Density and current response functions in strongly disordered electron systems: Diffusion, electrical conductivity and Einstein relation

We study consequences of gauge invariance and charge conservation of an electron gas in a strong random potential perturbed by a weak electromagnetic field. We use quantum equations of motion and Ward identities for one- and two-particle averaged Green functions to establish exact relations between density and current response functions. In particular we find precise conditions under which we can extract the current-current correlation function from the density-density correlation function and vice versa. We use these results in two different ways to extend validity of a formula associating the density response function with the electrical conductivity from semiclassical equilibrium to quantum nonequilibrium systems. Finally we introduce quantum diffusion via a response relating the current with the negative gradient of the charge density. With the aid of this response function we derive a quantum version of the Einstein relation and prove the existence of the diffusion pole in the zero-temperature electron-hole correlation function with the the long-range spatial fluctuations controlled by the static diffusion constant.Comment: 16 pages, REVTeX4, 6 EPS figure

The National Juvenile Online Victimization Study: Methodology Report.

The National Juvenile Online Victimization Study (N‐JOV) was conducted by the Crimes against Children Research Center at the University of New Hampshire. Wave 1 of this study was funded by the National Center for Missing & Exploited Children and the Office of Juvenile Justice & Delinquency Prevention, U.S. Department of Justice. Wave 2 of this study was funded through grants from the Office of Juvenile Justice and Delinquency Prevention, U.S. Department of Justice. Researchers collected information from a national sample of law enforcement agencies about the prevalence of arrests for, and characteristics of, Internet sex crimes against minors in the criminal justice system in the 12 months following July 1, 2000 and again in calendar year 2006. The goal of this methodology was to : 1) utilize a representative national sample of law enforcement agencies that would give us an overall picture of these crimes in the United States, 2) understand how these cases emerged and were handled in a diverse group of agencies, 3) get detailed data about the characteristics of these crimes from well‐informed, reliable sources, and 4) see how the prevalence and characteristics of such crimes may have changed in a 5 to 6‐year time frame. For both Waves 1 and 2, we used a two‐phase process to collect data from a national sample of the same local, county, state, and federal law enforcement agencies. In Phase 1, we sent mail surveys to a national sample of law enforcement agencies asking if they had made arrests for Internet sex crimes against minors in a specific one‐year time frame. In Phase 2, we conducted telephone interviews with law enforcement investigators about a sample of the arrest cases reported in the mail survey. The final data set, weighted to account for sampling procedures and other factors, includes data from 612 completed case‐level interviews from Wave 1 and 1,051 different completed case‐level interviews from Wave 2

National Juvenile Online Victimization Study (N-JOV): Methodology Report.

The National Juvenile Online Victimization Study (N-JOV Study) was conducted by the Crimes against Children Research Center at the University of New Hampshire, under grants from the National Center for Missing & Exploited Children and the Office of Juvenile Justice and Delinquency Prevention, U.S. Department of Justice. The N-JOV study collected information from a national sample of law enforcement agencies about the characteristics of Internet sex crimes against minors and the numbers of arrests for these crimes during a one-year period. The goals of our methodology were to 1) design a representative national sample of law enforcement agencies that would give us an overall picture of these crimes in the U.S., 2) understand how these cases emerged and were handled in a diverse group of agencies, and 3) get detailed data about the characteristics of these crimes from well-informed, reliable sources. We used a two-phase process to collect data from a national sample of local, county, state and federal law enforcement agencies. In Phase 1, we sent a mail survey to a national sample of law enforcement agencies asking if they had made arrests in Internet-related child pornography or sexual exploitation cases between July 1, 2000 and June 30, 2001. In Phase 2, we conducted telephone interviews with law enforcement investigators about a sample of the cases reported in the mail survey. The final data set, weighted to account for sampling procedures and other factors, includes data from 612 completed interviews

Internet Sex Crimes Against Minors: The Response of Law Enforcement.

The Internet1 and computers have come to play a growing role in sex crimes that are committed against children and youth.2 Since the mid-1990s these developing technologies have posed challenges for law enforcement requiring them to confront situations not anticipated in criminal statutes, master technical advances, develop new investigative techniques, and handle criminal cases that often span multiple jurisdictions. To assist, legislators have acted on a number of fronts creating new statutes that encompass Internet offenses, stiffening penalties, and creating a national clearinghouse for reports of Internet-related crimes against children and the CyberTipline® operated by the National Center for Missing & Exploited Children. In addition the federal government has increased funding in this area creating Internet Crimes Against Children Task Forces to support state and local law enforcement and specialized Internet, child-exploitation units in federal, law-enforcement agencies. Unfortunately the results of these initiatives are difficult to track. Criminaljustice authorities do not collect information specifically about Internet-related crimes. The National Juvenile Online Victimization (N-JOV) Study was undertaken to get a sense of the scope and types of law-enforcement activity in this area and serve as a baseline for monitoring the growth of Internet sex crimes against minors and related law-enforcement activities

Trends in Law Enforcement Responses toTechnology‐facilitated Child Sexual Exploitation Crimes: TheThird National Juvenile OnlineVictimization Study (NJOV‐3)

Abstract Overall arrests for technology‐facilitated child sexual exploita‐ tion crimes did not continue to increase from 2006 to 2009 as they had earlier in the decade. However, arrests for child por‐ nography possession increased by about 50% from 2006 to 2009. In addition, arrests for technology‐facilitated sex crimes with identified victims doubled, but the increase was in cases where offenders knew their victims in person, not cases in which they met online. Arrests of offenders who solicited undercover police posing as minors declined between 2006 and 2009, after rising earlier in the decade. The decline may be because of shifts in law enforcement strategies that included more focus on child pornography offenses

Online victimization: A report on the nation’s youth.

The Internet is an exciting new territory for many young people. Nearly 24 million youth ages 10 through 17 were online regularly in 1999, and millions more are expected to join them shortly. They go there to Iearn, play, meet people, and explore the world. But stories from law-enforcement officials, parents, and young people themselves suggest that not every online adventure is a happy one. The Internet has a seamier side that young people seem to he encountering with great frequency. This national survey confirms many of the stories. Large numbers of young people are encountering sexual solicitations they did not want, sexual material they did not seek, and people who threatened and harassed them in a variety of ways. While many are able to glide past these encounters as mere litter on the information super highway, some experience them as real collisions with a reality they did not expect and were distressed to find. Some of these young people report being upset and afraid in the wake of their encounters and have elevated symptoms of stress and depression. This report describes the variety of disconcerting experiences young lnternet users say they have online and ways they react. It also provides a window into how families and young people are addressing matters of danger and protection on the Internet. Some of the news is reassuring. At the same time, it suggests that the seamy side of the Internet spills into the lives of an uncomfortably large number of youth and relatively few families or young people do much about it. It highlights a great need for private and public initiatives to raise awareness and provide solutions. Nothing in this report contradicts the increasingly well-documented fact that youth and their families are excited about the Internet and its possibilities. They are voting for the Internet with their fingers and pocket books, even as they are aware of some of its drawbacks. But because it is destined to play such an important role in the lives of those growing up today, the question of how to temper some of the drawbacks of this revolutionary medium is worthy of thorough consideration now at the dawn of its development

Is talking online to unknown people always risky? Distinguishing online interaction styles in a national sample of youth Internet users.

Abstract We examined the risk of unwanted online sexual solicitations and characteristics associated with four online interaction styles among youth Internet users. The interaction styles took into account the people with whom youth interacted online (people known in person only, unknown people met through face-to-face friends, unknown people met in chatroom, and other places online) and high- and low-risk patterns of online behavior. The aim was to provide a basis for identifying which youth may be most at risk from interacting online with unknown people