Learning the Right Lessons from Iraq

Foreign policy experts and policy analysts are misreading the lessons of Iraq. The emerging conventional wisdom holds that success could have been achieved in Iraq with more troops, more cooperation among U.S. government agencies, and better counterinsurgency doctrine. To analysts who share these views, Iraq is not an example of what not to do but of how not to do it. Their policy proposals aim to reform the national security bureaucracy so that we will get it right the next time. The near-consensus view is wrong and dangerous. What Iraq demonstrates is a need for a new national security strategy, not better tactics and tools to serve the current one. By insisting that Iraq was ours to remake were it not for the Bush administration's mismanagement, we ignore the limits on our power that the war exposes and in the process risk repeating our mistake. The popular contention that the Bush administration's failures and errors in judgment can be attributed to poor planning is also false. There was ample planning for the war, but it conflicted with the Bush administration's expectations. To the extent that planning failed, therefore, the lesson to draw is not that the United States national security establishment needs better planning, but that it needs better leaders. That problem is solved by elections, not bureaucratic tinkering. The military gives us the power to conquer foreign countries, but not the power to run them. Because there are few good reasons to take on missions meant to resuscitate failed governments, terrorism notwithstanding, the most important lesson from the war in Iraq should be a newfound appreciation for the limits of our power

Efficient sorting of free electron orbital angular momentum

We propose a method for sorting electrons by orbital angular momentum (OAM). Several methods now exist to prepare electron wavefunctions in OAM states, but no technique has been developed for efficient, parallel measurement of pure and mixed electron OAM states. The proposed technique draws inspiration from the recent demonstration of the sorting of OAM through modal transformation. We show that the same transformation can be performed on electrons with electrostatic optical elements. Specifically, we show that a charged needle and an array of electrodes perform the transformation and phase correction necessary to sort OAM states. This device may enable the analysis of the spatial mode distribution of inelastically scattered electrons

A new representation of the Adler function for lattice QCD

We address several aspects of lattice QCD calculations of the hadronic vacuum polarization and the associated Adler function. We implement a representation derived previously which allows one to access these phenomenologically important functions for a continuous set of virtualities, irrespective of the flavor structure of the current. Secondly we present a theoretical analysis of the finite-size effects on our particular representation of the Adler function, based on the operator product expansion at large momenta and on the spectral representation of the Euclidean correlator at small momenta. Finally, an analysis of the flavor structure of the electromagnetic current correlator is performed, where a recent theoretical estimate of the Wick-disconnected diagram contributions is rederived independently and confirmed.Comment: 9 pages, 5 figure

Re-examining Late Chalcolithic Cultural Collapse in South-East Europe

Research into the Balkan Chalcolithic often overlooks the dramatic changes in society that occurred beginning in the late Fifth Millennium BCE. Most settlements were abandoned along with changes in mortuary customs, ceramic and decorative traditions, domestic rituals, crafts, housing styles, mining, and metallurgy. These changes happened at a time when these Chalcolithic societies seemed to be at their peak. Theories as to what caused these changes include migrations/invasions, anthropogenic environmental degradation, gradual internal changes through innovation and outside contacts, and climate change. This thesis attempts to synthesize, and critique material relating to this topic, and ultimately provide my own opinions and suggestions for further research

On-board processing satellite network architecture and control study

The market for telecommunications services needs to be segmented into user classes having similar transmission requirements and hence similar network architectures. Use of the following transmission architecture was considered: satellite switched TDMA; TDMA up, TDM down; scanning (hopping) beam TDMA; FDMA up, TDM down; satellite switched MF/TDMA; and switching Hub earth stations with double hop transmission. A candidate network architecture will be selected that: comprises multiple access subnetworks optimized for each user; interconnects the subnetworks by means of a baseband processor; and optimizes the marriage of interconnection and access techniques. An overall network control architecture will be provided that will serve the needs of the baseband and satellite switched RF interconnected subnetworks. The results of the studies shall be used to identify elements of network architecture and control that require the greatest degree of technology development to realize an operational system. This will be specified in terms of: requirements of the enabling technology; difference from the current available technology; and estimate of the development requirements needed to achieve an operational system. The results obtained for each of these tasks are presented

Charge transport and vector meson dissociation across the thermal phase transition in lattice QCD with two light quark flavors

We compute and analyze correlation functions in the isovector vector channel at vanishing spatial momentum across the deconfinement phase transition in lattice QCD. The simulations are carried out at temperatures $T/T_c=0.156, 0.8, 1.0, 1.25$ and $1.67$ with $T_c\simeq203$MeV for two flavors of Wilson-Clover fermions with a zero-temperature pion mass of $\simeq270$MeV. Exploiting exact sum rules and applying a phenomenologically motivated ansatz allows us to determine the spectral function $\rho(\omega,T)$ via a fit to the lattice correlation function data. From these results we estimate the electrical conductivity across the deconfinement phase transition via a Kubo formula and find evidence for the dissociation of the $\rho$ meson by resolving its spectral weight at the available temperatures. We also apply the Backus-Gilbert method as a model-independent approach to this problem. At any given frequency, it yields a local weighted average of the true spectral function. We use this method to compare kinetic theory predictions and previously published phenomenological spectral functions to our lattice study.Comment: 28 pages, 6 figure