Jonathan Leach - Academia.edu (original) (raw)
Papers by Jonathan Leach
Materials Science Forum
4H SiC high power photoconductive semiconductor switching devices were fabricated. A highly doped... more 4H SiC high power photoconductive semiconductor switching devices were fabricated. A highly doped n+-GaN subcontact epilayer was grown on SiC by organometallic vapor phase epitaxy in order to improve ohmic contact and avoid contact damage or degradation due to current filamentation, under high power operation. With an n+-GaN subcontact layer, the contact resistance was reduced and current crowding alleviated. Therefore the electrodes were not damaged or degraded at high power operation. Photocurrent up to 200 A and breakdown voltage up to 2900 V have been observed for the devices.
Science advances, 2018
When two indistinguishable photons are each incident on separate input ports of a beamsplitter, t... more When two indistinguishable photons are each incident on separate input ports of a beamsplitter, they "bunch" deterministically, exiting via the same port as a direct consequence of their bosonic nature. This two-photon interference effect has long-held the potential for application in precision measurement of time delays, such as those induced by transparent specimens with unknown thickness profiles. However, the technique has never achieved resolutions significantly better than the few-femtosecond (micrometer) scale other than in a common-path geometry that severely limits applications. We develop the precision of Hong-Ou-Mandel interferometry toward the ultimate limits dictated by statistical estimation theory, achieving few-attosecond (or nanometer path length) scale resolutions in a dual-arm geometry, thus providing access to length scales pertinent to cell biology and monoatomic layer two-dimensional materials.
Journal of the Royal Army Medical Corps
To assess emergency ambulance workload in terms of patients treated, casemix and whether or not a... more To assess emergency ambulance workload in terms of patients treated, casemix and whether or not a member of the British Forces Community, between May 1995 and April 1998 within the British Eastern Sovereign Base area in Cyprus. Methods Retrospective analysis of all incidents attended within the study period. Results A total of 452 patients were treated of which 47% were members of the British Forces Community in Cyprus. 14 Deaths were attended of which 9 were due to road traffic accidents. Of all incidents attended 45% were following a road traffic accident and over three quarters of all patients treated had suffered trauma to some degree. Conclusion The British military ambulance and supporting medical services located in the Eastern Sovereign Base Area in Cyprus provide a service to the British Forces Community, but the majority of patients treated are primarily the local Greek Cypriots with a sizeable minority of visiting tourists. Comment is made on the high incidence of morbidity and mortality from road traffic accidents within Cyprus as a whole.
The set of complex numbers with absolute value one (i.e., of the form e iθ) forms a group under c... more The set of complex numbers with absolute value one (i.e., of the form e iθ) forms a group under complex multiplication. This group is commutative. This group is the unit circle, denoted S 1. 2.7. Invertible matrices. For each positive integer n, the set of all n × n invertible matrices with real entries forms a group with respect to the operation of matrix multiplication. This group in non-commutative, for n ≥ 2. We check closure: the product of two invertible matrices is invertible, since (AB) −1 = B −1 A −1. Matrix multiplication is associative; the identity matrix (with ones down the diagonal, and zeros elsewhere) is the identity element; by definition, an invertible matrix has an inverse. Simple examples show that the group is noncommutative, except in the trivial case n = 1. (See Exercise 8.) This group is called the general linear group (over the reals), and is denoted GL(n; R). 2.8. Symmetric group (permutation group). The set of one-to-one, onto maps of the set {1, 2, • • • n} to itself forms a group under the operation of composition. This group is non-commutative for n ≥ 3. We check closure: the composition of two one-to-one, onto maps is again oneto-one and onto. Composition of functions is associative; the identity map (which sends 1 to 1, 2 to 2, etc.) is the identity element; a one-to-one, onto map has an inverse. Simple examples show that the group is non-commutative, as long as n is at least 3. (See Exercise 10.) This group is called the symmetric group, and is denoted S n. A one-to-one, onto map of {1, 2, • • • n} is a permutation, and so S n is also called the permutation group. The group S n has n! elements. 2.9. Integers mod n. The set {0, 1, • • • n − 1} forms a group under the operation of addition mod n. This group is commutative. Explicitly, the group operation is the following. Consider a, b ∈ {0, 1 • • • n − 1}. If a + b < n, then a + b mod n = a + b, if a + b ≥ n, then a + b mod n = a + b − n. (Since a and b are less than n, a+b−n is less than n; thus we have closure.) To show associativity, note that both (a+b mod n)+c mod n and a+(b+c mod n) mod n are equal to a + b + c, minus some multiple of n, and hence differ by a multiple of n. But since both are in the set {0, 1, • • • n − 1}, the only possible multiple on n is zero. Zero is still the identity for addition mod n. The inverse of an element a ∈ {0, 1, • • • n − 1} is n − a. (Exercise: check that n − a is in {0, 1, • • • n − 1}, and that a + (n − a) mod n = 0.) The group is commutative because ordinary addition is commutative. This group is referred to as "Z mod n," and is denoted Z n. 3. Subgroups, the Center, and Direct Products Definition 1.7. A subgroup of a group G is a subset H of G with the following properties: 1. The identity is an element of H. 2. If h ∈ H, then h −1 ∈ H. 3. If h 1 , h 2 ∈ H, then h 1 h 2 ∈ H .
Orbital angular momentum (OAM) entanglement is investigated in the Bessel-Gauss (BG) basis. Havin... more Orbital angular momentum (OAM) entanglement is investigated in the Bessel-Gauss (BG) basis. Having a readily adjustable radial scale, BG modes provide a more favourable basis for OAM entanglement over Laguerre-Gaussian (LG) modes. The OAM bandwidth in terms of BG modes can be increased by selection of particular radial modes and leads to a flattening of the spectrum. The flattening of the spectrum allows for higher entanglement. We demonstrate increased entanglement in terms of BG modes by performing a Bell-type experiment and violating the appropriate Clauser Horne Shimony Holt (CHSH) inequality. In addition, we reconstruct the quantum state of BG modes entangled in high-dimensions.
This paper describes a certain part of Leonard Gross's work in infinite-dimensional analysis, con... more This paper describes a certain part of Leonard Gross's work in infinite-dimensional analysis, connected to the Gross Ergodicity Theorem. I then look at way in which Gross's work helped to create a new subject within (mostly) finite-dimensional analysis, a subject which may be called "harmonic analysis with respect to heat kernel measure." This subject transfers to Lie groups certain constructions on R n that involves a Gaussian measure. On the Lie group, the role of the Gaussian measure is played by a heat kernel measure.
Superlattice Microstruct, 1990
Cancer Research, May 15, 2001
Transient generation of reactive oxygen or nitrogen (ROS/RNS), detected with dihydrodichlorofluor... more Transient generation of reactive oxygen or nitrogen (ROS/RNS), detected with dihydrodichlorofluoroscein by fluorescence microscopy, occurs within minutes of exposing cells to ionizing radiation. In the 1-10 Gy dose range, the amount of ROS/RNS produced/cell is constant, but the percentage of producing cells increases with dose (20 to 80%). Reversible depolarization of the mitochondrial membrane potential (⌬⌿) and decrease in fluorescence of a mitochondria-entrapped dye, calcein, are observed coincidentally. Radiation-induced ROS/RNS, ⌬⌿ depolarization, and calcein fluorescence decrease are inhibited by the mitochondrial permeability transition inhibitor, cyclosporin A, but not the structural analogue, cyclosporin H. Radiation-stimulated ROS/RNS is also inhibited by overexpressing the Ca 2؉-binding protein, calbindin 28K, or treating cells with an intracellular Ca 2؉ chelator. Radiation-induced ROS/RNS is observed in several cell types with the exception of o cells deficient in mitochondrial electron transport. o cells show neither radiation-induced ROS/RNS production nor ⌬⌿ depolarization. We propose that radiation damage in a few mitochondria is transmitted via a reversible, Ca 2؉dependent mitochondrial permeability transition to adjacent mitochondria with resulting enhanced ROS/RNS generation. Measurements of radiation-induced mitogen-activated protein kinase activity indicate that this sensing/amplification mechanism is necessary for activation of some cytoplasmic signaling pathways by low doses of radiation. MATERIALS AND METHODS Cells and Cell Culture. The A431 squamous carcinoma, MDA-MB-231 breast carcinoma, DU145 and PC-3 prostate carcinomas, and CHO cell lines were purchased from American Type Culture Collection (Gaithersburg, MD). MCF-7 breast carcinoma cells were provided by Dr.
Sae Transactions, 2001
... Author(s): Brendan Hall - Honeywell Engines & Systems; Brian Sellner - Honeywell Engines ... more ... Author(s): Brendan Hall - Honeywell Engines & Systems; Brian Sellner - Honeywell Engines & Systems; Reinhard Maier - TTTech. ... This paper describes the integration of tool chains from two commercial vendors, the BEACON tool chain from Applied Dynamics International ...
Contemporary Mathematics, 2000
Introduction 1 2. Basics of holomorphic function spaces 2 3. Examples of holomorphic function spa... more Introduction 1 2. Basics of holomorphic function spaces 2 3. Examples of holomorphic function spaces 7 4. A special property of the Segal-Bargmann and weighted Bergman spaces 12 5. Canonical commutation relations 16 6. The Segal-Bargmann transform 21 7. Quantum mechanics and quantization 30 8. Toeplitz operators, anti-Wick ordering, and phase space probability densities 38 9. The Segal-Bargmann transform for compact Lie groups 44 10. To infinity and beyond 52 References 58
Proceedings of the Institution of Electrical Engineers, 1974
Nature Communications, 2015
The technologies of heating, photovoltaics, water photocatalysis and artificial photosynthesis de... more The technologies of heating, photovoltaics, water photocatalysis and artificial photosynthesis depend on the absorption of light and novel approaches such as coherent absorption from a standing wave promise total dissipation of energy. Extending the control of absorption down to very low light levels and eventually to the single-photon regime is of great interest and yet remains largely unexplored. Here we demonstrate the coherent absorption of single photons in a deeply subwavelength 50% absorber. We show that while the absorption of photons from a travelling wave is probabilistic, standing wave absorption can be observed deterministically, with nearly unitary probability of coupling a photon into a mode of the material, for example, a localized plasmon when this is a metamaterial excited at the plasmon resonance. These results bring a better understanding of the coherent absorption process, which is of central importance for light harvesting, detection, sensing and photonic data processing applications.
2001 MILCOM Proceedings Communications for Network-Centric Operations: Creating the Information Force (Cat. No.01CH37277), 2001
The Army's communications capability must keep pace with the evolution of a globally deployable J... more The Army's communications capability must keep pace with the evolution of a globally deployable Joint Task Force (JTF) and force projection Army, while supporting forced entry and contingency operations. The warfighter must have the freedom and flexibility to move quickly on the battlefield using a communications terminal that is tactically responsive, mobile, interoperable, and provides SATCOM-on-the-move (SOTM) and SATCOM-on-thepause (SOTP) capability. PM MILSATCOM is helping to define this nextgeneration ARMY SATCOM terminal that is referred to as the Multi-Band Integrated Satellite Terminal (MIST) and is currently scheduled to be fielded in several phased out to 2014. In so doing, PM MILSATCOM initiated several studies to better define the MIST program, help formulate the acquisition strategy, validate the MIST funding schedule, and to initiate Government cost estimates for the MIST program. The purpose of this paper is to summarize the key findings of the study performed by the MITRE Corporation in support of PM MILSATCOM. Our focus here is to summarize the notional terminal architecture design options postulated in that study, and to identify the key technology areas that need to be advanced in order to ensure successful operation of the MIST terminal.
5th International Workshop on Laser and Fiber-Optical Networks Modeling, 2003. Proceedings of LFNM 2003., 2003
New Journal of Physics, 2003
An optical beam with an e ilφ phase structure carries an orbital angular momentum of lh per photo... more An optical beam with an e ilφ phase structure carries an orbital angular momentum of lh per photon. For integer l values, the phase fronts of such beams form perfect helices with a single screw-phase dislocation, or vortex, on the beam axis. For non-integer l values, Berry (2004 J. Opt. A: Pure Appl. Opt. 6 259) predicts a complex-phase structure comprising many vortices at differing positions within the beam cross-section. Using a spatial light modulator we produce e ilφ beams with varying l. We examine the phase structure of such beams after propagation through an interference-based phase-measurement technique. As predicted, we observe that for half-integer l values, a line of alternating charge vortices is formed near the radial dislocation.
Journal of the Royal Naval Medical Service, 2005
To measure the probable prevalence of psychological morbidity in military healthcare professional... more To measure the probable prevalence of psychological morbidity in military healthcare professionals using the General Health Questionnaire 28. 21 (35%) of military healthcare workers showed psychological ill health. Royal Air Force health staff had a significantly higher prevalence of ill health than both the Army [12 (63%) vs 6 (23%)] and the Royal Navy [12 (63%) vs 1 (8%)]. RAF non-commissioned staff were found to have a highly significant prevalence of ill health compared to the Army non-commissioned staff [7(70%) vs 1 (7%)], and Royal Navy non-commissioned staff [7 (70%) vs 0 (0%)]. The study shows significant differences in psychological ill health between Services at the RCDM. Comparison with civilian data showed that the overall prevalence of psychological morbidity was no higher than in NHS staff. The elevated level of ill health in the Royal Air Force staff warrants further investigation and possible intervention.
Structured Light and Its Applications, 2008
Research in Optical Sciences, 2014
ABSTRACT Mutually unbiased bases (MUBs) are a key concept in quantum science. Local measurements ... more ABSTRACT Mutually unbiased bases (MUBs) are a key concept in quantum science. Local measurements of entangled photons in MUBs of orbital angular momentum are instrumental in the implementations of high-dimensional quantum protocols.
Materials Science Forum
4H SiC high power photoconductive semiconductor switching devices were fabricated. A highly doped... more 4H SiC high power photoconductive semiconductor switching devices were fabricated. A highly doped n+-GaN subcontact epilayer was grown on SiC by organometallic vapor phase epitaxy in order to improve ohmic contact and avoid contact damage or degradation due to current filamentation, under high power operation. With an n+-GaN subcontact layer, the contact resistance was reduced and current crowding alleviated. Therefore the electrodes were not damaged or degraded at high power operation. Photocurrent up to 200 A and breakdown voltage up to 2900 V have been observed for the devices.
Science advances, 2018
When two indistinguishable photons are each incident on separate input ports of a beamsplitter, t... more When two indistinguishable photons are each incident on separate input ports of a beamsplitter, they "bunch" deterministically, exiting via the same port as a direct consequence of their bosonic nature. This two-photon interference effect has long-held the potential for application in precision measurement of time delays, such as those induced by transparent specimens with unknown thickness profiles. However, the technique has never achieved resolutions significantly better than the few-femtosecond (micrometer) scale other than in a common-path geometry that severely limits applications. We develop the precision of Hong-Ou-Mandel interferometry toward the ultimate limits dictated by statistical estimation theory, achieving few-attosecond (or nanometer path length) scale resolutions in a dual-arm geometry, thus providing access to length scales pertinent to cell biology and monoatomic layer two-dimensional materials.
Journal of the Royal Army Medical Corps
To assess emergency ambulance workload in terms of patients treated, casemix and whether or not a... more To assess emergency ambulance workload in terms of patients treated, casemix and whether or not a member of the British Forces Community, between May 1995 and April 1998 within the British Eastern Sovereign Base area in Cyprus. Methods Retrospective analysis of all incidents attended within the study period. Results A total of 452 patients were treated of which 47% were members of the British Forces Community in Cyprus. 14 Deaths were attended of which 9 were due to road traffic accidents. Of all incidents attended 45% were following a road traffic accident and over three quarters of all patients treated had suffered trauma to some degree. Conclusion The British military ambulance and supporting medical services located in the Eastern Sovereign Base Area in Cyprus provide a service to the British Forces Community, but the majority of patients treated are primarily the local Greek Cypriots with a sizeable minority of visiting tourists. Comment is made on the high incidence of morbidity and mortality from road traffic accidents within Cyprus as a whole.
The set of complex numbers with absolute value one (i.e., of the form e iθ) forms a group under c... more The set of complex numbers with absolute value one (i.e., of the form e iθ) forms a group under complex multiplication. This group is commutative. This group is the unit circle, denoted S 1. 2.7. Invertible matrices. For each positive integer n, the set of all n × n invertible matrices with real entries forms a group with respect to the operation of matrix multiplication. This group in non-commutative, for n ≥ 2. We check closure: the product of two invertible matrices is invertible, since (AB) −1 = B −1 A −1. Matrix multiplication is associative; the identity matrix (with ones down the diagonal, and zeros elsewhere) is the identity element; by definition, an invertible matrix has an inverse. Simple examples show that the group is noncommutative, except in the trivial case n = 1. (See Exercise 8.) This group is called the general linear group (over the reals), and is denoted GL(n; R). 2.8. Symmetric group (permutation group). The set of one-to-one, onto maps of the set {1, 2, • • • n} to itself forms a group under the operation of composition. This group is non-commutative for n ≥ 3. We check closure: the composition of two one-to-one, onto maps is again oneto-one and onto. Composition of functions is associative; the identity map (which sends 1 to 1, 2 to 2, etc.) is the identity element; a one-to-one, onto map has an inverse. Simple examples show that the group is non-commutative, as long as n is at least 3. (See Exercise 10.) This group is called the symmetric group, and is denoted S n. A one-to-one, onto map of {1, 2, • • • n} is a permutation, and so S n is also called the permutation group. The group S n has n! elements. 2.9. Integers mod n. The set {0, 1, • • • n − 1} forms a group under the operation of addition mod n. This group is commutative. Explicitly, the group operation is the following. Consider a, b ∈ {0, 1 • • • n − 1}. If a + b < n, then a + b mod n = a + b, if a + b ≥ n, then a + b mod n = a + b − n. (Since a and b are less than n, a+b−n is less than n; thus we have closure.) To show associativity, note that both (a+b mod n)+c mod n and a+(b+c mod n) mod n are equal to a + b + c, minus some multiple of n, and hence differ by a multiple of n. But since both are in the set {0, 1, • • • n − 1}, the only possible multiple on n is zero. Zero is still the identity for addition mod n. The inverse of an element a ∈ {0, 1, • • • n − 1} is n − a. (Exercise: check that n − a is in {0, 1, • • • n − 1}, and that a + (n − a) mod n = 0.) The group is commutative because ordinary addition is commutative. This group is referred to as "Z mod n," and is denoted Z n. 3. Subgroups, the Center, and Direct Products Definition 1.7. A subgroup of a group G is a subset H of G with the following properties: 1. The identity is an element of H. 2. If h ∈ H, then h −1 ∈ H. 3. If h 1 , h 2 ∈ H, then h 1 h 2 ∈ H .
Orbital angular momentum (OAM) entanglement is investigated in the Bessel-Gauss (BG) basis. Havin... more Orbital angular momentum (OAM) entanglement is investigated in the Bessel-Gauss (BG) basis. Having a readily adjustable radial scale, BG modes provide a more favourable basis for OAM entanglement over Laguerre-Gaussian (LG) modes. The OAM bandwidth in terms of BG modes can be increased by selection of particular radial modes and leads to a flattening of the spectrum. The flattening of the spectrum allows for higher entanglement. We demonstrate increased entanglement in terms of BG modes by performing a Bell-type experiment and violating the appropriate Clauser Horne Shimony Holt (CHSH) inequality. In addition, we reconstruct the quantum state of BG modes entangled in high-dimensions.
This paper describes a certain part of Leonard Gross's work in infinite-dimensional analysis, con... more This paper describes a certain part of Leonard Gross's work in infinite-dimensional analysis, connected to the Gross Ergodicity Theorem. I then look at way in which Gross's work helped to create a new subject within (mostly) finite-dimensional analysis, a subject which may be called "harmonic analysis with respect to heat kernel measure." This subject transfers to Lie groups certain constructions on R n that involves a Gaussian measure. On the Lie group, the role of the Gaussian measure is played by a heat kernel measure.
Superlattice Microstruct, 1990
Cancer Research, May 15, 2001
Transient generation of reactive oxygen or nitrogen (ROS/RNS), detected with dihydrodichlorofluor... more Transient generation of reactive oxygen or nitrogen (ROS/RNS), detected with dihydrodichlorofluoroscein by fluorescence microscopy, occurs within minutes of exposing cells to ionizing radiation. In the 1-10 Gy dose range, the amount of ROS/RNS produced/cell is constant, but the percentage of producing cells increases with dose (20 to 80%). Reversible depolarization of the mitochondrial membrane potential (⌬⌿) and decrease in fluorescence of a mitochondria-entrapped dye, calcein, are observed coincidentally. Radiation-induced ROS/RNS, ⌬⌿ depolarization, and calcein fluorescence decrease are inhibited by the mitochondrial permeability transition inhibitor, cyclosporin A, but not the structural analogue, cyclosporin H. Radiation-stimulated ROS/RNS is also inhibited by overexpressing the Ca 2؉-binding protein, calbindin 28K, or treating cells with an intracellular Ca 2؉ chelator. Radiation-induced ROS/RNS is observed in several cell types with the exception of o cells deficient in mitochondrial electron transport. o cells show neither radiation-induced ROS/RNS production nor ⌬⌿ depolarization. We propose that radiation damage in a few mitochondria is transmitted via a reversible, Ca 2؉dependent mitochondrial permeability transition to adjacent mitochondria with resulting enhanced ROS/RNS generation. Measurements of radiation-induced mitogen-activated protein kinase activity indicate that this sensing/amplification mechanism is necessary for activation of some cytoplasmic signaling pathways by low doses of radiation. MATERIALS AND METHODS Cells and Cell Culture. The A431 squamous carcinoma, MDA-MB-231 breast carcinoma, DU145 and PC-3 prostate carcinomas, and CHO cell lines were purchased from American Type Culture Collection (Gaithersburg, MD). MCF-7 breast carcinoma cells were provided by Dr.
Sae Transactions, 2001
... Author(s): Brendan Hall - Honeywell Engines & Systems; Brian Sellner - Honeywell Engines ... more ... Author(s): Brendan Hall - Honeywell Engines & Systems; Brian Sellner - Honeywell Engines & Systems; Reinhard Maier - TTTech. ... This paper describes the integration of tool chains from two commercial vendors, the BEACON tool chain from Applied Dynamics International ...
Contemporary Mathematics, 2000
Introduction 1 2. Basics of holomorphic function spaces 2 3. Examples of holomorphic function spa... more Introduction 1 2. Basics of holomorphic function spaces 2 3. Examples of holomorphic function spaces 7 4. A special property of the Segal-Bargmann and weighted Bergman spaces 12 5. Canonical commutation relations 16 6. The Segal-Bargmann transform 21 7. Quantum mechanics and quantization 30 8. Toeplitz operators, anti-Wick ordering, and phase space probability densities 38 9. The Segal-Bargmann transform for compact Lie groups 44 10. To infinity and beyond 52 References 58
Proceedings of the Institution of Electrical Engineers, 1974
Nature Communications, 2015
The technologies of heating, photovoltaics, water photocatalysis and artificial photosynthesis de... more The technologies of heating, photovoltaics, water photocatalysis and artificial photosynthesis depend on the absorption of light and novel approaches such as coherent absorption from a standing wave promise total dissipation of energy. Extending the control of absorption down to very low light levels and eventually to the single-photon regime is of great interest and yet remains largely unexplored. Here we demonstrate the coherent absorption of single photons in a deeply subwavelength 50% absorber. We show that while the absorption of photons from a travelling wave is probabilistic, standing wave absorption can be observed deterministically, with nearly unitary probability of coupling a photon into a mode of the material, for example, a localized plasmon when this is a metamaterial excited at the plasmon resonance. These results bring a better understanding of the coherent absorption process, which is of central importance for light harvesting, detection, sensing and photonic data processing applications.
2001 MILCOM Proceedings Communications for Network-Centric Operations: Creating the Information Force (Cat. No.01CH37277), 2001
The Army's communications capability must keep pace with the evolution of a globally deployable J... more The Army's communications capability must keep pace with the evolution of a globally deployable Joint Task Force (JTF) and force projection Army, while supporting forced entry and contingency operations. The warfighter must have the freedom and flexibility to move quickly on the battlefield using a communications terminal that is tactically responsive, mobile, interoperable, and provides SATCOM-on-the-move (SOTM) and SATCOM-on-thepause (SOTP) capability. PM MILSATCOM is helping to define this nextgeneration ARMY SATCOM terminal that is referred to as the Multi-Band Integrated Satellite Terminal (MIST) and is currently scheduled to be fielded in several phased out to 2014. In so doing, PM MILSATCOM initiated several studies to better define the MIST program, help formulate the acquisition strategy, validate the MIST funding schedule, and to initiate Government cost estimates for the MIST program. The purpose of this paper is to summarize the key findings of the study performed by the MITRE Corporation in support of PM MILSATCOM. Our focus here is to summarize the notional terminal architecture design options postulated in that study, and to identify the key technology areas that need to be advanced in order to ensure successful operation of the MIST terminal.
5th International Workshop on Laser and Fiber-Optical Networks Modeling, 2003. Proceedings of LFNM 2003., 2003
New Journal of Physics, 2003
An optical beam with an e ilφ phase structure carries an orbital angular momentum of lh per photo... more An optical beam with an e ilφ phase structure carries an orbital angular momentum of lh per photon. For integer l values, the phase fronts of such beams form perfect helices with a single screw-phase dislocation, or vortex, on the beam axis. For non-integer l values, Berry (2004 J. Opt. A: Pure Appl. Opt. 6 259) predicts a complex-phase structure comprising many vortices at differing positions within the beam cross-section. Using a spatial light modulator we produce e ilφ beams with varying l. We examine the phase structure of such beams after propagation through an interference-based phase-measurement technique. As predicted, we observe that for half-integer l values, a line of alternating charge vortices is formed near the radial dislocation.
Journal of the Royal Naval Medical Service, 2005
To measure the probable prevalence of psychological morbidity in military healthcare professional... more To measure the probable prevalence of psychological morbidity in military healthcare professionals using the General Health Questionnaire 28. 21 (35%) of military healthcare workers showed psychological ill health. Royal Air Force health staff had a significantly higher prevalence of ill health than both the Army [12 (63%) vs 6 (23%)] and the Royal Navy [12 (63%) vs 1 (8%)]. RAF non-commissioned staff were found to have a highly significant prevalence of ill health compared to the Army non-commissioned staff [7(70%) vs 1 (7%)], and Royal Navy non-commissioned staff [7 (70%) vs 0 (0%)]. The study shows significant differences in psychological ill health between Services at the RCDM. Comparison with civilian data showed that the overall prevalence of psychological morbidity was no higher than in NHS staff. The elevated level of ill health in the Royal Air Force staff warrants further investigation and possible intervention.
Structured Light and Its Applications, 2008
Research in Optical Sciences, 2014
ABSTRACT Mutually unbiased bases (MUBs) are a key concept in quantum science. Local measurements ... more ABSTRACT Mutually unbiased bases (MUBs) are a key concept in quantum science. Local measurements of entangled photons in MUBs of orbital angular momentum are instrumental in the implementations of high-dimensional quantum protocols.