Minimum‐time control of systems with Coulomb friction: near global optima via mixed integer linear programming

This work presents a method of finding near global optima to minimum‐time trajectory generation problems for systems that would be linear if it were not for the presence of Coulomb friction. The required final state of the system is assumed to be maintainable by the system, and the input bounds are assumed to be large enough so that the role of maintaining zero acceleration during finite time intervals of zero velocity (the role of static friction) can always be assumed by the input. Other than the previous work for generating minimum‐time trajectories for robotic manipulators for which the path in joint space is already specified, this work represents, to the best of our knowledge, the first approach for generating near global optima for minimum‐time problems involving a non‐linear class of dynamic systems. The reason the optima generated are near global optima instead of exactly global optima is due to a discrete‐time approximation of the system (which is usually used anyway to simulate such a system numerically). The method closely resembles previous methods for generating minimum‐time trajectories for linear systems, where the core operation is the solution of a Phase I linear programming problem. For the non‐linear systems considered herein, the core operation is instead the solution of a mixed integer linear programming problem. Copyright © 2001 John Wiley & Sons, Ltd.     

On the discontinuity of the costates for optimal control problems with Coulomb friction

This work points out that the costates are actually discontinuous functions of time for optimal control problems with Coulomb friction. In particular these discontinuities occur at the time points where the velocity of the system changes sign. To our knowledge, this has not been noted before. This phenomenon is demonstrated on a minimum‐time problem with Coulomb friction and the consistency of discontinuous costates and switching functions with respect to the input switches is shown. Copyright © 2001 John Wiley & Sons, Ltd.     

The role of galanin receptors in anticonvulsant effects of low-frequency stimulation in perforant path-kindled rats

Low-frequency stimulation (LFS) has antiepileptogenic effects on kindled seizures. In the present study, the role of galanin receptors in the inhibitory effect of LFS on perforant path kindling acquisition was investigated in rats. Animals were kindled by perforant path stimulation in a rapid kindling manner (six stimulations per day). LFS (0.1 ms pulses at 1 Hz, 600 pulses, and 80-150 microA) was applied immediately after termination of each kindling stimulation. M35 (0.5 and 1.0 nM per site), a nonselective galanin receptor antagonist and M871 (1.0 microM per site), a selective galanin receptor type 2 (GalR2) antagonist, were daily microinjected into the dentate gyrus before starting the stimulation protocol. The expression of GalR2 in the dentate gyrus was also investigated using semi-quantitative RT-PCR. Application of LFS significantly retarded the kindling acquisition and delayed the expression of different kindled seizure stages. In addition, LFS significantly reduced the increment of daily afterdischarge duration during kindling development. Intra-dentate gyrus microinjection of both M35 and M871 significantly prevented the inhibitory effects of LFS on kindling parameters. During the focal kindled seizure stages (1-3) M871 had no significant effect. However, during generalized seizure stages (4 and 5), M871 had the same effect as M35. Semi-quantitative RT-PCR also showed that after kindling acquisition, the GalR2 mRNA level decreased in the dentate gyrus but application of LFS prevented this decrease. Obtained results show that activation of galanin receptors by endogenous galanin has a role in mediating the inhibitory effect of LFS on perforant path-kindled seizures. This role is exerted through GalR1 during focal- and through GalR2 during generalized-kindled seizures.     

Morphological reflections of evolutionary adaptations in the tongue of the white-headed duck

During an organism’s evolution, functional adaptations help species to become better suited to their ecological niches. From the morphological aspect, these adaptations are reflected in the anatomical specializations of different organs. Specializations of the lingual organ is a critical adaptation of birds, such as the white-headed duck (Oxyura leucocephala), that enables their nutritional requirements to be met. For optimal use of the available food resources, the white-headed duck utilizes three methods of food collection, namely pecking, grazing and filter-feeding. Since this species is classified as endangered, we conducted the present study on two carcasses of the white-headed duck (death due to natural causes) employing routine histological methods, light microscopy and scanning electron microscopy. Our results show that the tongue of this bird shares some similarities and some differences with the tongue of other members of the family Anatidae. The results confirm that it is better adapted to the filter-feeding method rather than to other types of food intake. This adaptation is reflected by anatomical specializations of its lingual structures, including the stair-like outline shape, bi-sectional lingual body, a deep median sulcus, lateral conical papillae, mucus secreting glands, lack of serous secreting glands, cartilaginous skeleton and the triangular fibromuscular structure of the lingual body. The so-called triangular structure and cartilaginous skeleton are the major structures involved in the lingual motions during the filter-feeding method. The presence of the triangular structure and its connection with the cartilaginous skeleton and lingual mucosa have not previously been reported in any species of birds.     

An Automatic and Robust Decision Support System for Accurate Acute Leukemia Diagnosis from Blood Microscopic Images

This paper proposes an automatic and robust decision support system for accurate acute leukemia diagnosis from blood microscopic images. It is a challenging issue to segment leukocytes under uneven imaging conditions since features of microscopic leukocyte images change in different laboratories. Therefore, this paper introduces an automatic robust method to segment leukocyte from blood microscopic images. The proposed robust segmentation technique was designed based on the fact that if background and erythrocytes could be removed from the blood microscopic image, the remainder area will indicate leukocyte candidate regions. A new set of features based on hematologist visual criteria for the recognition of malignant leukocytes in blood samples comprising shape, color, and LBP-based texture features are extracted. Two new ensemble classifiers are proposed for healthy and malignant leukocytes classification which each of them is highly effective in different levels of analysis. Experimental results demonstrate that the proposed approach effectively segments leukocytes from various types of blood microscopic images. The proposed method performs better than other available methods in terms of robustness and accuracy. The final accuracy rate achieved by the proposed method is 98.10% in cell level. To the best of our knowledge, the image level test for acute lymphoblastic leukemia (ALL) recognition was performed on the proposed system for the first time that achieves the best accuracy rate of 89.81%.     

Sarcoptic mange of gazelle (<Emphasis Type="Italic">Gazella subguttarosa</Emphasis>) and its medical importance in Iran

Sarcoptes scabiei infestation was diagnosed in four freshly dead and three net-captured gazelle while ranging freely. The captured animals presented with an alopecic pruritic skin disease with signs of crusted skin lesions, numerous small nodules which first appeared on the lips or nostrils and then it also extended towards the eyelids, around the ears, and, in some cases, over entire face, neck, trunk, and legs. Skin over the affected area gradually became bald, thick and hard, being dry and doughy to the touch, and serous fluid or sometimes blood oozes from the lesions which had a severe malodor. Skin scrapings confirmed the presence of the mite S. scabiei. Histopathology of lesions demonstrated marked acanthosis, hyperkeratosis, and parakeratosis. Microscopical examination also revealed all stages of S. scabiei, which were located mainly in the stratum corneum and also in the stratum granulosum. During the capture and sampling of the animals, four persons ranging in age from 25 to 62 years were exposed to scabies. Two relatives of one of them have been also affected by familiar contact. Clinical signs appeared within 9 days of exposure. They developed several pruretic erythematous papules with intense itching.     

Helminth Infections of House Mouse (Mus musulus) and Wood Mouse (Apodemus sylvaticus) from the Suburban Areas of Hamadan City,Western Iran

Background

To determine the prevalence and intensity of helminths and their zoonotic importance in small rodents inhabiting in the suburban areas of Hamadan City, Iran.

Methods

The present survey was conducted on the helminth infections of two species of rodents Apodemus sylvaticus (n=60) and Mus musculus(n=72) in the suburban areas of Hamadan City during 2010-2012. Rodents were collected and examined for helminth in the different organs. The nematodes were collected in 5% formalin solution and cleared in lactophenol, cestodes and trematodes collected from intestine fixed in AFA solution and stained by acetocarmine, cleared in xylol for identification.

Results

Helminths found in A. sylvaticus and M. musculus and their prevalence for the first time in suburban areas of Hamadan City were as follows; In A. sylvaticus: Cysticercus fasciolaris(3.33%), Syphacia fredrici(26.67%), S. stroma(8.33%), Anoplocephalidae sp. (1.67%), Skrjabinotaenia lobata(5%), Plagiorchis muris(1.67%) and in M. musculus:Hymenolepis nana (16.67%), H.diminuta (5.55%), S. obvelata(30.56%), S. ohtarom (9.72%), Rodentolepis crassa (1.39%), C. fasciolaris (1.39%). Among 11 species in two rodents 4 species including S. obvelata, H. nana, H.diminuta,and P. muris have zoonotic importance. Statistically the relation between gender and their helminth infections was not significant in either M. musculus or A. sylvaticus (P>0.05).

Conclusion

This study reports 11 species of helminths and on the other hand 3 species were identified for the first time in Iran and 5 species of them have potential health importance for public health and cat.     

Effects of Frequent Announced Parasitology Quizzes on the Academic Achievement

Background

The effect of frequent examinations on the students’ learning has had inconsistent results. This study aimed to assess the effectiveness of frequent announced quizzes on the learning of a representative sample of Iranian medical students.

Methods

This experimental study was conducted among 37 fifth semester medical students who had taken the course in Protozoology and Helminthology, in which the same basic information were provided about different types of protozoa and worms. Initially, in the teaching of helminthology, ten routine sessions were handled with lectures and interactive questions and answers. Then at the beginning of the protozoology topic in the beginning of all of the next 9 sessions, the students were informed that they will have a quiz at the end of each session. At the end of the semester, the total scores of quizzes were compared with the mean final scores of protozoology and helminthology using paired t and repeated measure tests.

Results

The mean final scores of the protozoology lesson were not significantly different from that of the helminthology (10.45 ± 2.75 vs.11.25 ± 2.56 on the scale of 20, respectively, P=0.13). There was no significant difference in the mean score of the five quizzes compared with the mean final term score of protozoology. The overall mean scores in the helminthology lesson (11.25±2.56), protozoology lesson (10.45±2.75), and the quizzes (9.16 ± 3.55) were significantly different (P <0.0001).

Conclusion

Frequent announced quizzes were not effective on increasing the medical students’ motivation and learning.