Background: Surgical conditions contribute significantly to the disease burden in sub-Saharan Afr... more Background: Surgical conditions contribute significantly to the disease burden in sub-Saharan Africa. Yet there is an apparent neglect of surgical care as a public health intervention to counter this burden. There is increasing enthusiasm to reverse this trend, by promoting essential surgical services at the district hospital, the first point of contact for critical conditions for rural populations. This study investigated the scope of surgery conducted at district hospitals in three sub-Saharan African countries.
Background: There is a growing recognition that the provision of surgical services in low-income ... more Background: There is a growing recognition that the provision of surgical services in low-income countries is inadequate to the need. While constrained health budgets and health worker shortages have been blamed for the low rates of surgery, there has been little empirical data on the providers of surgery and cost of surgical services in Africa. This study described the range of providers of surgical care and anesthesia and estimated the resources dedicated to surgery at district hospitals in three African countries.
We demonstrate highly-efficient generation of green-blue light using 20-fs femtosecond laser puls... more We demonstrate highly-efficient generation of green-blue light using 20-fs femtosecond laser pulses propagating in short highly-nonlinear photonic crystal fibres. Three 5-mm-long fibres with different zero dispersion wavelengths were pumped by Ti:Sapphire pulses centred around 800-nm, and the relevant spectral characteristics of the generated radiation were studied as a function of pulse energy and chirp. In addition to the non-solitonic green-blue light, a well-defined infrared peak was simultaneously observed that follows the same power and wavelength dependence found on the green-blue peak. This work shows that short photonic crystal fibres can be used as an efficient source of ultrashort blue-green pulses (and possibly near-IR pulses) since linear dispersion (and consequent temporal broadening) and absorption of fused silica are minimized when using short fibres.
In this work, the authors demonstrate the efficient focusing of 2.5-cycle laser pulses from a pha... more In this work, the authors demonstrate the efficient focusing of 2.5-cycle laser pulses from a phase-stabilized broadband laser oscillator with a repetition rate of 80 MHz (Femtolasers Rainbow) using a simple and compact setup based on octave-spanning double-chirped mirrors to pre-compensate the dispersion of microscope objectives. The beam diameter was kept at <2 mm at the entrance of the objectives in order to minimize undesirable radius-depend group-delay dispersion effects. Temporal characterization was performed with a modified SHG interferometric autocorrelator capable of measuring the pulse duration directly at the focus of the objectives, and the spot size was measured by imaging it with another microscope objective and CCD camera. For an input pulse energy of 2.5 nJ, a 63 x microscope objective (N.A.= 0.85) resulted in clean 6.8 fs (FWHM) pulses with spot sizes as small as 1.1 mum (FWHM).
We present what is to our knowledge the most complete 1-D numerical analysis of the evolution and... more We present what is to our knowledge the most complete 1-D numerical analysis of the evolution and the propagation dynamics of an ultrashort laser pulse in a Ti:Sapphire laser oscillator. This study confirms the dispersion managed model of mode-locking, and emphasizes the role of the Kerr nonlinearity in generating mode-locked spectra with a smooth and well-behaved spectral phase. A very good agreement with experimental measurements of pulse energy, spectrum, and temporal width of extracavity compressed pulses is found.
Limits in high-energy laser pulse compression using gas-filled fibres. [Proceedings of SPIE 6190,... more Limits in high-energy laser pulse compression using gas-filled fibres. [Proceedings of SPIE 6190, 619010 (2006)]. João L. Silva, Helder Crespo, Miguel Miranda, Luís M. Bernardo. Abstract. The production of high-energy ultra-short ...
The cyanobacterial small CAB-like proteins (SCPs) are one-helix proteins with compelling similari... more The cyanobacterial small CAB-like proteins (SCPs) are one-helix proteins with compelling similarity to the first and third transmembrane helix of proteins belonging to the CAB family of light-harvesting complex proteins in plants. The SCP proteins are transiently expressed at high light intensity and other stress conditions but their exact function remains largely unknown. Recently we showed association of ScpD with light-stressed, monomeric Photosystem II in Synechocystis sp. PCC 6803 (Yao et al. J Biol Chem 282:267–276, 2007). Here we show that ScpB associates with Photosystem II at normal growth conditions. Moreover, upon introduction of a construct into Synechocystis so that ScpB is expressed continuously under normal growth conditions, ScpE was detected under non-stressed conditions as well, and was copurified with tagged ScpB and Photosystem II. We also report on a one-helix protein, Slr1544, that is somewhat similar to the SCPs and whose gene is cotranscribed with that of ScpD; Slr1544 is another member of the extended light-harvesting-like (Lil) protein family, and we propose to name it LilA.
The cyanobacterial small CAB-like proteins (SCPs) are one-helix proteins with compelling similari... more The cyanobacterial small CAB-like proteins (SCPs) are one-helix proteins with compelling similarity to the first and third transmembrane helix of proteins belonging to the CAB family of light-harvesting complex proteins in plants. The SCP proteins are transiently expressed at high light intensity and other stress conditions but their exact function remains largely unknown. Recently we showed association of ScpD with light-stressed, monomeric Photosystem II in Synechocystis sp. PCC 6803 (Yao et al. J Biol Chem 282:267–276, 2007). Here we show that ScpB associates with Photosystem II at normal growth conditions. Moreover, upon introduction of a construct into Synechocystis so that ScpB is expressed continuously under normal growth conditions, ScpE was detected under non-stressed conditions as well, and was copurified with tagged ScpB and Photosystem II. We also report on a one-helix protein, Slr1544, that is somewhat similar to the SCPs and whose gene is cotranscribed with that of ScpD; Slr1544 is another member of the extended light-harvesting-like (Lil) protein family, and we propose to name it LilA.
The cyanobacterial small CAB-like proteins (SCPs) are one-helix proteins with compelling similari... more The cyanobacterial small CAB-like proteins (SCPs) are one-helix proteins with compelling similarity to the first and third transmembrane helix of proteins belonging to the CAB family of light-harvesting complex proteins in plants. The SCP proteins are transiently expressed at high light intensity and other stress conditions but their exact function remains largely unknown. Recently we showed association of ScpD with light-stressed, monomeric Photosystem II in Synechocystis sp. PCC 6803 (Yao et al. J Biol Chem 282:267–276, 2007). Here we show that ScpB associates with Photosystem II at normal growth conditions. Moreover, upon introduction of a construct into Synechocystis so that ScpB is expressed continuously under normal growth conditions, ScpE was detected under non-stressed conditions as well, and was copurified with tagged ScpB and Photosystem II. We also report on a one-helix protein, Slr1544, that is somewhat similar to the SCPs and whose gene is cotranscribed with that of ScpD; Slr1544 is another member of the extended light-harvesting-like (Lil) protein family, and we propose to name it LilA.
Background: Surgical conditions contribute significantly to the disease burden in sub-Saharan Afr... more Background: Surgical conditions contribute significantly to the disease burden in sub-Saharan Africa. Yet there is an apparent neglect of surgical care as a public health intervention to counter this burden. There is increasing enthusiasm to reverse this trend, by promoting essential surgical services at the district hospital, the first point of contact for critical conditions for rural populations. This study investigated the scope of surgery conducted at district hospitals in three sub-Saharan African countries.
Background: There is a growing recognition that the provision of surgical services in low-income ... more Background: There is a growing recognition that the provision of surgical services in low-income countries is inadequate to the need. While constrained health budgets and health worker shortages have been blamed for the low rates of surgery, there has been little empirical data on the providers of surgery and cost of surgical services in Africa. This study described the range of providers of surgical care and anesthesia and estimated the resources dedicated to surgery at district hospitals in three African countries.
We demonstrate highly-efficient generation of green-blue light using 20-fs femtosecond laser puls... more We demonstrate highly-efficient generation of green-blue light using 20-fs femtosecond laser pulses propagating in short highly-nonlinear photonic crystal fibres. Three 5-mm-long fibres with different zero dispersion wavelengths were pumped by Ti:Sapphire pulses centred around 800-nm, and the relevant spectral characteristics of the generated radiation were studied as a function of pulse energy and chirp. In addition to the non-solitonic green-blue light, a well-defined infrared peak was simultaneously observed that follows the same power and wavelength dependence found on the green-blue peak. This work shows that short photonic crystal fibres can be used as an efficient source of ultrashort blue-green pulses (and possibly near-IR pulses) since linear dispersion (and consequent temporal broadening) and absorption of fused silica are minimized when using short fibres.
In this work, the authors demonstrate the efficient focusing of 2.5-cycle laser pulses from a pha... more In this work, the authors demonstrate the efficient focusing of 2.5-cycle laser pulses from a phase-stabilized broadband laser oscillator with a repetition rate of 80 MHz (Femtolasers Rainbow) using a simple and compact setup based on octave-spanning double-chirped mirrors to pre-compensate the dispersion of microscope objectives. The beam diameter was kept at <2 mm at the entrance of the objectives in order to minimize undesirable radius-depend group-delay dispersion effects. Temporal characterization was performed with a modified SHG interferometric autocorrelator capable of measuring the pulse duration directly at the focus of the objectives, and the spot size was measured by imaging it with another microscope objective and CCD camera. For an input pulse energy of 2.5 nJ, a 63 x microscope objective (N.A.= 0.85) resulted in clean 6.8 fs (FWHM) pulses with spot sizes as small as 1.1 mum (FWHM).
We present what is to our knowledge the most complete 1-D numerical analysis of the evolution and... more We present what is to our knowledge the most complete 1-D numerical analysis of the evolution and the propagation dynamics of an ultrashort laser pulse in a Ti:Sapphire laser oscillator. This study confirms the dispersion managed model of mode-locking, and emphasizes the role of the Kerr nonlinearity in generating mode-locked spectra with a smooth and well-behaved spectral phase. A very good agreement with experimental measurements of pulse energy, spectrum, and temporal width of extracavity compressed pulses is found.
Limits in high-energy laser pulse compression using gas-filled fibres. [Proceedings of SPIE 6190,... more Limits in high-energy laser pulse compression using gas-filled fibres. [Proceedings of SPIE 6190, 619010 (2006)]. João L. Silva, Helder Crespo, Miguel Miranda, Luís M. Bernardo. Abstract. The production of high-energy ultra-short ...
The cyanobacterial small CAB-like proteins (SCPs) are one-helix proteins with compelling similari... more The cyanobacterial small CAB-like proteins (SCPs) are one-helix proteins with compelling similarity to the first and third transmembrane helix of proteins belonging to the CAB family of light-harvesting complex proteins in plants. The SCP proteins are transiently expressed at high light intensity and other stress conditions but their exact function remains largely unknown. Recently we showed association of ScpD with light-stressed, monomeric Photosystem II in Synechocystis sp. PCC 6803 (Yao et al. J Biol Chem 282:267–276, 2007). Here we show that ScpB associates with Photosystem II at normal growth conditions. Moreover, upon introduction of a construct into Synechocystis so that ScpB is expressed continuously under normal growth conditions, ScpE was detected under non-stressed conditions as well, and was copurified with tagged ScpB and Photosystem II. We also report on a one-helix protein, Slr1544, that is somewhat similar to the SCPs and whose gene is cotranscribed with that of ScpD; Slr1544 is another member of the extended light-harvesting-like (Lil) protein family, and we propose to name it LilA.
The cyanobacterial small CAB-like proteins (SCPs) are one-helix proteins with compelling similari... more The cyanobacterial small CAB-like proteins (SCPs) are one-helix proteins with compelling similarity to the first and third transmembrane helix of proteins belonging to the CAB family of light-harvesting complex proteins in plants. The SCP proteins are transiently expressed at high light intensity and other stress conditions but their exact function remains largely unknown. Recently we showed association of ScpD with light-stressed, monomeric Photosystem II in Synechocystis sp. PCC 6803 (Yao et al. J Biol Chem 282:267–276, 2007). Here we show that ScpB associates with Photosystem II at normal growth conditions. Moreover, upon introduction of a construct into Synechocystis so that ScpB is expressed continuously under normal growth conditions, ScpE was detected under non-stressed conditions as well, and was copurified with tagged ScpB and Photosystem II. We also report on a one-helix protein, Slr1544, that is somewhat similar to the SCPs and whose gene is cotranscribed with that of ScpD; Slr1544 is another member of the extended light-harvesting-like (Lil) protein family, and we propose to name it LilA.
The cyanobacterial small CAB-like proteins (SCPs) are one-helix proteins with compelling similari... more The cyanobacterial small CAB-like proteins (SCPs) are one-helix proteins with compelling similarity to the first and third transmembrane helix of proteins belonging to the CAB family of light-harvesting complex proteins in plants. The SCP proteins are transiently expressed at high light intensity and other stress conditions but their exact function remains largely unknown. Recently we showed association of ScpD with light-stressed, monomeric Photosystem II in Synechocystis sp. PCC 6803 (Yao et al. J Biol Chem 282:267–276, 2007). Here we show that ScpB associates with Photosystem II at normal growth conditions. Moreover, upon introduction of a construct into Synechocystis so that ScpB is expressed continuously under normal growth conditions, ScpE was detected under non-stressed conditions as well, and was copurified with tagged ScpB and Photosystem II. We also report on a one-helix protein, Slr1544, that is somewhat similar to the SCPs and whose gene is cotranscribed with that of ScpD; Slr1544 is another member of the extended light-harvesting-like (Lil) protein family, and we propose to name it LilA.
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Papers by Helder Miranda