F.T.H. den Hartog

Convergence of residential gateway technology

A new OSI-based model is described that can be used for the classification of residential gateways. It is applied to analyze current gateway solutions and draw evolutionary paths for the medium to long term. From this it is concluded that particularly set-top boxes and broadband modems, as opposed to game consoles and PCs, have a strong potential to evolve toward gateways that deliver network services to the home on all OSI layers, although they probably will not converge. In our model, we have not found any compelling reasons for the residential gateway industry to support concurrent multiple broadband access network connections on a single residential gateway in the near future.

Spectral Distributions of “Trap” Pigments in the RC, CP47, and CP47−RC Complexes of Photosystem II at Low Temperature: A Fluorescence Line-Narrowing and Hole-Burning Study

Broad-band absorption and fluorescence, fluorescence line-narrowing (FLN), and spectral hole-burning experiments have been performed on the Qy-band of three subcore reaction-center complexes of photosystem II between 1.2 and 4.2 K:  the isolated reaction center (RC), the inner core antenna CP47, and the CP47−RC complex. In the RC, fluorescence line-narrowing (FLN) is observed for excitation wavelengths λexc ≥ 676 nm, whereas in CP47, this occurs for λexc ≥ 680 nm. The FLN spectra of CP47−RC appear to be the sum of the individual spectra of the RC and CP47, an indication that this complex has two “traps”. This has been confirmed from the spectral distributions obtained by measuring the hole depth (at constant hole width) as a function of λexc, as previously done for the RC [Groot, M. L., et al. J. Phys. Chem. 100, 1996, 11488]. The maxima of these distributions are at ∼682 nm for the RC “trap” and at ∼690 nm for the CP47 “trap” within the CP47−RC complex. Further support that the two distributions of pigme...

First experiences with Personal Networks as an enabling platform for service providers

By developing demonstrators and performing small-scale user trials, we found various opportunities and pitfalls for deploying personal networks (PNs) on a commercial basis. The demonstrators were created using as many as possible legacy devices and proven technologies. They deal with applications in the health sector, home services, tourism, and the transportation sector. This paper describes the various architectures and our experiences with the end users and the technology. We conclude that context awareness, service discovery, and content management are very important in PNs and that a personal network provider role is necessary to realize these functions under the assumptions we made. The PNPay Travel demonstrator suggests that PN service platforms provide an opportunity to develop true trans-sector services.

Spectral diffusion induced by energy transfer in doped organic glasses: Delay-time dependence of spectral holes

A new effect in doped organic glasses, which we refer to as “energy transfer (ET)-induced spectral diffusion (SD),” ET→SD, has recently been reported by us. In this process “extra” SD, in addition to “normal” SD in glasses, is triggered by the energy balance released on “downhill” ET. Quantitative aspects of the ET→SD process have been investigated by means of time-resolved hole-burning experiments on free-base chlorin (H2Ch) in polystyrene (PS) presented here. The “effective” homogeneous linewidth Γhom′ was determined as a function of delay time td (10−5−103 s), temperature (1.2 to 4.2 K) and concentration (c=1×10−5 to 6×103 M), at various excitation wavelengths within the S1←S0 0-0 band. Γhom′ as a function of temperature was found to obey the relation Γhom′=Γ0′+aT1.3, characteristic for glasses, and we present an analysis of the residual linewidth Γ0′ and the coupling constant a. In this analysis we determined (i) the separate contributions to Γ0′ arising from the fluorescence lifetime, ET, and ET→SD, ...

The effect of pressure, time and concentration in hole-burning studies

Abstract The effective homogeneous line width Γ′hom of the S1 ← S0 0-0 transitions of bacteriochlorophyll-a (BChl-a) in the glass triethylamine (TEA) and of free-base chlorin (H2Ch) in polystyrene (PS) have been studied, respectively, under the influence of high pressure (~30 kbar) and for a range of concentrations (~ 10−4–10−2 M). The aim was to get a better understanding of spectral diffusion and energy transfer processes in amorphous systems. The dependence of Γ′hom on temperature (1.2–4.2 K), excitation wavelength (within the 0-0 band) and delay time (10−6–105 s) was measured for both systems by means of spectral hole burning.

Glass versus protein dynamics at low temperature studied by time-resolved spectral hole burning

Low-temperature dynamics of doped organic glasses and photosynthetic pigment-protein complexes has been studied by time-resolved hole burning. The systems investigated are:

On the definition and relevance of context-awareness in Personal Networks

Personal networks (PNs) enable users to be connected with their devices and services at any time and any place. Context-awareness will further enrich PNs. This paper shows some examples, presents definitions of context and context-awareness for PNs, and introduces a high-level architecture for context-awareness that is tailored to PNs

Spectral diffusion induced by energy transfer and high-pressure effects in doped organic glasses: A hole-burning study

Abstract Time-resolved hole-burning (HB) experiments have been performed on the S 1 ← S 0 0−0 transitions of free-base chlorin in polystyrene (H 2 Ch in PS) and bacteriochlorophyll-a in triethylamine (BChl-a in TEA) as a function of temperature (1.2–4.2 K), excitation wavelength, concentration, and delay time between burning and probing. At concentrations higher than 5 × 10 −4 M a new type of spectral diffusion process takes place, even at T → 0, which is induced by energy transfer. Moreover, HB-experiments on BChl-a in TEA with delay times between microseconds and hours at high ( Δp ≈ 30 kbar) pressure demonstrate that a transition from a glassy- to a locally ordered structure occurs in this sample, suggesting that the number of “two-level-systems” in the glass responsible for spectral diffusion is reduced by compression.

Remote Management of Mobile Devices with Broadband Forum's TR-069

Remote device and network management can play an important role in realizing efficient and user-friendly deployment of fixed-mobile converged network services. TR-069 is currently the most popular remote-management protocol in the DSL world, but is not used in mobile networks. This paper investigates the applicability of TR-069 for remote device management of mobile devices. We installed a TR-069 client on a mobile phone, and measured the performance of the protocol in relation to the properties of the mobile data connection and the small footprint of the mobile device. The results confirm theoretical considerations derived from literature. The main conclusion is that TR-069 can be safely used for remote management of mobile devices, but requires a higher connection capacity of the remote management server due to the longer connection times in mobile networks.

Low-Temperature Protein Dynamics in Purple Bacteria and Green Plants Studied by Time-Resolved Hole-Burning

Proteins display both crystalline and glassy properties. In their native state they have well-defined tertiary structures which are reflected in their crystalline properties. Unlike crystals, which are static, proteins are dynamic systems that undergo conformational changes between a large number of nearly isoenergetic structures [1]. Each individual conformational substate (CS) is represented by a valley in the so-called energy landscape [2], which describes the energy of all possible protein structures for a given primary sequence. At very low temperatures, each protein remains “frozen” in a particular CS. Jumps from one CS to another, which may be induced by pumping energy into the system, cause protein motions. The difference between the CSs in proteins and the two-level-systems (TLSs) in glasses [3] is that CSs are assumed to be organized in a hierarchy of a number of tiers [4] characterized by different barrier heights separating the individual CSs, whereas glasses are random.