Networks of Recurrent Events, a Theory of Records, and an Application to Finding Causal Signatures in Seismicity

We propose a method to search for signs of causal structure in spatiotemporal data making minimal a priori assumptions about the underlying dynamics. To this end, we generalize the elementary concept of recurrence for a point process in time to recurrent events in space and time. An event is defined to be a recurrence of any previous event if it is closer to it in space than all the intervening events. As such, each sequence of recurrences for a given event is a record breaking process. This definition provides a strictly data driven technique to search for structure. Defining events to be nodes, and linking each event to its recurrences, generates a network of recurrent events. Significant deviations in properties of that network compared to networks arising from random processes allows one to infer attributes of the causal dynamics that generate observable correlations in the patterns. We derive analytically a number of properties for the network of recurrent events composed by a random process. We extend the theory of records to treat not only the variable where records happen, but also time as continuous. In this way, we construct a fully symmetric theory of records leading to a number of new results. Those analytic results are compared to the properties of a network synthesized from earthquakes in Southern California. Significant disparities from the ensemble of acausal networks that can be plausibly attributed to the causal structure of seismicity are: (1) Invariance of network statistics with the time span of the events considered, (2) Appearance of a fundamental length scale for recurrences, independent of the time span of the catalog, which is consistent with observations of the ``rupture length'', (3) Hierarchy in the distances and times of subsequent recurrences.Comment: 19 pages, 13 figure

A multi-satellite climatology of clouds, radiation and precipitation in southern West Africa and comparison to climate models

Southern West Africa (SWA) has a large population that relies on highly variable monsoon rainfall, yet climate models show little consensus over projected precipitation in this region. Understanding of the current and future climate of SWA is further complicated by rapidly increasing anthropogenic emissions and a lack of surface observations. Using multiple satellite observations, the ERA-Interim reanalysis, and four climate models, we document the climatology of cloud, precipitation and radiation over SWA in June-July, highlight discrepancies among satellite products, and identify shortcomings in climate models and ERA-Interim. Large differences exist between monthly mean cloud cover estimates from satellites, which range from 68 to 94 %. In contrast, differences among satellite observations in top of atmosphere outgoing radiation and surface precipitation are smaller, with monthly means of about 230 W m–2 of longwave radiation, 145 W m–2 of shortwave radiation and 5.87 mm day–1 of precipitation. Both ERA-Interim and the climate models show less total cloud cover than observations, mainly due to underestimating low cloud cover. Errors in cloud cover, along with uncertainty in surface albedo, lead to a large spread of outgoing shortwave radiation. Both ERA-Interim and the climate models also show signs of convection developing too early in the diurnal cycle, with associated errors in the diurnal cycles of precipitation and outgoing longwave radiation. Clouds, radiation and precipitation are linked in an analysis of the regional energy budget, which shows that inter-annual variability of precipitation and dry static energy divergence are strongly linked

Misreporting in a randomized clinical trial for smoking cessation in adolescents

Introduction: Misreporting smoking behavior is common among younger smokers participating in clinical trials for smoking cessation. This study focused on the prevalence of and factors associated with adolescent misreporting of smoking behaviors within the context of a randomized clinical trial for smoking cessation. Methods: Adolescent smokers (N = 129) participated in a randomized clinical trial that compared two brief interventions for smoking cessation. Following the final (6-month) follow-up, a confidential, self-administered exit questionnaire examined the extent to which participants admitted to having misreported smoking quantity, frequency and/or consequences during the study. Factors associated with under- and over-reporting were compared to accurate-reporting. Results: One in 4 adolescent smokers (25.6%) admitted to under-reporting during the study and 14.7% admitted to over-reporting; 10.9% of the adolescents admitted to both under- and over-reporting. Rates of admitted misreporting did not differ between treatment conditions or recruitment site. Compared to accurate-reporting, under- and over-reporting were significantly associated with home smoking environment and the belief among adolescents that the baseline interviewer wanted them to report smoking more or less than they actually smoked. Compared to accurate reporters, over-reporters were more likely to be non-White and to report being concerned with the confidentiality of their responses. Conclusions: A post-study confidential debriefing questionnaire can be a useful tool for estimating rates of misreporting and examining whether potential differences in misreporting might bias the interpretation of treatment effects. Future studies are needed to thoroughly examine potentially addressable reasons that adolescents misreport their smoking behavior and to develop methods for reducing misreporting

Motivational interviewing to reduce substance-related consequences: Effects for incarcerated adolescents with depressed mood

Background: The impact of depressed mood on Motivational Interviewing (MI) to reduce risky behaviors and consequences in incarcerated adolescents was examined in this brief report. Methods: Adolescents (N = 189) were randomly assigned to receive MI or Relaxation Training (RT). Results: At 3-month follow-up assessment, MI significantly reduced risks associated with marijuana use, with a trend towards reducing risks associated with alcohol use. There was also a trend for depressive symptoms to be associated with reduced risks after release. Interaction effects were non-significant, indicating no moderating effects for depressed mood on treatment outcome. Conclusions: MI may be a useful treatment for incarcerated adolescents in order to reduce risks and consequences associated with substance use after release

Randomized Clinical Trial of Motivational Enhancement of Substance Use Treatment Among Incarcerated Adolescents: Post-Release Condom Non-Use

Evaluated impact of motivational enhancement (ME) of substance abuse treatment compared to relaxation training (RT) on sex without condoms (overall and involving substance use) 3 months following release among incarcerated adolescents. This randomized clinical trial involved 114 incarcerated adolescents from the Northeast. Regression analyses determined if treatment condition, baseline levels of depressive symptoms, and their interaction predicted condom non-use 3 months post-release, controlling for baseline condom non-use. Among those who reported fewer baseline depressive symptoms, those in ME condition reported significantly less condom non-use, in general and involving marijuana use compared with those in RT condition. Periods of incarceration represent opportunities to help juvenile detainees reduce behaviors that impact their health and the health of those with whom they interact in the community

Motivation to change alcohol use and treatment engagement in incarcerated youth

Adolescents have been reported to be less motivated to engage and remain in substance abuse treatment than adults. When they appear motivated, it is often due to external motivators such as family pressure or court mandated treatment. The purpose of this study was to determine if adolescents\u27 motivation to change alcohol use was related to treatment engagement while incarcerated and alcohol use after release. Participants (N = 114) were youth in a state correctional facility in the Northeast and included adolescents who engaged in at least monthly drinking. Motivation to change alcohol use was measured by the Alcohol Ladder (AL), and treatment engagement was measured by the Treatment Participation Questionnaire (comprised of positive and negative treatment engagement). Measures were administered at baseline, 2 months in facility follow up, and 3 months post release follow up. Analysis indicated acceptable test-retest stability (r = .388, p ≤ .001). The AL at 3 months post release significantly predicted quantity and frequency of alcohol use after release. The AL at baseline also significantly predicted positive and negative treatment engagement at 2 months into incarceration (i.e., 2 months in facility follow up) indicating predictive validity. These results suggest that the AL is a reliable, valid, and useful instrument for incarcerated youth

Globalisation, adjustment and the structural transformation of African economies?: the role of international financial institutions

Under the auspices of the World Bank and IMF, for almost two decades, sub-Saharan African countries have implemented structural adjustment, an orthodox package of economic reform measures. During this period there has been an unprecedented proliferation of technology investment and trade in the world economy. However sub-Saharan Africa has performed poorly under adjustment and has been largely marginalized from the international economy. The paper investigates the problems with the theoretical model underlying structural adjustment policies to explain why the model is not conducive to either African development or Africa’s increasing participation in the global economy. An example is used to illustrate the existence of an alternative set of policies that may be better suited for Africa

Kostnader ved høydosebehandling med autolog stam-cellestøtte ved fire norske sentra

Høydosebehandling med autolog stamcellestøtte (HMAS) er rutinebehandling hos selekterte grupper av pasienter med malignt lymfom og myelomatose. Hva er kostnadene ved denne type behandling? I perioden mai 2001-desember 2001 utførte vi en prospektiv kostnadsanalyse av behandlingsforløp som grovt kan deles i 3 faser: 1) den tumorreduserende kjemoterapifasen, 2) fasen med mobilisering, høsting og nedfrysing av autologe stamceller og 3) selve høydosefasen (HMAS-fasen). 30 pasienter med myelomatose ble fulgt ved tre forskjellige universitetssykehus og 10 pasienter med lymfom ble fulgt ved det fjerde sykehuset. Direkte pasientrelaterte kostnader ble registrert daglig. Indirekte kostnader ble fordelt på pasientene basert på estimater og ut fra forhåndsdefinerte fordelingsnøkler fra relevante avdelinger. Alle kostnadsdata ble beregnet i 2001 priser. Den gjennomsnittlige totale kostnaden for alle tre faser var kr. 306 904 kr (variasjonsbredde 244 035-379 127). Vi fant en statistisk signifikant korrelasjon mellom varighet av sykehusopphold og sykehusenes kostnader i alle tre behandlingsfaser. En stor del av kostnadene i høstefasen var knyttet til medikamenter brukt til stamcellemobilisering. I høydosefasen, som var den mest kostnadskrevende fasen, var de største kostnadene knyttet til sykepleiepersonalet. Det var betydelige variasjoner i kostnader mellom sykehusene. Den gjennomsnittlige totalkostnaden var vesentlig høyere enn full DRG-pris for myelomatose og myelomatose i 2001. Sykehusene måtte selv bære differansen mellom de reelle kostnadene og DRG-prisen. Per i dag (2008) er differansen redusert da det er etablert en sideutbetaling for HMAS- behandling.Kostnadsberegning; kreft; stamcelle; sykehus

PENGARUH KUALITAS PRODUK DAN HARGA TERHADAP KEPUASAN KONSUMEN PADA PT. MARGA TIRTA KENCANA (Survei Pada Penghuni Perumahan Permata Buah Batu 1)

ABSTRAK Penelitian ini bertujuan untuk mengetahui pengaruh Kualitas Produk dan Harga terhadap Kepuasan Konsumen pada PT. Marga Tirta Kencana (Survei Pada Perumahan Permata Buah Batu 1 Bandung). Rumusan masalah dalam penelitian ini adalah bagaimana tanggapan konsumen mengenai kualitas produk yang ditawarkan, bagaimana tanggapan konsumen mengenai harga yang ditawarkan, bagaimana kepuasan konsumen, dan seberapa besar pengaruh kualitas produk dan harga terhadap kepuasan konsumen di PT. Marga Tirta Kencana Bandung secara simultan dan parsial. Metode yang digunakan penulis dalam penelitian ini adalah penelitian deskriptif dan verifikatif dengan tehnik pengumpulan data dengan interview (wawancara), kuesioner (angket) dan observasi (pengamatan). Adapun ukuran populasinya 619 orang dengan sampel 87 orang. Sedangkan tehnik sampling yang digunakan untuk menghitung besarnya ukuran sampel dalam non-probability sampling. Sesuai dengan perhitungan statistik, Kualitas Produk berada dalam kategori baik dan Harga berada dalam kategori baik terhadap Kepuasan Konsumen pada PT. Marga Tirta Kencana yang berada dalam kategori puas. Kata Kunci : Kualitas Produk, Harga, Kepuasan Konsume