Familial Longevity Is Marked by Lower Diurnal Salivary Cortisol Levels: The Leiden Longevity Study

BACKGROUND: Reported findings are inconsistent whether hypothalamic-pituitary-adrenal (HPA) signaling becomes hyperactive with increasing age, resulting in increasing levels of cortisol. Our previous research strongly suggests that offspring from long-lived families are biologically younger. In this study we assessed whether these offspring have a lower HPA axis activity, as measured by lower levels of cortisol and higher cortisol feedback sensitivity. METHODS: Salivary cortisol levels were measured at four time points within the first hour upon awakening and at two time points in the evening in a cohort comprising 149 offspring and 154 partners from the Leiden Longevity Study. A dexamethasone suppression test was performed as a measure of cortisol feedback sensitivity. Age, gender and body mass index, smoking and disease history (type 2 diabetes and hypertension) were considered as possible confounding factors. RESULTS: Salivary cortisol secretion was lower in offspring compared to partners in the morning (Area Under the Curve = 15.6 versus 17.1 nmol/L, respectively; p = 0.048) and in the evening (Area Under the Curve = 3.32 versus 3.82 nmol/L, respectively; p = 0.024). Salivary cortisol levels were not different after dexamethasone (0.5 mg) suppression between offspring and partners (4.82 versus 5.26 nmol/L, respectively; p = 0.28). CONCLUSION: Offspring of nonagenarian siblings are marked by a lower HPA axis activity (reflected by lower diurnal salivary cortisol levels), but not by a difference in cortisol feedback sensitivity. Further in-depth studies aimed at characterizing the HPA axis in offspring and partners are needed

The Feasibility, Semantics, and Scope of Mobile Wireless Device-to-Device Networking

Wireless networking technology, as prevalently realized according to the IEEE 802.11 standard, successfully complements wired access to local networks and the Internet. Current mobile devices, such as smartphones, manifest wireless networking within everyday mobile scenarios and diverse and dynamic device-to-device (D2D) communication contexts that are independent from any network infrastructure, motivating the research directions of Mobile Ad-Hoc, Delay Tolerant, and Opportunistic Networking as well as Ubiquitous Communication. In these directions, D2D communication strives to facilitate mobile applications and therefore requires a technological basis for wireless networking between mobile devices that comprehensively manifests application semantics within the temporal and spatial scope of mobile communication contexts. Indeed, the 802.11 wireless networking capabilities of current mobile devices are, in principle, suited to provide this basis, enabling users to freely instantiate localized and autonomous communication structures.In spite of this, very few academic approaches achieve the jump to real-world implementations and applications. We attribute this fact to three shortcomings in realizing mobile D2D networking within the wireless communication capabilities of current mobile devices and envisioned communication contexts. First, a lack of support for the 802.11 ad-hoc mode (AM), the traditionally assumed basis for mobile D2D networking, reduces its basic feasibility on current mobile devices. Second, the original design of 802.11 as a one-hop extension of wired networks cannot express application semantics that enable purposeful discovery of application participants within the sheer number of devices that make up current mobile scenarios. Similarly, the fundamental notion of an Ethernet-like binding of devices in networks in 802.11 cannot enable a comprehensive communication scope that makes the ubiquity of wireless devices accessible and available for communication.This thesis addresses these specific shortcomings and proposes mechanisms that comprehensively enable mobile wireless D2D networking. First, we establish D2D networking in a network design that builds on the ubiquitously supported 802.11 infrastructure mode (IM), mitigating the lack of support for the AM and exposing the performance gains of the IM to mobile wireless networking. Our design affords network connectivity equivalent to the 802.11 AM with significantly fewer devices serving as forwarders and enables energy savings at both forwarding devices and commodity network participants.Second, we propose a design to build wireless D2D networking around the availability of desired applications and content, mitigating the inability to express interests and semantics in 802.11. Our design exploits the pervasive and unrestricted scope of wireless broadcasts for discovery and subsequently instantiates D2D networking in dedicated 802.11 networks to facilitate high-performance mobile content exchange.Third, we realize unrestricted ubiquitous wireless networking with all encountered devices in a network-less communication mechanism that exposes the temporal and spatial dynamics, diversity, and scope of wireless contexts to mobile applications. Building on this scope, we propose multiple compelling multimedia use cases that leverage local and immediate communication for direct interaction between mobile and stationary wireless devices

Opening the Loops - Towards Semantic, Information-centric Networking in the Internet of Things

Abstract-The advent of the Internet of Things (IoT) paradigm in increasing deployments promises a pervasive proliferation of smart things, capable of sensing, actuating, and processing information. In typical designs, however, application of each thing is restricted to a dedicated use case in a single network of connected devices, resulting in a closed loop of information flow. We argue that, given the envisioned diversity, capabilities, and sheer number of smart things, this obstructs the possibility of creating diverse and exciting applications that benefit of the generated information in public, global usage scenarios. In this paper, we thus aim to initiate the discussion of creating a true Internet of Things, i.e., interconnected IoT networks, based on provision and requests of generated information in a public infrastructure. We highlight the challenges in designing this infrastructure for feasible integration in the current Internet and IoT designs, comprehensive provision and retrieval of information, and versatile derivation of higher information contexts from single information sources. Assessing advantages and shortcomings of existing approaches, we propose a suitable approach and discuss both a centralized and distributed implementation of the proposed infrastructure