A Study of Z-Transform Based Encryption Algorithm

It has become increasingly important to ensure the protection of information, especially data in transit. Therefore, it is the primary goal of any encryption algorithm to safeguard the protection of information against security attacks. It is equally important to design high-performance solutions with affordable cost of implementation. Encryption algorithms are used to transform plain text to the ciphertext in order to protect privacy, prevent data fraud, and prevent unauthorized access of data in daily transactions. There are multiple types of encryption algorithms, each with its niche tactics to enhance security. For instance, different kinds of algorithms include but are not limited to the following: Blowfish, RSA, AES, DES, Triple DES. This paper contributes an efficient and secure encryption algorithm technique for information security based on Z transformation and XOR function known as the Z Transformation Encryption (ZTE) technique. To elaborate, this technique implements concepts of Z transformation and XOR operations at the source. The reverse process is applied at the receiving end of the transaction wherein the inverse of Z transformation and XOR is applied to reveal the original plain text message. The simulation of the proposed algorithm is conducted using the R language. The results show a promising performance comparing to other symmetric algorithms

Benefit/risk Ratio of Low-dose Methotrexate in Cutaneous Lesions of Mycosis Fungoides and Sézary Syndrome

International audienceLow-dose methotrexate is widely used in mycosis fungoides and Sézary syndrome, but few studies have evaluated this treatment. The aim of this study was to evaluate the benefit/risk ratio of this regimen on skin lesions. A retrospective survey of a series of patients treated for mycosis fungoides or Sézary syndrome with low-dose methotrexate and followed for at least one year in a tertiary referral centre was performed. From a total of 48 patients, complete response and partial response were achieved in 10 (21%) and 25 (52%) patients, respectively, with no significant difference in response rates between mycosis fungoides and Sézary syndrome. Of the responders, 20 out of 35 (57%) relapsed after a median time of 11 months. Forty-four of the total of 48 patients discontinued methotrexate, mainly due to primary or secondary failure and/or limiting toxicity (9 patients). Overall, the benefit/risk ratio of low-dose methotrexate in mycosis fungoides and Sézary syndrome appears favorable and this treat-ment remains a valid option in mycosis fungoides/Sézary syndrome. However, its activity is limited in duration and significant toxicity may occur in some patients

Noninvasive diagnosis of pulmonary hypertension with hyperpolarised 129Xe magnetic resonance imaging and spectroscopy

Background The diagnosis of pulmonary hypertension (PH) remains challenging. Pre- and post-capillary PH have different signatures on noninvasive 129Xe gas-exchange magnetic resonance imaging (MRI) and dynamic MR spectroscopy (MRS). We tested the accuracy of 129Xe MRI/MRS to diagnose PH status compared to right heart catheterisation (RHC). Methods 129Xe MRI/MRS from 93 subjects was used to develop a diagnostic algorithm, which was tested in 32 patients undergoing RHC on the same day (n=20) or within 5 months (42±40 days) (n=12). Three expert readers, blinded to RHC, used 129Xe MRI/MRS to classify subjects as pre-capillary PH, post-capillary PH, no PH and no interstitial lung disease (ILD), or ILD. Results For pre-capillary PH, 129Xe MRI/MRS diagnostic accuracy was 75% (95% CI 66–84) with a sensitivity of 67% (95% CI 54–79) and a specificity of 86% (95% CI 75–96); for post-capillary PH accuracy was 69% (95% CI 59–78) with sensitivity of 54% (95% CI 34–74) and specificity of 74% (95% CI 63–84). The model performed well in straightforward cases of pre-capillary PH but was less accurate in its diagnosis in the presence of mixed disease, particularly in the presence of ILD or combined post- and pre-capillary PH. Conclusion This study demonstrates the potential to develop 129Xe MRI/MRS into a modality with good accuracy in detecting pre- and post-capillary PH. Furthermore, the combination of 129Xe dynamic MRS and gas-exchange MRI uniquely provide concurrent, noninvasive assessment of both haemodynamics and gas-exchange impairment that may aid in the detection of PH

Acute echocardiographic and hemodynamic response to his-bundle pacing in patients with first-degree atrioventricular block

Background: Atrial pacing and right ventricular (RV) pacing are both associated with adverse outcomes among patients with first-degree atrioventricular block (1°AVB). His-bundle pacing (HBP) provides physiological activation of the ventricle and may be able to improve both atrioventricular (AV) and inter-ventricular synchrony in 1°AVB patients. This study evaluates the acute echocardiographic and hemodynamic effects of atrial, atrial-His-bundle sequential (AH), and atrial-ventricular (AV) sequential pacing in 1°AVB patients. Methods: Patients with 1°AVB undergoing atrial fibrillation ablation were included. Following left atrial (LA) catheterization, patients underwent atrial, AH- and AV-sequential pacing. LA/left ventricular (LV) pressure and echocardiographic measurements during the pacing protocols were compared. Results: Thirteen patients with 1°AVB (mean PR 221 ± 26 ms) were included. The PR interval was prolonged with atrial pacing compared to baseline (275 ± 73 ms, p =.005). LV ejection fraction (LVEF) was highest during atrial pacing (62 ± 11%), intermediate with AH-sequential pacing (59 ± 7%), and lowest with AV-sequential pacing (57 ± 12%) though these differences were not statistically significant. No significant differences were found in LA or LV mean pressures or LV dP/dT. LA and LV volumes, isovolumetric times, electromechanical delays, and global longitudinal strains were similar across pacing protocols. Conclusion: Despite pronounced PR prolongation, the acute effects of atrial pacing were not significantly different than AH- or AV-sequential pacing. Normalizing atrioventricular and/or inter-ventricular dyssynchrony did not result in acute improvements in cardiac output or loading conditions

Acute echocardiographic and hemodynamic response to his-bundle pacing in patients with first-degree atrioventricular block

BACKGROUND: Atrial pacing and right ventricular (RV) pacing are both associated with adverse outcomes among patients with first-degree atrioventricular block (1°AVB). His-bundle pacing (HBP) provides physiological activation of the ventricle and may be able to improve both atrioventricular (AV) and inter-ventricular synchrony in 1°AVB patients. This study evaluates the acute echocardiographic and hemodynamic effects of atrial, atrial-His-bundle sequential (AH), and atrial-ventricular (AV) sequential pacing in 1°AVB patients. METHODS: Patients with 1°AVB undergoing atrial fibrillation ablation were included. Following left atrial (LA) catheterization, patients underwent atrial, AH- and AV-sequential pacing. LA/left ventricular (LV) pressure and echocardiographic measurements during the pacing protocols were compared. RESULTS: Thirteen patients with 1°AVB (mean PR 221 ± 26 ms) were included. The PR interval was prolonged with atrial pacing compared to baseline (275 ± 73 ms, p = .005). LV ejection fraction (LVEF) was highest during atrial pacing (62 ± 11%), intermediate with AH-sequential pacing (59 ± 7%), and lowest with AV-sequential pacing (57 ± 12%) though these differences were not statistically significant. No significant differences were found in LA or LV mean pressures or LV dP/dT. LA and LV volumes, isovolumetric times, electromechanical delays, and global longitudinal strains were similar across pacing protocols. CONCLUSION: Despite pronounced PR prolongation, the acute effects of atrial pacing were not significantly different than AH- or AV-sequential pacing. Normalizing atrioventricular and/or inter-ventricular dyssynchrony did not result in acute improvements in cardiac output or loading conditions