632 research outputs found
The Development of Security Community in Croatia: Leading the Pack
Of the former Yugoslav republics, Croatia is in an enviable position. After years of difficult reforms and restructuring, its efforts are paying off. The country recently assumed a seat on the UN Security Council, it joined NATO and there is an expectation of forthcoming EU membership. Through these steps, the country has begun to integrate into the well-established Euro-Atlantic community. This article explores the depths of this integration through the theoretical lens of security community. We draw conclusions regarding security community in Croatia to provide lessons for NATOâs New Strategic Concept. Ultimately, we argue that NATO must remember that there remain security concerns in the European neighborhood, even in apparent successes like Croatia
Detection and Estimation Theory
Contains reports on theses completed and four research projects.Joint Services Electronics Programs (U. S. Army, U. S. Navy, and U. S. Air Force) under Contract DA 28-043-AMC-02536(E
Optimal Location of Two Laser-interferometric Detectors for Gravitational Wave Backgrounds at 100 MHz
Recently, observational searches for gravitational wave background (GWB) have
been developed and given constraints on the energy density of GWB in a broad
range of frequencies. These constraints have already resulted in the rejection
of some theoretical models of relatively large GWB spectra. However, at 100
MHz, there is no strict upper limit from direct observation, though an indirect
limit exists due to He4 abundance due to big-bang nucleosynthesis. In our
previous paper, we investigated the detector designs that can effectively
respond to GW at high frequencies, where the wavelength of GW is comparable to
the size of a detector, and found that the configuration, a so-called
synchronous-recycling interferometer is best at these sensitivity. In this
paper, we investigated the optimal location of two synchronous-recycling
interferometers and derived their cross-correlation sensitivity to GWB. We
found that the sensitivity is nearly optimized and hardly changed if two
coaligned detectors are located within a range 0.2 m, and that the sensitivity
achievable in an experiment is far below compared with the constraint
previously obtained in experiments.Comment: 17 pages, 6 figure
Development of soil moisture profiles through coupled microwaveâthermal infrared observations in the southeastern United States
The principle of maximum entropy (POME) can be used to develop
vertical soil moisture (SM) profiles. The minimal inputs required by the POME
model make it an excellent choice for remote sensing applications. Two of the
major input requirements of the POME model are the surface boundary condition
and profile-mean moisture content. Microwave-based SM estimates from the Advanced
Microwave Scanning Radiometer (AMSR-E) can supply the surface boundary
condition whereas thermal infrared-based moisture estimated from the
Atmospheric Land EXchange Inverse (ALEXI) surface energy balance model can
provide the mean moisture condition. A disaggregation approach was followed
to downscale coarse-resolution (ââŒâ25 km) microwave SM estimates to match
the finer resolution (ââŒâ5 km) thermal data. The study was conducted over
multiple years (2006â2010) in the southeastern US. Disaggregated soil
moisture estimates along with the developed profiles were compared with the
Noah land surface model (LSM), as well as in situ measurements from 10
Natural Resource Conservation Services (NRCS) Soil Climate Analysis Network
(SCAN) sites spatially distributed within the study region. The overall
disaggregation results at the SCAN sites indicated that in most cases
disaggregation improved the temporal correlations with unbiased root mean
square differences (ubRMSD) in the range of 0.01â0.09 m3 mâ3. The
profile results at SCAN sites showed a mean bias of 0.03 and 0.05
(m3 mâ3); ubRMSD of 0.05 and 0.06 (m3 mâ3); and correlation
coefficient of 0.44 and 0.48 against SCAN observations and Noah LSM,
respectively. Correlations were generally highest in agricultural areas where
values in the 0.6â0.7 range were achieved.</p
Spacelab Science Results Study
Beginning with OSTA-1 in November 1981 and ending with Neurolab in March 1998, a total of 36 Shuttle missions carried various Spacelab components such as the Spacelab module, pallet, instrument pointing system, or mission peculiar experiment support structure. The experiments carried out during these flights included astrophysics, solar physics, plasma physics, atmospheric science, Earth observations, and a wide range of microgravity experiments in life sciences, biotechnology, materials science, and fluid physics which includes combustion and critical point phenomena. In all, some 764 experiments were conducted by investigators from the U.S., Europe, and Japan. The purpose of this Spacelab Science Results Study is to document the contributions made in each of the major research areas by giving a brief synopsis of the more significant experiments and an extensive list of the publications that were produced. We have also endeavored to show how these results impacted the existing body of knowledge, where they have spawned new fields, and if appropriate, where the knowledge they produced has been applied
Thermal history of the plasma and high-frequency gravitons
Possible deviations from a radiation-dominated evolution, occurring prior the
synthesis of light nuclei, impacted on the spectral energy density of
high-frequency gravitons. For a systematic scrutiny of this situation, the
CDM paradigm must be complemented by (at least two) physical
parameters describing, respectively, a threshold frequency and a slope. The
supplementary frequency scale sets the lower border of a high-frequency domain
where the spectral energy grows with a slope which depends, predominantly, upon
the total sound speed of the plasma right after inflation. While the infra-red
region of the graviton energy spectrum is nearly scale-invariant, the expected
signals for typical frequencies larger than 0.01 nHz are hereby analyzed in a
model-independent framework by requiring that the total sound speed of the
post-inflationary plasma be smaller than the speed of light. Current (e.g.
low-frequency) upper limits on the tensor power spectra (determined from the
combined analysis of the three large-scale data sets) are shown to be
compatible with a detectable signal in the frequency range of wide-band
interferometers. In the present context, the scrutiny of the early evolution of
the sound speed of the plasma can then be mapped onto a reliable strategy of
parameter extraction including not only the well established cosmological
observables but also the forthcoming data from wide band interferometers.Comment: 47 pages, 31 included figures, to appear in Classical and Quantum
Gravit
The relation between school leadership from a distributed perspective and teachers' organizational commitment: examining the source of the leadership function
Purpose: In this study the relationship between school leadership and teachersâ organizational commitment is examined by taking into account a distributed leadership perspective. The relation between teachersâ organizational commitment and contextual variables of teachersâ perceptions of the quality and the source of the supportive and supervisory leadership function, participative decision making, and cooperation within the leadership team are examined. Research Design: A survey was set up involving 1,522 teachers from 46 large secondary schools in Flanders (Belgium). Because the data in the present study have an inherent hierarchical structure, that is, teachers are nested into schools, hierarchical linear modeling techniques are applied. Findings: The analyses reveal that 9% of the variance in teachersâ organizational commitment is attributable to differences between schools. Teachersâ organizational commitment is mainly related to quality of the supportive leadership, cooperation within the leadership team, and participative decision making. Who performed the supportive leadership function plays only a marginally significant positive role. The quality of the supervisory leadership function and the role of the leadership team members in this function were not significantly related to teachersâ organizational commitment. Conclusions: The implications of the findings are that to promote teachersâ organizational commitment teachers should feel supported by their leadership team and that this leadership team should be characterized by group cohesion, role clarity, and goal orientedness. Recommendations for further research are provided
Acceleration disturbances and requirements for ASTROD I
ASTRODynamical Space Test of Relativity using Optical Devices I (ASTROD I)
mainly aims at testing relativistic gravity and measuring the solar-system
parameters with high precision, by carrying out laser ranging between a
spacecraft in a solar orbit and ground stations. In order to achieve these
goals, the magnitude of the total acceleration disturbance of the proof mass
has to be less than 10−13 m s−2 Hz−1/2 at 0.1 m Hz. In this
paper, we give a preliminary overview of the sources and magnitude of
acceleration disturbances that could arise in the ASTROD I proof mass. Based on
the estimates of the acceleration disturbances and by assuming a simple
controlloop model, we infer requirements for ASTROD I. Our estimates show that
most of the requirements for ASTROD I can be relaxed in comparison with Laser
Interferometer Space Antenna (LISA).Comment: 19 pages, two figures, accepted for publication by Class. Quantum
Grav. (at press
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