Churn, Baby, Churn: Strategic Dynamics Among Dominant and Fringe Firms in a Segmented Industry

This paper integrates and extends the literatures on industry evolution and dominant firms to develop a dynamic theory of dominant and fringe competitive interaction in a segmented industry. It argues that a dominant firm, seeing contraction of growth in its current segment(s), enters new segments in which it can exploit its technological strengths, but that are sufficiently distant to avoid cannibalization. The dominant firm acts as a low-cost Stackelberg leader, driving down prices and triggering a sales takeoff in the new segment. We identify a “churn” effect associated with dominant firm entry: fringe firms that precede the dominant firm into the segment tend to exit the segment, while new fringe firms enter, causing a net increase in the number of firms in the segment. As the segment matures and sales decline in the segment, the process repeats itself. We examine the predictions of the theory with a study of price, quantity, entry, and exit across 24 product classes in the desktop laser printer industry from 1984 to 1996. Using descriptive statistics, hazard rate models, and panel data methods, we find empirical support for the theoretical predictions

Management of the hospitalized transplant patient.

Significant hyperglycemia is commonly observed immediately after solid organ and bone marrow transplant as well as with subsequent hospitalizations. Surgery and procedures are well known to cause pain and stress leading to secretion of cytokines and other hormones known to aggravate insulin action. Immunosuppression required for transplant and preexisting risk are also major factors. Glucose control improves outcomes for all hospitalized patients, including transplant patients, but is often more challenging to achieve because of frequent and sometimes unpredictable changes in immunosuppression doses, renal function, and nutrition. As a result, risk of hypoglycemia can be greater in this patient group when trying to achieve glucose control goals for hospitalized patients. Key to successful management of hyperglycemia is regular communication between the members of the care team as well as anticipating and rapidly implementing a new treatment paradigm in response to changes in immunosuppression, nutrition, renal function, or evidence of changing insulin resistance

Proctitis following stereotactic body radiation therapy for prostate cancer

Background Proctitis after radiation therapy for prostate cancer remains an ongoing clinical challenge and critical quality of life issue. SBRT could minimize rectal toxicity by reducing the volume of rectum receiving high radiation doses and offers the potential radiobiologic benefits of hypofractionation. This study sought to evaluate the incidence and severity of proctitis following SBRT for prostate cancer. Methods Between February 2008 and July 2011, 269 men with clinically localized prostate cancer were treated definitively with SBRT monotherapy at Georgetown University Hospital. All patients were treated to 35-36.25Gy in 5 fractions delivered with the CyberKnife Radiosurgical System (Accuray). Rectal bleeding was recorded and scored using the CTCAE v.4. Telangiectasias were graded using the Vienna Rectoscopy Score (VRS). Proctitis was assessed via the Bowel domain of the Expanded Prostate Index Composite (EPIC)-26 at baseline and at 1, 3, 6, 9, 12, 18 and 24 months post-SBRT. Results The median age was 69 years with a median prostate volume of 39 cc. The median follow-up was 3.9 years with a minimum follow-up of two years. The 2-year actuarial incidence of late rectal bleeding ≥ grade 2 was 1.5%. Endoscopy revealed VRS Grade 2 rectal telangiectasias in 11% of patients. All proctitis symptoms increased at one month post-SBRT but returned to near-baseline with longer follow-up. The most bothersome symptoms were bowel urgency and frequency. At one month post-SBRT, 11.2% and 8.5% of patients reported a moderate to big problem with bowel urgency and frequency, respectively. The EPIC bowel summary scores declined transiently at 1 month and experienced a second, more protracted decline between 6 months and 18 months before returning to near-baseline at two years post-SBRT. Prior to treatment, 4.1% of men felt their bowel function was a moderate to big problem which increased to 11.5% one month post-SBRT but returned to near-baseline at two years post-SBRT. Conclusions In this single institution cohort, the rate and severity of proctitis observed following SBRT is low. QOL decreased on follow-up; however, our results compare favorably to those reported for patients treated with alternative radiation modalities. Future prospective randomized studies are needed to confirm these observations

Impact of COVID-19 on cardiovascular testing in the United States versus the rest of the world

Objectives: This study sought to quantify and compare the decline in volumes of cardiovascular procedures between the United States and non-US institutions during the early phase of the coronavirus disease-2019 (COVID-19) pandemic. Background: The COVID-19 pandemic has disrupted the care of many non-COVID-19 illnesses. Reductions in diagnostic cardiovascular testing around the world have led to concerns over the implications of reduced testing for cardiovascular disease (CVD) morbidity and mortality. Methods: Data were submitted to the INCAPS-COVID (International Atomic Energy Agency Non-Invasive Cardiology Protocols Study of COVID-19), a multinational registry comprising 909 institutions in 108 countries (including 155 facilities in 40 U.S. states), assessing the impact of the COVID-19 pandemic on volumes of diagnostic cardiovascular procedures. Data were obtained for April 2020 and compared with volumes of baseline procedures from March 2019. We compared laboratory characteristics, practices, and procedure volumes between U.S. and non-U.S. facilities and between U.S. geographic regions and identified factors associated with volume reduction in the United States. Results: Reductions in the volumes of procedures in the United States were similar to those in non-U.S. facilities (68% vs. 63%, respectively; p = 0.237), although U.S. facilities reported greater reductions in invasive coronary angiography (69% vs. 53%, respectively; p < 0.001). Significantly more U.S. facilities reported increased use of telehealth and patient screening measures than non-U.S. facilities, such as temperature checks, symptom screenings, and COVID-19 testing. Reductions in volumes of procedures differed between U.S. regions, with larger declines observed in the Northeast (76%) and Midwest (74%) than in the South (62%) and West (44%). Prevalence of COVID-19, staff redeployments, outpatient centers, and urban centers were associated with greater reductions in volume in U.S. facilities in a multivariable analysis. Conclusions: We observed marked reductions in U.S. cardiovascular testing in the early phase of the pandemic and significant variability between U.S. regions. The association between reductions of volumes and COVID-19 prevalence in the United States highlighted the need for proactive efforts to maintain access to cardiovascular testing in areas most affected by outbreaks of COVID-19 infection

Igneous petrology of the Ni-Cu-PGE mineralized Tamarack intrusion, Aitkin and Carlton Counties, Minnesota

University of Minnesota M.S. thesis. March 2011. Major: Geological sciences. Advisor: Dr. James Miller. 1 computer file (PDF); viii, 156 pages, appendices A-D.The Tamarack intrusion is an unexposed mineralized cumulate ultramafic intrusion located near the town of Tamarack, about 80 kilometers west of Duluth, Minnesota. Rio Tinto Exploration (previously Kennecott Exploration) has been conducting exploration drilling of the Tamarack intrusion for Cu-Ni-PGE sulfide deposits since 2001. The intrusion was emplaced into black slates of the Paleoproterozoic Animikie Basin during the early magmatic stage of the 1.1Ga Midcontinent Rift. A new U-Pb baddeleyite age reported here yields an age of 1105.6 ± 1.2 Ma and confirms its association with the Midcontinent Rift. Drilling and geophysical data indicate that the Tamarack intrusion has a tadpole-like shape that is about 13 km long and is between 1 and 4 km wide. The narrow tail area of the intrusion, which is the site of greatest exploration drilling, is composed exclusively of ultramafic rock types. The wider “body” area at the southeastern end of the intrusion is composed of a wider variety of rock types ranging from lherzolite to granophyric gabbronorite. Core logging, petrographic observations, mineral chemical analyses, lithogeochemical analyses, and XRF scanning of drill core were employed on four drill cores from the Tamarack intrusion to evaluate its emplacement and crystallization history. Core logging and petrography show that the lherzolitic cumulates of the tail area can be subdivided into two texturally and modally distinct units – a lower Feldspathic Lherzolite Unit characterized by coarse olivine primocrysts, and an upper Lherzolite Unit characterized by medium-grained olivine. The contact between the two lherzolite units was investigated in three cores. In one core, the contact occurs across a zone of intense alteration; in another, it shows the two lherzolite lithologies irregularly interlayered; and in a third, the feldspathic lherzolite contains gabbroic inclusions of unknown origin. In the drill core from the body area, a lherzolite similar to the upper Lherzolite Unit of the tail area grades upsection to an intergranular olivine websterite, and then to a gabbronorite, which locally contains interstitial to irregular segregations of granophyre. Disseminated Ni-Cu-PGE sulfide mineralization is present throughout most of the lithologies studied here, but is particularly abundant in the tail area at the basal contact of the Feldapathic Lherzolite unit and in a zone straddling the contact between the two lherzolite units. Whereas mineral compositions and whole rock chemical analysis within the Feldspathic Lherzolite and Lherzolite Units found in the tail of the intrusion show little cryptic variation, the chemical attributes of lithologies in the body areas show evidence of extreme differentiation. Olivine composition ranges from Fo84 in the lowermost lherzolite and becomes progressively evolved to Fo10 in the uppermost granophyric gabbronorite. Other mineral and whole rock data both show smooth gradations from the lherzolite to the gabbronorite which are consistent with these lithologies having formed from a single mafic parental magma by fractional crystallization in a closed system. The main petrologic conclusions of this study are: 1) The two lherzolitic units in the tail area formed from a similar high-Mg olivine tholeiitic parent magma. The composition of this parent magma is estimated from subtracting 30% Fo89 olivine phenocryst composition from a chilled margin found at the basal contact of the Feldspathic Lherzolite unit. The resulting composition is comparable to other picritic basalt compositions found at the base of the MCR-related Mamainse Point Volcanics. 2) The emplacement of the lower feldspathic lherzolite preceded that of the upper lherzolite in the tail area. The differences in texture and modal mineralogy between the two lherzolite units are attributed to more rapid cooling of the earlier feldspathic lherzolite, creating an orthocumulate in contrast to the more adcumulate upper lherzolite. 3) The sulfide mineralization straddling the lherzolite contact in the tail area is attributed to country rock assimilation and sulfur contamination in the leading edge of the lherzolite parent magmas during the two main emplacement episodes. The sulfide mineralization in the upper part of the Feldspathic Lherzolite is thought to be related to downward infiltration of sulfide liquid from the overlying Lherzolite unit magma upon its emplacement into the semi-molten core of the Feldspathic Lherzolite. 4) Finally, the well differentiated lithologic sequence comprising the body area is interpreted to have resulted from closed-system fractional crystallization of the second magma pulse that created the upper Lherzolite Unit in the tail area

Nanopore callers for epigenetics from limited supervised data

AbstractNanopore sequencing platforms combined with supervised machine learning (ML) have been effective at detecting base modifications in DNA such as 5mC and 6mA. These ML-based nanopore callers have typically been trained on data that span all modifications on all possible DNA k-mer backgrounds—a complete training dataset. However, as nanopore technology is pushed to more and more epigenetic modifications, such complete training data will not be feasible to obtain. Nanopore calling has historically been performed with Hidden Markov Models (HMMs) that cannot make successful calls for k-mer contexts not seen during training because of their independent emission distributions. However, deep neural networks (DNNs), which share parameters across contexts, are increasingly being used as callers, often outperforming their HMM cousins. It stands to reason that a DNN approach should be able to better generalize to unseen k-mer contexts. Indeed, herein we demonstrate that a common DNN approach (DeepSignal) outperforms a common HMM approach (Nanopolish) in the incomplete data setting. Furthermore, we propose a novel hybrid HMM-DNN approach, Amortized-HMM, that outperforms both the pure HMM and DNN approaches on 5mC calling when the training data are incomplete. Such an approach is expected to be useful for calling 5hmC and combinations of cytosine modifications, where complete training data are not likely to be available.</jats:p

38-LB: One- to Six-Month Outcomes Forecasts for Diabetes and Related Conditions

Background: Treatment goals for diabetes and related conditions including hypertension and prediabetes are defined as reductions in health metrics: blood glucose concentration (BG), blood pressure (BP) and weight. Accurately predicting these metrics enables the delivery of timely treatment and lifestyle recommendations, leading to improved outcomes. We used health and self-care data collected in the One Drop app to forecast changes in BG, BP and weight, one to six months in advance. Method: Data from a sample of over 50,000 app users were used to train a suite of patent-pending supervised learning models, each for a different health metric (weight, BP or BG) and time horizon (1-2, 2-3, 3-4, or 4-6 months). People in the sample were not enrolled in One Drop programs focused on reducing weight or blood pressure. Data collected prior to 2019 were used for training; data from January 2019 through February 2020 were used for testing. Prediction root mean square error (RMSE) was compared to the RMSE that would result from assuming persistence (no change from current values). For each health metric, population subsets were identified, based on information available at prediction time, for whom predictions were more accurate. Results: The test set comprised over 200,000 predictions. Error reduction relative to persistence varied by metric, forecast horizon, and subset. For weight, persistence RMSE ranged from 2.2-5.4 kg; predictions reduced RMSE by 6.0-9.3%. For 30-day average systolic BP, persistence RMSE ranged from 11.3-16.1 mm Hg; predictions reduced RMSE by 14.2-20.0%. For 30-day average BG, persistence RMSE ranged from 19.4 to 58.8 mg/dL; predictions reduced RMSE by 12.6-40.5%. Conclusion: Machine learning models based on app-collected health and self-care data can predict changes in BG, BP and weight up to six months in advance. These predictions can contribute to prioritizing interventions and guiding self-care, potentially improving outcomes. Disclosure Y. Wexler: Employee; Self; One Drop. D. Goldner: Employee; Self; One Drop. G. Merchant: Employee; Self; One Drop. A. Hirsch: Employee; Self; Informed Data Systems Inc. B. Huddleston: Employee; Self; One Drop. Stock/Shareholder; Self; One Drop. J. Dachis: Board Member; Self; One Drop. Employee; Self; One Drop. Stock/Shareholder; Self; One Drop. </jats:sec

14-LB: Overnight Hypoglycemia Prediction for CGM Users

Background: Knowing at bedtime whether hypoglycemia is likely to occur while sleeping could empower people with diabetes to take preventive action, and could reduce concerns about either being awoken by a continuous glucose monitor (CGM) alarm, or sleeping through the alarm and not being able to respond. We used CGM and self-care data collected in the One Drop app to predict the occurrence of overnight hyperglycemia. Method: Over 500,000 person-nights of sleep, blood glucose (BG), self-care and contextual data from over 3000 app users with CGMs were pooled and used to train and test a supervised learning model to predict, as of bedtime, the minimum BG value for the coming night. A related model was trained to predict the probability of any BG value being lower than 70 mg/dL during the night. Results: Test-set predictions of minimum overnight BG value had a mean absolute relative deviation (MARD) of 18.6%. For test-set predictions of the probability of BG lower than 70 mg/dL, the area under the receiver operating characteristic curve (AUC) was 82.2%. About 30% of predictions could be identified at prediction time as having higher accuracy. For those, test-set minimum BG prediction MARD was 15.4%, and probability of BG lower than 70 mg/dL prediction AUC was 87.0%. Conclusion: Pooling sleep, BG, behavioral and self-care data from thousands of One Drop app users who also use CGM accurately predicts the probability of overnight hypoglycemia. Having such predictions at bedtime can facilitate preventative action, reduce anxiety and improve both sleep and quality of life. Disclosure Y. Wexler: Employee; Self; One Drop. D. Goldner: Employee; Self; One Drop. G. Merchant: Employee; Self; One Drop. A. Hirsch: Employee; Self; Informed Data Systems Inc. B. Huddleston: Employee; Self; One Drop. Stock/Shareholder; Self; One Drop. J. Dachis: Board Member; Self; One Drop. Employee; Self; One Drop. Stock/Shareholder; Self; One Drop. </jats:sec