Robust Stabilization of Linear Time-Delay Systems under Denial-of-Service Attacks.

This research examines new methods for stabilizing linear time-delay systems that are subject to denial-of-service (DoS) attacks. The study takes into account the different effects that a DoS attack can have on the system, specifically delay-independent and -dependent behaviour. The traditional proportional-integral-derivative (PID) acts on the error signal, which is the difference between the reference input and the measured output. The approach in this paper uses what we call the PID state feedback strategy, where the controller acts on the state signal. Our proposed strategy uses the Lyapunov-Krasovskii functional (LKF) to develop new linear matrix inequalities (LMIs). The study considers two scenarios where the time delay is either a continuous bounded function or a differentiable and time-varying function that falls within certain bounds. In both cases, new LMIs are derived to find the PID-like state feedback gains that will ensure robust stabilization. The findings are illustrated with numerical examples.

A Five-year Survey of Cancer Prevalence in Sudan.

BACKGROUND: While cancer epidemiology is well-investigated in developed countries, the cancer burden in Africa is less well documented. We provide cancer statistics of 33,201 patients from all Sudan diagnosed at the Radiation and Isotope Centre in Khartoum (RICK). This hospital covers approximately 80% of patients with cancer in Sudan and is, therefore, considered representative for the situation in this country. MATERIALS AND METHODS: Data from 2009-2013 were collected at RICK. Cancer diagnoses were made by standard pathological and radiological methods. Epidemiological data were categorized by age, gender, resident state, marital status etc. and subjected to statistical analyses by SPSS 21v. RESULTS: The cancer prevalence rate per year was 5,000-7,000 among adults and 300-400 among children, with increasing tendency for adults. Male:female ratios were 1:1.18 for adults and 1.46:1 for children. The five most frequent tumour types were breast cancer, leukaemia, prostatic carcinoma, lymphoma and colorectal carcinoma in adults and leukaemia, lymphoma, eye tumours, sarcoma and brain tumours in children. Remarkably, the median age of cancer diagnosis was 10-20 years higher in men than in women, mainly due to earlier onset of gender-related tumours in females (cancer of breast, cervix, or ovary) than in men (prostatic carcinoma). Chronic myeloid leukaemia was the most frequent haematopoietic malignancy in adults and acute lymphoblastic leukaemia in children. Comparing cancer cases with population numbers of Sudanese states, Northern Sudan, River Nile and Khartoum revealed up to 8-fold higher cancer incidence rates than Al Gedarif, Southern Dafur and Blue Nile. The other states had intermediate incidence rates. Interestingly, oesophageal carcinoma occurred proportionally more frequently in Kassala (rank 3) than in the entire Sudan (rank 7) or other states. CONCLUSION: This is the largest survey on cancer burden in Sudan. It may serve as basis for governmental programmes for assessing risk factors, improving cancer prevention (e.g. by educational and vaccination programmes) and cancer therapy in the future.

Poor practice and knowledge among traditional birth attendants in Eastern Sudan.

To identify and understand knowledge and practice among traditional birth attendants (TBAs), a total of 111 TBAs were interviewed at Kassala, Eastern Sudan between March and April 2011. Hand-washing prior to the delivery was a universal practice but only 25.2% of the interviewed TBAs used sterilised equipment. TBAs in this study appeared to have a low level of awareness about when a mother should be referred to hospital, and lacked basic information on family planning and HIV/AIDS. None of these 111 TBAs knew or used equipment for neonatal resuscitation (such as bag, tube and mask) or knew neonatal signs that needed extra attention such as change in skin colour, weak suckling and respiratory distress, and nearly one-third (28.8%) of the respondents believed in a few days delay in milk production. Thus, substantial effort is needed to improve the knowledge and practice among TBAs in Eastern Sudan, including training programmes, and this might be the best hope to achieve the Millennium Development Goals.

Anemia in Kassala Area Eastern Sudan

Objective The objective of this study was to determine the types and the ways of diagnosis of anemia at Kassala region; Sudan. Methods In this study we examined and investigate 210 patients with anemia.Full blood cell count including peripheral picture; blood film for malaria; urine analysis and stool examination were done for every patient.Bone marrow aspiration was done for patients with splenomegaly with or without pancytopenia and or presence of immature cells in the peripheral blood. Serum iron and serum ferritin; for confirmation of iron deficiency were measured in some patients. Results Out of all patients; 45(21) had chronic illness; 42(20) had history of repeated attacks of malaria and 3(18) patients had nutritional anemia. Sixty three (30) patients presented with severe anemia; 32(15) with mild anemia and 115(55)with moderate anemia. Eighty patients presented with enlarge spleen.26 (33) out of the latter group had features of hypersplenism. Conclusion Common causes of anemia in this area were chronic illness; followed by nutritional and repeated malaria infection. Splenomegaly and hypersplenism are common. We recommended that full blood count; peripheral blood picture and estimation of serum iron and serum ferritin should be performed for every anaemic patient. Blood film for malaria should be done for every anaemic patient and negative films should be repeated by immunochromatography test for plasmodium falciparum and vivax

Complications of Couching and Visual Outcome after IOL Implantation - a Study of 60 Patients in Sudan

Aims: to describe visual outcome and complications of traditional cataract surgery (couching) which is still practiced in some regions in West Darfur; Sudan. Material and Methods: This case series studied the use of Scleral-fixated IOL in the management of patients who underwent traditional cataract surgery (couching) in West Darfur; between July; 2006 and June; 2007. Results: The study included 60 patients; of which 36 were males and 24 were females. The mean age of patients was 70 years (range 55-90 years). Fifty seven patients had poor vision in one eye; and only three patients had poor vision in both eyes. Complications of couching included secondary glaucoma and optic nerve atrophy (38); endophthalmitis (22); Majority of patients (60) ended up with no perception of light (NPL) vision. In 9 patients sclera fixated IOL and in 4 patients ACIOL implantation procedures were done. Best corrected vision postoperatively ranged between 6/9 and 6/18 in both groups. Conclusion: Couching results in poor visual outcome and blinding complications in most of the patients. Hence; traditional healers performing couching should be banned by the government; not only by setting legislations against them; but also by organizing wide campaigns of heath education and mobile cataract surgery facilities (eye camps) that target the areas of action

Evaluation of malaria parasite screening procedures among Sudanese blood donors.

OBJECTIVE: To compare the standard microscopic examination, the polymerase chain reaction (PCR), and the immunochromatography test (ICT) to determine the best method for screening blood donors for malaria parasites in Sudan. METHODS: A total of 100 blood donors were screened for malaria parasites by standard microscopic technique, ICT, and PCR Blood films were examined microscopically using standard Giemsa staining techniques. Qurum (Canadian Company) malaria kits were used to perform the ICT. For performing PCR, DNA was extracted using Chelex method and amplified by the moderately repetitive DNA sequence pBRK-l. RESULTS: Using PCR, a total of 21 blood samples were positive; 8 (38%) of them showed negative blood films and 7 (33%) were negative on ICT. Four blood samples that tested positive by ICT despite a negative PCR and microscopic examination were proved to be false positives. The false negativity of both the microscopic examination and ICT was found to be significant. The sensitivity of microscopy was 61.9% and of ICT was 66.7%, while the specificity of microscopy was 100% and of ICT was 94.9%. When direct microscopy was considered as the standard technique the sensitivity of ICT was 100% and the specificity was 94.3%. CONCLUSION: Although PCR is more sensitive and more specific, it is unaffordable. Microscopy for malaria when compared to ICT showed similar sensitivity at low cost. However, all human plasmodium species can be detected using the microscopy while only two species (P. falciparum and P. vivax) can be detected by ICT. The detected false positivity of ICT is not inconsequential since this implies the rejection of a greater proportion of blood donations. Therefore, microscopy is considered more suitable for screening Sudanese blood donors for malaria parasites prior to donation at the present time. RECOMMENDATIONS: To establish a reference malaria diagnosis unit in each blood bank in Sudan as well as to train blood bankers to perform microscopic examinations.

The significance of blood levels of IgM, IgA, IgG and IgG subclasses in Sudanese visceral leishmaniasis patients.

We developed an ELISA test using leishmania antigenic extracts to detect antigen-specific antibody responses, including subclass and isotype analysis, in visceral leishmaniasis (VL) patients from the Sudan. A total of 92 parasitologically proven patients were compared with cutaneous leishmaniasis, schistosomiasis, malaria, onchocerciasis and tuberculosis patients, as well as with healthy endemic and non-endemic controls. Some VL patients were examined before and after chemotherapy. VL patients showed significantly higher IgG responses compared with all other groups (93.4% sensitivity, 93.7% specificity), and higher (but not significantly) IgM responses. All groups showed low IgA levels. All IgG subclasses, IgG1, 2, 3, and 4, showed higher levels in patients than all other groups, with IgG1 and IgG3 levels being significantly reduced following treatment. The rank order for specificity and sensitivity for IgG subclasses was IgG3 > IgG1 > IgG2 > IgG4.

Interleukin 10 production correlates with pathology in human Leishmania donovani infections.

We have found that an important Th2 cytokine, IL-10, is produced by tissues from patients acutely infected with Leishmania donovani. In all individuals tested, IL-10 mRNA production was increased in lymph nodes taken during acute disease over that observed in postacute samples. In contrast, both pre- and posttreatment lymph nodes had readily detected mRNA for IFN-gamma and IL-2. A down-regulating effect of IL-10 on leishmania-induced proliferative responses was demonstrated when Hu rIL-10 was added to cultures of PBMC from clinically cured individuals. PBMC from individuals with acute visceral leishmaniasis responded to stimulation with leishmania lysate by producing IL-10 mRNA. Simultaneously cultured PBMC collected from the same patients after successful chemotherapy produced no detectable IL-10 mRNA after leishmania antigen stimulation. Neutralizing anti-IL-10 mAb added to PBMC from patients with acute visceral leishmaniasis markedly increased the proliferative response to leishmania lysate. Finally, we observed mRNA for IL-10 and IFN-gamma concurrently in a lesion from a patient with post-kala-azar dermal leishmaniasis (PKDL). These results indicate the production of IL-10 during L. donovani infection, and suggest a role for this cytokine in the regulation of immune responsiveness during visceral leishmaniasis.

A rapid and simple diagnostic test for active visceral leishmaniasis.

We have developed an immunodot assay for the serodiagnosis of active visceral leishmaniasis (AVL) which utilizes protein A colloidal gold as the visualizing agent. The test is simple, requires few reagents, and can be completed in two hours. It is sensitive and specific for active visceral leishmaniasis, and generally correlates with the ELISA. Either whole blood or sera in minute quantities may be used as test antibody. In addition, the use of the protein A gold immunodot is shown to detect anti-leishmania antibodies in infected dogs.

An improved serodiagnostic procedure for visceral leishmaniasis.

The enzyme-linked immunosorbent assay (ELISA) is a sensitive and specific serodiagnostic method for leishmaniasis. In this report, we describe how this versatile assay can be improved by the use of protein A or protein G conjugates for the specific detection of Leishmania antibody in the sera of patients with visceral leishmaniasis. In direct comparisons with anti-immunoglobulin conjugate, enzyme-linked protein A gave significantly higher absorbance values for positive sera without a corresponding increase in absorbance values for sera from normal individuals or from patients with other diseases known to cross-react with leishmaniasis. The effect was to increase the distance between positive and negative values, which aided in the interpretation of the results. This also permitted visual distinction between positive sera and negative or weakly reactive sera. The assay was effective using either blood or serum as the source of primary antibody. A further advantage of protein A over anti-Ig conjugate was its ability to detect specific antibody in dog as well as human sera. Finally, we demonstrated the usefulness of the protein A ELISA with a recombinant leishmania antigen, gp63.

Visceral leishmaniasis in Sudan. Clinical features.

Kala azar is a disease endemic to the Sudan and a cause of major morbidity and mortality to affected patients when the diagnosis or treatment has been delayed. In this report we described the clinical features of 99 parasite proven patients with visceral leishmaniasis. The Sudanese kala azar patient is young in age (teens to 20's), has marked weight loss despite a continuous, excellent appetite and suffers from insomnia, epistaxis and abdominal pain. Hepatosplenomegaly is universally present. Generalized lymphadenopathy is a prominent feature (72%). The high prevalence of lymphadenopathy has a wide range of implications: for diagnosis, i.e., the use of lymph node aspiration; for response to treatment, i.e., the resolution of lymphadenopathy; and for studies of immunoregulation in this systemic infection.

Visceral leishmaniasis in the Sudan: comparative parasitological methods of diagnosis.

Patients with suspected kala-azar had aspirations of spleen, lymph node and bone marrow performed to compare the relative merit of each procedure. Splenic aspiration remains the method most likely to provide microscopic proof of leishmanial infection (18 of 19 samples) and was the only site positive in 5 patients. Lymph node aspirates contained parasites in 20 of 29 patients, whereas bone marrow aspirates provided the diagnosis in 18 of 28. Therefore, lymph node aspiration, with its minimal morbidity, is indicated as the primary diagnostic method in patients in the Sudan with suspected kala-azar. If negative, splenic aspiration should be performed.

New mutational variants of Neurospora NADP-specific glutamate dehydrogenase.

The am locus of Neurospora codes for NADP-dependent glutamate dehydrogenase (GDH). Four new am mutants that produced mutationally altered GDH have been characterized. Mutant am119 is a CRM-negative, complementing mutant that maps between am2 and am1. The other three mutants are CRM formers that produce varieties of GDH that can be activated by glutamate or succinate. The GDH of am130 and am131 is similar in terms of activation properties to that of am3. The GDH of am122 requires very high concentrations of dicarboxylate for activity. The mutation in am130 maps between am14 and am2 and resulted in a replacement at residue 75 of the GDH (pro leads to ser). The mutation in am122 maps near am11 and apparently resulted in the replacement of the tryptophan residue at position 389 with an unknown amino acid. The mutation in am131 maps between am2 and am1.