Frequency-modulated continuous-wave lidar using I/Q modulator for simplified heterodyne detection

A frequency-modulated continuous-wave (FMCW) lidar is demonstrated with heterodyne detection. The lidar transmitter utilizes an electro-optic I/Q modulator for the first time to generate carrier-suppressed and frequency-shifted FM modulation. This eliminates the need for an acousto-optic frequency shifter commonly used in heterodyne lidar transmitters. It also allows the use of a much wider modulation bandwidth to improve the range resolution. The capability of complex optical field modulation of the I/Q modulator provides an additional degree of freedom compared with an intensity modulator, which will benefit future lidar applications.

SU-E-T-88: Evaluating Gantry Sag on Linear Accelerators and Introducing an MLC-Based Compensation Strategy

PURPOSE

Gantry sag is one of the well-known sources of mechanical imperfections that compromise the spatial accuracy of radiation dose delivery. This study aims to quantify the gantry sag on multiple linacs and to investigate a multiple leaf collimator (MLC)-base strategy to compensate for gantry sag.

METHODS

We used the Winston-Lutz method to measure the gantry sag on three Varian linacs. A ball-bearing phantom was imaged with a square radiation field during gantry rotation. The images were analyzed to derive the radiation isocenter and subsequently the gantry sag, that is, the superior-inferior wobble of the radiation field center from the radiation isocenter as a function of gantry angle. Compensation for gantry sag was attempted by offsetting the MLC leaves at 90-degree collimator angle. The amount of offset was the opposite of measured gantry sag, which was gantry angle-specific.

RESULTS

Gantry sag was reproducible within a six-month period. On the three linacs, the maximum gantry sag was found to vary from 0.7 mm to 1.0 mm, depending on the linac and the collimator angle. The radiation field center moved inferiorly, or away from the gantry, when the gantry was rotated from 0 to 180 degrees. Comparison of gantry sag at 0- and 90-degree collimator angles showed that the uncertainty in MLC leaf positions did not increase the gantry sag. Instead, gantry sag was caused primarily by nonideal gantry rotation. After the MLC compensation was applied, the maximum gantry sag was reduced to less than 0.2 mm.

CONCLUSIONS

The results indicated that gantry sag on a linac can be quantitatively measured with sub-millimeter precision, using a simple ball-bearing phantom and the electronic portal imaging device. Reduction of gantry sag is feasible by applying a gantry angle-specific correction to MLC leaf positions at 90 degree collimator angle.

Multiclass microarray data classification based on confidence evaluation

Microarray technology is becoming a powerful tool for clinical diagnosis, as it has potential to discover gene expression patterns that are characteristic for a particular disease. To date, this possibility has received much attention in the context of cancer research, especially in tumor classification. However, most published articles have concentrated on the development of binary classification methods while neglected ubiquitous multiclass problems. Unfortunately, only a few multiclass classification approaches have had poor predictive accuracy. In an effort to improve classification accuracy, we developed a novel multiclass microarray data classification method. First, we applied a "one versus rest-support vector machine" to classify the samples. Then the classification confidence of each testing sample was evaluated according to its distribution in feature space and some with poor confidence were extracted. Next, a novel strategy, which we named as "class priority estimation method based on centroid distance", was used to make decisions about categories for those poor confidence samples. This approach was tested on seven benchmark multiclass microarray datasets, with encouraging results, demonstrating effectiveness and feasibility.

Hypertension and incident dementia in community-dwelling elderly Yoruba Nigerians

OBJECTIVES

To investigate the relationship between hypertension and dementia incidence in community-dwelling elderly Yoruba (aged 70 years and above) because of sparse information on dementia and its risk factors in developing countries.

MATERIALS AND METHODS

Community-based, prospective study of consenting elderly Yoruba using two-stage design. Blood pressure was measured during the baseline evaluation at 2001 and hypertension was defined as BP ≥ 140/90 mmHg. Diagnosis of dementia and normal cognition was by consensus using standard criteria. Non-demented subjects from the 2001 evaluation wave were re-evaluated during the 2004 and 2007 waves for dementia. Logistic regression was used to examine the association of baseline hypertension and incident dementia, after adjusting for age, gender, education, and histories of stroke and smoking. P-values <0.05 were considered significant.

RESULTS

During the 6-year follow-up, 120 individuals developed dementia, while 1633 remained non-demented. The frequency of hypertension in the demented group was significantly higher than in the non-demented (70.0% vs 60.2%, P = 0.034). Baseline hypertension was a significant risk factor for dementia (OR = 1.52; 95% CI 1.01-2.30). Higher systolic, diastolic or pulse pressure was associated with increased risk (P < 0.05). Participants with diastolic BP ≥ 90 mmHg were at a significantly greater risk than those with readings below 70 mmHg (OR = 1.65; 95% CI 1.01-2.69).

CONCLUSIONS

Hypertension was associated with increased risk of dementia in elderly Yoruba and its appropriate treatment may lower the risk.

Frontotemporal dementia caregivers and researchers: partnering for brain donation

This study utilized a community-based, participatory research model between the Association for Frontotemporal Degeneration (AFTD) and the Education Core of the Indiana Alzheimer Disease Center. A total of 30 caregivers of persons with frontotemporal dementia (FTD) participated in 6 focus groups in 3 cities. The majority of participants were spouses of the person with FTD and had been providing care for an average of 6 years. Transcript analysis revealed 7 prominent themes: willingness to participate, when/how the issue of brain donation is raised, who initiates discussion about brain donation, who is involved in decisions about brain donation, motivation for participating in brain donation, lack of effective communication, and barriers to research participation. Caregivers demonstrated a strong desire to participate in research and contribute to advancing knowledge. The lack of effective communication between the clinicians and caregivers was a barrier to developing positive rapport, detrimentally impacting research participation.

Chloropicrin emissions after shank injection: two-dimensional analytical and numerical model simulations of different source methods and field measurements

Understanding the control mechanisms of fumigant movement in soil is a fundamental step for developing management strategies to reduce atmospheric emissions. Most soil fumigants including chloropicrin (CP) are applied by shank injection, and the application process often leaves vertical soil fractures that would potentially cause preferential fumigant movement and increased emissions. This potential transport pathway was evaluated by comparing cumulative emissions and soil air concentrations of CP from direct field measurements with those predicted using analytical and numerical models after assuming either point or rectangle sources for the injected CP. Results clearly showed that shank-injected CP, when treated as vertical rectangle sources, produced cumulative emission losses similar to the field measurements. Treating the shanked CP as point sources caused approximately 50% underprediction than the field measurements. The study also demonstrated that fumigant cumulative emissions can be predicted, with reasonable accuracy, using either analytical or numerical simulations.

Managing agricultural emissions to the atmosphere: state of the science, fate and mitigation, and identifying research gaps

The impact of agriculture on regional air quality creates significant challenges to sustainability of food supplies and to the quality of national resources. Agricultural emissions to the atmosphere can lead to many nuisances, such as smog, haze, or offensive odors. They can also create more serious effects on human or environmental health, such as those posed by pesticides and other toxic industrial pollutants. It is recognized that deterioration of the atmosphere is undesirable, but the short- and long-term impacts of specific agricultural activities on air quality are not well known or understood. These concerns led to the organization of the 2009 American Chemical Society Symposium titled . An outcome of this symposium is this special collection of 14 research papers focusing on various issues associated with production agriculture and its effect on air quality. Topics included emissions from animal feeding operations, odors, volatile organic compounds, pesticides, mitigation, modeling, and risk assessment. These papers provide new research insights, identify gaps in current knowledge, and recommend important future research directions. As the scientific community gains a better understanding of the relationships between anthropogenic activities and their effects on environmental systems, technological advances should enable a reduction in adverse consequences on the environment.

The paraventricular nucleus modulates thyroidal motilin release and rat gastric motility

Motilin, an important endocrine regulator of gastrointestinal motility, was once considered to be produced in the gastrointestinal tract and brain. In recent years, however, motilin has been found in the human thyroid, as well as in that of the guinea pig. The physiological function and central modulation of thyroidal motilin remain poorly understood. To determine the functional role of thyroidal motilin, we observed the concentration of motilin in the plasma and also gastric motility before and after thyroidectomy. Our studies show that both the concentration of plasma motilin and gastric motility were decreased after thyroidectomy. To explore modulation-related nuclei, a c-Fos immune response experiment was carried out. The PVN of the hypothalamus was the main area of reactivity after thyroidectomy. Subsequently, we studied the effects of electrical excitation and PVN lesions on gastric motility and the expression of motilin in the thyroid and plasma. Excitation of the PVN was shown to prompt gastric motility that was partly prevented by the motilin receptor antagonist, GM-109. The effects of PVN excitation on gastric contraction were significantly reduced in thyroidectomised rats. In addition, the expression of motilin in the thyroid was significantly increased after PVN excitation and decreased after PVN lesions. The changes in the concentration of motilin in plasma induced by PVN stimulation were positively correlated with changes of gastric motility. In our in vitro study, the motilin secreted from TT cells (a parafollicular cell line originating from human thyroid medullary carcinoma) gradually increased on day 6 of culture, and motilin and calcitonin (CT) were co-expressed in TT cells. These results demonstrate that motilin from the thyroid could be secreted into the peripheral plasma and affect gastric motility and that PVN was a central nucleus for modulating gastric motility and motilin expression in the thyroid.

Characterization and polymorphic analysis of 4.5 kb genomic full-length HLA-C in the Chinese Han population

This study used long-range polymerase chain reaction to sequence 4.5 or 4.3 kb of genomic DNA covering human leukocyte antigen C (HLA-C) and its flanks in 45 Chinese Han subjects to better characterize variation in the gene in a single population. Sequences of 35 HLA-C alleles were obtained from the population, including major alleles of 13 lineages of HLA-C. Four novel alleles, C*03:04:01:02, C*04:01:01:03, C*08:22, and C*17:01:01:02, were identified, and complete full-length sequences of 18 HLA-C alleles were obtained for the first time. All sequences herein reported also represent extensions through the promoter region and the 3'-untranslated region. Fourteen 5'-nucleotide sequences and 14 3'-nucleotide sequences were detected outside the coding region. In total, 316 single-nucleotide polymorphisms unequally distributed in HLA-C subregions were observed. In addition to exons 2 and 3, nucleotide variability was found to be particularly high in exon 5, which encodes the transmembrane region. The differentiation of the C*07 and C*17 lineages in this region accounts for the high variability. The congruence of phylogeny across most regions of the gene suggests that gene conversion or recombination has not markedly influenced divergence between lineages in the evolution of HLA-C.

Effect of motilin on gastric distension sensitive neurons in arcuate nucleus and gastric motility in rat

BACKGROUND

Intestinal motilin is known to stimulate gastrointestinal (GI) motility and the arcuate nucleus (Arc) of hypothalamus is shown to be involved in the regulation of GI motility.

METHODS

Single unit discharges in the Arc were recorded extracellularly by implantation of a force transducer into the stomach in rats, to evaluate the effect of motilin on gastric motility. Projection of nerve fiber and expression of motilin were observed by retrograde tracer deposits of Fluoro-Gold (FG) and fluo-immunohistochemistry staining.

KEY RESULTS

65.5% of neurons in Arc responded to gastric distension (GD), 55.6% of which showed excitation (GD-E), and 44.4% showed inhibition (GD-I). After GD, the firing rate of GD-E neurons significantly increased (P<0.01), but decreased for GD-I neurons (P<0.01). Most of both GD-E and GD-I neurons were activated by motilin (P<0.05). The frequency and amplitude of gastric contractions significantly increased by administration of motilin in Arc with a dose dependent manner (P<0.05-0.01). However, pretreatment with GM109 could abolish the responses of neurons and excitatory effect of gastric motility induced by motilin. Motilin immunoreactive neurons were increased in Arc via gastric distention (P<0.05). Motilin/FG-labeled neurons were detected in hypothalamus paraventricular nucleus (PVN).

CONCLUSIONS & INFERENCES

Our findings suggest that motilin neurons in Arc may accept peripheral somatosensory afferent inputs from gastric mechanoreceptors of the stomach, and also may acts as a stimulatory factor in Arc to regulate gastric motility via some inferior nucleus relay pathway. The results provide insight into the role of Arc in the control of digestion mediated via motilin.

Chinese ischemic stroke subclassification

Accurate classification of stroke has significant impact on patient care and conduction of stroke clinical trials. The current systems such as TOAST, SSS-TOAST, Korean TOAST, and A–S–C–O have limitations. With the advent of new imaging technology, there is a need to have a more accurate stroke subclassification system. Chinese ischemic stroke subclassification (CISS) system is a new two step system aims at the etiology and then underlying mechanism of a stroke. The first step classify stroke into five categories: large artery atherosclerosis (LAA), including atherosclerosis of aortic arch and intra-/extracranial large arteries, cardiogenic stroke, penetrating artery disease, other etiology, and undetermined etiology. The second step is to further classify the underlying mechanism of ischemic stroke from the intracranial and extracranial LAA into the parent artery (plaque or thrombosis) occluding penetrating artery, artery-to-artery embolism, hypoperfusion/impaired emboli clearance, and multiple mechanisms. Although clinical validation of CISS is being planned, CISS is an innovative system that offers much more detailed information on the pathophysiology of a stroke.

Abstract P1-09-02: Health Care Costs Incurred by Post-Menopausal Women with Hormone-Positive Breast Cancer Following the Initial Diagnosis of Metastasis

Objectives: Estimate the healthcare costs before and after progression to chemotherapy in a population of post-menopausal hormone-receptor positive (HR+) metastatic breast cancer (mBC) patients. Methods:

This retrospective cohort study used claims from a large national US health plan. Females age 55 to 63 were selected if they were diagnosed with metastatic breast cancer between 7/1/01 and 12/31/07, and initiated hormonal therapy before progressing to chemotherapy. Incident metastatic patients were followed until the earliest of disenrollment from the health plan, death, or 12/31/08. The pre-chemotherapy period was defined as the period between the incident diagnosis of metastases and the earlier of the initiation of chemotherapy and the end of the study period. Among the subset of patients with use of chemotherapy, the post-chemotherapy period was defined as the time following chemotherapy initiation until the end of the study. Inflation-adjusted costs were examined during the pre-and post-chemotherapy periods. Descriptive analyses were supplemented with Kaplan-Meier sample-average to adjust for variable follow-up time and censoring. Results:

A total of 1,202 patients were identified, 366 (30.4%) of whom progressed to chemotherapy following the onset of metastases. The mean age ± SD was 58.9 ± 2.6 years.

On average, patients incurred $79,139 (SD± $121,489) per year in total health care costs before the initiation of chemotherapy and $132,786 (SD± $117,635) after the initiation of chemotherapy. In the pre-chemotherapy and post-chemotherapy phases, medical expenses were $74,149 (SD± $119,838) and $120,942 (SD± $116,225) per patient-year, respectively, while outpatient medications filled at a retail pharmacy or through a mail system pharmacy cost $4,990 (SD± $5033) and $11,843 (SD± $14,431) per patient-year, respectively. On average, most of the observed medical expenses were incurred during outpatient visits with $44,405 (SD± $55,710) and $87,299 (SD± $75,360) per patient-year in the pre-and post-chemotherapy phases respectively. Inpatient stays accounted for $27,147 (SD± $101,405) and $30,118 (SD± $73,216) per patient-year during the pre-and post-chemotherapy periods, respectively. ER visits cost an average of $424 (SD± $1,871) per patient-year during the pre-chemotherapy period and $1,274 (SD± $5,686) per patient-year during the post chemotherapy period, on average. During the post-chemotherapy period, combined costs for both inpatient and outpatient chemotherapy were $33,559 (SD± $38,692) per patient-year on average, and costs for services associated with supportive care for chemotherapy during the same time period accounted for an additional $18,676 (SD± $30,281) per patient-year on average. After adjusting for variable follow-up times, cumulative total healthcare costs were $54,725, $73,107, and $84,200 for years one, two, and three of the pre-chemotherapy period, respectively, and were $92,639, $148,228, and $176,163 during the same portions of the post-chemotherapy period. Conclusions:

Post-menopausal HR+ mBC patients incur significant healthcare costs both before and after progressing to chemotherapy. The main cost driver was medical costs in both the pre-and post-chemotherapy periods.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P1-09-02.