Showing papers by "University of Bologna published in 1981"
TL;DR: In this paper, the authors considered the problem of routing vehicles to supply customers with known demands, in such a way as to minimize the total distance traveled, which is referred to as the vehicle routing problem (VRP).
Abstract: We consider the problem of routing vehicles stationed at a central facility (depot) to supply customers with known demands, in such a way as to minimize the total distance travelled The problem is referred to as the vehicle routing problem (VRP) and is a generalization of the multiple travelling salesman problem that has many practical applications We present tree search algorithms for the exact solution of the VRP incorporating lower bounds computed from (i) shortest spanning k-degree centre tree (k-DCT), and (ii) q-routes The final algorithms also include problem reduction and dominance tests Computational results are presented for a number of problems derived from the literature The results show that the bounds derived from the q-routes are superior to those from k-DCT and that VRPs of up to about 25 customers can be solved exactly
541 citations
TL;DR: This paper gives a survey of a general relaxation procedure whereby the state-space associated with a given dynamic programming recursion is relaxed in such a way that the solution to the relaxed recursion provides a bound which could be embedded in general branch and bound schemes for the solution of the problem.
Abstract: It is well-known that few combinatorial optimization problems can be solved effectively by dynamic programming alone, since the number of vertices of the state space graph is enormous. What we are proposing here is a general relaxation procedure whereby the state-space associated with a given dynamic programming recursion is relaxed in such a way that the solution to the relaxed recursion provides a bound which could be embedded in general branch and bound schemes for the solution of the problem. This state space relaxation method is analogous to Langrangian relaxation in integer programming. This paper gives a survey of this new methodology, and gives, as examples, applications to the traveling salesman problem (TSP), the timeconstrained TSP and the vehicle routing problem (VRP). Valid state space relaxations are discussed for these problems and several bounds are derived in each case. Subgradient optimization and “state space ascent” are discussed as methods of maximizing the resulting lower bounds. More details of the procedures surveyed in this paper can be found in [2 ,3 ,41.
338 citations
TL;DR: Life events reported to have occurred 6 months before the onset of illness were compared in 40 outpatients who had a first episode of primary depression and a matched normal control group, consistent with the view that certain recent life events play a substantial role as precipitants in some depressed patients.
336 citations
TL;DR: Five patients between the ages of 7 and 74 years presented with nocturnal episodes characterized by coarse, often violent movements of the limbs and by a tonic phase of variable duration, indicating a distinct nosological entity whose pathophysiology is not yet understood.
Abstract: Five patients between the ages of 7 and 74 years presented with nocturnal episodes characterized by coarse, often violent movements of the limbs and by a tonic phase of variable duration. Seizures recurred every night or almost every night during slow wave (NREM) sleep and were not associated with electroencephalographic (EEG) abnormalities. Interictal EEGs were normal during both sleep and wakefulness. Carbamazepine treatment was effective in all patients. Uniform clinical behavior and EEG patterns indicate a distinct nosological entity whose pathophysiology is not yet understood.
214 citations
TL;DR: Adequacy of treatment had an important influence on the incidence of recurrence, length of survival, and length of disease-free survival of patients seen at the Istituto Ortopedico Rizzoli.
Abstract: We retrospectively reviewed the records of 125 patients with chondrosarcoma seen at the Istituto Ortopedico Rizzoli. All of the patients had been followed for at least five years, and ninety-six patients had been followed for at least ten years. The requirements for the adequacy of treatment were carefully defined. Metastasis and survival were related to the histological grade of the tumor. Nine per cent of the grade-1 lesions and 44 per cent of the grade-3 lesions metastasized. Ninety-four per cent of the patients with grade-1 lesions survived for five years, compared with only 44 per cent of patients with grade-3 lesions. The ten-year survival rates were 87 per cent and 27 per cent, respectively. Adequacy of treatment had an important influence on the incidence of recurrence, length of survival, and length of disease-free survival. The incidence of recurrence in adequately treated patients was 6 per cent, but in inadequately treated patients it was 69 per cent. The five-year survival rates in these two groups were 81 per cent and 53 per cent, respectively. Seventy-eight per cent of the adequately treated patients were disease-free at follow-up (mean, 11.1 years) compared with only 6 per cent of the inadequately treated patients. We compared the results of this review with those of other reviews of chondrosarcoma.
207 citations
TL;DR: It is suggested that nifedipine may be advantageously used in the medical treatment of achalasia of mild or moderate degree.
181 citations
TL;DR: The photophysical and electron transfer properties of the lowest excited state of nine ruthenium (polypyridine) complexes have been characterized in this article, where the results show that the Ru (bpy)2(DMCH)2+ complex is expected to be a more efficient mediator than Ru(bpy)-2+3 in the water splitting reaction by solar energy.
Abstract: The photophysical and electron transfer properties of the lowest excited state of nine ruthenium (polypyridine) complexes have been characterized. The complexes studied are Ru (bpy)3-n (LL)2+n, where n varies from 0 to 3, and LL is 4, 4′-di-t-butyl-2,2′-bipyridine (DTB-bpy), 3, 3′-dimethyl-2, 2′-bipyridine (DM-bpy), or a 2, 2′-diquinolyl derivative (DMCH). The results obtained show that the Ru (bpy)2(DMCH)2+ complex is expected to be a more efficient mediator than Ru (bpy)2+3 in the water-splitting reaction by solar energy.
167 citations
TL;DR: Twenty year's experience in the treatment of osteosarcoma at the Bone Tumor Center of the Istituto Ortopedico Rizzoli is presented and reference is made to the advantages of a large and homogeneous caseload deriving from a single institution to avoid preselection bias and evaluate the effectiveness of new therapeutic approaches when patient randomization has not been employed.
Abstract: Twenty year's (1959-1979) experience in the treatment of osteosarcoma at the Bone Tumor Center of the Istituto Ortopedico Rizzoli is presented. During this period 433 cases were recorded, but only 266 were considered. All the patients underwent surgery but after 1970 whole-lung irradiation (1971), immunotherapy (1971), and chemotherapy (1972 onward) were added as adjuvant therapies on a nonrandomized basis. In the group treated with surgery alone the prognosis was very poor: 10% survived nine years or more after the diagnosis, an average disease-free interval of 7.7 months and an average survival time of 13 months. Monolateral whole-lung irradiation had negative results and was abandoned after six cases. Adjuvant immunotherapy with irradiated autologous tumor cells gave moderately positive results in 16 patients, but only by delaying the appearance of first metastases, therefore increasing the time of survival. Adjuvant chemotherapy was performed with three different protocols: one protocol with ADM only and two protocols using VCR + MTX (at medium dose) + ADM, administered according to two different schedules. Superimposable results were obtained with these three regimens. With equal follow-up, the percentage of continuously disease-free patients treated with adjuvant chemotherapy was significantly higher than that of patients treated with surgery alone (P less than 0.001). The patients in the chemotherapy group who had relapses showed a prolonged time (mean = 12.3 months) to the onset of the first metastasis. Adjuvant chemotherapy caused virtually no morbidity and no deaths. Reference is made to the advantages of a large and homogeneous caseload deriving from a single institution to avoid preselection bias and evaluate the effectiveness of new therapeutic approaches when patient randomization has not been employed.
152 citations
TL;DR: In this paper, the authors deal with the models for estimating the life of electrical insulation under multiple stress conditions and propose a new model for insulation life under combined stresses, perfectly symmetrical in thermal and electrical stress.
Abstract: The paper deals with the models for estimating the life of electrical insulation under multiple stress conditions. In a first approach, simple models, the inverse-power law and the exponential, are considered for electrical aging; they are combined with the Arrhenius model to find the life equation of insulating materials under temperature and voltage. This equation is discussed and the corresponding surface studied and drawn. Since experimental results often disagree with these models in the low-stress range, an improved electrical model is proposed in which a threshold electrical gradient is introduced. This also involves the introduction of a threshold temperature, variable with electrical stress. Using some simple assumptions about the thresholds, it is possible to attain a new model for insulation life under combined stresses, perfectly symmetrical in thermal and electrical stress. The results of both voltage endurance tests on various insulating materials and multiple stress tests on a composite material agree with the proposed model and show its capability by accurately predicting the longtermerm behavior of insulation.
147 citations
TL;DR: A state-of-the-art review of electron interferometry and interference electron microscopy is given in this article, with particular reference to off-axis electron holography.
Abstract: A state-of-the-art review of electron interferometry and interference electron microscopy is given. The various types of interferometry device, interferometers and interference microscopes, which have been proposed and/or constructed are reviewed and commented upon. The electron biprism, by far the most successful interferometry device, is treated in some detail from both the experimental and theoretical (geometric and wave optics) points of view. The applications of electron interferometry are presented with particular reference to off-axis electron holography. Finally the future perspectives are indicated.
142 citations
TL;DR: It is shown how the image of a complete set of independent invariants for the considered equivalence relation can be used to parametrize a subset of canonical forms in the given set.
TL;DR: It is suggested that gangliosides cause strong side-side head group interactions on the bilayer surface--betweenganglioside oligosaccharide chains and between gangliosiside and phosphatidylcholine polar portions--which lead the lipid chains to assembly in a more rigid fashion.
TL;DR: In this paper, a series of analyses performed on the carbonaceous particles and on thin sections of sulfated layers show that these particles are probably the most important, if not the determinant, agents of the observed deterioration.
01 May 1981
TL;DR: In this paper, the fracture toughness parameters K1C,G1C and J1C for some aggregative materials were determined using load-displacement curves, following the procedure suggested by Begley and Landes for steel alloys.
Abstract: The object of the paper is to determine the fracture toughness parameters K1C,G1C and J1C for some aggregative materials. Values of the J-integral are calculated from load-displacement curves, following the procedure suggested by Begley and Landes for steel alloys. Some recurring experimental incoherences are explained applying Buckingham's Theorem for physical similitude and scale modeling to Fracture Mechanics. Thus a non-dimensional parameter can be defined (the test brittleness number), which governs the fracture-sensitivity phenomenon. The fracture parameters K1C and J1C are connected by a fictitious Young's modulus E*, which is lower than the real modulus E and represents the stiffness of the damaged material near the crack tip before the extension. When the specimen sizes are so small that the material becomes fracture insensitive, then E* appears higher than E.
TL;DR: In this article, the fatty acid constituents of the lipid fraction of royal jelly were characterized by thin layer chromatography of corresponding methyl esters, and the most common characteristic of the organic acids was that most contained 8 or 10 carbon atoms, whether saturated or unsaturated, linear or branched.
Abstract: This present work characterizes the fatty acid constituents of the lipid fraction of royal jelly. Among the organic acids found after fractionation by thin layer chromatography of the corresponding methyl esters, the following compounds were identified by combined GC-MS: saturated and unsaturated linear fatty acids, saturated and unsaturated linear and branched dicarboxylic acids, mono-and dihydroxy acids. The most common characteristic of the organic acids was that most contained 8 or 10 carbon atoms, whether saturated or unsaturated, linear or branched.
TL;DR: When lymphocytes from normotensive subjects without familial hypertension were incubated in plasma of patients with essential hypertension there was an increase in their sodium content, and Incubation with ouabain increased lymphocyte sodium concentration in the normOTensive subjects and patients withessential hypertension.
Abstract: Summary 1. The sodium concentration in lymphocytes was measured in a group of 66 normotensive subjects (40 without familial hypertension and 26 with familial hypertension), in a group of 81 patients with essential hypertension and in a group of 14 patients with secondary hypertension. 2. The mean value (~sD) in normotensive subjects with no history of familial hypertension was 21.9 L- 3-1 mmollkg wet weight, which was significantly lower (P < 0.005) than that of normotensive subjects with familial hypertension (mean value 27.9 k 4.2 mmol/kg). Lymphocyte sodium concentration was significantly higher in patients with essential hypertension (33.2 & 3.3 mmollkg; P < 0.001) than in the subjects with normal blood pressure without familial hypertension. 3. In the patients with essential hypertension there was a significant correlation between lymphocyte sodium concentration and systolic (P < 0-OOS), diastolic (P < 0.001) and mean (P < 0.001) blood pressure. In the normotensive subjects there was no correlation between the lymphocyte sodium concentration and the blood pressure. 4. The patients with secondary forms of hypertension had normal lymphocyte sodium concentration, except in the case of Conn's disease. 5. Incubation with ouabain increased Correspondence: Professor E. Ambrosioni, Cattedra di Farmacologia Clinica, Policlinico s. Orsola, Via Massarenti 9,40138 Bologna, Italia. lymphocyte sodium concentration in the normotensive subjects and patients with essential hypertension; the final sodium concentration was similar in the two groups. 6. When lymphocytes from normotensive subjects without familial hypertension were incubated in plasma of patients with essential hypertension there was an increase in their sodium content.
TL;DR: It is concluded that muscle protein catabolism is increased in cirrhotics, possibly as a result of hyperglucagonemia or the reduced insulin/glucagons ratio, which agrees with the clinical observation of a progressive reduction in lean body mass which becomes evident in an advanced stage of the disease.
TL;DR: In this paper, the authors studied the Cauchy problem for minimally coupled classical Yang-Mills and scalar fields in space-time in the temporal gauge and proved the existence and uniqueness of solutions for small time intervals and for anyn.
Abstract: We study the Cauchy problem for minimally coupled classical Yang-Mills and scalar fields inn+1 dimensional space-time in the temporal gauge. We prove the existence and uniqueness of solutions for small time intervals and for anyn. We then develop a general theory of solutions in local spaces and extend the previous local (in time) results to this more general setting. In space-time dimensions two and three, we prove the existence of global (in time) solutions by the method of a priori estimates, both in global and local spaces. In space-time dimension four, our estimates yield only partial results on the global existence problem.
TL;DR: In this article, the authors derived the pseudoscalar coupling constant g p μ = 8.7 ± 1.9 for the pμp molecule and showed that the coupling constant can be interpreted to extract the ortho-molecular capture rate.
TL;DR: Findings demonstrate that polypeptide hormone or amine production is not restricted to islet cell tumours and it is suggested that both endocrine and exocrine components of the tumours studied might have derived from a common precursor.
Abstract: Eleven cases of primary pancreatic adenocarcinomas have been investigated histochemically, immunohistochemically and with electron-microscopy. Endocrine-paracrine (EP) cells were present in six of these tumours. In one case numerous 5HT-enterochromaffin cells (EC) of the intestinal type and a few somatostatin immunoreactive D cells were found. Two cases contained insulin-immunoreactive cells and another case displayed glucagon-IR elements. In the remaining two cases argyrophilic cells were present. These findings demonstrate that polypeptide hormone or amine production is not restricted to islet cell tumours. It is suggested that both endocrine and exocrine components of the tumours studied might have derived from a common precursor.
TL;DR: The results indicate that biosynthesis of RNA and polyamines precedes tube emergence in germinating Malus domestica Borkh and Starkrimson pollen and that the enzymes involved in polyamine biosynthesis are very active.
Abstract: Variations of RNA, protein, and free- and trichloroacetic acid-soluble bound polyamine levels were determined during tube growth in germinating Malus domestica Borkh. cv. Starkrimson pollen. During rehydration of pollen no marked differences were observed, whereas, during germination, RNA, proteins, and polyamines showed parallel decreases. At the same time, there was synthesis of RNA and polyamines as indicated by use of labeled precursors. The data indicate that during germination: (a) the genes for rRNA, tRNA, and probably mRNA are active; (b) the enzymes involved in polyamine biosynthesis are very active. High levels of free arginine during the first 15 minutes were observed, probably in response to a demand for this precursor in polyamine biosynthesis. Moreover, profiles of the variations in the specific activities of RNA and polyamines showed similar patterns. The results indicate that biosynthesis of RNA and polyamines precedes tube emergence. The possible role of these compounds, which are known to be released into the medium in the progamic phase of the fertilization processes, is considered.
Journal Article•
TL;DR: The hypothesis that a deficiency of the T-dependent regulatory system is an intrinsic feature of Down's syndrome is supported and the precocious aging of the immune system in these subjects is confirmed.
Abstract: The immune competence of the T lymphocyte system was studied in 28 noninstitutionalized subjects with Down's syndrome (DS) and were compared with sex- and age-matched healthy controls. The ability of enriched T lymphocytes to respond to 3 different T cell stimulants revealed a selective impairment of T lymphocyte subset(s). Subjects with DS showed normal responsiveness in allogeneic mixed lymphocyte reactions, but their response to phytohemagglutinin and in autologous mixed lymphocyte reactions was severely impaired. Non-T cells from DS subjects stimulated equally well both normal and DS allogeneic T lymphocytes. The blood concentration of serum thymic factor in the majority of DS subjects was much lower than that found in age-matched healthy controls. These data support the hypothesis that a deficiency of the T-dependent regulatory system is an intrinsic feature of DS and confirm the precocious aging of the immune system in these subjects.
TL;DR: The microwave spectrum of the two possible O-monodeuterated species has been measured in a mixture containing roughly 25% of each of the four possible OD OD isotopic species.
TL;DR: The findings reported here on the strong correlation existing between ER and PR presence or amount agree with previous observations on normal and neoplastic specimens from human breast and endometrial tissues.
Abstract: The cytoplasmic receptors for 17 beta-estradiol (ER), 5 alpha-dihydrotestosterone (AR), progesterone (PR), and cortisol (GR) have been quantified in 36 specimens from the human ovary (13 disease-free, 5 benign, and 18 malignant) by a dextran-coated charcoal (DCC) technique. The occurrence of receptor-positive biopsies were: ER 46%, AR 85%, PR 54%, GR 92%, in normal tissue; ER 40%, AR 100%, PR 20%, GR 50%, in benign tumors; and ER 67%, AR 72%, PR 50%, GR 88%, in malignant lesions. Furthermore, the simultaneous occurrence of ER and PR in malignant tumors was 50% yet all four receptors were found to be present only in 44% of the cases. The findings reported here on the strong correlation existing between ER and PR presence or amount agree with previous observations on normal and neoplastic specimens from human breast and endometrial tissues.
TL;DR: This work defines a particular tree-search technique for the ILP, which makes use of a lower bound to determine the branches to follow in the decision tree, and applies it to the solution of the Zero-One Multiple Knapsack Problem.
TL;DR: In this paper, a detailed account of the one-loop QCD corrections to the annihilation widths into hadrons and into two photons of P wave quarkonium states of JPC = 0++, 2++ is given.
TL;DR: A cycle of postlarval growth is described in the white portion of the lateralis muscle of Mugilidae, which was identified histochemically by the myosin-ATPase reaction.
Abstract: A cycle of postlarval growth is described in the white portion of the lateralis muscle of Mugilidae. The cycle was identified histochemically by the myosin-ATPase reaction.
TL;DR: In this paper, the lifetime τ μ − = 2194.903 ± 0.066 ns and τ μ + = 2197.182 ± 0.121 ns were derived for the pμp molecular ions.
TL;DR: In this article, primary amines bearing an α-hydrogen atom are quantitatively converted to symmetrical secondary amines by heating at 185°C for 5 h in the presence of a catalytic amount of RuCl 2 (Ph 3 ) 3.