Validity of the Adiabatic Approximation

We analyze the validity of the adiabatic approximation, and in particular the reliability of what has been called the "standard criterion" for validity of this approximation. Recently, this criterion has been found to be insufficient. We will argue that the criterion is sufficient only when it agrees with the intuitive notion of slowness of evolution of the Hamiltonian. However, it can be insufficient in cases where the Hamiltonian varies rapidly but only by a small amount. We also emphasize the distinction between the adiabatic {\em theorem} and the adiabatic {\em approximation}, two quite different although closely related ideas.Comment: 4 pages, 1 figur

Optimization of Airfield Parking and Fuel Asset Dispersal to Maximize Survivability and Mission Capability Level

While the US focus for the majority of the past two decades has been on combatting insurgency and promoting stability in Southwest Asia, strategic focus is beginning to shift toward concerns of conflict with a near-peer state. Such conflict brings with it the risk of ballistic missile attack on air bases. With 26 conflicts worldwide in the past 100 years including attacks on air bases, new doctrine and modeling capacity are needed to enable the Department of Defense to continue use of vulnerable bases during conflict involving ballistic missiles. Several models have been developed to date for Air Force strategic planning use, but these models have limited use on a tactical level or for civil engineer use. This thesis presents the development of a novel model capable of identifying base layout characteristics for aprons and fuel depots to maximize dispersal and minimize impact on sortie generation times during normal operations. This model is implemented using multi-objective genetic algorithms to identify solutions that provide optimal tradeoffs between competing objectives and is assessed using an application example. These capabilities are expected to assist military engineers in the layout of parking plans and fuel depots that ensure maximum resilience while providing minimal impact to the user while enabling continued sortie generation in a contested region

A new perturbative approach to the adiabatic approximation

A new and intuitive perturbative approach to time-dependent quantum mechanics problems is presented, which is useful in situations where the evolution of the Hamiltonian is slow. The state of a system which starts in an instantaneous eigenstate of the initial Hamiltonian is written as a power series which has a straightforward diagrammatic representation. Each term of the series corresponds to a sequence of "adiabatic" evolutions, during which the system remains in an instantaneous eigenstate of the Hamiltonian, punctuated by transitions from one state to another. The first term of this series is the standard adiabatic evolution, the next is the well-known first correction to it, and subsequent terms can be written down essentially by inspection. Although the final result is perhaps not terribly surprising, it seems to be not widely known, and the interpretation is new, as far as we know. Application of the method to the adiabatic approximation is given, and some discussion of the validity of this approximation is presented.Comment: 9 pages. Added references, discussion of previous results, expanded upon discussion of main result and application of i

Reconciling new with old injury paradigms and the need to dig deeper – comment on Nigg et al.

In response to the target article by Nigg et al (2017) suggesting the need to shift towards new running injury paradigms, we comment on the need to continue investigating a variety of paradigms, new and old, and on poorly studied factors that necessitate the need to continue digging deeper in the pursuit of better prediction of injury development. Lastly, we argue that new and old paradigms can be reconciled under the more general paradigm that running injuries are most directly an issue of tissue adaptation

Atlantic water on the Chukchi Shelf

An anomalously warm saline layer in the bottom of the shallow Chukchi Sea in August 1975 is believed due to a surge which drove water from the Atlantic Layer of the Arctic Ocean up onto the shelf. Two earlier occurrences of this kind of water in the Chukchi Sea have been identified in historical data.Submitted to: Director, Arctic Submarine Laboratory Naval Undersea Center, San Diego, CA.http://archive.org/details/atlanticwateronc00bourProject Order No. 00010N

Observations on the coastal current of Arctic Alaska

This paper describes characteristics of the warm coastal current in the vicinity of the ice margin in the Chukchi and Beaufort seas. The warm current originates in Bering Strait and is traced around Pt. Barrow to longitude 152°W in the Beaufort Sea. In the Chukchi Sea it is concentrated near the surface, overlying dense relict bottom water trapped by the shallow depths. Eastward, as the bottom deepens, the warm water descends to mid-depth, eventually becoming warmest near bottom in depths of 30 to 50 m. Mechanisms for cooling and dilution of the warm water are discussed

USNS BARTLETT Cruise to the Greenland Sea in September 1989: Data Report

As a component of the Greenland Sea Project, a hydrographic cruise was conducted on board the USNS BARTLETT during September 1989 in the southern Greenland Sea to characterize the water mass structure and circulation features of the Jan Mayen Current (JMC). A total of 48 high-quality CTD stations were occupied to depths of 1000 m; five stations extended to 3000 m or more. Five north-south tending transects permitted tracking of the JMC by its low temperature (< 0°C) , low salinity near-surface core. The JMC could also be well defined from its warm, saline intermediate water properties. Deep stations made in the trough of the Jan Mayen Fracture Zone suggest that the interchange of deep and bottom water from the Greenland and Norwegian Seas via this trough is a slow diffusive process and not an active advective feature as previously thought.Arctic Submarine Laboratory, Naval Ocean Systems Center, San Diego, CA.http://archive.org/details/usnsbartlettcrui00bourO&MN, Direct Fundin