Peter Chan - Academia.edu (original) (raw)

Papers by Peter Chan

Lecture Notes in Computer Science, 2003

In this article, we propose a new soft constraint called preference constraint, squaring well wit... more In this article, we propose a new soft constraint called preference constraint, squaring well with the decision theory concept of preference binary relation. We show how to use it for designing complex hierarchical preference information based on preference binary relations for combinatorial problems. Finally, preference-based constraint systems are defined and associated best quality choice problems are introduced. This new model offers greater flexibility to represent and make complex decisions with computers.

This paper reports on the global potential for carbon sequestration in forest plantations, and th... more This paper reports on the global potential for carbon sequestration in forest plantations, and the reduction of carbon emissions from deforestation, in response to four carbon price scenarios from 2000 to 2100. The world forest sector was disaggregated into ten regions, four largely temperate, developed regions: the European Union, Oceania, Russia, and the United States; and six developing, mostly tropical, regions: Africa, Central America, China, India, Rest of Asia, and South America. Three mitigation options -- long- and short-rotation forestry, and the reduction of deforestation -- were analyzed using a global dynamic partial equilibrium model (GCOMAP). Four carbon price scenarios two starting in 2013 and the other two in 2015 with carbon prices ranging from 20to20 to 20to35 per t CO 2 were analyzed. Key findings of this work are that cumulative carbon gain ranges from 126.6 to 145.5 Gt C by 2100, higher carbon prices early lead to earlier carbon gain and vice versa, and avoided defor...

Analytical Methods, 2015

Phthalates are a group of chemicals used in a variety of products worldwide.

Two models, the California Energy Planning Model and the California Input-Output Model, are summa... more Two models, the California Energy Planning Model and the California Input-Output Model, are summarized. These assess the impacts of a wide variety of energy supply and transportation facilities, as well as a limited number of conservation measures. Results are summarized of analyses using these models on two scenarios for future energy use, one conventional and the other projecting more use

Canadian journal of psychiatry. Revue canadienne de psychiatrie, 2013

Mindfulness practices are associated with changes in different cortical regions, including the do... more Mindfulness practices are associated with changes in different cortical regions, including the dorsolateral prefrontal cortices (DLPFCs). Our study sought to examine how an index course of repetitive transcranial magnetic stimulation (rTMS) over the DLPFC improved components of mindfulness as assessed by Baer's Five Facet Mindfulness Questionnaire (FFMQ) and the Experience Questionnaire (EQ). Our preliminary study is a retrospective chart review of 32 patients who had undergone an index course of rTMS for major depressive episode between 2009 and 2012. The following information was collected prior to rTMS: patient demographics, diagnosis, and age of onset of primary diagnosis. The following information was collected prior to and after rTMS: 21-item Hamilton Rating Scale for Depression (HRSD) scores, Patient-Health Questionnaire (PHQ-9) scores, Generalized Anxiety Disorder 7-item (GAD-7) scale scores, FFMQ scores, and EQ scores. Following rTMS, results showed statistically signif...

ABSTRACT The goal of this LBL project is to develop tools and procedures that measure the financi... more ABSTRACT The goal of this LBL project is to develop tools and procedures that measure the financial impacts of load shape changes to utility ratepayers and society. This application studies the financial impacts of policies that raise the efficiencies of residential appliances. The analysis is based on detailed forecasts of energy use by computer simulation models developed at LBL. These models disaggregate both annual energy use and hourly system electric loads at the end-use level for the residential sector. This detail is essential for calculating production and capacity cost benefits, and tariff-class specific revenue changes. This report is the technical documentation for our case study of the Texas Power and Light (TP and L) service territory of the Texas Utilities Electric Company (TUEC). It provides the interested reader with the underlying assumptions, modeling procedures, and intermediate results used to assess the financial impacts of policies that increase the efficiency of residential appliances.

Energy Efficiency, 2009

New single-family home construction represents a significant and important market for the introdu... more New single-family home construction represents a significant and important market for the introduction of energy-efficient gas-fired space heating and water-heating equipment. In the new construction market, the choice of furnace and water-heater type is primarily driven by first cost considerations and the availability of power vent and condensing water heaters. Few analysis have been performed to assess the economic impacts of the different combinations of space and water-heating equipment. Thus, equipment is often installed without taking into consideration the potential economic and energy savings of installing space and waterheating equipment combinations. In this study, we use a life-cycle cost analysis that accounts for uncertainty and variability of the analysis inputs to assess the economic benefits of gas furnace and water-heater design combinations. This study accounts not only for the equipment cost but also for the cost of installing, maintaining, repairing, and operating the equipment over its lifetime. Overall, this study, which is focused on US single-family new construction households that install gas furnaces and storage water heaters, finds that installing a condensing or power-vent water heater together with condensing furnace is the most cost-effective option for the majority of these houses. Furthermore, the findings suggest that the new construction residential market could be a target market for the large-scale introduction of a combination of condensing or power-vent water heaters with condensing furnaces.

This report describes a new Berkeley Lab approach for modeling the likely peak electricity load r... more This report describes a new Berkeley Lab approach for modeling the likely peak electricity load reductions from proposed energy efficiency programs in the National Energy Modeling System (NEMS). This method is presented in the context of the commercial unitary air conditioning (CUAC) energy efficiency standards. A previous report investigating the residential central air conditioning (RCAC) load shapes in NEMS revealed that the peak reduction results were lower than expected. This effect was believed to be due in part to the presence of the squelch, a program algorithm designed to ensure changes in the system load over time are consistent with the input historic trend. The squelch applies a system load-scaling factor that scales any differences between the end-use bottom-up and system loads to maintain consistency with historic trends. To obtain more accurate peak reduction estimates, a new approach for modeling the impact of peaky end uses in NEMS-BT has been developed. The new approach decrements the system load directly, reducing the impact of the squelch on the final results. This report also discusses a number of additional factors, in particular non-coincidence between end-use loads and system loads as represented within NEMS, and their impacts on the peak reductions calculated by NEMS. Using Berkeley Lab's new double-decrement approach reduces the conservation load factor (CLF) on an input load decrement from 25% down to 19% for a SEER 13 CUAC trial standard level, as seen in NEMS-BT output. About 4 GW more in peak capacity reduction results from this new approach as compared to Berkeley Lab's traditional end-use decrement approach, which relied solely on lowering end use energy consumption. The new method has been fully implemented and tested in the Annual Energy Outlook 2003 (AEO2003) version of NEMS and will routinely be applied to future versions. This capability is now available for use in future enduse efficiency or other policy analysis that requires accurate representation of time varying load reductions ix

Journal of Cancer Survivorship, 2014

Purpose The objective of our study was to evaluate the reproductive outcome of male cancer surviv... more Purpose The objective of our study was to evaluate the reproductive outcome of male cancer survivors treated with intracytoplasmic sperm injection (ICSI) using cryopreserved sperm and compare it with the same treatment in non-cancer males. Methods We retrospectively analyzed database derived from cancer and non-cancer patients undergoing sperm cryopreservation from August 2008 to August 2012 at a university-based center. We evaluated the reproductive outcome of those cancer and non-cancer patients that had frozen sperm and returned subsequently to the clinic for assisted reproduction. Results We studied 272 males with cancer and 296 infertile males. The most prevalent types of cancer in our cohort were lymphoma (25.3 %), testicular cancer (19.2 %), leukemia (7.3 %), and other malignancies including sarcoma, gastrointestinal, and central nervous system malignancies (48.2 %). The use rate of cryopreserved sperm was 10.7 % for cancer patients and 30.7 % for non-cancer patients. The mean age of males with cancer who returned to the clinic for fertility treatment was 36.7±6 years, and the diagnoses were testis cancer (43.4 %), lymphoma (36.9 %), leukemia (13 %), and other malignancies (6.7 %). Live birth rate of the cancer cohort was 62.1 %, which was higher than that of the normospermic non-cancer population (p<0.0047). Conclusions The use rate of cryopreserved sperm from oncofertility preservation cases is at around 10 %. The live birth rate using assisted reproductive technologies among these patients is at least comparable to that of the non-cancer population. Implications for Cancer Survivors To our knowledge, this was the first comparative study of male cancer survivors treated with ICSI using cryopreserved sperm, which were compared to non-cancer males undergoing the same treatment. Male fertility preservation is a highly valued service that should be strongly encouraged prior to beginning cytotoxic cancer treatment. These results can help healthcare professionals in oncology to improve the quality of counseling on fertility preservation when managing young men with newly diagnosed cancer that require gonadotoxic treatment.

Journal of the American Geriatrics Society, 2014

To evaluate whether implementation of symptom-triggered administration of a benzodiazepine protoc... more To evaluate whether implementation of symptom-triggered administration of a benzodiazepine protocol reduces the severity (total cumulative dose), duration, and complications of alcohol withdrawal syndrome (AWS). Retrospective health record review. Tertiary care center in Vancouver, Canada. Individuals aged 70 and older admitted to the Acute Care for Elders and Acute Medicine Unit wards with diagnostic codes for AWS from 2008 to 2012. Median duration and cumulative dose of benzodiazepine treatment, number of severe AWS complications, severe benzodiazepine-associated adverse effects, and need for adjunct therapy. Thirty-three participants in the preprotocol group and 30 in the protocol-implemented group met the inclusion criteria. Median duration of benzodiazepine treatment decreased from 96 hours (interquartile range (IQR) 72-120 hours) in the preprotocol period to 48 hours (IQR 0-108 hours; P=.04), and median cumulative benzodiazepine dose administered decreased from 9 mg (IQR 5-19.8 mg) to 3 mg (IQR 0-10 mg; P=.001). Statistically significantly lower incidence of severe AWS complications (P=.007) and adjunct therapy use (P=.02) was seen in the protocol-implemented group. A symptom-triggered protocol for dosing of benzodiazepine therapy in the management of AWS in individuals aged 70 and older significantly reduced the total duration of benzodiazepine use, cumulative benzodiazepine dose, and use of adjunctive medications in the treatment of AWS.

The Journal of ECT, 2013

The objective of this study was to present survey data on the teaching of electroconvulsive thera... more The objective of this study was to present survey data on the teaching of electroconvulsive therapy (ECT) in health care centers across Canada. Methods: Of 1273 centers identified, 175 were found to practice ECT. These centers were asked to complete a questionnaire, and 107 (61%) of them answered 5 questions dealing specifically with ECT teaching. These questions were as follows: (1) Does your facility have an ECT teaching program for residents in psychiatry? (2) How is ECT taught to residents in psychiatry? (3) If direct supervision of the administration of ECT is a requirement of the psychiatry training program, is there a minimum number of supervised treatments or minimum duration of training period? (4) Do residents provide unsupervised ECT at your center? (5) Which other groups of learners, if any, are provided with orientation, teaching, or training in ECT? Results: Sixty percent of respondents had no ECT teaching program for psychiatry residents. Pedagogical methods varied, ranging from direct observation of ECT treatments to directed readings. Few centers required a minimum number of supervised treatments. No resident-administered ECT is performed without direct supervision. Interestingly, various groups of health care professionals were often invited to participate in ECT training. Conclusions: The situation regarding ECT teaching continues to be a cause for concern given the noted absence of organized, structured, and mandatory programs. No resident administering ECT, however, goes unsupervised, which is in keeping with good practice. Electroconvulsive therapy is taught in many different ways, and teaching is accessible to different groups of health care professionals. However, much remains to be done to standardize ECT teaching to render this therapy available to all those who need it and to overcome the stigma and bias associated with it.

The Journal of ECT, 2009

Objective: To compare the minimum intensity to elicit a seizure using two different pulse widths,... more Objective: To compare the minimum intensity to elicit a seizure using two different pulse widths, the brief pulse (width = 0.5 miliseconds) and the ultrabrief pulse (width = 0.3 miliseconds). Background: Ultra-brief pulses (G0.5 ms) are closer to axonal chronaxies and are thought to be more efficient in eliciting therapeutic seizures during electroconvulsive therapy. Current knowledge suggests that it is more useful when unilateral electrode placement is used. Comparisons performed so far have used very different widths between brief and ultra-brief, usually 1.5 ms and 0.3, respectively. There is no data, however, comparing more close widths. As 0.5 ms is a somewhat arbitrary value to distinguish width duration, we were interested in comparing seizure thresholds using both pulse widths for right unilateral ECT. Design/Methods: We compared retrospectively the last 30 patients in our ECT unit whose seizure thresholds were titrated using a pulse-width = 0.5 ms and the last 30 patients whose seizure thresholds were titrated using ultrabrief pulses (width = 0.3 ms). The former were clinically treated patients and the latter were participating in a clinical trial on the use of ultra-brief pulse treatment. Most patients continued to use psychotropic medications. Seizure threshold was titrated for all patients in the first treatment. For the brief pulse group, pulse width was kept fixed at 0.5 ms and current at 0.8 Ampere. Initially duration was changed keeping a 20 Hz frequency (1 sec = 16 mC; 2 sec = 32 mC; 4 sec = 64 mC; 8 sec = 128 mC); when maximum device_s duration was reached, frequency was changed (40 Hz = 256 mC; 80 Hz = 512 mC). For the ultra-brief-pulse, basically the same thing was done, fixing the pulse width at 0.3 ms and current at 0.8 A, duration was changed first, keeping a frequency of 20 Hz (1 sec = 9.6 mC; 2 sec = 19.2 mC; 4 sec = 38.4; 8 sec = 76.8 mC); if maximum duration was reached without a seizure, frequency was increased (40 Hz = 153.6 mC; 80 Hz = 307.2; 120 Hz = 460.8 mC). Results: For the brief pulse group, mean age was 46 (S.D. = 15.2) years and 23 were female. Mean EEG duration was 60.1 (S.D. = 23.9) seconds and mean motor duration was 54.1 (S.D. = 24.9) seconds. Initial seizure threshold was as follows: One patient = 16 mC; 21 = 32 mC, and eight = 64 mC. For the ultra-brief group, mean age was 52 (S.D. = 15.2) years and 18 were female. Mean EEG duration was 52.7 (S.D. = 30.5) seconds and mean motor duration was 42.3 (S.D. = 15.5) seconds. Initial seizure threshold was as follows: one patient = 307.2 mC, two patients = 76.8 mC, 21 patients = 38.4 mC, three patients = 19.2 and three patients = 9.6 mC. Conclusions: If we exclude the outlier from the ultra-brief group (ST = 307 mC), we can observe that most of the patients in both groups had a ST between 30 and 40 mC. No patient in the brief pulse group showed a lower ST than 16 mC, because this was the first step of titration for this group. The data suggest that the difference between 0.3 ms and 0.5 ms may not be big, although randomized studies with a more precise and similar titration schedule and that consider clinical response and side effect profile are needed.

Optics Express, 2008

We demonstrated, for the first time, a field trial of 160 (16 lambda x 10) Gbit/s, fine granulari... more We demonstrated, for the first time, a field trial of 160 (16 lambda x 10) Gbit/s, fine granularity, DWDM-based optical packet switching and transmission by newly-developed burst-mode EDFAs and an optical packet switch prototype with multiple all-optical label processors. We achieved 64 km field transmission and switching of 160 (16 lambda x 10) Gbit/s DWDM-based optical packets encapsulating almost 10 Gbit/s IP packets with error-free operation (IP-packet-loss-rate &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;10(-6) and bit-error-rate &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;10(-9)).

Optical and Quantum Electronics, 2008

The WDM flatness easily collapses due to substantial changes in input power, an inherent problem ... more The WDM flatness easily collapses due to substantial changes in input power, an inherent problem in optical packet communication because of dynamic changes in traffic density. We propose a burst-mode EDFA with a novel configuration based on the concept of a mid-position gain flattening filter (GFF) with overpumping. This configuration can effectively suppress gain transience while maintaining WDM flatness.

Ophthalmic and Physiological Optics, 1996

Journal of Urology, 2005

Vasoepididymostomy remains one of the most technically challenging procedures in all of microsurg... more Vasoepididymostomy remains one of the most technically challenging procedures in all of microsurgery. The technique has evolved from an end-to-end, to an end-to-side technique, then to intussusception end-to-side methods. We recently reported the superiority of 2-suture longitudinal and 3-suture triangulation intussusception techniques in rats. In the present study we report our results in humans. We evaluated all vasoepididymostomies performed by 1 surgeon from January 1992 until the present for patency, pregnancy and for disappearance of sperm after initial return of sperm to the ejaculate. We recorded the results of 153 consecutive vasoepdidymostomies done by 1 surgeon (MG) from January 1992 until February 2004. Four techniques were used, namely end-to-end (EE), end-to-side (ES), 3-suture triangulation intussusception (TIVE) and 2-suture longitudinal intussusception (LIVE). Data collected included technique, months of followup, sperm density, motility and morphology (WHO 1992 criteria), pregnancy outcome and late failures. Late failures were defined as having return of sperm to the ejaculate after vasoepididymostomy and then becoming azoospermic on at least 2 subsequent semen analyses. A total of 153 men underwent bilateral vasoepididymostomies. The most recent 17 were LIVE, preceeded by 38 TIVE, 32 ES and 66 EE. Mean followup for the groups were 17.2 (LIVE), 70.8 (TIVE), 116.7 (ES) and 140.2 (EE) months, respectively. Intact sperm were seen in the ejaculates of 12 men (80%) in the LIVE group, 16 in the TIVE group (84%), 20 in the ES group (74%) and 30 men in the EE group (73%). Motile sperm were found in the ejaculates of 10 of 15 (67%) in the LIVE group, 13 of 19 (68%) in the TIVE group, 10 of 27 (37%) in the ES group and 20 of 41 (49%) in the EE group (p =0.2). Mean times for return of sperm to the ejaculate were 2.9, 2.8, 2.8 and 3.5 months, respectively. Pregnancies were reported by 4 men in the LIVE group all before 12 months, 6 in the TIVE group and 3 were by 12 months, and 4 each by the ES and EE groups with 3 and 2 by 12 months (p =0.07). Thus far, there have been no late failures in the LIVE group, only 1 in the TIVE group (8%), 5 in the ES group (50%) and 6 in the EE group (30%) (p =0.04). Although vasoepididymostomy remains a technically demanding microsurgical procedure, recent technical innovations of TIVE and LIVE offer better or comparable outcomes compared with EE and ES procedures with the use of fewer sutures, which simplifies the performance of the anastomosis. In addition, the late failure rate is lower with the use of the intussusception techniques (LIVE and TIVE) with only 1 late failure in 22 men with return of sperm to the ejaculate procedures (4%) compared with 11 of 30 (37%) in the nonintussusception groups (p =0.006).

The Journal of Urology, 2011

We determined the role of factor inhibiting hypoxia-inducible factor-1 in prostate cancer specime... more We determined the role of factor inhibiting hypoxia-inducible factor-1 in prostate cancer specimens. Materials and Methods: A tissue microarray of 152 prostate cancers was constructed and stained for factor inhibiting hypoxia-inducible factor-1, hypoxiainducible factor-1␣ and 2␣, and glucose transporter 1 as a prototypical downstream target of hypoxia-inducible factor-1␣. Correlation analysis was done between these variables, and between factor inhibiting hypoxia-inducible factor-1, and clinical and pathological variables, including prostate specific antigen as a surrogate of recurrence. Results: Factor inhibiting hypoxia-inducible factor-1 was expressed in the cytoplasm and/or the nucleus in 86.5% of tumors, including exclusive cytoplasmic expression in 51.3% and exclusive nuclear expression in 5.3%. Any nuclear and exclusive expression of factor inhibiting hypoxia-inducible factor was associated with poor prognosis on univariate analysis (p ϭ 0.007 and 0.042, respectively). On multivariate analysis men with nuclear expression in tumors were twice as likely to experience recurrence (p ϭ 0.034). Conclusions: Factor inhibiting hypoxia-inducible factor-1 is widely expressed in prostate tumors. Its differential subcellular expression suggests that regulation of its expression is an important factor in the activity of the hypoxia-inducible factor pathway. Its modulation may help treat hypoxia-inducible factor driven aggressive prostate cancer.

Today's highly competitive economy calls for new methods of man- agement. Advanced practices... more Today's highly competitive economy calls for new methods of man- agement. Advanced practices have been proposed to manage human resources, often acclaimed to be the most important assets of any organisation. However, computer models and applications to support these methods are often not avail- able, or not until it is much too late. This paper presents several directions for advances in strategic employee scheduling, as well as our approach for imple- menting these concepts.