Traffic grooming and wavelength conversion in optical networks

Wavelength Division Multiplexing (WDM) using wavelength routing has emerged as the dominant technology for use in wide area and metropolitan area networks. Traffic demands in networks today are characterized by dynamic, heterogeneous flows. While each wavelength has transmission capacity at gigabit per second rates, users require connections at rates that are lower than the full wavelength capacity. In this thesis, we explore network design and operation methodologies to improve the network utilization and blocking performance of wavelength routing networks which employ a layered architecture with electronic and optical switching. First we provide an introduction to first generation SONET/SDH networks and wavelength routing networks, which employ optical crossconnects. We explain the need and role of wavelength conversion in optical networks and present an algorithm to optimally place wavelength conversion devices at the network nodes so as to optimize blocking performance. Our algorithm offers significant savings in computation time when compared to the exhaustive method.;To make the network viable and cost-effective, it must be able to offer sub-wavelength services and be able to pack these services efficiently onto wavelengths. The act of multiplexing, demultiplexing and switching of sub-wavelength services onto wavelengths is defined as traffic grooming. Constrained grooming networks perform grooming only at the network edge. Sparse grooming networks perform grooming at the network edge and the core. We study and compare the effect of traffic grooming on blocking performance in such networks through simulations and analyses. We also study the issue of capacity fairness in such networks and develop a connection admission control (CAC) algorithm to improve the fairness among connections with different capacities. We finally address the issues involved in dynamic routing and wavelength assignment in survivable WDM grooming networks. We develop two schemes for grooming primary and backup traffic streams onto wavelengths: Mixed Primary-Backup Grooming Policy (MGP) and Segregated Primary-Backup Grooming Policy (SGP). MGP is useful in topologies such as ring, characterized by low connectivity and high load correlation and SGP is useful in topologies, such as mesh-torus, with good connectivity and a significant amount of traffic switching and mixing at the nodes

10Gbit/s modulation of a fast switching slotted Fabry-Pérot tunable laser

The device used is a three-section, 3mum wide ridge waveguide laser based on commercially available material. During the fabrication a series of slots are introduced into the front and back sections, which act as sites of internal reflections. The slots are etched to a depth that just penetrates the top of the upper waveguide resulting in an internal reflectance of-1% at each slot. The front, middle, and back sections are 180, 690 and 170 microns long respectively. In this work the back and middle sections are tied together electrically allowing simpler control of the device. By varying the applied DC currents, eight discrete channels are observed over a range of approximately 19nm

Energy efficient partition-lightpath scheme for IP over WDM core networks

In this paper, the research focus on the development of energy saving schemes with roots in sleep modes that support the evolution of greener core optical IP networks. The cornerstone of the adopted strategy is partition-lightpath schemes underpinned by the hibernation state implemented through a modification of the intelligent control plane, in particular for transparent network architectures under different scenarios. An enhanced multi-level operational hibernation mode through partition-lightpath was defined including functionality, structure considering its implementation issues. Through the use of appropriate design parameters the impact on blocking probability, wavelengths assignment, LSP connection requests, degree of node connectivity and network utilization can be minimized while also achieving energy savings. Evaluation of this scheme indicates potential reduction in power consumption from 9% up to 17% at the expense of reduced network performance

Traffic Grooming in Bidirectional WDM Ring Networks

We study the minimization of ADMs (Add-Drop Multiplexers) in optical WDM bidirectional rings considering symmetric shortest path routing and all-to-all unitary requests. We precisely formulate the problem in terms of graph decompositions, and state a general lower bound for all the values of the grooming factor $C$ and $N$, the size of the ring. We first study exhaustively the cases $C=1$, $C = 2$, and $C=3$, providing improved lower bounds, optimal constructions for several infinite families, as well as asymptotically optimal constructions and approximations. We then study the case $C>3$, focusing specifically on the case $C = k(k+1)/2$ for some $k \geq 1$. We give optimal decompositions for several congruence classes of $N$ using the existence of some combinatorial designs. We conclude with a comparison of the cost functions in unidirectional and bidirectional WDM rings

Variation in amino acid and lipid composition of latent fingerprints

The enhancement of latent fingerprints, both at the crime scene and in the laboratory using an array of chemical, physical and optical techniques, permits their use for identification. Despite the plethora of techniques available, there are occasions when latent fingerprints are not successfully enhanced. An understanding of latent fingerprint chemistry and behaviour will aid the improvement of current techniques and the development of novel ones. In this study the amino acid and fatty acid content of ‘real’ latent fingerprints collected on a non-porous surface was analysed by gas chromatography–mass spectrometry. Squalene was also quantified in addition. Hexadecanoic acid, octadecanoic acid and cis-9- octadecenoic acid were the most abundant fatty acids in all samples. There was, however, wide variation in the relative amounts of each fatty acid in each sample. It was clearly demonstrated that touching sebum-rich areas of the face immediately prior to fingerprint deposition resulted in a significant increase in the amount of fatty acids and squalene deposited in the resulting ‘groomed’ fingerprints. Serine was the most abundant amino acid identified followed by glycine, alanine and aspartic acid. The significant quantitative differences between the ‘natural’ and ‘groomed’ fingerprint samples seen for fatty acids were not observed in the case of the amino acids. This study demonstrates the variation in latent fingerprint composition between individuals and the impact of the sampling protocol on the quantitative analysis of fingerprints

Emotion and Cognition in High and Low Stress Sensitive Mouse Strains: A Combined Neuroendocrine and Behavioral Study in BALB/c and C57BL/6J Mice

Emotionally arousing experiences and stress influence cognitive processes and vice versa. Understanding the relations and interactions between these three systems forms the core of this study. We tested two inbred mouse strains (BALB/c, C57BL/6J; male; 3-month-old) for glucocorticoid stress system markers (expression of MR and GR mRNA and protein in hippocampus, amygdala, and prefrontal cortex; blood plasma corticosterone), used behavioral tasks for emotions and cognitive performance (elevated plus maze, holeboard) to assess the interdependence of these factors. We hypothesize that BALB/c mice have a stress-vulnerable neuroendocrine phenotype and that emotional expressions in BALB/c and C57BL/6J mice will differentially contribute to learning and memory. We applied factor analyses on emotional and cognitive parameters to determine the behavioral structure of BALB/c and C57BL/6J mice. Glucocorticoid stress system markers indeed show that BALB/c mice are more stress-vulnerable than C57BL/6J mice. Moreover, emotional and explorative factors differed between naïve BALB/c and C57BL/6J mice. BALB/c mice display high movement in anxiogenic zones and high risk assessment, while C57BL/6J mice show little movement in anxiogenic zones and display high vertical exploration. Furthermore, BALB/c mice are superior learners, showing learning related behavior which is highly structured and emotionally biased when exposed to a novel or changing situation. In contrast, C57BL/6J mice display a rather “chaotic” behavioral structure during learning in absence of an emotional factor. These results show that stress vulnerability coincides with more emotionality, which drives well orchestrated goal directed behavior to the benefit of cognition. Both phenotypes have their advantage depending on environmental demands

HYPOTHALAMIC CIRCUITS IN THE CONTROL OF FEEDING AND EMOTIONAL BEHAVIORS

Feeding results from the integration of both nutritional and affective states, and is guided by complex neural circuitry in the brain. The hypothalamus is a critical center controlling feeding and motivated behaviors. We found that targeted photostimulation of projections from the lateral hypothalamus (LH) to the paraventricular hypothalamus (PVH) in mice elicited voracious feeding and repetitive self-grooming behavior. GABA neurotransmission in the LH-\u3ePVH circuit mediated the evoked feeding behavior, and elicited behavioral approach, whereas glutamate release promoted repetitive self-grooming, which was stress-related in nature. Optogenetic inhibition of LHGABA -\u3ePVH circuit reduced feeding after fasting, whereas photostimulation abruptly stopped ongoing self-grooming and immediately elicited feeding. Oppositely, optogenetic inhibition of LHGlutamate-\u3ePVH circuit reduced repetitive self-grooming, whereas photostimulation suppressed fast-refeeding in exchange for repetitive self-grooming. Optogenetically activating and silencing PVH neurons directly recapitulated these findings, and demonstrated the necessity of glutamatergic PVH neurons in mediating the competition between self-grooming and feeding. Together, these results provided evidence that the mutually exclusive nature of feeding and self-grooming behaviors are in part mediated by distinct components in the LH-\u3ePVH circuit. Interestingly, photostimulating PVH neurons with greater intensity promoted transitions from grooming to frantic escape-jumping, suggesting scalability of stress-related behaviors mediated by PVH neural activity. Because evoked jumping resembled attempts to escape, we posited PVH neurons mediate defensive responses. Validating this, photostimulating PVH neurons induced avoidance and increased locomotion, two classic behavioral indicators of active defense strategies. Anterograde tracing showed that PVH neurons densely projected to the midbrain region in and surrounding the ventral tegmental area (VTA), a brain region well-known for its roles in motivated behaviors. Indeed, photostimulation of PVH-\u3emidbrain projections produced escape behaviors and conditioned place aversion. Combined optogenetic and chemogenetic experiments showed that glutamatergic-midbrain neurons were required for escape behaviors. Further, glutamatergic-midbrain neurons displayed increased neural population activity in vivo during a fear-provoking situation, validating a role for this population in processing threat. Taken together, our work reveals novel hypothalamic circuits in the control of feeding, emotional valence, and behaviors related to stress and defense. These findings shed light on possible neural mechanisms underlying complex disease states characterized by feeding abnormalities, anxiety and fear