Nonlinear fiber optics for bio-imaging

Two-photon excitation (TPE) is a modern technology with applications in microscopy and spectroscopy that has gained a great amount of attention in recent years. This technique is the best suitable to analyze thick tissues and live animals as it works in the near-infrared (NIR) region. In this work we implement and evaluate a two-photon setup that allows the shifting of the working wavelength over a wide range using the soliton self-frequency shift (SSFS) effect. The shifter is implemented using a pulsed fiber laser and a photonic crystal fiber (PCF). We also include a numerical evaluation of the dependency of the fiber shift on the input average power and the fiber length. A semi-analytical model is proposed to investigate the characteristics of the SSFS in optical fibers. SSFS in two different types of fibers were evaluated and the results agree very well with those of numerical simulations. We show that when the frequency shift is small enough, it is inversely proportional to the fourth power of the initial soliton pulse width. However, with large frequency shift, this fourth power rule needs to be modified. We finally show the first two-photon images obtained at the University of Kansas

COLLECTING POWER CONSUMPTION METRICS FROM OPERATIONALLY INACCESSIBLE NETWORKS

Operational traffic, such as management plane traffic carrying power consumption metrics from a device in the field, is often inaccessible to a device’s vendor. Techniques are presented herein that support a novel mechanism for encoding power consumption metrics in standard communication protocols such as, for example, domain name system (DNS) requests. Aspects of the presented techniques ensure the atomicity of self-contained messages, as well as the confidentiality and integrity of the metrics that are sent to the corresponding vendors. Further aspects of the presented techniques support selectable levels of anonymity during the exporting of the above-described metrics. For example, selectable Terms and Conditions may not only allow administrators to choose among different levels of anonymity, but also facilitate frictionless operations and automatic configuration during the activation of a license

Advantages of a PCE-based control plane for LISP

The Locator/Identifier Separation Protocol (LISP) is one of the candidate solutions to address the scalability issues in inter-domain routing. The current proposals for its control plane (e.g., ALT, CONS, NERD) have various shortcomings, including the potential dropping of packets at LISP routers during the resolution of the EID-to-RLOC mapping. In this paper, we introduce a new Control Plane (CP) for LISP supported by an architecture that borrows concepts from both the Path Computation Element (PCE) and Intelligent Route Control (IRC). Our CP is able to tackle three different problems simultaneously: (i) packets sourced from end-hosts are neither dropped nor queued during the mapping resolution; (ii) the EID-to-RLOC mapping can be obtained and configured approximately within the DNS resolution time needed to fetch the destination EID address; and (iii) our approach can blend IRC with the PCE capabilities, to perform upstream/ downstream Traffic Engineering (TE) through the dynamic management of the mappings. In particular, our CP supports the utilization of different LISP ingress and egress local routers for the same flow sourced from a domain.Peer ReviewedPostprint (author’s final draft

Managing Interdomain Traffic in Latin America: A New Perspective based on LISP

The characteristics of Latin American network infrastructures have global consequences, particularly in the area of interdomain traffic engineering. As an example, Latin America shows the largest de-aggregation factor of IP prefixes among all regional Internet registries, being proportionally the largest contributor to the growth and dynamics of the global BGP routing table. In this article we analyze the peculiarities of LA interdomain routing architecture, and provide up-to-date data about the combined effects of the multihoming and TE practices in the region. We observe that the Internet Research Task Force initiative on the separation of the address space into locators and identifiers can not only alleviate the growth and dynamics of the global routing table, but can also offer appealing TE opportunities for LA. We outline one of the solutions under discussion at the IRTF, the Locator/Identifier Separation Protocol, and examine its potential in terms of interdomain traffic management in the context of LA. The key advantage of LISP is its nondisruptive nature, but the existing proposals for its control plane have some problems that may hinder its possible deployment. In light of this, we introduce a promising control plane for LISP that can solve these issues, and at the same time has the potential to bridge the gap between intradomain and interdomain traffic management.Peer ReviewedPostprint (published version

Stochastic techniques for time series with applications to materials accountancy

SIGLEAvailable from British Library Document Supply Centre- DSC:D66799/86 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Understanding IPv4 prefix de-aggregation: challenges for routing scalability

The Internet has become a vast and complex infrastructure. One of the aspects of deeper concern in the community is routing scalability, which involves both the size and dynamics of the global Internet routing table. Many Future Internet initiatives stand for “clean slate” or disruptive approaches to overcome this issue; nevertheless, network operators need evolutionary solutions. In this paper we put forward a characterization of the IP prefix de-aggregation factor focussing on the Latin American region, where we found that a significant contribution to the growth of the routing table could be prevented by improving BGP configuration. In the context of our participation in the LISP+ALT testbed (an evolutionary Future Internet initiative), we identify initial management requirements for its deployment, according to our findings regarding the size and dynamics of the routing table.Peer Reviewe

iPV6 nonahi baliatzeko gidaliburua

Azken erabiltzailea. - Home Office (bizitokietako sareak). - IPv6-rekin dabiltzen zerbitzuak - Enpresa. - Hezkuntza- eta ikerketa-ingurunea. - Internet zerbitzu-hornitzaileak (ISPak). - Epilogoa

Two-photon microscopy with wavelength switchable fiber laser excitation

This is the publisher's version, also available electronically from http://www.opticsinfobase.org/oe/abstract.cfm?uri=oe-14-21-9825.Two-photon scanning fluorescence microscopy has become a powerful tool for imaging living cells and tissues. Most applications of two-photon microscopy employ a Ti:sapphire laser excitation source, which is not readily portable or rapidly tunable. This work explores the use of two-photon fiber laser excitation (TP-FLEX) as an excitation source for scanning two-photon microscopy. We have further demonstrated the use of a photonic crystal fiber (PCF) for facile tuning of the excitation wavelength over the range from 810 nm to 1100 nm. We generated two-photon fluorescence images at excitation wavelengths from 850 nm to 1100 nm detected on a scanning-stage microscope. By PCF wavelength tuning the dye BODIPY fl was selectively excited at 1000 nm whereas MitoTracker red was excited preferentially at 1100 nm. We discuss the potential for fiber laser sources coupled with PCF wavelength tuning as an attractive tunable excitation source for two-photon scanning fluorescence microscopy

iPV6 nonahi baliatzeko gidaliburua

Azken erabiltzailea. - Home Office (bizitokietako sareak). - IPv6-rekin dabiltzen zerbitzuak - Enpresa. - Hezkuntza- eta ikerketa-ingurunea. - Internet zerbitzu-hornitzaileak (ISPak). - Epilogoa