Nonlinear Mean Reversion and Arbitrage in the Gold Futures Market

Previous literatures take transaction costs as being negligible when analyzing the futures basis behavior in linear dynamic framework. However, we argue that the relationship between the futures and spot prices with the conventional linear cointegration approach may not be appropriate after taking transaction costs into account. In this paper, an incorporation of transaction costs presented by Dumas (1992) and Michael (1997) into the exponential smooth transition autoregressive (ESTAR) model developed by Granger and Terasvita (1993) is motivated to examine the dynamic relationship between daily gold futures and spot prices and the nonlinear behavior of the gold futures basis. Transaction costs may lead to the existence of neutral band for futures market speculation within which profitable trading opportunities are impossible. Further, our results indicate that the ESTAR model provides higher forecasting power than the linear AR(1) model.

Nonlinear Mean Reversion and Arbitrage in the Gold Futures Market

Previous literatures take transaction costs as being negligible when analyzing the futures basis behavior in linear dynamic framework. However, we argue that the relationship between the futures and spot prices with the conventional linear cointegration approach may not be appropriate after taking transaction costs into account. In this paper, an incorporation of transaction costs presented by Dumas (1992) and Michael (1997) into the exponential smooth transition autoregressive (ESTAR) model developed by Granger and Terasvita (1993) is motivated to examine the dynamic relationship between daily gold futures and spot prices and the nonlinear behavior of the gold futures basis. Transaction costs may lead to the existence of neutral band for futures market speculation within which profitable trading opportunities are impossible. Further, our results indicate that the ESTAR model provides higher forecasting power than the linear AR(1) model.

Exploring the Impacts of Web-Based e-Procurement on Organizational Performance

Web-enabled applications for business-to-business (B2B) procurement are not only expected to reduce the cost of purchasing process but also to alter the activities of purchasing, transform the purchasing process from an operational into a strategic activity, and provide opportunities for improving market coordination by reducing asset specificity and by making additional partners available. From organizational and inter-organizational perspectives, this study proposes a performance impact model of implementing Web-based e-procurement system for direct procurement. In the performance impact model, the strategic dimension is about partner relationship, and the operational efficiency dimension includes supplier performance, buyer performance, process integration, and process automation. Based on a survey of Taiwanese manufacturing firms, the results of this study show that the electronic execution of purchasing activities improves both of the operational efficiency dimension and the strategic dimension. The results demonstrate implementing Web-based e-procurement system not only could enhance the performance of the buyer organization but also could enhance the performance of the supplier organization and improve partner relationship management

Portal Vein Gas in a Diabetic Patient with Gas-forming Pararenal Abscess

The incidence of portal vein gas (PVG), which used to be an ominous sign of intestinal sepsis, has increased with progressive improvements in imaging modalities. Therefore, the clinical significance of PVG has changed. Emphysematous pyelonephritis (EPN) is a rare, potentially life-threatening and gas-forming infection of the renal parenchyma and/or its surroundings. Gas-forming pararenal abscess presenting with PVG is even rarer. We hereby present the case of a diabetic female with poor glycemic control, who was diagnosed to have EPN and PVG concurrently by computed tomography. She underwent percutaneous catheter drainage (PCD) of the pyelonephritis. Both cultures of blood and pus grew Klebsiella pneumoniae. Her subsequent clinical course was uneventful. In summary, EPN is a rare but potentially fatal urinary tract infection in diabetic patients, and finding PVG on computed tomography can aid in diagnosis. Conservative treatment with intravenous antibiotics and PCD of pus may be adequate for the patient with EPN. However, nephrectomy may be necessary if the patient deteriorates and PCD fails to contain the infection

A 52-Year-Old Woman with a Palpable Abdominal Mass

A 52-year-old woman presented with a history of diabetes mellitus under medical treatment and a surgical history of a cesarean section 20 years ago. The patient was referred to our emergency department because of a 2-week hypermenorrhea and unspecific abdominal pain without nausea and vomiting, fever, or other symptoms. She did not complain of weight loss

Hemolytic Uremic Syndrome Caused by Enteroviral Infection

A 4-year-old boy presented with enteroviral infection complicated with atypical hemolytic uremic syndrome (aHUS). Enterovirus RNA was detected by reverse transcription polymerase chain reaction (RT-PCR) of both blood and kidney biopsy specimens. A survey of the complement system did not reveal a specific complement defect. Supportive therapy with blood components transfusion, plasma therapy, and immunosuppressants was administered, however, renal function did not recover. The results of this report demonstrate that the enterovirus is the cause of aHUS

Dynamic Effects of Axial Loading on the Lumbar Spine During Magnetic Resonance Imaging in Patients with Suspected Spinal Stenosis

BackgroundPrevious studies have shown that axial compression in extension (ACE) of the spine during magnetic resonance imaging (MRI) has revealed unexpected pathological features compared with the conventional psoas-relaxed position (PRP) used in imaging. The purpose of this study was to evaluate the dynamic effect of axial loading on lumbar spinal stenosis using MRI in patients with spinal stenosis.MethodsA total of 14 women and 11 men with lumbar spinal stenosis were examined in both PRP and ACE positions. We calculated the dural-sac cross-sectional area (DCSA) to evaluate severity of spinal canal stenosis. DCSA, as well as the dural-sac anteroposterior diameter (DAPD) and dural-sac transverse diameter (DTD) in both positions were measured using a digital image view station. A paired t test determined the differences in DCSA, DAPD and DTD between the two positions at each intervertebral disc level.ResultsAxial loading increased severity of lumbar spinal stenosis during MRI, as demonstrated by a decrease in DCSA from 20.5% to 6.3% (mean, 11.40 ± 3.66%) between the PRP and ACE positions (p < 0.01). Significant differences were also noted in DAPD and DTD between the PRP and ACE positions (p < 0.01). A significant correlation was found between the decrease in mean DCSA and that in DAPD and DTD. The decrease in mean DCSA, DAPD and DTD following axial compression was greatest at the L4/5 and L5/S1 levels.ConclusionAxial loading increases severity of lumbar canal stenosis and the effect of axial loading on MRI examination is greatest at the L4/5 and L5/S1 levels

HBV replication is significantly reduced by IL-6

Interleukin-6 (IL-6) is a pleiotropic cytokine with pivotal functions in the regulation of the biological responses of several target cells including hepatocytes. The level of serum IL-6 has been reported to be elevated in patients with chronic hepatitis B, cirrhosis and hepatocellular carcinoma and represents the best marker of HBV-related clinical progression as compared with several other cytokines. In this study, we found that IL-6 was able to effectively suppress hepatitis B virus (HBV) replication and prevent the accumulation of HBV covalently closed circular DNA (cccDNA) in a human hepatoma cell line. We also demonstrated that the suppression of HBV replication by IL-6 requires concurrently a moderate reduction of viral transcripts/core proteins and a marked decrease in viral genome-containing nucleocapsids. Studies on the stability of existing viral capsids suggest that the IL-6 effect on the reduction of genome-containing nucleocapsids is mediated through the prevention of the formation of genome-containing nucleocapsids, which is similar to the effect of interferons. However, IFN-α/β and IFN-γ did not participate in the IL-6-induced suppression of HBV replication. Taken together, our results will provide important information to better understand the role of IL-6 in the course of HBV infection

Rapid Increase in the Height and Width of the Upper Chest in Adolescents with Primary Spontaneous Pneumothorax

BackgroundWe determined the chest height in a cohort of patients with primary spontaneous pneumothorax (PSP) who had received chest radiographic examinations prior to the attack. The aim of this study was to determine when their chest height began to change and how this was related to the PSP.MethodsFrom June 2009 to February 2012, the chest posteroanterior radiographs of 156 patients with PSP (Group 1) were reviewed. Among another 3134 patients with PSP, we identified 52 patients who had a chest posteroanterior radiograph prior to the attack (Group 2). We also recruited 196 controls for comparison (Group 3). The chest height and chest width at different levels were measured and analyzed.ResultsBefore 14 years of age, the chest height of patients in Group 2 was no different from that of patients in Group 3. By the age of 14 years, however, the chest height and upper chest width of patients with PSP was significantly higher than that of the normal controls. The difference from normal chest height did not increase at adulthood.ConclusionThe rapid increase in chest height and upper chest width is a unique finding in patients with PSP. It might be attributable to the occurrence of PSP. This finding may also help to identify patients who are at risk of PSP