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Propofol is rapidly acting intravenous agent used for induction in general anaesthesia.It causes pain while administering,being uncomfortable to patients .So an observational study was done to compare the effects of different time duration of venous occlusion on pretreatment with injection Ketamine for prevention of pain at injection site. After approval of ethical committee and written informed consent,ASA grade I and II,60 patients of either gender, aged between 18-60 years were assigned to three groups of 20 each under GA and divided as GROUP K20,K40,and K60 according to venous occlusion duration of 20,40,and 60 seconds respectively on administration of ketamine(0.2mg/kg)as pretreatment for propofol injection pain.Following injection of ketamine ,25% dose of propofol was given and patient was asked for any sensation of pain at the site of injection and graded accordingly. Haemodynamics were compared in all the three groups. All 60 patients were reviewed for propofol pain and haemodynamics were recorded before pretreatment with ketamine and after pretreatment for 5 minutes and results evaluated through chi square test.P value was significant for 20 seconds (p value

Background Treatment patterns for intrahepatic cholangiocarcinoma (ICC) and extrahepatic cholangiocarcinoma (ECC) differ, but limited studies exist comparing them. This study examines differences in molecular profiling rates and treatment patterns in these populations, focusing on use of adjuvant, liver-directed, targeted, and investigational therapies. Methods This multicenter collaboration included patients with ICC or ECC treated at 1 of 8 participating institutions. Retrospective data were collected on risk factors, pathology, treatments, and survival. Comparative statistical tests were 2-sided. Results Among 1039 patients screened, 847 patients met eligibility (ICC = 611, ECC = 236). Patients with ECC were more likely than those with ICC to present with early stage disease (53.8% vs 28.0%), undergo surgical resection (55.1% vs 29.8%), and receive adjuvant chemoradiation (36.5% vs 4.2%) (all P Conclusions Patients with advanced ECC have low rates of molecular profiling, possibly in part because of insufficient tissue. They also have low rates of targeted therapy use and clinical trial enrollment. While these rates are higher in advanced ICC, the prognosis for both subtypes of cholangiocarcinoma remains poor, and a pressing need exists for new effective targeted therapies and broader access to clinical trials.

Purpose:To study the clinical profile of patients of snake venom ophthalmia presenting to the tertiary health care centre. Methods:This was a prospective observational study that involved25 patients with snake venom ophthalmia complaining of pain, diminution of vision, photophobia, conjunctival congestion , chemosis, corneal edema, corneal erosions and anterior chamber reaction. Results:There were 18 males and 7 females and the age group taken was 30 to 75 years. Most common presentation in snake venom ophthalmia patients is pain in 92% patients followed bydiminution of vision in 90% patients,conjunctival congestion in 88% patients, photophobia in 84% patients, chemosis in 80% patients, corneal edema in 65% patients, corneal erosions in 55% patients and anterior chamber reaction in 35% patients. Conclusion:Snake venom ophthalmia due tovenom spitting is a reflex mechanism aimed at ejecting venom forcefully into the eyes of the victims.Snake venom may contain a mixture of neurotoxins, cytotoxins, phospholipases and cardiotoxins. The ocular effects of the venom depend on duration of contact of ocular surface with venom. Snake venom ophthalmia is rare form of envenoming which presents as intensely painful blurred vision associated with photophobia, conjunctival congestion, chemosis, corneal epithelial defects and anterior chamber reaction. &nbsp

Purpose:To study the ocular pathology of hyperopic patients presenting to the tertiary health care centre. Methods:This was a retrospective observational study that involved 60 eyes of 30 patients with hypermetropia complaining of diminution of vision with asthenopic symptoms like tiredness of eyes, frontal or frontotemporal headache, watering and mild photophobia. There were three groups based on the criteria of age, i.e, Results:There were 15 males and 15 females. The common hypermetropiarelated findings in patients varying between age of 0-20 years was strabismus and amblyopia. Recurrent styes, recurrent blepharitis infection, recurrent chalazion were seen in equal proportions in all age groups. Primary open angle glaucoma and angle closure glaucoma were reported more in adults ranging between 20-40 years and 40-60 years.Fundus examination in high hypermetropic patients revealed a small optic disc with ill defined margins simulating papillitis which is pseudopapillitis because there is no swelling of the disc and the retina shines due to greater brilliance of light reflections giving shot silk appearance of retina. Conclusion:Hyperopia also termedhypermetropiaorfarsightedness, is a commonrefractive errorin children and adults. Its effect on an individual and the symptoms produced varies greatly, depending on the magnitude ofhyperopia, the age of the individual, the status of the accommodative and convergence system, and the demands placed on the visual system. Individuals with uncorrected hyperopia may experience symptoms such as blurred vision, asthenopia (e.g., headaches and eyestrain) while reading, accommodative/binocular dysfunction,amblyopia, and/or strabismus. Furthermore, uncorrected amblyopia in case of adults can lead to various complications like open angle or angle closure glaucoma, uveal effusion syndrome, non arteritic anterior ischemic optic neuropathy, central serous chorioretinopathy, age related macular degeneration, etc. &nbsp

Purpose:To study the clinical profile and relationship between time of presentation andvisual outcome in patients with central serous chorioretinopathy . Material and Method:Total 100 eyes of 50 patients were selected for the study who presented with complaints of blurring and or sudden painless loss of vision ,out of which 10 eyes of 5 patients were excluded due to corneal opacity, diabetic retinopathy, hypertensive retinopathy ,cataract and retinal detachment, retinitis pigmentosa. Total 90 eyes of 45 patients were included in the study and divided into two groups according to the time of presentation :1) Group 1-Within 15 days of onset of symptoms.2) Group 2 -After 2 months of onset of symptoms. Result:Group 1 patients showed the better visual outcome(BCVA 6/36-6/9) than the group 2 patients(BCVA 6/36-6/24). Conclusion:The time of presentation to the tertiary care centre was the major factors influence the visual outcome in patients with CSR.

Numerous public health hurdles, including pandemics such as COVID-19, have led to concerns about community health practices in relation, necessitating the application of an ethical perspective. International research ethics guidelines are only used in a restricted range of contexts of public health. As a result, a variety of frameworks have been established to assist ethical analysis of public health concerns. In this study, we have used the Nancy Kass framework for analyzing COVID-19 surveillance in Karnataka state of India, which is a six-step approach that can assist public health practitioners in evaluating the ethical consequences of interventions, policy initiatives, services, and so on. In order to supervise the compliance of home quarantine, the government of Karnataka mandated uploading selfies as a digital tracking surveillance measure for the COVID-19 outbreak. However, these measures raised several ethical questions, especially related to an individual’s privacy, confidentiality, autonomy, and liberty. An established state surveillance mechanism with includes enforced measures for data security along with the moral duty of an individual to protect the health of the community can probably balance the principles of ethics.

Purpose -To study the clinical profile of patients of panophthalmitis presenting to the tertiary health care centre. Methods-This was a prospective observational study that involved25 patients with panophthalmitis complaining of blurring of vision, redness, pain, purulent discharge, photophobia and eyelid swelling. Results-There were 18 males and 7 females and the age group taken was 30 to 75 years.14 patients belonged to the age group of 30 to 45 years, out of which 10 were males and 4 were females. 7 patients belonged to age group of 46 to 60 years, out of which 5 were males and 2 were females. 4 patients belonged to the age group of 61 to 75 years, out of which 3 were males and 1 was female. Most common presentation in panophthalmitis patients is loss of vision in 88% patients followed by redness in 76% patients, pain in 72% patients, purulent discharge in 68% patients,photophobia in 55% patients and eyelid swelling in 48% patients. Majority of patients belong to low socioeconomic class. The most common cause was post traumatic followed by post operative and some endogenous infections spread through hematogenous route. Of the 25 cases of culture-positive panophthalmitis, 18 cases (75%) had bacterial growth and 7 cases (25%) had fungal growth. In post-traumaticpanophthalmitis, Gram-positive bacteria were the predominant species, followed by Gram-negative bacteria and fungi. In endogenous panophthalmitis, Gram-negative bacteria were the predominant species, followed by fungi and Gram-positive bacteria. In postsurgical panophthalmitis, all infections were bacterial. Conclusion-Panophthalmitis is a dreaded ocular disease and tends to occur more commonly in males of 30 to 45 years agegroup. Most common presentation of panophthalmitis is loss of vision followed by redness, pain, purulent discharge, photophobia and eyelid swelling and signs include eyelid edema, hypopyon, circumcilliary congestion, corneal haze and ulcer and vitreous haze. Most common cause of panophthalmitis was post traumatic with gram positive bacteria followed by endogenous causes with gram negative bacteria and post operative cases with gram positive bacteria isolated. &nbsp

OBJECTIVES:We examined the trends in the rate of Henoch-Schönlein purpura (HSP) hospitalizations and the associated resource use among children in the United States from 2006 through 2014.METHODS:Pediatric hospitalizations with HSP were identified by using International Classification of Diseases, Ninth Revision, code 287.0 from the National Inpatient Sample. HSP hospitalization rate was calculated by using the US population as the denominator. Resource use was determined by length of stay (LOS) and hospital cost. We used linear regression for trend analysis.RESULTS:A total of 16 865 HSP hospitalizations were identified, and the HSP hospitalization rate varied by age, sex, and race. The overall HSP hospitalization rate was 2.4 per 100 000 children, and there was no trend during the study period. LOS remained stable at 2.8 days, but inflation-adjusted hospital cost increased from $2802.20 in 2006 to $3254.70 in 2014 (P < .001).CONCLUSIONS:HSP hospitalization rate in the United States remained stable from 2006 to 2014. Despite no increase in LOS, inflation-adjusted hospital cost increased. Further studies are needed to identify the drivers of increased hospitalization cost and to develop cost-effective management strategies.

We model a supply chain consisting of a supplier and multiple retailers facing deterministic demand. We denote some retailers as strategic in the sense that given the supplier inventory information, they will implement the optimal stocking policy by incorporating such information. On the other hand some retailers are denoted as naive in the sense that they ignore supply information and resort to a simplistic ordering policy. Naive retailers learn the optimal policy over time and adjust their orders accordingly. We study the dynamics of this game and investigate the impact of such strategic and naive retailers on the cost, ordering pattern and stocking policies of all parties. We analyze the supply chain under two scenarios: the centralized supply chain where the objective is to minimize the total supply chain cost, and the decentralized supply chain where each self-interested player minimizes its own cost in a Stackelberg game setting. We fully characterize the optimal policies under both centralized and decentralized scenarios and show that, surprisingly, the supply chain might be better off by virtue of naive retailers. The result is driven by the fact that strategic and naive players’ decisions shift the positioning of inventory in the supply chain with its final impact being determined by the relative costs of different retailer-types. Our results also offer managerial insights into how access to supply information can improve supply chain performance. This article is protected by copyright. All rights reserved.

BACKGROUND Biliary tract cancers (BTCs) typically present at an advanced stage, and systemic chemotherapy is often of limited benefit. METHODS Hybrid capture–based comprehensive genomic profiling (CGP) was performed for 412 intrahepatic cholangiocarcinomas (IHCCAs), 57 extrahepatic cholangiocarcinomas (EHCCAs), and 85 gallbladder carcinomas (GBCAs). The mutational profile was correlated with the clinical outcome of standard and experimental therapies for 321 patients. Clinical variables, detected mutations, and administered therapies were correlated with overall survival (OS) in a Cox regression model. RESULTS The most frequent genetic aberrations (GAs) observed were tumor protein 53 (TP53; 27%), cyclin-dependent kinase inhibitor 2A/B (CDKN2A/B; 27%), KRAS (22%), AT-rich interactive domain-containing protein 1A (ARID1A; 18%), and isocitrate dehydrogenase 1 (IDH1; 16%) in IHCCA; KRAS (42%), TP53 (40%), CDKN2A/B (17%), and SMAD4 (21%) in EHCCA; and TP53 (59%), CDKN2A/B (19%), ARID1A (13%), and ERBB2 (16%) in GBCA. Fibroblast growth factor receptor (FGFR; 11%) and IDH mutations (20%) were mostly limited to IHCCA but appeared to be mutually exclusive. In the IHCCA group, TP53 and KRAS mutations were associated significantly with poor OS, whereas FGFR2 mutations were associated with improved OS (P = .001), a younger age at onset, and female sex. IDH1/2 mutations were not prognostic. In a multivariate model, the effects of TP53 and FGFR GAs remained significant (P

Background Biliary tract cancers (BTCs) are uncommon and are associated with a dismal prognosis. Combinations of gemcitabine and platinum chemotherapy (gemcitabine and platinum-based therapy [GP]) form the standard approach for treating advanced BTC. To characterize the spectrum of mutations and to identify potential biomarkers for a GP response in BTC, this study evaluated the genomic landscape and assessed whether mutations affecting DNA repair were associated with GP resistance. Methods Pretreatment, formalin-fixed, paraffin-embedded samples from 183 BTC patients treated with GP were analyzed. Cox regression models were used to determine the association between mutations, progression-free survival (PFS), and overall survival (OS). Results When genes with an incidence > 10% were considered, no individual gene was independently predictive of a GP response. In patients with unresectable BTC who received GP as their first-line therapy, the joint status of cyclin-dependent kinase inhibitor 2A (CDKN2A), tumor protein 53 (TP53), and AT-rich interaction domain 1A (ARID1A) was associated with PFS (P = .0004) and OS (P ≤ .0001). Patients with mutations in CDKN2A and TP53 were identified as a poor-prognosis cohort with a median PFS of 2.63 months and a median OS of 5.22 months. Patients with mutant ARID1A, regardless of the single-mutation status of TP53 or CDKN2A, had similar outcomes. A patient who exhibited mutations in all 3 genes had a median PFS of 20.37 months, and OS was not reached. Conclusions In the largest exploratory analysis of this kind for BTC, 3 prevalent, mutually exclusive mutations represent distinct patient cohorts. These mutations are prognostic and may represent a predictive biomarker for a GP response. Prospective studies to validate these findings are needed, and they should include the incorporation of therapies that exploit the genomic instability observed with these mutations in BTC. Cancer 2016;122:3657-66. © 2016 American Cancer Society.

We analyze a model of rental and return process where limited inventory of a product is rented to two customer classes that differ in their return behavior and penalty costs. The rental demand is a decreasing function of time. We consider two cases: where a demand that is not met is lost and where an unmet demand returns. We show that to minimize penalty cost, the optimal allocation policy may give priority to different classes at different points in time and may decline lower-class demand for some time. Computational results show the benefit of the optimal allocation policy over a priority scheme reportedly used in practice.

Biliary tract cancers (BTCs) are relatively uncommon orphan tumors that have an aggressive disease course and a poor clinical outcome. Surgery is the only curative treatment, but most patients present with advanced disease and therefore have a limited survival. Gemcitabine and cisplatin based chemotherapy has been the only widely accepted standard systemic therapy regimen in these patients but these tumors can be chemoresistant, further complicating their management. In recent times, there has been considerable research in the genetics of BTC and with the advent of new, advanced technologies like next-generation sequencing (NGS) we are achieving a greater understanding of its disease biology. With the help of NGS, we have now been able to identify actionable mutations such as in the isocitrate dehydrogenase 1 ( IDH1 ), FGFR2, BRAF and HER2/neu genes for targeted therapeutics and correlate the genetic variations with distinct clinical prognoses. This recent genetic information has the potential to make precision medicine a part of routine clinical practice for the management of BTC patients.

Background: BRCA-associated protein 1, an enzyme encoded by the BAP1 gene, is commonly mutated in uveal melanoma, mesothelioma, and renal cancers. Tumors with BAP1 mutation follow an aggressive course. BAP1 mutations have also been observed in cholangiocarcinoma (CCA). The clinical phenotype of BAP1 mutant CCA may yield useful prognostic and therapeutic information but has not been defined. Methods: The records of CCA patients who underwent next-generation sequencing (NGS) were reviewed, and data on clinical, histopathological, genetic, and radiological features; response to therapy; time to progression; and survival were analyzed. Results: Twenty-two cases of BAP1 -mutation associated CCA were diagnosed from January 1, 2009, to February 1, 2015, at our center. Twenty patients had intrahepatic CCA and two had extrahepatic CCA. Tumor sizes (largest dimension) ranged from 2 to 16 cm (mean, 8.5 cm). Twelve patients had tumors that were poorly differentiated. Majority of the patients had advanced disease at presentation and 13 had bone metastases. Thirteen patients (59%) experienced rapidly progressive disease following primary therapy (chemotherapy or surgical resection). The mean time to tumor progression was 3.8 months after the first line chemotherapy. Conclusions: BAP1 mutation in CCA may be associated with aggressive disease and poor response to standard therapies. Therefore, BAP1 -targeted therapies need to be investigated.

Biliary tract cancers (BTCs) are uncommon and are associated with a dismal prognosis. Combinations of gemcitabine and platinum chemotherapy (gemcitabine and platinum-based therapy [GP]) form the standard approach for treating advanced BTC. To characterize the spectrum of mutations and to identify potential biomarkers for a GP response in BTC, this study evaluated the genomic landscape and assessed whether mutations affecting DNA repair were associated with GP resistance.Pretreatment, formalin-fixed, paraffin-embedded samples from 183 BTC patients treated with GP were analyzed. Cox regression models were used to determine the association between mutations, progression-free survival (PFS), and overall survival (OS).When genes with an incidence 10% were considered, no individual gene was independently predictive of a GP response. In patients with unresectable BTC who received GP as their first-line therapy, the joint status of cyclin-dependent kinase inhibitor 2A (CDKN2A), tumor protein 53 (TP53), and AT-rich interaction domain 1A (ARID1A) was associated with PFS (P = .0004) and OS (P ≤ .0001). Patients with mutations in CDKN2A and TP53 were identified as a poor-prognosis cohort with a median PFS of 2.63 months and a median OS of 5.22 months. Patients with mutant ARID1A, regardless of the single-mutation status of TP53 or CDKN2A, had similar outcomes. A patient who exhibited mutations in all 3 genes had a median PFS of 20.37 months, and OS was not reached.In the largest exploratory analysis of this kind for BTC, 3 prevalent, mutually exclusive mutations represent distinct patient cohorts. These mutations are prognostic and may represent a predictive biomarker for a GP response. Prospective studies to validate these findings are needed, and they should include the incorporation of therapies that exploit the genomic instability observed with these mutations in BTC. Cancer 2016;122:3657-66. © 2016 American Cancer Society.

Background Recently released American College of Cardiology/American Heart Association (ACC/AHA) guideline recommends the Pooled Cohort equations for evaluating atherosclerotic cardiovascular risk of individuals. The impact of the clinical input variable uncertainties on the estimates of ten-year cardiovascular risk based on ACC/AHA guidelines is not known. Methods Using a publicly available the National Health and Nutrition Examination Survey dataset (2005–2010), we computed maximum and minimum ten-year cardiovascular risks by assuming clinically relevant variations/uncertainties in input of age (0–1 year) and ±10 % variation in total-cholesterol, high density lipoprotein- cholesterol, and systolic blood pressure and by assuming uniform distribution of the variance of each variable. We analyzed the changes in risk category compared to the actual inputs at 5 % and 7.5 % risk limits as these limits define the thresholds for consideration of drug therapy in the new guidelines. The new-pooled cohort equations for risk estimation were implemented in a custom software package. Results Based on our input variances, changes in risk category were possible in up to 24 % of the population cohort at both 5 % and 7.5 % risk boundary limits. This trend was consistently noted across all subgroups except in African American males where most of the cohort had ≥7.5 % baseline risk regardless of the variation in the variables. Conclusions The uncertainties in the input variables can alter the risk categorization. The impact of these variances on the ten-year risk needs to be incorporated into the patient/clinician discussion and clinical decision making. Incorporating good clinical practices for the measurement of critical clinical variables and robust standardization of laboratory parameters to more stringent reference standards is extremely important for successful implementation of the new guidelines. Furthermore, ability to customize the risk calculator inputs to better represent unique clinical circumstances specific to individual needs would be highly desirable in the future versions of the risk calculator. Electronic supplementary material The online version of this article (doi:10.1186/s12872-016-0352-x) contains supplementary material, which is available to authorized users.

In this paper, we discuss the replenishment decision of seasonal products in a two-echelon distribution system consisting of a supplier and multiple retailers. Because of long manufacturing lead time, the supplier orders its entire stock for the season well in advance. The retailers, on the other hand, can replenish their inventory from the supplier throughout the season as demand realizes. Demand at each retailer follows a Poisson process. Each retailer order incurs a fixed cost, and the usual understocking and overstocking costs occur. When retailer lead time is negligible, we show that it is optimal for the retailer to follow a time-based, order-up-to policy and order only when inventory is depleted. We also characterize the structure of the optimal policy and propose a number of heuristics for easier computation. For the supplier, we express the distribution of total demand. This allows the supplier to solve a classic newsvendor problem to determine the total stock for the season. We find that the optimal retailer policy can sometimes cause large demand variation for the supplier, resulting in lower supplier profit. In centralized settings, this may even result in lower system profit than some naïve retailer heuristics, creating inefficiency in the supply chain. We offer insights on potential causes and managerial implications.

We study a dual channel supply chain in which a manufacturer sells to a retailer as well as to consumers directly. Consumers choose the purchase channel based on price and service qualities. The manufacturer decides the price of the direct channel and the retailer decides both price and order quantity. We develop conditions under which the manufacturer and the retailer share the market in equilibrium. We show that the difference in marginal costs of the two channels plays an important role in determining the existence of dual channels in equilibrium. We also show that demand variability has a major influence on the equilibrium prices and on the manufacturer’s motivation for opening a direct channel. In the case that the manufacturer and the retailer coordinate and follow a centralized decision maker, we show that adding a direct channel will increase the overall profit. Our numerical results show that an increase in retailer’s service quality may increase the manufacturer’s profit in dual channel and a larger range of consumer service sensitivity may benefit both parties in the dual channel. Our results suggest that the manufacturer is likely to be better off in the dual channel than in the single channel when the retailer’s marginal cost is high and the wholesale price, consumer valuation and the demand variability are low.

Gallbladder cancer (GBC) is an aggressive malignancy. Although surgical resection may be curable, most patients are diagnosed at an advanced unresectable disease stage. Cholelithiasis is the major risk factor; however the pathogenesis of the disease, from gallstone cholecystitis to cancer, is still not understood. To understand the molecular genetic underpinnings of this cancer and explore novel therapeutic targets for GBC, we examined the key genes and pathways involved in GBC using RNA sequencing. We performed gene expression analysis of 32 cases of surgically-resected GBC along with normal gallbladder tissue controls. We observed that 519 genes were differentially expressed between GBC and normal GB mucosal controls. The liver X receptor (LXR)/retinoid X receptor (RXR) and farnesoid X receptor (FXR) /RXR pathways were the top canonical pathways involved in GBC. Key genes in these pathways, including SERPINB3 and KLK1, were overexpressed in GBC, especially in female GBC patients. Additionally, ApoA1 gene expression suppressed in GBC as compared with normal control tissues. LXR and FXR genes, known to be important in lipid metabolism also function as tumor suppressors and their down regulation appears to be critical for GBC pathogenesis. LXR agonists may have therapeutic value and as potential therapeutic targets.

Analysis of the impact of input variable variations in categorizing subjects based on ten-year risk threshold of 5Â % (with Hispanics). (DOCX 14Â kb)

Analysis of the impact of input variable variations in categorizing subjects based on ten-year risk threshold of 7.5Â % (with Hispanics). (DOCX 15Â kb)

We investigate the value of pooling capacity in supply chains that serve product demands of different variabilities. We build and analyze models that integrate production queuing models with base stock inventory systems serving demands with different inter-arrival time distributions. The first model combines hyperexponential and exponential demand inter-arrival time distributions. Exact analysis of the model allows us to develop insights into the impact of the difference in demand variabilities on the value of pooling capacity. Simulation experiments allow us to validate these insights for more general settings. We then find one special case that combines exponential and deterministic demand arrivals with deterministic service, where pooling capacity results in increasing the total cost.

We develop a model and analyze reverse information sharing, a growing business practice in supply chain management in which a manufacturer shares information about supply with a retailer. We model the manufacturer as a production queue with finished goods warehouse, the retailer as an inventory location, and other customers as an external demand stream. In our model, the manufacturer allows the retailer access to inventory status at the warehouse. To take advantage of this new information, the retailer changes from a single-level base-stock policy to a two-level, state-dependent base-stock policy. We provide an exact method for computing performance and develop a procedure for evaluating optimal policy. We demonstrate the impact of the new policy on the manufacturer and other customers. Numerical computations lead to insights about the value of information to the retailer, and to guidelines for the manufacturer on sharing information.

In most organizations, proposed investments in software dependability compete for limited resources with proposed investments in software and system functionality, response time, adaptability, speed of development, ease of use, and other system capabilities. The lack of good return-on-investment models for software dependability makes determining the overall business case for dependability investments difficult. So, with a weak business case, investments in software dependability and the resulting system dependability are frequently inadequate. Dependability models will need to support stakeholders in determining their desired levels for each dependability attribute and estimating the cost, value, and ROI for achieving those. At the University of Southern California, researchers have developed software cost- and quality-estimation models and value-based software engineering processes, methods, and tools. We used these models and the value-based approach to develop an Information Dependability Attribute Value Estimation model (iDAVE) for reasoning about software dependability's ROI.

We model two separate, decentralized systems, each consisting of a warehouse and a production capacity. The demand processes experienced by the systems have different variabilities. The two decentralized systems consider an agreement to pool their production capacities. We examine the impact of the pooling of capacity on inventory costs under two operating rules: (i) the orders from the two warehouses are treated in a first-come–first-served manner, and (ii) the orders from the lower-variability warehouse are given nonpreemptive priority. We examine this issue using an analytical model that integrates base-stock inventory models with queuing models for the production capacity. The higher-variability demand is modeled as a hyperexponential renewal process, and the lower-variability demand is modeled as a Poisson process. In case of pooled capacity, the arrival process at the production queue is the superposition of the two processes. We prove conditions under which the first-come–first-served operating rule will fail to achieve a Pareto improvement over the separate systems because it would increase inventory cost at the lower-variability warehouse. We then show cases under which the high-variability warehouse will see a reduction in inventory cost over the split system even if it accepts lower priority.

We model a supply chain with two retail warehouses that place replenishment orders with a common manufacturing capacity. The two retailers differ in the variability of their order-streams. The order-stream from one retail warehouse is modeled as a Poisson process and from the other as a hyperexponential renewal process. Each retail warehouse uses a base-stock policy to place replenishment orders with the manufacturer. The manufacturer is modeled as a first-come-first-serve, single exponential server queue. We analyze the supply-side impact of this mixture of order-streams received by the manufacturer on both retailers. An exact analysis of this base-model generates closed-form expressions for distributions of the lead-time, outstanding orders, and expected inventory costs for each retailer, and leads to comparative results about the two retailers- performance measures. The base-model is extended to accommodate finished goods at the manufacturer, more than two retailers, and bulk-arrivals. We use the model to suggest managerial insights about the impact of the presence of a high-variability retailer on other retailers who share capacity, the distorting impact of manufacturer finished goods inventory on retailer incentives, and the incentives for retailers to participate in variability-reduction programs in the grocery industry.