Number Of Contractions Research Articles

Epidemiology of pneumonia in hospitalized adults ≥18 years old in four districts of Ulaanbaatar, Mongolia, 2015–2019

Community-acquired pneumonia is a leading cause of morbidity and mortality among children and adults worldwide. Adult pneumonia surveillance remains limited in many low- and middle-income settings, resulting in the disease burden being largely unknown. A retrospective cohort study was conducted by reviewing medical charts for respiratory admissions at four district hospitals in Ulaanbaatar during January 2015-February 2019. Characteristics of community-acquired pneumonia cases were summarized by disease severity and age. To explore factors associated with severe pneumonia, we ran univariable and age-adjusted logistic regression models. Incidence rates were calculated using population denominators. In total, 4290 respiratory admissions met the case definition for clinical pneumonia, including 430 admissions of severe pneumonia. The highest proportion of severe pneumonia admissions occurred in adults >65 years (37.4%). After adjusting for age, there were increased odds of severe pneumonia in males (adjusted odds ratio [aOR]: 1.63; 95% confidence interval [CI]: 1.33-2.00) and those with ≥1 underlying medical condition (aOR: 1.46; 95% CI: 1.14-1.87). The incidence of hospitalized pneumonia in adults ≥18 years increased from 13.49 (95% CI: 12.58-14.44) in 2015 to 17.65 (95% CI: 16.63-18.71) in 2018 per 10,000 population. The incidence of severe pneumonia was highest in adults >65 years, ranging from 9.29 (95% CI: 6.17-13.43) in 2015 to 12.69 (95% CI: 9.22-17.04) in 2018 per 10,000 population. Vaccination and other strategies to reduce the risk of pneumonia, particularly among older adults and those with underlying medical conditions, should be prioritized. Pfizer clinical research collaboration agreement (contract number: WI236621).

Digitalization for Preserving the Book Heritage of the University Library at “Angel Kanchev” University of Ruse

This paper presents the project “Creating a digital collection in the fund of the University library in University of Ruse “Angel Kanchev” (Centre for digitalization), contract number No 2022- РУ -04, funded by the National Research Fund. Aim of the project is digitizing the first book collection in the University library’s fund and presenting it to the wide audience.

Influence of Legal Traditions and Legal Culture on the Institution of Marriage Contracts and the Possibility of its Improvement: The Experience of Kazakhstan

Since the Republic of Kazakhstan gained independence, it developed market relations and established private property as the leading type of ownership. Such fundamental changes required corresponding changes in the system of law, including family law. However, such reforms often depend on the mindset, legal culture, and legal traditions that have developed in society. In Kazakhstan, the practice of concluding marriage contracts (which govern property relations between spouses) has not developed or been seriously limited. Thus, this sphere needs to be considered for further improvement. The study aims at determining the social and legal factors affecting the regulation of marital relations through the conclusion of marriage contracts in Kazakhstan. Based on an expert survey, the authors of the article have revealed both positive and negative aspects of concluding a marriage contract and considered the main reasons for a small number of such contracts concluded between citizens of Kazakhstan. There a marriage contract is a special extrajudicial way of settling property relations between spouses that may arise in the future, a means of protecting their property rights and exercising property obligations. However, this method of regulation and protection is resorted to families with a high-income level and great life experience and often in special life situations.
 
 Received: 6 June 2022 / Accepted: 15 August 2022 / Published: 2 September 2022

Ausbildungsmarkt unter Druck: die aktuelle Entwicklung und deren Antworten darauf

AbstractThe number of new apprenticeship training contracts has been declining for years. The decline can be explained by a variety of factors. It can initially be assumed that the economic development due to the COVID-19 pandemic and the associated loss of training places offer an explanation. However, the trend is of a longer nature. This article examines proposed solutions, such as the training fund allocation that is currently in discussion, seem more like an expression of futile politics.

Individual Сontract as a Form of Law and its Normativity

Modern society cannot be imagined without the institution of individual contractual regulation – our daily life is surrounded by a large number of contractual legal relations. In this regard, it is relevant to consider such a controversial topic as the recognition of the status of a form of law for an individual contract. The object of the study is social relations related to the conclusion, modification and termination of an individual contract. The empirical base consists of labor and civil law contracts. Based on this, the article has an interdisciplinary character – therefore, the subject is in the field of development of three legal sciences at once – the theory of state and law, civil and labor law. The science of the theory of state and law acts as a methodological basis necessary for evaluating the obtained industry data. General scientific methods are used – structural and functional method, analysis and synthesis, induction and deduction, analogy. Both private scientific methods are used – a formal dogmatic method necessary for the study of law, and a retrospective (historical) method for looking at the problem not in statics, but in dynamics. The novelty is expressed in the substantiation of the normativity of an individual contract and the recognition of its status as a form of law not only within the existing paradigm, but also by offering a different view of the very concept of normativity. The analysis of contracts is proposed to be carried out with the hypothesis of the presence of regulatory regulation in them as well. This approach allows us to talk about contracts that were previously recognized as containing only individual regulation, at least partially normative and, as a result, to see them as a right. As the main conclusion, it should be noted that a significant number of individual contracts contain not only individual, but also regulatory regulation. It also seems reasonable to talk about the existence of individual contracts consisting entirely of regulatory regulation.

On the ruin probability of a generalized Cramér–Lundberg model driven by mixed Poisson processes

AbstractWe propose a generalized Cramér–Lundberg model of the risk theory of non-life insurance and study its ruin probability. Our model is an extension of that of Dubey (1977) to the case of multiple insureds, where the counting process is a mixed Poisson process and the continuously varying premium rate is determined by a Bayesian rule on the number of claims. We use two proofs to show that, for each fixed value of the safety loading, the ruin probability is the same as that of the classical Cramér–Lundberg model and does not depend on either the distribution of the mixing variable of the driving mixed Poisson process or the number of claim contracts.

A Signaling Game of Family Doctors and Residents from the Perspective of Personalized Contracted Service.

The role of the family doctor contracted service system in China’s medical and health system is increasing day by day. However, with the steady increase in contracting coverage, the phenomenon of “signing up but not contracting” has become common; to improve the current situation, the personalized signing service model has been strongly advocated. To promote the smooth implementation of the personalized contracted service model with family doctor competency as its core, this study used the signal game model to analyze the market equilibrium state of the signing service model. The results of this analysis reveal the following: (1) The camouflage of the number of contracts leads to distortion of the signal effect and to market failure, that is, the cost of competency camouflage is the primary factor affecting the equilibrium of contracted services. (2) The incompleteness of contracted services leads to quantity but not quality in the contracting market, that is, the payment of personalized service packages, the value-added utility of personalized services, and service gaps are the key factors that affect the decision-making behavior of the public. With this knowledge in mind, a compensation incentive mechanism that matches the competence level of the family doctor should be established, the formulation of contracted service agreements should be improved, and the participation of family doctors and residents should be encouraged, while the promotion of personalized contracted services should be enhanced and relevant supporting measures should be improved.

P16. Biomechanical assessments of the spine during a 2000M ergometer row test

<h3>BACKGROUND CONTEXT</h3> Ergometer rowing has gained popularity as a "low-impact" form of exercise. Lumbar spine injuries are the most common injury in rowers. Previous studies have shown ergometer training to be associated with an increased risk of injury. Muscular fatigue and spine range of motion may correlate to pain or injury in ergometer rowing. <h3>PURPOSE</h3> The purpose of the present study is to utilize 3D motion capture and electromyography (EMG) assessments to 1) evaluate how muscular activation relates to lumbar spine mechanics; 2) determine the impact of fatigue on back muscle activation and biomechanics. <h3>STUDY DESIGN/SETTING</h3> Prospective analysis. <h3>PATIENT SAMPLE</h3> Seventeen rowers (M=8, F=9) with a mean age of 38 ± 9.1 years and a VO2 max of 44.4 ± 7.8 ml·kg·min-1. <h3>OUTCOME MEASURES</h3> Pull force, kinematics and muscle activation were recorded at 200m, 600m, 1000m, 1400m and 1800m distances. Spine flexion (degrees) was investigated. <h3>METHODS</h3> Seventeen rowers (m=8, F=9; age=38±9.1 years, VO2max=44.4±7.8 ml·kg·min-1) participated and performed a 2000-meter row on an ergometer. Pull force, kinematics and muscle activation were recorded using a load cell, motion capture system and a wireless EMG, respectfully. Data was recorded at 200m, 600m, 1000m, 1400m and 1800m distances. Spine flexion was calculated at three points in the sagittal plane and labeled as upper-, mid- and lower-spine. A mixed-model ANOVA repeated on row distance and a Tukey's post-hoc test was used to compare biomechanical assessments. Type-I error was set at a=0.05. <h3>RESULTS</h3> Average time to complete the test was 8.4 ± 1.0 min. Trapezius and mid-spinal erector activation was maintained through the row. A steady decrease in mean and peak latissimus dorsi activation was observed with increasing distance (p < 0.05), paired with an increase in peak lumbar spinal erector activation (p < 0.05), indicating fatigue of the upper back musculature followed by compensatory reliance on low back muscles to maintain/increase force. Upper spinal flexion (min and max) increased by 1000m, indicating an increase in the overall state of flexion with progressing distance (p < 0.05). Mid-spinal flexion demonstrated increased min flexion (indicating reduced peak extension) beginning at 1400m (P < 0.05). Lumbar spine flexion was maintained throughout the row, indicating that the primary mechanics fatigue change was a result of upper back rounding due to upper back muscle fatigue. Results indicate that low back pain and injuries associated with rowing may not be because of altered flexion/extension of the lumbar spine but rather, a result of increased workload placed on low back musculature to compensate fatiguing muscles and changes in the row mechanics of the upper and mid spine. Although ergometer rowing is often considered "low-impact," given the high number of contractions over a short time (<10min), it may be advisable for rowers to avoid multiple days of fatiguing row ergometer training per week. <h3>CONCLUSIONS</h3> The present findings will provide greater insight into the potential mechanisms of fatigue during ergometer rowing. Results will also give medical professionals a better understanding of the origins and presentation of soft tissue injuries in the spine in recreational rowers. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.

Prospectively assessed perceived stress associated with early pregnancy losses among women with history of pregnancy loss.

What is the association between perceived stress during peri-conception and early pregnancy and pregnancy loss among women who have experienced a prior pregnancy loss? Daily perceived stress above the median is associated with over a 2-fold risk of early pregnancy loss among women who have experienced a prior loss. Women who have experienced a pregnancy loss may be more vulnerable to stress while trying to become pregnant again. While prior research has indicated a link between psychological stress and clinically confirmed miscarriages, research is lacking among a pre-conceptional cohort followed prospectively for the effects of perceived stress during early critical windows of pregnancy establishment on risk of both hCG-detected pregnancy losses and confirmed losses, while considering important time-varying confounders. Secondary data analysis of the EAGeR trial (2007-2011) among women with an hCG-detected pregnancy (n = 797 women). Women from four US clinical centers enrolled pre-conceptionally and were followed ≤6 cycles while attempting pregnancy and, as applicable, throughout pregnancy. Perceived stress was captured via daily diaries and end-of-month questionnaires. Main outcome measures include hCG-detected and clinically recognized pregnancy losses. Among women who had an hCG-confirmed pregnancy, 188 pregnancies (23.6%) ended in loss. Women with high (>50th percentile) versus low (≤50th percentile) peri-implantation or early pregnancy weekly perceived stress had an elevated risk of experiencing any pregnancy loss (hazard ratio (HR): 1.69, 95% CI: 1.13, 2.54) or clinical loss (HR: 1.58, 95% CI: 0.96, 2.60), with higher risks observed for women experiencing an hCG-detected loss (HR: 2.16, 95% CI: 1.04, 4.46). Models accounted for women's age, BMI, employment, marital status, income, education, race, parity, prior losses, exercise and time-varying nausea/vomiting, caffeine, alcohol and smoking. We were limited in our ability to clearly identify the mechanisms of stress on pregnancy loss due to our sole reliance on self-reported perceived stress, and the lack of biomarkers of different pathways of stress. This study provides new insight on early pregnancy perceived stress and risk of pregnancy loss, most notably hCG-detected losses, among women with a history of a prior loss. Our study is an improvement over past studies in its ability to account for time-varying early pregnancy symptoms, such as nausea/vomiting, and lifestyle factors, such as caffeine, alcohol and smoking, which are also risk factors for psychological stress and pregnancy loss. This work was supported by the Intramural Research Program of the Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland (Contract numbers: HHSN267200603423, HHSN267200603424, HHSN267200603426, HHSN275201300023I). Additionally, K.C.S. was supported by the National Institute on Aging of the National Institutes of Health under Award Number K01AG058781. The authors have no conflicts of interest to disclose. #NCT00467363.

The role of corporate social responsibility (CSR) information in supply-chain contracting: Evidence from the expansion of CSR rating coverage

We examine the effect of CSR information on stakeholder decision-making, specifically on supply-chain contracting. To obtain plausibly exogenous variation in CSR information, we exploit the 2017 expansion of CSR rating coverage from Russell 1000 to Russell 2000 firms (hereafter, “treated firms”) by Thomson Reuters Asset4. Using a difference-in-differences design with the previously covered Russell 1000 supplier firms as the control group, we find a negative effect of the CSR information shock for treated suppliers with comparatively low CSR ratings. On average, these suppliers experience reductions in their number of contracts and corporate customers. In cross-sectional analyses, we document variation in our treatment effects consistent with two underlying mechanisms: (i) benchmarking of suppliers' CSR by corporate customers and (ii) CSR-related public pressure on customer-supplier contracting. Collectively, our findings provide novel evidence on the causal effect of CSR information on stakeholder decision-making.

Greater effects by performing a small number of eccentric contractions daily than a larger number of them once a week.

Our previous study found that one maximal voluntary eccentric contraction (MVC-ECC) performed daily for 5 days a week for 4 weeks increased MVC-ECC, isometric (MVC-ISO), and concentric contraction (MVC-CON) torque of the elbow flexors more than 10%. The present study investigated the effects of six maximal voluntary eccentric contractions on the MVC torques and biceps brachii and brachialis muscle thickness (MT). Thirty-six healthy young adults were placed to one of the three groups (N=12 per group); the 6 × 1 group that performed one set of six contractions once a week, the 6 × 5 group that performed one set of six contractions a day for 5 days a week, and the 30 × 1 group that performed five sets of six contractions a day in a week. The training duration was 4 weeks for all groups, and changes in MVC-ECC, MVC-CON and MVC-ISO torque, and MT before and after the 4-week training were compared among the groups. The 6 × 1 group did not show significant changes in muscle strength and MT. Significant (p < 0.05) increases in MVC-ECC (13.5 ± 11.5%), MVC-ISO (9.3 ± 5.5%), MVC-CON torque (11.1 ± 7.4%) were evident for the 6 × 5 group only, and increases in MT were found for the 6 × 5 (10.4 ± 4.4%) and 30 × 1 (8.0 ± 5.8%) groups without a significant difference. These results suggest that performing a small number of eccentric contractions 5 days a week is more effective for increasing muscle strength than performing a larger volume of eccentric contractions once a week. However, it appears that training volume is a factor for muscle hypertrophy in a short-term training.

E&amp;P Notes (August 2022)

E&amp;P Notes (August 2022)

Protective effects of hydrogen sulfide pretreatment on cyclophosphamide-induced bladder dysfunction in rats via suppression of bladder afferent nerves

Cyclophosphamide (CYP), a broad-spectrum anticancer drug, causes serious side effects, such as haemorrhagic cystitis (HC). Hydrogen sulfide (H2S), an endogenous gasotransmitter, has physiological properties, including anti-inflammation, anti-oxidation, and neuromodulation. In this study, we investigated the effects of NaHS (H2S donor) pretreatment on bladder dysfunction in CYP-treated rats. Male Wistar rats were intraperitoneally pretreated with NaHS (3 or 10 μmol/kg) or vehicle once daily for 7 days before cystometry, and CYP (150 mg/kg) or saline was intraperitoneally administered 2 days before cystometry. After cystometry, the bladder tissues were collected for haematoxylin and eosin staining. In some rats, capsaicin (CAP), which can desensitise CAP-sensitive afferent nerves, was subcutaneously injected at 125 mg/kg 4 days before cystometry. CYP reduced intercontraction intervals (ICI) and bladder compliance (Comp) and increased the number of non-voiding contractions (NVCs) compared with the saline-treated control group. NaHS pretreatment dose-dependently improved the CYP-induced these changes. In bladder tissues, CYP increased histological scores of neutrophil infiltration, haemorrhage, and oedema, while NaHS had no effect on these CYP-induced changes. CAP showed a tendency to suppress CYP-induced changes in ICI. NaHS-induced improvement in CYP-induced changes in urodynamic parameters were not detected in CAP-treated rats. These findings suggest that NaHS pretreatment prevented bladder dysfunction in CYP-treated rats by suppressing CAP-sensitive bladder afferent nerves, but not by suppressing bladder inflammation. Therefore, H2S represents a new candidate as a protective drug for bladder dysfunction induced by HC, a side effect of CYP chemotherapy.

The effect of tocolytics in women with preterm labor after 34 weeks of gestation: A propensity score-matched study

ObjectivesSince late preterm neonates are physiologically less mature than term neonates, the use of antenatal corticosteroids in the late preterm period has been recommended. The use of tocolytics can also be considered to gain valuable time for using antenatal corticosteroids in the late preterm period. In this study, we examined the efficacy of tocolytics on prolonging pregnancy in the late preterm period, by comparing women who received tocolytics with those who received none. Study designThis retrospective cohort study included women who were admitted due to preterm labor after 34 weeks of gestation and delivered in the late preterm period. Primary outcome was time from admission to delivery (days). Secondary outcomes were the proportion of preterm births within 2 days, and within 7 days, completed cycles of antenatal corticosteroids, and the neonatal outcomes. Primary and secondary outcomes were compared according to the use of tocolytics. Propensity score matching was performed to create comparable groups. The maternal age, pre-pregnancy body mass index, nulliparity, history of preterm birth, hypertensive disease during pregnancy, gestational diabetes mellitus, history of preterm labor, gestational age at admission, cervical length, and the number of contractions were the baseline characteristics included in the propensity score. ResultsOf 275 women, 44 women received tocolytics (tocolytics group) and 231 women did not (no tocolytics group). We matched 44 women who received tocolytics and 44 women who didn’t. The tocolytics group was shown to exhibit a longer time from admission to delivery than the no tocolytics group, with a hazard ratio for tocolytics of 0.4 (95 % confidence interval, 0.2–0.6). In addition, the proportion of preterm births occurring within 2 days and 7 days were lower in those receiving tocolytics compared to those that didn’t. ConclusionIn this propensity score matched-study, the use of tocolytics had a significant effect on pregnancy prolongation, which allows more time for use of corticosteroids in women with preterm labor after 34 weeks of gestation.

Earlier detection of SARS-CoV-2 infection by blood RNA signature microfluidics assay.

Earlier detection of SARS-CoV-2 infection by blood RNA signature microfluidics assay.

Investigation of Graphite Electrode Degradation in Lithium-Ion Cells Using 4D-STEM

The development of longer lasting and faster charging lithium-ion batteries (LIBs) remains a critical engineering priority for the U.S. Department of Energy. To enable the next-generation technology, it is essential to understand the nature and extent of materials failure during battery operation. Under fast-charging conditions, it has been shown that graphite particles, which comprise the active material of the LIB anode, suffer irreversible material degradation that limits ultimate battery performance. This damage to the graphite manifests as turbostratic lattice disorder, severe morphological roughening, and anode swelling [1]. While these findings are essential to understand the nature of damage to the anode under fast-charge conditions, it remains to be seen whether such damage occurs at slower rates or is instead accelerated by extreme rate conditions and aging. In this regard, the recent advances in high-resolution electron microscopy (HREM) and four-dimensional scanning transmission electron microscopy (4D-STEM) methods provide the essential tools to enable nanoscopic quantification of battery degradation [2], [3].In this work, we use advanced analytical electron microscopy and diffraction strategies to analyze nanoscopic degradation of graphite anode material under different cycling rate and aging conditions. The results of this work will demonstrate novel strategies for identifying nanoscale structural disorder that arise in battery materials as well as provide key understanding of graphite material failure to aid in the development of high-performance anode materials. We study (in post-mortem) the graphite particle cross-sections harvested from LIBs at different aging conditions for both C/2 (i.e., 2 hours to full charge) and 6C (i.e., 10 minutes to full charge) rate. At the nano- to atomic-scale, we rely primarily on aberration-corrected STEM for imaging and diffraction acquisition for each sample (see Figure 1 for the results). High resolution imaging reveals the extent of lattice disorder and amorphous character localized at graphite pore edges. The 4D-STEM data helps to further quantify the extent and distribution of nanoscale structural disorder (including permanent strain and turbostratic disorder). The experimental methods employed to acquire the datasets and the strategies employed to interpret the data to understand the nature of the resulting damage, including recent progress into Cepstral STEM, will be discussed. Additional supporting evidences of graphite disorder from Raman spectroscopy studies and rate-dependent anode swelling from scanning electron microscopy will also be presented. References : [1] S. Pidaparthy, M.-T. F. Rodrigues, J.-M. Zuo, and D. P. Abraham, “Increased Disorder at Graphite Particle Edges Revealed by Multi-length Scale Characterization of Anodes from Fast-Charged Lithium-Ion Cells,” J. Electrochem. Soc., vol. 168, no. 10, p. 100509, 2021.[2] J.-M. Zuo et al., “Data-Driven Electron Microscopy: Electron Diffraction Imaging of Materials Structural Properties,” arXiv Prepr. arXiv2110.02070, 2021.[3] E. Padgett et al., “The exit-wave power-cepstrum transform for scanning nanobeam electron diffraction: robust strain mapping at subnanometer resolution and subpicometer precision,” Ultramicroscopy, vol. 214, p. 112994, 2020. Acknowledgements: SP acknowledges support from the U. S. Department of Energy Graduate Student Research (SCGSR) program. The SCGSR program is administered by the Oak Ridge Institute for Science and Education for the U. S. Department of Energy under contract number DE‐SC0014664. This work was carried out in part in the Materials Research Laboratory Central Research Facilities, University of Illinois. DA and MTFR acknowledge support from DOE’s Vehicle Technologies Office. This document has been created by UChicago Argonne, LLC, Operator of Argonne National Laboratory (“Argonne”). Argonne, a U.S. Department of Energy Office of Science laboratory, is operated under Contract No. DE-AC02-06CH11357. Figure 1

Issue analysis of contracts termination in Russian state and municipal public procurement procedures

The article points out the problem of quality of interaction between the customer and the supplier of goods, works or services in the sphere of state and municipal public procurement procedures of Russian Federation. One of the manifestations of the problem is the high percentage of contract termination between procurement participants (approximately 20 % of the number of contracts concluded). The objective of the study was to suggest potential directions for improving the quality of interaction between procurement participants, against the background of considering the legal grounds for contracts termination. Based on the results of the study, the author identified the problem of lack of technics in the procurement control process, which reduce consequences of the uncertainty external environment impact and fair risk responsibility sharing of non-performing contract liabilities between the procurement participants.

Integrating Empirical Analysis and Normative Inquiry in Health Technology Assessment: The Values in Doing Assessments of Health Technologies Approach.

Health technology assessment (HTA) aims, through empirical analysis, to shed light on the value of health technologies (O'Rourke et al. [2020, International Journal of Technology Assessment in Health Care 36, 187-90]). HTA is, then, where facts and values meet. But how, where, and when do facts and values meet in HTA? Currently, HTA is usually portrayed as a sequential process, starting with empirical analysis (assessment), followed by a deliberation on the implications of the findings for a judgment of a health technology's value (appraisal). In this paper, we will argue that in HTA, empirical analysis and normative inquiry are much more closely entwined. In fact, as we hope to show, normative commitments act as an indispensable guide for the collection and interpretation of empirical evidence. Drawing on policy sciences, we will suggest a concrete methodology that can help HTA practitioners to integrate empirical analysis and normative inquiry in a transparent way. The proposed methodology can be conceived as a concrete means for conducting a scoping exercise in HTA. Moreover, it offers a distinct way of giving stakeholders a structural and constructive role in HTA. This paper outlines the approach developed by the values in doing assessments of health technologies project, a project funded by the Erasmus+ program (contract number 2018-1-NL01-KA203-038960), which is the European Union's program to support education, training, youth, and sport in Europe. The project has resulted in an E-learning course, an accompanying handbook, and a consensus statement, all freely available from the project's website www.validatehta.eu.

COMPARATIVE ANALYSIS OF THE DYNAMICS OF DEVELOPMENT OF INSURANCE IN THE SPHERE OF WATER TRANSPORT: UKRAINIAN PRACTICE AND FOREIGN EXPERIENCE

COMPARATIVE ANALYSIS OF THE DYNAMICS OF DEVELOPMENT OF INSURANCE IN THE SPHERE OF WATER TRANSPORT: UKRAINIAN PRACTICE AND FOREIGN EXPERIENCE

A MIP-based heuristic for a single trade routing and scheduling problem in roll-on roll-off shipping

We study a single trade ship routing and scheduling problem for a roll-on roll-off shipping company. Along the given trade, there is a number of contracts for transportation of cargoes between port pairs. Each contract states a minimum service frequency where the services should be evenly separated in time and possibly transit time requirements. Current planning practice is to visit all ports along the trade every time it is serviced. Here, we aim instead at determining the sailing route and schedule of each voyage along the trade, i.e., which ports to visit when, which contracts to serve, and the sailing speeds, so that all contract requirements are satisfied at minimum cost. To solve this problem, we have developed a three-phase MIP-based heuristic, where each phase consists of solving dedicated a mixed-integer programming (MIP) model. The heuristic constructs solutions by first identifying the most promising candidate routes along the trade. Next, a candidate route is allocated to each available vessel. Finally, the heuristic determines the allocation of cargoes between the vessels, as well as sailing speeds and arrival times. Computational tests show that the heuristic outperforms a commercial MIP-solver and provides high-quality solutions to realistically sized instances in reasonable time.