Bootstrapping vs. Asymptotic Theory in Property and Casualty Loss Reserving

One of the key functions of a property and casualty (P&C) insurance company is loss reserving, which calculates how much money the company should retain in order to pay out future claims. Most P&C insurance companies use non-stochastic (non-random) methods to estimate these future liabilities. However, future loss data can also be projected using generalized linear models (GLMs) and stochastic simulation. Two simulation methods that will be the focus of this project are: bootstrapping methodology, which resamples the original loss data (creating pseudo-data in the process) and fits the GLM parameters based on the new data to estimate the sampling distribution of the reserve estimates; and asymptotic theory, which resamples only the GLM parameters (fitted from an original set of data) from a multivariate normal distribution to estimate the sampling distribution of the reserve estimates. Using Excel, R, and SAS software, the copulas of the GLM parameter estimates from the stochastic methods will be compared to the copula from a multivariate normal distribution. Ultimately, the Value at Risk (VaR) and Tail Value at Risk (TVaR) results from each method’s sampling distribution will be compared to each other, with the goal of showing that the two methods produce significantly different reserve estimates and risk capital estimates at the low end of the reserve distribution. This would answer the question as to whether the asymptotic theory procedure sufficiently approximates real-world scenarios

Real Time Simulation and Hardware in the Loop Methods for Power Electronics Power Distribution Systems

System level testing of Power Electronics Power Distribution Systems (PEPDS) can be challenging when fine temporal resolution is required (time step below 100-200ns). In the recent years, our research group has proposed various methods to simulate in real-time PEPDS using FPGAs and time step as small as 50ns. While the proposed methods allow achieving the desired temporal resolution, they are extremely demanding in terms of resources usage and the size of the PEPDS that can be simulated on a single FPGA is strongly limited. In this dissertation -work that takes as an example application the US Navy electric Ship Zonal System (SZS)- a platform based on a commercial CPU based simulator and on a custom multi-FPGA simulator is presented. The multi-FPGA simulator enables system level PEPDS analysis while maintaining a very small-time step (70ns). Using a CPU commercial platform and multi rate execution, the power electronics part of the system is simulated together with the slow electro-mechanical portion of the PEPDS maintaining a unified vision. To achieve such a small simulation time step, the LBLMC method is applied and an innovative parallel bus interface architecture for a three FPGAs layout is introduced. The PEPDS model is decomposed for multi-FPGA executions using the nodal decomposition method. Two converters models, MMC and DAB, have been developed and included in the Open Real-Time Simulation (ORTiS) framework. To allow multi-rate execution a dedicated software and hardware interface has been developed so to interface the custom FPGA based simulator -operating with a 70ns time step- with the commercial CPU based simulator -operating at 25μs. Furthermore, to increase the flexibility and scalability of the proposed simulation platforms, a co-simulation interface based on the Aurora protocol and realizing communication between a multi-CPU and a multi-FPGA based platforms is introduced

Swiping Left or Right? Effective and Ineffective Dating Profiles

With the use of internet growing, online dating applications are becoming more relevant in today’s society. With the ever-evolving technology of today’s world, there is still much to be researched and learned. Due to the connectedness of the world shifting from face to face communication to technology based communication, the online dating world is growing rapidly. Online dating has become prevalent in today’s society as a means to meet others. Online dating applications allow users to share information and describe themselves and to be able to choose who they want to pursue as a romantic partner based on the information shared. This study focused on online dating, particularly on the effectiveness and ineffectiveness of an online dating profile. Various levels of self-presentation and self-disclosure were used to examine how they impacted people’s favorability to certain online dating profiles. Self-presentation focused on profile pictures and how participants convey themselves and the deception of online dating. Self-disclosure focused on how positively or negatively the amount of disclosure or lack thereof can affect the dating profile. The study focused on the dating profile itself and what content the user decides to share

Arrangements of selected American folk songs for string, woodwind, and brass ensembles of a secondary school level.

Thesis (M.M.E.)--Boston University, 195

Fresh Whole Blood Transfusions: Efficacy, Limitations, and the Future

Background: Loss of blood from traumas suffered on the battlefield is the most common cause of death among potentially treatable injuries in frontline military operations (Keenan and Riesberg 2017). Cessation of blood loss and fluid repletion have been major driving factors that can reduce battlefield casualties. Once the hemorrhage has been stopped, the next step is to replace lost volume to decrease cardiac failure or shock (Eastridge et al. 2012; Butler 2017). Uncontrolled hemorrhage can lead to the "trauma triad of death", which consists of hypothermia, acidosis, and impaired coagulation (Howard et al. 2017). Hemostatic resuscitation involves the blood components resembling whole blood. The goals are to avoid metabolic acidosis, hypothermia, treating coagulopathy and stabilizing the patient as soon as possible (Nickson n.d.). The resuscitation fluids of choice for casualties in hemorrhagic shock, listed from most to least preferred are: whole blood; plasma, RBCs and platelets in 1:1:1 ratio; plasma and RBCs in 1:1 ratio; plasma or RBCs alone, and crystalloid fluids (Nickson n.d.). Between October 2001 and June 2011, 4,596 battlefield fatalities were analyzed. Non-compressible hemorrhage is the cause of over 2/3 of battlefield deaths, which makes hemorrhages the leading cause of potentially survivable deaths in combat (Keenan and Riesberg 2017). The major body region bleeding focus accounting for mortality were torso 48%, extremities 31%, and neck/groin/ axilla region 21% (Eastridge et al. 2012). Casualties with severe hemorrhagic injury, the odds of KIA mortality were 83% lower for casualties who needed and received pre-hospital blood transfusion (Shackelford et al. 2017). Evaluating the influences on mortality is helpful for planning efforts that optimize placement, proximity, and provision of timely and effective transport and treatment capabilities to minimize casualty risk (Malsby et al. 2013). Combat wounded on today’s battlefield experience the highest survival rate in history. Advances in battlefield medicine during the conflicts in Iraq and Afghanistan have included the effective use of tourniquets, damage control resuscitation, trauma system development, en route care, use of tranexamic acid, and advanced topical hemostatic dressings (Malsby et al. 2013). In 2008, there was a mandate that all the injured personnel evacuation to surgeon must occur in less than 60 minutes, “The Golden Hour”, that contributed to the lowest mortality rate of any conflict in history (Keenan and Riesberg 2017). Component therapy remains the mainstay in trauma resuscitation. In prolonged field care, access to packed red blood cells, platelets, and fresh frozen plasma is often limited (Keenan and Riesberg 2017). Transfusion of fresh whole blood has been used when access to CT in these settings are limited or have been fully utilized . The process of separating and reconstituting blood can lessen its effectiveness. Current Prolonged Field Care standards identified that the best practice for transfusions would be to maintain a stock of pRBC and FFP and have type-specific donors identified for immediate FWB draw (Keenan and Riesberg 2017). PICOT​ ​Question:​ ​What​ ​are​ ​the​ ​limitations​ ​of​ ​Fresh​ ​Whole​ ​Blood​ ​transfusions​ ​or administration​ ​of​ ​blood​ ​products​ ​in​ ​prolonged​ ​point​ ​of​ ​injury​ ​care​ ​on​ ​the​ ​battlefield?Master of Health Scienc

Techniques of biliary reconstruction following bile duct resection (with video)

In several clinical situations, including resection of malignant or benign biliary lesions, reconstruction of the biliary system using the Roux-en-Y jejunum limb has been adopted as the standard procedure. The basic technique and the procedural knowledge essential for most gastroenterological surgeons are described in this article, along with a video supplement. Low complication rates involving anastomotic insufficiency or stricture can be achieved by using proper surgical techniques, even following small bile duct reconstruction. Using the ropeway method to stabilize the bile duct and jejunal limb allows precise mucosa-to-mucosa anastomosis with interrupted sutures of the posterior row of the anastomosis. Placement of a transanastomotic stent tube is the second step. The final step involves suturing the anterior row of the anastomosis. In contrast to the lower extrahepatic bile duct, the wall of the hilar or intrahepatic bile duct can be recognized within the fibrous connective tissue in the Glissonean pedicle. The portal side of the duct should be selected for the posterior wall during anastomosis owing to its thickness. Meticulous inspection to avoid overlooking small bile ducts could decrease the chance of postoperative intractable bile leakage. In reconstruction of small or fragile branches, a transanastomotic stent tube could work as an anchor for the anastomosis

Pregnancy-Associated Breast Disease: Radiologic Features and Diagnostic Dilemmas

In this paper, we evaluate the radiological features of pregnancy-associated breast lesions and discuss the difficulties in diagnosis by imaging. We selected patients who were diagnosed with pregnancy-associated breast lesions during the previous 5 years. All patients complained of palpable lesions in the breast and underwent ultrasonographic (US) examination, the first choice for examination of pregnancy-related breast lesions. Any suspicious lesions found by the US were recommended for a US-guided core biopsy, US-guided fine needle aspiration (FNA), or surgery. Various breast lesions were detected during pregnancy and lactation, including breast cancer, mastitis and abscesses, lactating adenoma, galactoceles, lobular hyperplasia, and fibroadenomas. The imaging features of pregnancy-associated breast lesions did not differ from the features of non-pregnancy-associated breast lesions; however, some pregnancy-associated benign lesions had suspicious sonographic features. A US-guided core biopsy was necessary for differentiating benign from malignant. In patients with breast cancer, the cancer was often advanced at the time of diagnosis. In conclusion, various pregnancy-related breast lesions were detected and the imaging of these lesions had variable findings. Breast ultrasound could be an excellent imaging modality for diagnosis and differentiation between benign and malignant lesions. However, when the imaging results are suspicious, a biopsy should be performed to obtain a pathologic diagnosis

Postoperative Nutritional Effects of Early Enteral Feeding Compared with Total Parental Nutrition in Pancreaticoduodectomy Patients: A Prosepective, Randomized Study

The benefits of early enteral feeding (EEN) have been demonstrated in gastrointestinal surgery. But, the impact of EEN has not been elucidated yet. We assessed the postoperative nutritional status of patients who had undergone pancreaticoduodenectomy (PD) according to the postoperative nutritional method and compared the clinical outcomes of two methods. A prospective randomized trial was undertaken following PD. Patients were randomly divided into two groups; the EEN group received the postoperative enteral feed and the control group received the postoperative total parenteral nutrition (TPN) management. Thirty-eight patients were included in our analyses. The first day of bowel movement and time to take a normal soft diet was significantly shorter in EEN group than in TPN group. Prealbumin and transferrin were significantly reduced on post-operative day (POD) 7 and were slowly recovered until POD 90 in the TPN group than in the EEN group. EEN group rapidly recovered weight after POD 21 whereas it was gradually decreased in TPN group until POD 90. EEN after PD is associated with preservation of weight compared with TPN and impact on recovery of digestive function after PD

Low back pain as the presenting sign in a patient with primary extradural melanoma of the thoracic spine - A metastatic disease 17 Years after complete surgical resection

Primary spinal melanomas are extremely rare lesions. In 1906, Hirschberg reported the first primary spinal melanoma, and since then only 40 new cases have been reported. A 47-year-old man was admitted suffering from low back pain, fatigue and loss of body weight persisting for three months. He had a 17-year-old history of an operated primary spinal melanoma from T7-T9, which had remained stable for these 17 years. Routine laboratory findings and clinical symptoms aroused suspicion of a metastatic disease. Multislice computed tomography and magnetic resonance imaging revealed stage-IV melanoma with thoracic, abdominal and skeletal metastases without the recurrence of the primary process. Transiliac crest core bone biopsy confirmed the diagnosis of metastatic melanoma. It is important to know that in all cases of back ore skeletal pain and unexplained weight loss, malignancy must always be considered in the differential diagnosis, especially in the subjects with a positive medical history. Patients who have back, skeletal, or joint pain that is unresponsive to a few weeks of conservative treatment or have known risk factors with or without serious etiology, are candidates for imaging studies. The present case demonstrates that complete surgical resection alone may result in a favourable outcome, but regular medical follow-up for an extended period, with the purpose of an early detection of a metastatic disease, is highly recommended