We describe the recent progress in our cesium atomic fountains at National Metrology Institute of Japan (NMIJ). We have developed three atomic fountains: NMIJ-F1, NMIJ-F2, and a truncated atomic beam fountain. NMIJ-F1 has been the primary frequency standard with uncertainty of 4×10 -15 since 2004. Especially in the last 4 years, we have reported the data to Bureau International des Poids et Mes...

For almost two decades, caesium fountain primary frequency standards (PFS) have represented the best realization of the definition of the second in the International System of units. Their accuracy has progressively improved with time, reaching a few parts in 1016. In this paper, we present the accuracy evaluation of ITCsF2, the new Cs fountain PFS developed at the Italian National Metrological...

The proliferation of applications that must reliably distribute large, rich content to a vast number of autonomous receivers motivates the design of new multicast and broadcast protocols. We describe an ideal, fully scalable protocol for these applications that we call a digital fountain. A digital fountain allows any number of heterogeneous receivers to acquire content with optimal efficiency ...

We propose a novel cross layer scheme to reduce the power consumption of ADCs in OFDM systems. The ADCs in a receiver can consume up to 50% of the total baseband energy. Our scheme is based on resolution-adaptive ADCs and Fountain codes. In a wireless frequency-selective channel some subcarriers have good channel conditions and others are attenuated. The key part of the proposed system is that ...

This paper deals with Fountain codes, and especially with their encoding matrices, which are required here to be invertible. A result is stated that an encoding matrix induces a permutation. Also, a result is that encoding matrices form a group with multiplication operation. An encoding is a transformation, which reduces the entropy of an initially high-entropy input vector. A special encoding ...

OBJECTIVE To detect an outbreak-related source of Legionella, control the outbreak, and prevent additional Legionella infections from occurring. DESIGN AND SETTING Epidemiologic investigation of an acute outbreak of hospital-associated Legionnaires disease among outpatients and visitors to a Wisconsin hospital. PATIENTS Patients with laboratory-confirmed Legionnaires disease who resided in ...

Simulations of an isolated Milky Way-like galaxy, in which supernovae power a galactic fountain, reproduce the observed velocity and 21 cm brightness statistics of galactic neutral hydrogen (H i). The simulated galaxy consists of a thin H i disk, similar in extent and brightness to that observed in the Milky Way, and extra-planar neutral gas at a range of velocities due to the galactic fountain...

In this thesis, the problem of transmitting data in the form of multicast and broadcast traffic has been studied. The traffic can be from a real-time application which has a short block length or it can be a general broadcast traffic in an ad-hoc network. The goal is to reduce the total number of transmissions which results in reducing the delay and improving the energy efficiency of the system...

ABSTRACT We use a dynamical model of galactic fountain to study the neutral extraplanar gas (EPG) in nearby spiral galaxy NGC 2403. have modelled EPG as combination material ejected from disc by stellar feedback (i.e. fountain) and accreting inner circumgalactic medium (CGM). This accretion is expected occur because cooling/condensation hot CGM (corona) triggered fountain. Our reproduces distri...

This article examines the design and social impact of waterways in Athens early 5thC BCE. While Athenian political landscape transitioned from a series tyrannies to democracy at end Archaic period (ca. 650-480 BCE), archaeological record also shows widespread innovation development public water systems, particularly sanitation supply. A movement away buildings constructed by tyrants facilitated...