Imaging the Subsurface with Ambient Noise Autocorrelations

2020 ◽  
Vol 91 (2A) ◽  
pp. 930-935 ◽  
Author(s):  
Robert W. Clayton

Abstract Autocorrelations created by stacks of near-offset traces from virtual source gathers are used to form an image of the deeper subsurface. We minimize the masking effects of the effective source time function by subtracting the survey-wide average autocorrelation from each trace. The result is a zero-offset reflection image of the subsurface generated by ambient noise correlation. The technique can be particularly useful for imaging the mid and lower crust, in which traditional seismic methods have penetration problems. We show examples from a one-component 3D survey and a three-component 2D profile. The 3D example shows the crust in the transition zone between the continent and the Inner Borderland in the Los Angeles, California, area, and for the first time, shows an image of the lower crust. The 2D profile provides both a P image and an S image of the basement interface in the San Bernardino basin in southern California.

1977 ◽  
Author(s):  
James G. Evans ◽  
Leroy Pankraatz ◽  
James Ridenour ◽  
Steven W. Schmauch ◽  
Nicholas T. Zilka

1998 ◽  
Vol 18 (1) ◽  
pp. 121-137 ◽  
Author(s):  
Pamela I. Erickson

In 1995, the Latina adolescent birth rate surpassed that of African Americans for the first time. This article investigates cultural and social factors affecting the initiation of sexual intercourse among Latina adolescent mothers in Los Angeles. The data are from life history interviews with forty young mothers and their partners conducted in 1994 to 1997. Results suggest that sexual intercourse is initiated within the context of the couple's developing relationship, and that the course of relationships is highly scripted. Men pressure for sex and women resist. Women should be ignorant about sex, but control access to intercourse. Sex is never discussed. Thus, it is unexpected, and contraception other than withdrawal is not used. This script places young Latinas at enormous risk for pregnancy and STDs.


Experiment ◽  
2014 ◽  
Vol 20 (1) ◽  
pp. 297-316
Author(s):  
Lorin Johnson ◽  
Donald Bradburn

In the 1970s and 1980s, Los Angeles audiences saw Soviet defectors Mikhail Baryshnikov, Alexander Godunov, Natalia Makarova, and Rudolf Nureyev in the prime of their careers at the Hollywood Bowl, The Dorothy Chandler Pavilion and the Greek Theater. Dance photographer Donald Dale Bradburn, a local Southern California dancer describes his behind-the-scenes access to these dancers in this interview. Perfectly positioned as Dance Magazine’s Southern California correspondent, Bradburn offers a candid appraisal of the Southern California appeal for such high-power Russian artists as well as their impact on the arts of Los Angeles. An intimate view of Russian dancers practicing their craft on Los Angeles stages, Bradburn’s interview is illustrated by fourteen of his photographs, published for the first time in this issue of Experiment.


Author(s):  
Stephen Cooper

In this talk, delivered at the 2014 California State University, Long Beach, symposium celebrating the 75th anniversary of the publication of Ask the Dust, Cooper recounts the story of how he came to discover a remarkable letter, to that point unknown, written by John Fante in 1933. Addressed to fellow Italian American writer Jo Pagano, who like Fante had ventured west from Colorado to seek writing success in Los Angeles, the letter provides insight into the crippling doubts and frustrations that burdened the young Fante even as it reveals his deep-seated confidence that he would one day write a great novel. Published here for the first time, this letter prefigures another remarkable Fante letter, the one written in 1938 that is now known as the Prologue to Ask the Dust.


Author(s):  
Sara J Schiff ◽  
Afton Kechter ◽  
Kelsey A Simpson ◽  
Rachel C Ceasar ◽  
Jessica L Braymiller ◽  
...  

Abstract Introduction California implemented multiple strategies, such as a Tobacco 21 law and compliance checks, to reduce high rates of youth e-cigarette use. However, the prevalence of use among underage youth and young adults continues rising. Little is known about how underage individuals obtain e-cigarettes. Methods We conducted structured qualitative interviews with 61 young adult (18-25 years old) vapers in the Los Angeles, CA area between June 2018 and June 2019. Interviews were comprehensive and designed to elicit information on participants’ thoughts, feelings, and experiences related to vaping. We queried participants on where and how they obtained vaping products, and participants discussed their experiences accessing products while under the legal age for sale. Directed content analysis was used to analyze interviews. Results Four concepts emerged: (1) Early experimentation of e-cigarettes with peers often occurred in a school setting, (2) Continued use of e-cigarettes commonly obtained through peer sales, (3) Inconsistent implementation of age restrictions at in-person retailers and (4) at online retailers. Participants had peers purchase products on their behalf and frequented in-person and online retailers with few to no age verification processes. Few participants faced challenges when purchasing products from retailers. Conclusions The current study’s findings offer insight into where and how underage individuals obtain vaping products despite restrictions to prevent them from doing so. Participant accounts of mixed ease of underage purchasing in person and online suggest retailer education is needed, along with additional research to inform more effective policies to reduce underage access to vaping products. Implications Despite legal age restrictions, e-cigarettes remain accessible to underage individuals, but specific strategies that underage youth utilize to evade legal age restrictions are largely unknown. We found that participants often accessed vaping products for the first time at school. Sales between peers were common, and participants also reported frequenting in-person retailers that inconsistently enforced age restrictions. Many participants reported little to no age verification online, though some believed online age verification measures were increasingly difficult to surpass. Knowledge of strategies underage youth utilize to access e-cigarettes can inform enforcement efforts.


1976 ◽  
Vol 38 (2) ◽  
pp. 543-546 ◽  
Author(s):  
Marcelline Burns ◽  
Satanand Sharma

282 anonymous questionnaires were distributed in the Los Angeles area to assess the first-time subjective experiences under the influence of marihuana. A majority of the respondents did not experience the expected marihuana “high.” This supports the notion that multiple experiences are necessary to recognize a state of marihuana intoxication. Other assessments such as age of first use, social situations at first use, reasons for initial use, and frequency of current use were also made.


2007 ◽  
Vol 34 (6Part7) ◽  
pp. 2400-2401 ◽  
Author(s):  
P Tynan ◽  
S Stathakis ◽  
C Esquivel ◽  
C Shi ◽  
N Papanikolaou

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