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Journal Papers by Giovanni Tapang

Optics Letters, Vol. 39, Issue 7, pp. 2036-2039 (April 2014)

We present a method of reshaping light in three dimensions via phase modulation. The method calcu... more We present a method of reshaping light in three dimensions via phase modulation. The method calculates the target computer generated hologram individually and adds to it an appropriate transfer function to translate the reconstruction to any location in space. We are able to simultaneously generate independently controlled arbitrary patterns at diff erent positions using a single laser beam.

International Journal of Modern Physics C (Accepted)

International Journal of Modern Physics C, 2010

International Journal of Modern …, 2012

Proceedings of The National Academy of Sciences, 2003

International Journal of …, 2012

Optics Communications, 2009

We report parallel two-photon photopolymerization of microgear patterns by exposing a photoresist... more We report parallel two-photon photopolymerization of microgear patterns by exposing a photoresist to holographically generated optical vortices. The optical vortices are created by imparting a helical pitch onto the incident light using a programmable lithographic phase mask realized with a computer addressable phase-only spatial light modulator. By varying the phase levels of the spatial light modulator, the truncated helical phase of an optical vortex results in output intensity patterns that typifies that of microgears instead of perfect doughnut beams. Our experiments and simulations are in good agreement implying a more efficient and highly parallel two-photon photopolymerization scheme that can be subsequently used for non-scanning fabrication of microgears.

IEEE Transactions on Circuits and Systems Ii: Analog and Digital Signal Processing, 2002

Physica A 312 (2002) 609–618

We analyze the exit dynamics of pedestrians who are initially confined in a room. Pedestrians ar... more We analyze the exit dynamics of pedestrians who are initially confined in a room. Pedestrians are modeled as cellular automata and compete to escape via a known exit at the soonest possible time. A pedestrian could move forward, backward, left or right within each iteration time depending on adjacent cell vacancy and in accordance with simple rules that determine the compulsion to move and physical capability relative to his neighbors. The arching signatures of jamming were observed and the pedestrians exited in bursts of various sizes. Power-law behavior is found in the burst-size frequency distribution for exit widths w greater than one cell dimension (w > 1). The slope of the power-law curve varies with
w from −1.3092 (w= 2) to −1.0720 (w= 20). Streaming which is a diffusive behavior, arises in large burst sizes and is more likely in a single-exit room with w = 1 and leads to a counterintuitive result wherein an average exit throughput Q is obtained that is higher than with w = 2, 3, or 4. For a two-exit room (w= 1), Q is not greater than twice the yield of a single-exit room. If the doors are not separated far enough (< 4w), Q becomes even significantly less due to a collective slow-downthat emerges among pedestrians crossing in each other’s path (disruptive interference effect). For the same w and door number, Q is also higher with relaxed pedestrians than with anxious ones.

Conference Presentations by Giovanni Tapang

The behavior of photon-limited light is discussed in reference to its use in confocal microscopy.... more The behavior of photon-limited light is discussed in reference to its use in confocal microscopy. A ray-tracing based simulation of photons passing through a confocal optical imaging system is performed with the photon propagation determined by the photon distribution function at the photodetector. The formation of the image of a point source is considered with regard to how well the approximate distribution of photodetector events approaches the classical three-dimensional point spread function (PSF) as the number of detected photons increase. We find that the normalized mean-square error between the detected photon distribution function and the classical PSF (very high SNR) has a power-law behavior varying as N-1.001, where N is the number of detected photons.

Nonlinear Guided Waves …, 2004

The counterintuitive effects on noise in nonlinear systems are well known [1]. In this paper, we ... more The counterintuitive effects on noise in nonlinear systems are well known [1]. In this paper, we investigate the effects of noise in the dynamics of a multi-transverse mode laser model. The complex spatiotemporal oscillations observed in such lasers are the result of the competition ...

Frontiers in Optics, 2011

ABSTRACT We simulate the growth of a voxel in a photopolymerization reaction where the degree of ... more ABSTRACT We simulate the growth of a voxel in a photopolymerization reaction where the degree of polymerization is determined by the decrease in the photoinitiator concentration. Simulation was done for both single-photon and two-photon photopolymerization.

Frontiers in Optics, 2011

... After modulating the phase, the beam is passed through a lens (f = 250 mm) which performs the... more ... After modulating the phase, the beam is passed through a lens (f = 250 mm) which performs the Fourier transform. ... 9. D. Palima and V. Daria, "Holographic projection of arbitrary light patterns with a suppressed zeroorder beam," Appl. Opt. ...

Local Publications by Giovanni Tapang

Talks by Giovanni Tapang

The release of the Commission on Audit (COA) Special Audits Office Report No. 2012-03 opened a we... more The release of the Commission on Audit (COA) Special Audits Office Report No. 2012-03 opened a wealth of data that gives us a glimpse of how the Priority Development Assistance Fund (PDAF) and the so-called Various Infrastructure, Including Local Projects (VILP) funds were used by government agencies. The report gives a government-wide Performance Audit of the PDAF and the VILP of various implementing agencies from 2007 to 2009.

Papers by Giovanni Tapang

The effect of climate variability on the weekly incidence of acute bloody diarrhea, dengue and in... more The effect of climate variability on the weekly incidence of acute bloody diarrhea, dengue and influenza-like illness in the 17 regions of the Philippines is examined using correlation, mutual information and transfer entropy. Results show that the correlations between climate variables and disease incidences differ from one region to another. Interestingly, the diseases are directly correlated to each other for each region. This is explained by their common driving climate factors which are shown by large transfer entropy values. This work is important in further understanding the role of climate variability to the temporal dynamics of disease incidences.

Optics Letters, Vol. 39, Issue 7, pp. 2036-2039 (April 2014)

We present a method of reshaping light in three dimensions via phase modulation. The method calcu... more We present a method of reshaping light in three dimensions via phase modulation. The method calculates the target computer generated hologram individually and adds to it an appropriate transfer function to translate the reconstruction to any location in space. We are able to simultaneously generate independently controlled arbitrary patterns at diff erent positions using a single laser beam.

International Journal of Modern Physics C (Accepted)

International Journal of Modern Physics C, 2010

International Journal of Modern …, 2012

Proceedings of The National Academy of Sciences, 2003

International Journal of …, 2012

Optics Communications, 2009

We report parallel two-photon photopolymerization of microgear patterns by exposing a photoresist... more We report parallel two-photon photopolymerization of microgear patterns by exposing a photoresist to holographically generated optical vortices. The optical vortices are created by imparting a helical pitch onto the incident light using a programmable lithographic phase mask realized with a computer addressable phase-only spatial light modulator. By varying the phase levels of the spatial light modulator, the truncated helical phase of an optical vortex results in output intensity patterns that typifies that of microgears instead of perfect doughnut beams. Our experiments and simulations are in good agreement implying a more efficient and highly parallel two-photon photopolymerization scheme that can be subsequently used for non-scanning fabrication of microgears.

IEEE Transactions on Circuits and Systems Ii: Analog and Digital Signal Processing, 2002

Physica A 312 (2002) 609–618

We analyze the exit dynamics of pedestrians who are initially confined in a room. Pedestrians ar... more We analyze the exit dynamics of pedestrians who are initially confined in a room. Pedestrians are modeled as cellular automata and compete to escape via a known exit at the soonest possible time. A pedestrian could move forward, backward, left or right within each iteration time depending on adjacent cell vacancy and in accordance with simple rules that determine the compulsion to move and physical capability relative to his neighbors. The arching signatures of jamming were observed and the pedestrians exited in bursts of various sizes. Power-law behavior is found in the burst-size frequency distribution for exit widths w greater than one cell dimension (w > 1). The slope of the power-law curve varies with
w from −1.3092 (w= 2) to −1.0720 (w= 20). Streaming which is a diffusive behavior, arises in large burst sizes and is more likely in a single-exit room with w = 1 and leads to a counterintuitive result wherein an average exit throughput Q is obtained that is higher than with w = 2, 3, or 4. For a two-exit room (w= 1), Q is not greater than twice the yield of a single-exit room. If the doors are not separated far enough (< 4w), Q becomes even significantly less due to a collective slow-downthat emerges among pedestrians crossing in each other’s path (disruptive interference effect). For the same w and door number, Q is also higher with relaxed pedestrians than with anxious ones.

The behavior of photon-limited light is discussed in reference to its use in confocal microscopy.... more The behavior of photon-limited light is discussed in reference to its use in confocal microscopy. A ray-tracing based simulation of photons passing through a confocal optical imaging system is performed with the photon propagation determined by the photon distribution function at the photodetector. The formation of the image of a point source is considered with regard to how well the approximate distribution of photodetector events approaches the classical three-dimensional point spread function (PSF) as the number of detected photons increase. We find that the normalized mean-square error between the detected photon distribution function and the classical PSF (very high SNR) has a power-law behavior varying as N-1.001, where N is the number of detected photons.

Nonlinear Guided Waves …, 2004

The counterintuitive effects on noise in nonlinear systems are well known [1]. In this paper, we ... more The counterintuitive effects on noise in nonlinear systems are well known [1]. In this paper, we investigate the effects of noise in the dynamics of a multi-transverse mode laser model. The complex spatiotemporal oscillations observed in such lasers are the result of the competition ...

Frontiers in Optics, 2011

ABSTRACT We simulate the growth of a voxel in a photopolymerization reaction where the degree of ... more ABSTRACT We simulate the growth of a voxel in a photopolymerization reaction where the degree of polymerization is determined by the decrease in the photoinitiator concentration. Simulation was done for both single-photon and two-photon photopolymerization.

Frontiers in Optics, 2011

... After modulating the phase, the beam is passed through a lens (f = 250 mm) which performs the... more ... After modulating the phase, the beam is passed through a lens (f = 250 mm) which performs the Fourier transform. ... 9. D. Palima and V. Daria, "Holographic projection of arbitrary light patterns with a suppressed zeroorder beam," Appl. Opt. ...

The release of the Commission on Audit (COA) Special Audits Office Report No. 2012-03 opened a we... more The release of the Commission on Audit (COA) Special Audits Office Report No. 2012-03 opened a wealth of data that gives us a glimpse of how the Priority Development Assistance Fund (PDAF) and the so-called Various Infrastructure, Including Local Projects (VILP) funds were used by government agencies. The report gives a government-wide Performance Audit of the PDAF and the VILP of various implementing agencies from 2007 to 2009.

The effect of climate variability on the weekly incidence of acute bloody diarrhea, dengue and in... more The effect of climate variability on the weekly incidence of acute bloody diarrhea, dengue and influenza-like illness in the 17 regions of the Philippines is examined using correlation, mutual information and transfer entropy. Results show that the correlations between climate variables and disease incidences differ from one region to another. Interestingly, the diseases are directly correlated to each other for each region. This is explained by their common driving climate factors which are shown by large transfer entropy values. This work is important in further understanding the role of climate variability to the temporal dynamics of disease incidences.

Journal of Mechatronics, Electrical Power, and Vehicular Technology, 2015

International Conference on Photonics Solutions 2015, 2015

Frontiers in Optics 2014, 2014