We report the observation of sustained self-pulsing behavior of the output of a channel waveguide... more We report the observation of sustained self-pulsing behavior of the output of a channel waveguide Nd:YAG laser under a CW pump. The duration and repetition rate of the pulses observed were dependent on the pumping power. At the maximum pumping power available (44 mW of absorbed power), the pulse duration was around ∼40 ns, and the pulse repetition rate was ∼1.4 MHz. We discuss the possible physical mechanisms that generate the pulsing behavior, and their implications on the observed pump-power dependence of the repetition rate.
We undertook this study to evaluate the functional impact of coronary abnormalities in patients w... more We undertook this study to evaluate the functional impact of coronary abnormalities in patients with suspected coronary artery disease (CAD) by means of integrated positron emission tomography (PET) and coronary computed tomography angiography (CCTA) scan obtained on a hybrid state-of-the-art PET/CT scanner.We studied 29 consecutive, patients with a clinically suspected intermediate risk for CAD, using a hybrid PET/CT 64 slice scanner. During a single scanning session, CCTA was performed for coronary anatomy evaluation, and a rest/adenosine stress 13N-ammonia PET was performed for myocardial perfusion assessment in 3D mode with CT attenuation correction.Twenty four (82.7%) patients had atherosclerosis detected by CCTA; 15 patients had significant (≥50%) coronary stenoses and all 15 patients showed ischemia by PET; moreover, 10/15 patients had a Summed Stress Score >12.20/24 and 83.3% patients with atherosclerosis detected by CCTA showed ischemia by PET. Two of five patients with normal coronary arteries showed ischemia by PET. CCTA agreement in positive identification of PET ischemia was 91% and agreement in ruling out ischemia was 43%; PET agreement in detecting CCTA atherosclerosis was 83%, and agreement in ruling it out was 60%.We found a strong relation between significant coronary stenosis identified by CCTA and ischemia by PET. However, in cases with low-grade stenosis, PET scan can assess the functional significance of atherosclerotic abnormalities.
In this work the formation of optical channel waveguides in Nd:YAG crystals by either proton or c... more In this work the formation of optical channel waveguides in Nd:YAG crystals by either proton or carbon implantation is reported. The channel waveguides were obtained by a single implantation process through an electroformed mask of nickel-cobalt alloy. Experimental measurements of the optical properties of these waveguides are presented.
Background In 2002, 17.8% of the global cancer burden was attributable to infections. This study ... more Background In 2002, 17.8% of the global cancer burden was attributable to infections. This study assessed the age-standardized incidence and mortality rates of stomach, liver, and cervical cancer in Puerto Rico (PR) for the period 1992-2003 and compared them to those of Hispanics (USH), non-Hispanic Whites (NHW), and non-Hispanic Blacks (NHB) in the United States (US). Methods Age-standardized rates [ASR(World)] were calculated based on cancer incidence and mortality data from the PR Cancer Central Registry and SEER, using the direct method and the world population as the standard. Annual percent changes (APC) were calculated using the Poisson regression model from 1992-2003. Results The incidence and mortality rates from stomach, liver and cervical cancer were lower in NHW than PR; with the exception of mortality from cervical cancer which was similar in both populations. Meanwhile, the incidence rates of stomach, liver and cervical cancers were similar between NHB and PR; except for NHB women who had a lower incidence rate of liver cancer than women in PR. NHB had a lower mortality from liver cancer than persons in PR, and similar mortality from stomach cancer. Conclusions The burden of liver, stomach, and cervical cancer in PR compares to that of USH and NHB and continues to be a public health priority. Public health efforts are necessary to further decrease the burden of cancers associated to infections in these groups, the largest minority population groups in the US. Future studies need to identify factors that may prevent infections with cancer-related agents in these populations. Strategies to increase the use of preventive strategies, such as vaccination and screening, among minority populations should also be developed.
Background: Spot ferritin assay on dried serum spot (DSS) samples provides reliable and accurate ... more Background: Spot ferritin assay on dried serum spot (DSS) samples provides reliable and accurate assessment. Standard DSS preparations, however, involve precise serum aliquots and require some skill and training of field personnel. Objective: We evaluated the validity of the spot ferritin assay on DSS samples prepared by simplified approaches and standard technique in Guatemala City. Design: Venous blood (5 mL) was obtained from 104 subjects aged 24 Ȁ 15 y (x Ȁ SD) and transferred into nonheparin-containing (2 plain and 2 self-sealing) capillary blood collection tubes. Three DSS samples were prepared: A (standard, 20 L serum), B (blot, Ȃ30 -35 mm serum column), and C (dispenser, 20 L serum pushed directly from self-sealing capillary tubes with a dispenser). Spots were airdried and placed in hermetic plastic bags with a desiccant. Two weeks later, entire spots for DSS A and C samples and a circle in the center for DSS B samples were analyzed. Results: DSS ferritin A, B, and C correlated strongly with traditional ferritin (r ҃ 0.71-0.88, P 0.001). The geometric mean (Ҁ1 SD and ѿ1 SD) values for the DSS A, B, and C and traditional ferritin methods were 27.5 (12.6, 60.2), 32.4 (13.5, 77.6), 27.5 (11.7, 64.6), and 30.2 (13.8, 66.1) g/L, respectively, and did not differ significantly. The difference in ferritin values by various DSS approaches compared with the traditional approach was small (4 g/L; P 0.05). Conclusions: Simplified and standard DSS methods provide accurate iron-status assessment in population studies. The simplified DSS approaches for serum ferritin measurement need to be evaluated further in populations in whom iron deficiency is prevalent.
We study the (2 þ 1)-dimensional model proposed by Kadomtsev and Petviashvili (KP) to describe sl... more We study the (2 þ 1)-dimensional model proposed by Kadomtsev and Petviashvili (KP) to describe slowly varying nonlinear waves in a dispersive medium. Applying an appropriate Lie transformation and following the method introduced by Tajiri et al., the KP equation is reduced to a one-dimensional equation, that is, to a certain version of the Boussinesq equation (BqE). Then, we solve the BqE by the Hirota method, and finally we use the inverse transformation in order to obtain de KP solutions. We Analyze some remarkable properties of the solutions found in this work.
... Erick Alexanderson1,2,*, Jose Luis Romero1, Alejandro Ricalde1, Graciela Alexanderson3 and Al... more ... Erick Alexanderson1,2,*, Jose Luis Romero1, Alejandro Ricalde1, Graciela Alexanderson3 and Aloha Meave2 ... [36] Buus NH Hermansen F, Sander M, Nielsen TT, Mulvany MJ. ... [37] Nitenberg A, Ledoux S, Valensi P, Sachs R, Attali JR, Antony I. Impairment of coronary ...
The modulation of the striato-pallidal pathway by presynaptic adenosine A2a and dopamine D2 recep... more The modulation of the striato-pallidal pathway by presynaptic adenosine A2a and dopamine D2 receptors has gained attention in the study of Parkinson's disease. Here, we analyzed the effect of presynaptic A2a receptors in the spiking activity of globus pallidus (GP) neurons recorded during electrical stimulation of the striato-pallidal pathway, in both sham and ipsilaterally dopamine-denervated rats. We found that intrapallidal blockade of A2a by 100 pMol KF-17383 in sham and lesioned rats did not modify the spiking rate of GP neurons. Local infusion of 100 pMol CGS-21680, an A2a agonist, did not change the spiking rate in sham rats, whereas the same concentration of NMDA strongly increased the firing frequency of all neurons tested. Moreover, in sham rats, local blockade of A2a receptors by 100 pMol KF-17383 suppressed the inhibition evoked by activation of the striato-pallidal pathway, while in dopaminedenervated rats the same dose of KF-17383 did not modify the inhibition. Our results show that the contribution of A2a receptors to the spiking control of GP by the striatopallidal pathway depends on the state of the dopaminergic system.
We report the observation of sustained self-pulsing behavior of the output of a channel waveguide... more We report the observation of sustained self-pulsing behavior of the output of a channel waveguide Nd:YAG laser under a CW pump. The duration and repetition rate of the pulses observed were dependent on the pumping power. At the maximum pumping power available (44 mW of absorbed power), the pulse duration was around ∼40 ns, and the pulse repetition rate was ∼1.4 MHz. We discuss the possible physical mechanisms that generate the pulsing behavior, and their implications on the observed pump-power dependence of the repetition rate.
We undertook this study to evaluate the functional impact of coronary abnormalities in patients w... more We undertook this study to evaluate the functional impact of coronary abnormalities in patients with suspected coronary artery disease (CAD) by means of integrated positron emission tomography (PET) and coronary computed tomography angiography (CCTA) scan obtained on a hybrid state-of-the-art PET/CT scanner.We studied 29 consecutive, patients with a clinically suspected intermediate risk for CAD, using a hybrid PET/CT 64 slice scanner. During a single scanning session, CCTA was performed for coronary anatomy evaluation, and a rest/adenosine stress 13N-ammonia PET was performed for myocardial perfusion assessment in 3D mode with CT attenuation correction.Twenty four (82.7%) patients had atherosclerosis detected by CCTA; 15 patients had significant (≥50%) coronary stenoses and all 15 patients showed ischemia by PET; moreover, 10/15 patients had a Summed Stress Score >12.20/24 and 83.3% patients with atherosclerosis detected by CCTA showed ischemia by PET. Two of five patients with normal coronary arteries showed ischemia by PET. CCTA agreement in positive identification of PET ischemia was 91% and agreement in ruling out ischemia was 43%; PET agreement in detecting CCTA atherosclerosis was 83%, and agreement in ruling it out was 60%.We found a strong relation between significant coronary stenosis identified by CCTA and ischemia by PET. However, in cases with low-grade stenosis, PET scan can assess the functional significance of atherosclerotic abnormalities.
In this work the formation of optical channel waveguides in Nd:YAG crystals by either proton or c... more In this work the formation of optical channel waveguides in Nd:YAG crystals by either proton or carbon implantation is reported. The channel waveguides were obtained by a single implantation process through an electroformed mask of nickel-cobalt alloy. Experimental measurements of the optical properties of these waveguides are presented.
Background In 2002, 17.8% of the global cancer burden was attributable to infections. This study ... more Background In 2002, 17.8% of the global cancer burden was attributable to infections. This study assessed the age-standardized incidence and mortality rates of stomach, liver, and cervical cancer in Puerto Rico (PR) for the period 1992-2003 and compared them to those of Hispanics (USH), non-Hispanic Whites (NHW), and non-Hispanic Blacks (NHB) in the United States (US). Methods Age-standardized rates [ASR(World)] were calculated based on cancer incidence and mortality data from the PR Cancer Central Registry and SEER, using the direct method and the world population as the standard. Annual percent changes (APC) were calculated using the Poisson regression model from 1992-2003. Results The incidence and mortality rates from stomach, liver and cervical cancer were lower in NHW than PR; with the exception of mortality from cervical cancer which was similar in both populations. Meanwhile, the incidence rates of stomach, liver and cervical cancers were similar between NHB and PR; except for NHB women who had a lower incidence rate of liver cancer than women in PR. NHB had a lower mortality from liver cancer than persons in PR, and similar mortality from stomach cancer. Conclusions The burden of liver, stomach, and cervical cancer in PR compares to that of USH and NHB and continues to be a public health priority. Public health efforts are necessary to further decrease the burden of cancers associated to infections in these groups, the largest minority population groups in the US. Future studies need to identify factors that may prevent infections with cancer-related agents in these populations. Strategies to increase the use of preventive strategies, such as vaccination and screening, among minority populations should also be developed.
Background: Spot ferritin assay on dried serum spot (DSS) samples provides reliable and accurate ... more Background: Spot ferritin assay on dried serum spot (DSS) samples provides reliable and accurate assessment. Standard DSS preparations, however, involve precise serum aliquots and require some skill and training of field personnel. Objective: We evaluated the validity of the spot ferritin assay on DSS samples prepared by simplified approaches and standard technique in Guatemala City. Design: Venous blood (5 mL) was obtained from 104 subjects aged 24 Ȁ 15 y (x Ȁ SD) and transferred into nonheparin-containing (2 plain and 2 self-sealing) capillary blood collection tubes. Three DSS samples were prepared: A (standard, 20 L serum), B (blot, Ȃ30 -35 mm serum column), and C (dispenser, 20 L serum pushed directly from self-sealing capillary tubes with a dispenser). Spots were airdried and placed in hermetic plastic bags with a desiccant. Two weeks later, entire spots for DSS A and C samples and a circle in the center for DSS B samples were analyzed. Results: DSS ferritin A, B, and C correlated strongly with traditional ferritin (r ҃ 0.71-0.88, P 0.001). The geometric mean (Ҁ1 SD and ѿ1 SD) values for the DSS A, B, and C and traditional ferritin methods were 27.5 (12.6, 60.2), 32.4 (13.5, 77.6), 27.5 (11.7, 64.6), and 30.2 (13.8, 66.1) g/L, respectively, and did not differ significantly. The difference in ferritin values by various DSS approaches compared with the traditional approach was small (4 g/L; P 0.05). Conclusions: Simplified and standard DSS methods provide accurate iron-status assessment in population studies. The simplified DSS approaches for serum ferritin measurement need to be evaluated further in populations in whom iron deficiency is prevalent.
We study the (2 þ 1)-dimensional model proposed by Kadomtsev and Petviashvili (KP) to describe sl... more We study the (2 þ 1)-dimensional model proposed by Kadomtsev and Petviashvili (KP) to describe slowly varying nonlinear waves in a dispersive medium. Applying an appropriate Lie transformation and following the method introduced by Tajiri et al., the KP equation is reduced to a one-dimensional equation, that is, to a certain version of the Boussinesq equation (BqE). Then, we solve the BqE by the Hirota method, and finally we use the inverse transformation in order to obtain de KP solutions. We Analyze some remarkable properties of the solutions found in this work.
... Erick Alexanderson1,2,*, Jose Luis Romero1, Alejandro Ricalde1, Graciela Alexanderson3 and Al... more ... Erick Alexanderson1,2,*, Jose Luis Romero1, Alejandro Ricalde1, Graciela Alexanderson3 and Aloha Meave2 ... [36] Buus NH Hermansen F, Sander M, Nielsen TT, Mulvany MJ. ... [37] Nitenberg A, Ledoux S, Valensi P, Sachs R, Attali JR, Antony I. Impairment of coronary ...
The modulation of the striato-pallidal pathway by presynaptic adenosine A2a and dopamine D2 recep... more The modulation of the striato-pallidal pathway by presynaptic adenosine A2a and dopamine D2 receptors has gained attention in the study of Parkinson's disease. Here, we analyzed the effect of presynaptic A2a receptors in the spiking activity of globus pallidus (GP) neurons recorded during electrical stimulation of the striato-pallidal pathway, in both sham and ipsilaterally dopamine-denervated rats. We found that intrapallidal blockade of A2a by 100 pMol KF-17383 in sham and lesioned rats did not modify the spiking rate of GP neurons. Local infusion of 100 pMol CGS-21680, an A2a agonist, did not change the spiking rate in sham rats, whereas the same concentration of NMDA strongly increased the firing frequency of all neurons tested. Moreover, in sham rats, local blockade of A2a receptors by 100 pMol KF-17383 suppressed the inhibition evoked by activation of the striato-pallidal pathway, while in dopaminedenervated rats the same dose of KF-17383 did not modify the inhibition. Our results show that the contribution of A2a receptors to the spiking control of GP by the striatopallidal pathway depends on the state of the dopaminergic system.
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