 1.2^0.2 m/s, respectively. These ®ndings demonstrated that the combined methods are useful for experimental and clinical exploration of the physiological function and pathophysiological role of Ab-, Ad-and C-®bers of a given peripheral nerve. q

Research paper thumbnail of A Joint Network-Channel Coding Technique for Single-Hop Wireless Networks

Reliable transmission over an error-prone channel is typically accomplished via channel coding or... more Reliable transmission over an error-prone channel is typically accomplished via channel coding or retransmission of the lost information. In this paper, we investigate a joint network-channel coding technique to increase the bandwidth efficiency of wireless networks. In particular, we show that the proposed joint network-channel coding approach which combines the recent Network Coding (NC) concept with the traditional Forward Error Correction (FEC) technique, can increase the bandwidth efficiency in single-hop wireless networks such as WLAN or WiMAX networks. We present some analytical results on the bandwidth efficiency for both broadcast and unicast scenarios. Based on these theoretical results, we provide a heuristic algorithm that dynamically selects the optimal level of FEC to be used with network coding technique for given channel conditions. For typical channel characteristics, both simulations and theoretical results confirm that the proposed joint networkchannel coding approach can reduce the bandwidth usage up to five times over the Automatic Repeat reQuest (ARQ) technique and up to two times over the HARQ technique.

Research paper thumbnail of Conduction velocity of the spinothalamic tract in humans as assessed by CO 2 laser stimulation of C-fibers

Neuroscience Letters, 2001

We measured the conduction velocity (CV) of C-fibers in the spinothalamic tract (STT) following s... more We measured the conduction velocity (CV) of C-fibers in the spinothalamic tract (STT) following stimulation with a CO 2 laser using a new method. We delivered non-painful laser pulses to tiny areas of the skin overlying the vertebral spinous processes at different levels from the 7 th cervical (C7) to the 12 th thoracic (T12), and recorded cerebral evoked potentials in 11 healthy men. We used the term 'ultra-late laser evoked potentials' (ultra-late LEPs), since the peak latency was much longer than that for conventional LEPs related to Ad-fibers following painful laser stimulation (late LEPs). The mean CV of C-fibers in the STT was 2.2^0.6 m/s, which was significantly lower than the CV of the Ad-fibers (10.0^4.5 m/s). This technique is novel and simple, and should be useful as a diagnostic tool for assessing the level of spinal cord lesions. q

Research paper thumbnail of Cerebral responses following stimulation of unmyelinated C-fibers in humans: electro- and magneto-encephalographic study

Neuroscience Research, 2003

There are two kinds of pain, a sharp pain ascending through Ad fibers (first pain) and a second b... more There are two kinds of pain, a sharp pain ascending through Ad fibers (first pain) and a second burning pain ascending though C fibers (second pain). By using a novel method, the application of a low intensity CO 2 laser beam to a tiny area of skin using a very thin aluminum plate with numerous tiny holes as a spatial filter, we succeeded in selectively stimulating unmyelinated C fibers of the skin in humans, and could record consistent and clear brain responses using electroencephalography (EEG) and magnetoencephalography (MEG). The conduction velocity (CV) of the C fibers of the peripheral nerve and spinal cord, probably spinothalamic tract (STT), is approximately 1 Á/4 m/s, which is significantly slower than that of Ad (approximately 10 Á/15 m/s) and Ab fibers (approximately 50 Á/70 m/s). This method should be very useful for clinical application. Following C fiber stimulation, primary and secondary somatosensory cortices (SI and SII) are simultaneously activated in the cerebral hemisphere contralateral to the stimulation, and then, SII in the hemisphere ipsilateral to the stimulation is activated. These early responses are easily detected by MEG. Then, probably limbic systems such as insula and cingulate cortex are activated, and those activities reflected in EEG components. Investigations of the cortical processing in pain perception including both first and second pain should provide a better understanding of pain perception and, therefore, contribute to pain relief in clinical medicine. #

Research paper thumbnail of Preferential stimulation of Aδ fibers by intra-epidermal needle electrode in humans

Pain, 2002

We recorded evoked potentials (EPs) induced by conventional transcutaneous electrical stimulation... more We recorded evoked potentials (EPs) induced by conventional transcutaneous electrical stimulation (TS), laser stimulation (LS) and epidermal electrical stimulation (ES) using a specially made needle electrode. We evaluated the activated fibers by epidermal stimulation by assessing the conduction velocity (CV) of the peripheral nerves. The EPs were recorded from Cz electrode (vertex) of the International 10-20 system in 12 healthy subjects. For the ES, the tip of a stainless steel needle electrode was inserted in the epidermis of the skin (0.2 mm in depth). Distal and proximal sites of the upper limb were stimulated by the LS and ES with an intensity which induced a definite pain sensation. Similar sites were stimulated by TS with an intensity of two times the sensory threshold. A major EP positive response (P1) was obtained by stimulation by all three types of stimuli. The P1 latency for the TS (245^22 ms) was significantly shorter than that for the ES (302^17 ms, P , 0:0001) and LS (341^21 ms, P , 0:0001) and the peak latency P1 by the LS was also significantly longer, approximately 40 ms, than that by the ES ðP , 0:0001Þ. The CVs were 15.1, 15.3 and 44.1 m/s obtained by ES, LS and TS, respectively. The CV indicated that the fibers activated by the ES were mainly Ad fibers, which corresponded to the fibers stimulated by the LS. We considered that the ES with our newly developed needle electrode was a very convenient method for the selective stimulation of the Ad fibers, since it was very simple, not requiring any special apparatus, did not cause bleeding or burns and caused minimum uncomfortable feeling.

Research paper thumbnail of Supergravity duals of gauge theories from F(4) gauged supergravity in six dimensions

Journal of High Energy Physics, 2001

We construct supergravity solutions dual to twisted field theories that are the worldvolume theor... more We construct supergravity solutions dual to twisted field theories that are the worldvolume theories of D4-branes wrapped on 2, 3-cycles, and NS-fivebranes on 3-cycles. We first obtain the solutions for the Romans' six-dimensional gauged supergravity theories and then up-lift them to ten dimensions. In particular, we find solutions for field configurations with either non-Abelian fields or B-fields being excited. One of these solutions, in the massless case, is up-lifted to the massless type IIA string theory. This is the first example of such a kind. The cases studied provide new examples of the AdS/CFT duality involving twisted field theories.

Research paper thumbnail of Supergravity duals of gauge field theories from SU(2) × U(1) gauged supergravity in five dimensions

Journal of High Energy Physics, 2001

]. This solution contains purely magnetic non-Abelian and electric Abelian fields. It can be inte... more ]. This solution contains purely magnetic non-Abelian and electric Abelian fields. It can be interpreted as a reduction of seven-dimensional gauged supergravity on a torus, which comes from type IIB supergravity on S^3. We also show how to obtain that solution from six-dimensional Romans' theory on a circle. We then up-lift the solution to massless type IIA supergravity. The dual gauge field theory is twisted and is defined on the worldvolume of a NS-fivebrane wrapped on S^3. Two other spatial directions of the NS-fivebrane are on a torus. In the IR limit it corresponds to a three-dimensional gauge field theory with two supercharges.

Research paper thumbnail of Settings Vray ngoại thất, Vray Camera, Vray Sun

Chào các bạn, thể theo nguyện vọng của nhiều bạn mới học 3D và Vray, hôm nay tôi xin mạn phép viế... more Chào các bạn, thể theo nguyện vọng của nhiều bạn mới học 3D và Vray, hôm nay tôi xin mạn phép viết bài viết này hướng dẫ cơ bản về các Settings, ánh sáng Vray Sun, đặt Vray Camera và các thông số của nó. Các bạn sau khi xem xong bài viết này, nếu có thắc mắc, xin liên hệ với tôi theo các thông tin sau: Trương Tuấn Kiên Email: tuankien1311@gmail.com Skype: truongtuankien Yahoo: tk_46kd2 Mobile: 0904 664 662 Phone: 04 665 84 662 Tôi sẽ cố gắng giải đáp giúp các bạn. Nếu bài viết của tôi có sai sót, các bạn có thể đóng góp với tôi qua các địa chỉ trên để tôi có thể bổ sung, hoàn thiện nhằm giúp đỡ các bạn khác một cách tốt nhất. Xin cảm ơn! MỤC LỤC: SETTINGS: page 1 VRAY CAMERA: page 15 VRAY SUN: page 19