40 research outputs found
Substrate noise analysis and techniques for mitigation in mixed-signal RF systems
Get PDFThesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2005.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Includes bibliographical references (p. 151-158).Mixed-signal circuit design has historically been a challenge for several reasons. Parasitic interactions between analog and digital systems on a single die are one such challenge. Switching transients induced by digital circuits inject noise into the common substrate creating substrate noise. Analog circuits lack the large noise margins of digital circuits, thus making them susceptible to substrate voltage variations. This problem is exacerbated at higher frequencies as the effectiveness of standard isolation technique diminishes considerably. Historically, substrate noise was not a problem because each system was fabricated in its own package shielding it from such interactions. The work in this thesis spans all areas of substrate noise: generation, propagation, and reception. A set of guidelines in designing isolation structures was developed to assist designers in optimizing these structures for a particular application. Furthermore, the effect of substrate noise on two key components of the RF front end, the voltage controlled oscillator (VCO) and the low noise amplifier (LNA), was analyzed. Finally, a CAD tool (SNAT) was developed to efficiently simulate large digital designs to determine substrate noise performance.(cont.) Existing techniques have prohibitively long simulation times and are only suitable for final verification. Determination of substrate noise coupling during the design phase would be extremely beneficial to circuit designers who can incorporate the effect of the noise and re-design accordingly before fabrication. This would reduce the turn around time for circuits and prevent costly redesign. SNAT can be used at any stage of the design cycle to accurately predict (less than 12% error when compared to measurements) the substrate noise performance of any digital circuit with a large degree of computational efficiency.by Nisha Checka.Ph.D
Villkor och praxis : Bedömning av lärarstudenters yrkeskunskaper under verksamhetsförlagd lärarutbildning
No full textI föreliggande studie granskas bedömningens villkor, innehåll och processer i verksamhetsförlagd utbildning (VFU) vid ett lärarprogram i Sverige. Syftet med studien motiveras utifrån två tidigare studiers resultat kring hur kunskapsmål/kriterier beskrivs (Author, 2007) och lärarstudenters yrkeskunskaper bedöms (Author, in press) i VFU, samt utifrån bristen på forskning om villkor för bedömning och bedömningsprocesser i VFU. Det empiriska underlaget består av stöddokument för bedömning, åtta bedömningssamtal mellan lärarutbildare, mentorer och lärarstudenter, samt intervjuer med lärarutbildarna i en VFU-kurs. De analysverktyg som används är dels ett kunskapsteoretiskt ramverk kring lärarkunskap, dels modeller för bedömning av yrkeskunskap. Resultaten bekräftar delvis en av de tidigare studiernas resultat; att bedömningen till stora delar uttrycks formativt, och att det uteslutande är lärarstudenters procedurkunskaper utifrån ett kunskap-i-praktiken-perspektiv som bedöms. Bedömningsprocesserna kännetecknas av en bedömningsmodell där formulerade kunskapsmål/kriterier inte utgör norm för bedömning av lärarstudenters yrkeskunskaper. Det betyder att lärarutbildarna och mentorerna inte enkelt kan checka av yrkeshandlingar mot formella mål/kriterier, utan behöver grunda sina bedömningar på sin egen kunskapsbas och sina erfarenheter som lärare. En diskussion förs om kunskapsmåls/kriteriers betydelse vid bedömning av lärarstudenters yrkeskunskaper i en skolverksamhetskontext.</p
Cultural Preferences for Chaperone Use during Breast Examinations: A Preliminary Study.
No full textAbstract
Previous studies have demonstrated that use of chaperones by physicians occurs most consistently for pelvic and rectal exams than for breast examinations. Factors that may influence chaperone for breast examination include duration of doctor-patient relationship, gender of the examiner, and availability of an assistant. The purpose of this study is to characterize patient preferences, not previously reported, for chaperone use.A patient questionnaire was approved by the institutional IRB at NYU Langone Medical Center and Bellevue Hospital. It was translated into Chinese, Spanish, and Arabic. Responses were collected from 277 patients. Variables included age, marital status, highest level of education, income, family background, religion, primary language, and chaperone and examiner preferences. For the respondents who preferred a chaperone, education was categorized as some college or none, language was English or non-English-speaking, background was Caucasian or non-Caucasian, and religion was Christian or non-Christian. Descriptive analyses and Pearson's chi-square test was used to determine significance.Median age was 49 years, range 17-87 years. 28 (10%) respondents preferred to have a chaperone present. An equal proportion of respondents did not want a chaperone (N=95, 34%) or had no preference (N=95, 34%). An additional 19% (N=53) of patients indicated that they preferred to be asked about their wishes. 142 (52%) indicated that they preferred a female examiner, 2 (1%) preferred a male examiner, and 126 (46%) had no preference regarding the examiner's gender.Table 1. Respondent Characteristics (N=277)VariablesN (%)EDUCATION (N=256) Grade School10 (4%)High School44 (17%)College116 (45%)Graduate School86 (34%)FAMILY BACKGROUND (N = 251) Caucasian/European159 (64%)African-American18 (7%)Hispanic28 (11%)Middle-Eastern17 (7%)Asian28 (11%)Other1 (0%)RELIGION (N = 250) Christian137 (55%)Jewish, reform49 (20%)Jewish, orthodox16 (6%)Islam14 (5%)Buddhist5 (2%)Other22 (9%)LANGUAGE (N = 256) English198 (77%)Spanish15 (6%)Chinese9 (3%)Arabic12 (5%)Other22 (9%)CHAPERONE PREFERENCE (N = 277) Do not use95 (34%)Use28 (10%)No preference94 (34%)Like to be asked53 (19%)Unknown7 (3%)EXAMINER GENDER PREFERENCE (N = 273) Female142 (52%)Male2 (1%)No preference126 (46%)Unknown3 (1%) Of the 28 patients who did prefer a chaperone, there was a statistically significant difference, p=0.011, for family background that was non-Caucasian. There was no statistical finding for differences in education, religion, or language.Table 2. Characteristics of Respondents who Prefer a Chaperone (N = 28)VARIABLESP-VALUEEducation0.078Language0.409Family Background0.011*Religion0.161* Denotes Statistical SignificanceThe majority of women responding to our survey either did not want a chaperone present for a breast examination or had no preference. However, the majority of all respondents did prefer to have a female examiner. This may simply represent that these patients were comfortable with a woman performing the exam. Additional investigation will further evaluate possible cultural differences.
Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 6080.</jats:p
The impact of screening mammography in breast cancer patients age 40-49 at an urban city hospital.
No full textAbstract P2-01-02: The Incidence of Mammographically-Occult Breast Cancer in Women Older than Seventy Years
No full textAbstract
Background: Mammographic density generally decreases over time, which increases the sensitivity of screening mammography. However a significant proportion of older women have persistently dense breast tissue. This raises the question of how best to screen older women, particularly those with mammographically dense tissue or other risk factors. Little information exists about the accuracy of screening mammography in women older than seventy years. Additionally, the frequency of older women with mammographically-occult breast cancer is also unknown. The purpose of this study was to report the incidence of mammographicallyoccult breast cancer in women older than seventy and to describe the clinical factors that may be associated with this presentation.
Methods:
A retrospective chart review was conducted of women older than seventy diagnosed with breast cancer (intraductal carcinoma, invasive ductal carcinoma and invasive lobular carcinoma) at NYU Langone Medical Center from 2002-2009. Data collected included age, presentation, stage, mammographic density, BI-RADS results, breast ultrasound (US) and MRI results, and risk factors. Breast density was categorized according to BI-RADS definitions: 1. predominantly fatty, 2. scattered fibroglandular elements, 3. heterogeneously dense, or 4. extremely dense. Descriptive analyses were applied.
Results: A total of 401 women older than seventy years were diagnosed with breast cancer at our institution. A cohort of 20 (5%) had mammographically occult disease. The median age was 77 years (range 71 to 89 yrs). Of the 20 mammographically occult cases, the majority (75%) were detected as a palpable mass, one was detected by screening US and four were detected by screening MRI. The majority of the cohort (65%) had been screened regularly with mammography prior to diagnosis. When we examined mammographic density, 60% had heterogeneously dense or extremely dense tissue. Nineteen out of twenty were diagnosed with early stage disease. There were 4 cases of DCIS, 10 (50%) were stage 1, and 5 (25%) were stage 2. Seven (35%) had invasive lobular carcinoma on final histopathology. Nine (45%) patients also had an antecedent history of breast cancer; 4 had ipsilateral recurrences and 5 had contralateral new primaries. Only 4 (20%) had a history of HRT use and 7 (35%) had a family history of breast cancer.
Discussion: A meaningful proportion of women older than age seventy diagnosed with breast cancer at our institution had mammographicallyoccult disease. A majority (60%) of these patients had heterogeneously dense or extremely dense breast tissue, potentially limiting the sensitivity of mammographic screening in this cohort. In previous work, we evaluated a large number of screening mammograms and reported an incidence of 37% dense breast tissue in women of the same age group. This suggests that increased mammographic density, even in older women, may increase the potential for mammographically occult breast cancer. Particularly for women with increased risk based on a personal or family history of breast cancer, the addition of other imaging modalities may be of value in the presence of mammographically dense tissue regardless of patient age.
Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P2-01-02.</jats:p
Interacting with Proactive Community Displays
Get PDFIn this paper we describe the design and architecture of an adaptive proactive environment in which information, which reflects the communal interests of current inhabitants, is proactively displayed on large- scale public displays. Adaptation is achieved through implicit communication between the environment and personal sensor devices worn by users. These devices, called Pendle, serve two purposes: they store and make available to the environment user preferences, and they allow users to override the environment’s proactive behavior by means of simple gestures. The result is a smooth integration of environment-controlled interaction (experienced by the user as implicit interaction, triggered by their presence) and user-controlled explicit interaction. Initial results show that user-controlled adaptation leads to an engaging user experience that is unobtrusive and not distracting
Mammographic Density and Lobular Involution in Older Women with Abnormal Breast Imaging.
No full textAbstract
Mammographic density has been established as an independent risk factor for breast cancer, and there is data to suggest that the degree of lobular involution in the breast tissue may also function as an independent risk factor for the disease. The present study was designed to investigate the relationship between mammographic density and lobular involution in a population of mature women undergoing open biopsy for non-palpable breast lesions.A total of 199 women over the age of 60 who underwent breast biopsy with image-guided localization in 2008 at NYU Langone Medical Center formed the study population. Variables of interest included age, breast density, degree of involution, use of hormone replacement therapy (HRT) and biopsy histology (invasive ductal and lobular carcinoma and intraductal carcinoma vs. benign). Breast density was categorized according to BI-RADS classification as less dense (predominantly fatty and scattered fibroglandular elements) vs more dense (heterogeneously dense and extrememely dense). Degree of involution was classified as none (0%), partial (1-74%) and complete (&gt;75%). All specimens were reviewed by a single pathologist who used the criteria of Hartmann, et al in evaluating degree of involution. Statistical analysis was performed using Pearson's Chi-square test and logistic regression analyses.In agreement with our previously presented data, we found an inverse relationship between breast density and age (p=0.02). In our cohort of women over 60 with abnormal breast imaging, we found a trend toward an inverse relationship between age and degree of lobular involution, but this did not achieve statistical significance. 129 of our patients had biopsies yielding malignant histology. There was no significant relationship between degree of lobular involution and biopsy histology. Use of HRT did not correlate with breast density in our cohort. There was no discernable relationship between degree of involution and history of prior or current HRT use.Association of lobular involution with age, density, histology, and HRT INVOLUTION TOTALP-VALUE NONEPARTIALCOMPLETEN (%) AGE (YRS) 60-696337617 (9%)0.18270-797202959 (29%) 80-894618123 (62%) DENSITY Less Dense143477125 (63%)0.177More Dense3254674 (37%) HISTOLOGY Benign5194670 (35%)0.690Malignant124077129 (65%) HRT Never11246398 (70%)0.774Ever3112741 (30%) Our study reinforces the general observation that breast density decreases with age. Our data do not permit us to comment on the validity of lobular involution as a risk factor for breast cancer. However, the degree of lobular involution did not predict malignant histology in our cohort. There was a trend toward an inverse relationship between mammographic density and lobular involution. This observation suggests that other factors such as stromal features may be responsible for the increased mammographic density in these older patients. Further study is warranted to better understand the significance of lobular involution and its relationship with mammographic density in all age groups of women undergoing breast cancer screening.
Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 6072.</jats:p
Baseline factors predicting a response to neoadjuvant chemotherapy with implications for non-surgical management of triple-negative breast cancer
No full textAbstract
Background
Patients with triple-negative breast cancer (TNBC) and a pathological complete response (pCR) after neoadjuvant chemotherapy may be suitable for non-surgical management. The goal of this study was to identify baseline clinicopathological variables that are associated with residual disease, and to evaluate the effect of neoadjuvant chemotherapy on both the invasive and ductal carcinoma in situ (DCIS) components in TNBC.
Methods
Patients with TNBC treated with neoadjuvant chemotherapy followed by surgical resection were identified. Patients with a pCR were compared with those who had residual disease in the breast and/or lymph nodes. Clinicopathological variables were analysed to determine their association with residual disease.
Results
Of the 328 patients, 36·9 per cent had no residual disease and 9·1 per cent had residual DCIS only. Patients with residual disease were more likely to have malignant microcalcifications (P = 0·023) and DCIS on the initial core needle biopsy (CNB) (P = 0·030). Variables independently associated with residual disease included: DCIS on CNB (odds ratio (OR) 2·46; P = 0·022), T2 disease (OR 2·40; P = 0·029), N1 status (OR 2·03; P = 0·030) and low Ki-67 (OR 2·41; P = 0·083). Imaging after neoadjuvant chemotherapy had an accuracy of 71·7 (95 per cent c.i. 66·3 to 76·6) per cent and a negative predictive value of 76·9 (60·7 to 88·9) per cent for identifying residual disease in the breast and lymph nodes. Neoadjuvant chemotherapy did not eradicate the DCIS component in 55 per cent of patients.
Conclusion
The presence of microcalcifications on imaging and DCIS on initial CNB are associated with residual disease after neoadjuvant chemotherapy in TNBC. These variables can aid in identifying patients with TNBC suitable for inclusion in trials evaluating non-surgical management after neoadjuvant chemotherapy.
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Financial Toxicity, Hope, and Satisfaction With Life in Patients Receiving Ambulatory Cancer Care
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