Admission Threshold Research Articles

Playing Ping- Pong: Keeping Frail Older Adults Out Of Hospital

Abstract Background EDITH (Emergency Department in the home) is a rapid response team consisting of a doctor/Advanced Nurse Practitioner and Occupational Therapist who assess patients in their home to avoid an ED attendance. The Integrated Care Team for Older People (ICPOP) is a community-based specialist multidisciplinary team that provides assessment and intervention for frail older adults in order to maintain them living at home. The teams have developed a close working relationship and utilise each other’s services to provide right time, right place patient care with the ultimate shared goal of keeping older adults living well at home. Methods A high frequency service user was identified, and a retrospective chart review was completed between the two teams. Outcome measures such a CFS, 4AT, medical status, social supports and environment set up were noted. Patient journey was conceptualised and handover of medical responsibility from team to team was explored along with identifying other factors that maintain older adults living well in their homes. Results Over a 12-month period, patient X case was “ping ponged” between the two services. The patient attended ED with EDITH review in the home facilitating a direct discharge home. The ICPOP team provided ongoing interdisciplinary and specialised intervention. ICPOP also identified changes to medical status that warranted timely EDITH review and thus negated the need for ED attendance. Patient X avoided a hospital admission during that period due to co working and open communication between both teams. Conclusion Rapid access, timely communication and team work between the EDITH/ICPOP yielded a positive result for patient X and allowed them to remain at home, despite a high level of frailty and low threshold for hospital admission. It appears that having services working with a collaborative approach affords better outcomes for this vulnerable population and reduces pressure on hospital resources.

The HEARTRISK6 Scale: Predicting Short-Term Serious Outcomes in Emergency Department Acute Heart Failure Patients

BackgroundAcute heart failure (AHF) is a common emergency department (ED) presentation that may have poor outcomes but often does not require hospital admission. There is little evidence to guide dispositional decisions. ObjectivesThe authors sought to create a risk score for predicting short-term serious outcomes (SSO) in patients with AHF. MethodsWe pooled data from 3 prospective cohorts: 2 published studies and 1 new cohort. The 3 cohorts prospectively enrolled patients who required treatment for AHF at 10 tertiary care hospital EDs. The primary outcome was SSO, defined as death <30 days, intubation or noninvasive ventilation (NIV), myocardial infarction, or relapse to ED <14 days. The logistic regression model evaluated 13 predictors, used an AIC-based step-down procedure, and bootstrapped internal validation. ResultsOf the 2,246 patients in the 3 cohorts (N = 559; 1,100; 587), the mean age was 77.4 years, 54.5% were male, 3.1% received intravenous nitroglycerin, 5.2% received ED NIV, and 48.6% were admitted to the hospital. There were 281 (12.5%) SSOs including 70 deaths (3.1%) with many in discharged patients. The final HEARTRISK6 Scale included 6 variables: valvular heart disease, tachycardia, need for NIV, creatinine, troponin, and failed reassessment (walk test). Choosing HEARTRISK6 total-point admission thresholds of ≥1 or ≥2 would yield, respectively, sensitivities of 88.3% (95% CI: 83.9%-91.8%) and 71.5% (95% CI: 65.9%-76.7%) and specificities of 24.7% (95% CI: 22.8%-26.7%) and 50.1% (95% CI: 47.9%-52.4%) for SSO. ConclusionsUsing 3 large prospectively collected datasets, we created a concise and sensitive risk scale for patients with AHF in the ED. Implementation of the HEARTRISK6 scale could lead to safer and more efficient disposition decisions.

Learning and Balancing Unknown Loads in Large-Scale Systems

Consider a system of identical server pools where tasks with exponentially distributed service times arrive as a time-inhomogeneous Poisson process. An admission threshold is used in an inner control loop to assign incoming tasks to server pools, while in an outer control loop, a learning scheme adjusts this threshold over time to keep it aligned with the unknown offered load of the system. In a many-server regime, we prove that the learning scheme reaches an equilibrium along intervals of time when the normalized offered load per server pool is suitably bounded and that this results in a balanced distribution of the load. Furthermore, we establish a similar result when tasks with Coxian distributed service times arrive at a constant rate and the threshold is adjusted using only the total number of tasks in the system. The novel proof technique developed in this paper, which differs from a traditional fluid limit analysis, allows us to handle rapid variations of the first learning scheme, triggered by excursions of the occupancy process that have vanishing size. Moreover, our approach allows us to characterize the asymptotic behavior of the system with Coxian distributed service times without relying on a fluid limit of a detailed state descriptor. Funding: The work in this paper was supported by the Nederlandse Organisatie voor Wetenschappelijk Onderzoek [Gravitation Grant NETWORKS-024.002.003 and Vici Grant 202.068].

Performance of ChatGPT on Chinese Master's Degree Entrance Examination in Clinical Medicine.

ChatGPT is a large language model designed to generate responses based on a contextual understanding of user queries and requests. This study utilised the entrance examination for the Master of Clinical Medicine in Traditional Chinese Medicine to assesses the reliability and practicality of ChatGPT within the domain of medical education. We selected 330 single and multiple-choice questions from the 2021 and 2022 Chinese Master of Clinical Medicine comprehensive examinations, which did not include any images or tables. To ensure the test's accuracy and authenticity, we preserved the original format of the query and alternative test texts, without any modifications or explanations. Both ChatGPT3.5 and GPT-4 attained average scores surpassing the admission threshold. Noteworthy is that ChatGPT achieved the highest score in the Medical Humanities section, boasting a correct rate of 93.75%. However, it is worth noting that ChatGPT3.5 exhibited the lowest accuracy percentage of 37.5% in the Pathology division, while GPT-4 also displayed a relatively lower correctness percentage of 60.23% in the Biochemistry section. An analysis of sub-questions revealed that ChatGPT demonstrates superior performance in handling single-choice questions but performs poorly in multiple-choice questions. ChatGPT exhibits a degree of medical knowledge and the capacity to aid in diagnosing and treating diseases. Nevertheless, enhancements are warranted to address its accuracy and reliability limitations. Imperatively, rigorous evaluation and oversight must accompany its utilization, accompanied by proactive measures to surmount prevailing constraints.

Bronchiolitis in Infants and Children before the Surge of COVID-19: Predictors of Outcome and Length of Stay

Background:: Despite the available clinical practice guidelines, many management decisions in bronchiolitis are made subjectively, resulting in variable length of stay and unplanned ICU admissions. We hypothesized that certain independent predictors would affect the length of stay (LOS) and care escalation. Objectives:: To identify predictors for increased LOS and ICU admissions in acute bronchiolitis. Methods:: We conducted a retrospective descriptive cohort study involving 589 children admitted to MZH with acute bronchiolitis in 2 years. Predictors evaluated were age, gender, family history of asthma, prematurity, fever, hypoxemia, comorbidities, RSV, and medications (salbutamol, steroids, and antibiotics). Results:: Acute bronchiolitis comprised 8.75% of Pediatric admissions and 2.9% of total hospital admissions. The mean age is 8.28±6.1(2-30 months); 83% were infants, 39.2% were girls, 15% were preterm, and 25.1% had a family history of asthma. Despite 84.9% having X-rays, significant findings were present in 21.3%. RSV positive 22.5%. The mean LOS was 3.6±1.6(1-11 days). Age less than 2 months(P=0.029 OR=1.8, CI1.1 - 3.3), family history of asthma (P=0.03 OR=1.8, CI1.14 - 2.9), hypoxemia on admission (P&lt;0.001 OR=3, CI1.8 - 4.9), presence of comorbidity (P=0.012), and significant radiographic findings (P&lt;0.002, OR=2.7, CI1.6 - 4.6) were predictors of longer LOS. Prematurity (P&lt;0.001, OR 8.8, CI 2.7-28.4), RSV bronchiolitis (P&lt;0.002, OR=3.02, CI=1.5 – 6.03), and hypoxemia on admission (P&lt; 0.042 OR=4.6, CI1.1 - 14.9) are qualified as independent predictors for escalated care. Conclusion(s):: RSV bronchiolitis, especially in preterm infants, may prompt a low threshold for admission and escalate the care. Evidence-based treatments, respiratory support, and treatment of comorbidities help to achieve optimal LOS.

A longitudinal study on lecture listening difficulties and self-regulated learning strategies across different proficiency levels in EMI higher education

Abstract The absence of language admission thresholds in many English medium instruction (EMI) university programmes has led to marked heterogeneity in students’ English proficiency upon entry. These students may face diverse challenges when listening to academic lectures, adopt different strategies to cope, and undergo varying trajectories in listening over time. To unpack such complexities, this study adopts a longitudinal mixed-methods design, comprising questionnaire responses from 412 freshmen and semi-structured interviews with 34 students at the beginning, halfway, and end of their first semester studying at an EMI university in China. Students were divided into high, medium, and low proficiency cohorts based on their listening placement test scores. Multilevel modelling analyses highlight that students entering with lower proficiency reported sharper reductions in listening challenges over time. Interview findings also reveal that these students engaged in more industrious self-regulated listening practice outside of the classroom than their highly proficient peers. Regardless of disparities in students’ proficiency, all students developed a higher tolerance towards ‘non-native’ teacher accents and shifted attitudes towards handling disciplinary terminology. The findings offer pedagogical implications for supporting different groups of students’ needs for successful transitions into English-medium tertiary education.

Psychiatric inpatient care for persons with dissociative identity disorder: a scoping review protocol

IntroductionPsychiatric inpatient care (PIC) is often characterised by high pressure and thresholds for admission, brief periods of care and limited time for caring activities. Dissociative identity disorder (DID) is a...

Does education prevent job loss during downturns? Evidence from exogenous school assignments and COVID-19 in Barbados

Canonical human capital theories posit that education, by enhancing worker skills, reduces the likelihood that a worker will be laid-off during times of economic change. Yet, this has not been demonstrated causally. We link administrative education records from 1987 through 2002 to nationally representative surveys conducted before and after the COVID-19 onset in Barbados to explore the causal impact of improved education on job loss during this period. Using a regression discontinuity design, we show that females (but not males) who score just above the admission threshold for more selective secondary schools attain more years of education than those who scored just below (essentially holding initial ability fixed). We then find that these same females are much less likely to have lost a job after the onset of COVID-19. We show that these effects are not driven by labor supply decisions, selection into more resilient sectors and occupations, the ability to telework, job seniority, health status, fertility or access to child care, or improved social networks. Because employers observe incumbent worker productivity, these patterns are inconsistent with pure education signaling and suggest that education enhances worker skill.

Identification of major hemorrhage in trauma patients in the prehospital setting: diagnostic accuracy and impact on outcome

BackgroundHemorrhage is the most common cause of potentially preventable death after injury. Early identification of patients with major hemorrhage (MH) is important as treatments are time-critical. However, diagnosis can be...

Management of chest trauma in a District General Hospital - Audit of current practice

Abstract Aim Audit the management of chest trauma in a District General Hospital according to guidelines set by the regional major trauma centre (MTC). Methods Patients admitted with traumatic rib fractures over a six-month period were included. Clinical notes and imaging were reviewed. Primary outcomes were chest injury severity score (CISS), pain team review and referral to MTC. Secondary outcomes included 30-day readmission and mortality. Results 37 patients were included and only 2 had a CISS calculated on admission. Scores were retrospectively calculated with 89.2% scoring over 11 – the threshold for admission and aggressive management. 28 (75.7%) of patients met the criteria for referral to the MTC for consideration of rib fixation but only 8 were referred. 27 (73.0%) were seen by the pain team and 16 patients received a nerve block. There were 5 patients (13.5%) readmitted within 30 days of discharge with complaints of pain or dyspnoea. 3 were discharged from the emergency department, 2 required an additional inpatient stay. There were 2 deaths (5.4%) within 30 days of discharge. Cause of death was only available for 1 patient who had died of pneumonia. Conclusion Chest trauma has a high morbidity and is often managed by emergency general surgeons in centres without cardiothoracic services. Clear management guidance is vital to improving outcomes. As a result of this audit the trust’s pathway for chest trauma has been updated and new tools developed on our electronic patient record system to facilitate calculation of the CISS and completing the necessary referrals.

Do Children Less Than 3 Years with Sickle Cell Disease Need to be Routinely Admitted with Fever?

Background Due to functional asplenia, patients with sickle cell disease (SCD) are at increased risk of serious bacterial infection (SBI) with encapsulated organisms. With the advent of prophylactic penicillin, Haemophilus and Pneumococcal vaccination, this risk has decreased, though recommendations for admission in young children are not standardized and based on institutional practice. Historically, our standard at Benioff Children Hospital Oakland (CHO) has been to admit all children with SCD &amp;lt; 3 years with fever due to these historical concerns. We hypothesized that in a well appearing febrile cohort, the risk of complication would be very low (i.e., &amp;lt;3-5%), allowing liberalization of this stringent recommendation. Methods After IRB approval, we conducted a retrospective review of electronic medical records of children with SCD &amp;lt;3 years of age admitted with fever (i.e., ≥38.3ºC) from October 1 st, 2013 to May 30 th 2022 at CHO. We excluded patients who presented with fever and other complications in the emergency department (ED) that would have otherwise required admission including: 1) splenic sequestration; 2) acute chest syndrome (ACS); 3) hypoxia and/or respiratory distress; 4) vaso-occlusive crisis (VOC); 5) hemoglobin (Hb) drop ≥2 g/dL from baseline; 6) severe dehydration; 7) seizures or other neurological concerns; 8) complicated/complex medical history; 9) SARS-CoV-2 infection; 10) age &amp;lt;2 months; 11) soft tissue infection; and 12) UA concerning for infection. Results Sixty-four unique patients with 127 encounters were included with baseline features outlined in Table 1. Ninety-seven encounters were excluded due to presenting signs/symptoms. Rate of bacteremia was 1.6% (2 of 127). Twenty-six of the 127 encounters (20%, 21 unique patients) were deemed complicated, due to: 1) bacteremia (n=2); 2) splenic sequestration (n=6); 3) acute chest syndrome (n=1); 4) worsening anemia requiring transfusion (n=11); 5) pain crisis (n=1); 6) persistent fever (n=4) and 7) norovirus gastroenteritis (n=1). Eighty-five percent were in children 2 years or less. Complicated admissions were statistically longer and had lower hemoglobin and platelets at presentation than uncomplicated admissions (Table 2). There was no difference in age, white blood cell count (WBC) and maximum fever during presentation in the ED (Table 2). Fourteen of 26 complications (54%) occurred in the first two days of admission and the rest thereafter. Conclusions Although the rate of bacteremia was low as expected in children with SCD &amp;lt;3 years of age presenting to the ED with fever and without concerning presenting features, the overall rate of complications during admission for those encounters was much higher than our acceptable a priori threshold. Retrospectively, there were no easily discernible presenting features in this otherwise well-appearing cohort to determine need for admission. Complications often occurred beyond day 2 of admission. The majority of complications occurred in children ≤2 years of age; we therefore will continue to admit all children with SCD and fever ≤ 2 years of age with a low threshold for ongoing admission beyond the 48 hour rule out. Institutional standards must closely monitor for increased adverse events if utilizing more lenient ED discharge criteria in this population.

Implication of the 2014 World Health Organization Integrated Management of Childhood Illness Pneumonia Guidelines with and without pulse oximetry use in Malawi: A retrospective cohort study.

Under-5 pneumonia mortality remains high in low-income countries. In 2014 the World Health Organization (WHO) advised that children with chest indrawing pneumonia, but without danger signs or peripheral oxygen saturation (SpO 2) < 90% be treated in the community, rather than hospitalized. In Malawi there is limited pulse oximetry availability. Secondary analysis of 13,413 under-5 pneumonia cases in Malawi. Pneumonia associated case fatality ratios (CFR) were calculated by disease severity under the assumptions of the 2005 and 2014 WHO Integrated Management of Childhood Illness (IMCI) guidelines, with and without pulse oximetry. We investigated if pulse oximetry readings were missing not at random (MNAR). The CFR of patients classified as having non-severe pneumonia per the 2014 IMCI guidelines doubled under the assumption that pulse oximetry was not available (1.5% without pulse oximetry vs 0.7% with pulse oximetry, P<0.001). When 2014 IMCI guidelines were applied with pulse oximetry and a SpO 2 < 90% as the threshold for referral and/or admission, the number of cases meeting hospitalization criteria decreased by 70.3%. Unrecorded pulse oximetry readings were MNAR with an adjusted odds for mortality of 4.9 (3.8, 6.3), similar to that of a SpO 2 < 90%. Although fewer girls were hospitalized, female sex was an independent mortality risk factor. In Malawi, implementation of the 2014 WHO IMCI pneumonia guidelines, without pulse oximetry, will miss high risk cases. Alternatively, implementation of pulse oximetry may result in a large reduction in hospitalization rates without significantly increasing non-severe pneumonia associated CFR if the inability to obtain a pulse oximetry reading is considered a WHO danger sign.

Hospital ownership and admission rates from the emergency department, evidence from Florida.

In light of Department of Justice investigations of for-profit chains for over-admitting patients, we sought to evaluate whether for-profit hospitals are more likely to admit patients from the emergency department. We used statewide visit-level inpatient and emergency department records from Florida's Agency for Healthcare Administration for 2007-2019. We calculated differences in admission rates between for-profit and other hospitals, adjusting for patient and hospital characteristics. We also estimated instrumental variables models using differential distance to a for-profit hospital as an instrument. Our main analysis focuses on patients ages 65 and older treated in hospitals that primarily serve adults. Adjusted admission rates among patients ages 65 and older were 7.1 percentage points (95% CI: 5.1-9.1) higher at for-profit hospitals in 2019 (or 18.8% of the sample mean of 37.8%). Differences in admission rates have remained constant since 2009. Our results are consistent with allegations that for-profit hospitals maintain lower admission thresholds to increase occupancy levels.

Air pollution and topography in Tehran

Tehran is one of the most polluted cities in the world with 48 days of air pollution exceeding the admissible threshold (AQI &gt; 150) for 3 months of the 15 years studied. This period coincides with the time when Tehran’s inversion reaches its maximum stability. The purpose of this study was to determine the height of air pollution in Tehran in the days when pollution exceeds the permissible limit. Continuing to study the pressure and temperature conditions of these days, we then considered the geographical and topographic conditions, and finally identified the best of these cells for potential theoretical air turbulence. The results of this study, based on the Harmonic Analysis method and based on Tehran temperature and pressure data over a 15-year period (2003–2017), show that the highest elevation of Tehran inversion does not exceed 1800 m on polluted days. Only within 6 days of those beyond the admissible threshold, temperature and pressure cells with the highest Newtonian mass are formed. The center of these cells formed with a compressive difference of 32 mg in November, 7 mg in January, 11 mg in December, and temperature difference of 1.1° in November, 4.4° in January, and 1.9° in December. Generally, we considered the formed cells by the temperature and pressure difference and the gradient between them, as well as the difference in height between the cells and their location. This information, combined with the local winds causing the differences in temperature and pressure, allows us to elucidate conditions for creating air turbulence in Tehran and mitigating the amount and degree of air pollution.

Managing priorities on on-demand service platforms with waiting time differentiation

Inspired by recent applications, this article considers the problem of an on-demand service platform (e.g., Uber, Lyft, Deliveroo) that differentiates the service of customers according to their willingness to wait and to pay. Upon arrival, customers can be admitted to the system or rejected and, at any time, service providers can be allocated to admitted customers or reserved for future customers. We formulate this problem as a continuous-time Markov decision process, which is used to find the optimal policy. Exploiting properties of the value function, we first show that the optimal policy is described by state-dependent admission thresholds and a strict priority rule with respect to service provider allocation. In a numerical study, we then compare the performance of the optimal policy with simpler policies. We find that the platform, the customers, and the service providers can benefit from a policy that controls customer admission and service provider reservation. Finally, some evidence of the robustness of the policy is provided in two extensions.

Clinical characteristics and prognostic nomograms of 12555 non-severe COVID-19 cases with Omicron infection in Shanghai

BackgroundOmicron variant of the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) has rapidly become a global threat to public health. Numerous asymptomatic and mild cases had been admitted in shelter hospitals to quickly win the fight against Omicron pandemic in Shanghai. However, little is known about influencing factors for deterioration and length of stay (LOS) in hospitals among these non-severe cases.MethodsThis study included 12,555 non-severe cases with COVID-19 in largest shelter hospital of Shanghai, aiming to explore prognostic factors and build effective models for prediction of LOS.ResultsData showed that 75.0% of participants were initially asymptomatic. In addition, 94.6% were discharged within 10 days, only 0.3% with deterioration in hospitals. The multivariate analysis indicated that less comorbidities (OR = 1.792, P = 0.012) and booster vaccination (OR = 0.255, P = 0.015) was associated with the decreased risk of deterioration. Moreover, age (HR = 0.991, P < 0.001), number of symptoms (HR = 0.969, P = 0.005), time from diagnosis to admission (HR = 1.013, P = 0.001) and Cycle threshold (CT) values of N gene (HR = 1.081, P < 0.001) were significant factors associated with LOS. Based on these factors, a concise nomogram model for predicting patients discharged within 3 days or more than 10 days was built in the development cohort. In validation cohort, 0.75 and 0.73 of Areas under the curve (AUC) in nomograms, similar with AUC in models of simple machine learning, showed good performance in estimating LOS.ConclusionCollectively, this study not only provides important evidence to deeply understand clinical characteristics and risk factors of short-term prognosis in Shanghai Omicron outbreaks, but also offers a concise and effective nomogram model to predict LOS. Our findings will play critical roles in screening high-risk groups, providing advice on duration of quarantine and helping decision-makers with better preparation in outbreak of COVID-19.

81 Audit of Use of Oakland Score on Patients Presenting with PR Bleeding and Effect on Admissions with Retrospective Application

Abstract Aim To audit use of the validated Oakland Score for safe discharge of patients presenting to ED with PR bleeding and assess the effect of the Score on patient admissions. Method Retrospective audit of patients presenting to ED with PR bleeding between 1 Jan 22 - 30 Jun 22. Notes were reviewed and Oakland Score calculated. Threshold discharge scores of 8 and 10 were used to determine the effect on admission numbers. 88 patient notes were reviewed, 75 were included. Results 0/72 patients had an Oakland Score on initial clerking. Retrospective application of the Oakland Score with a threshold of 8 would have increased admissions by 20/37 (54%). An admission threshold of 10 would have increased admissions by 3/37 (8.1%). A threshold score of 8 suggests 27/37 patients were inappropriately discharged (73%) and 7/38 (18%) could have been safely discharged rather than admitted. 41/75 (55%) were admitted or discharged correctly. A threshold score of 10 suggests 18/37 patients (47%) were inappropriately discharged and that 15/38 (39%) could have been safely discharged rather than admitted. 42/75 (56%) were admitted or discharged correctly. Conclusions PR bleeding represents a significant number of patients presenting acutely to general surgery. Discharge and admission of patients presenting with PR bleeding is inconsistent and subjective. Introduction of the Oakland Score would provide objective criteria for safe discharge and appropriate admission. An admission threshold of 10 has a 91% confidence in safe discharge and would not result in a large increase in admissions of otherwise healthy patients.

Impact of Clinical Guidelines on Hospital Utilization in Children With Croup.

To assess the impact of croup guidelines on healthcare utilization and association between guideline-recommended racemic epinephrine (RE) treatments and admission. Cross-sectional study of children ≥3 months to ≤8 years with croup diagnosis (International Classification of Diseases, 10th Revision) from 38 hospitals within the Pediatric Health Information System between January 1, 2019 and June 30, 2022. Guidelines were categorized by minimum number of RE treatments recommended before admission. Exclusion criteria included complex chronic or croup mimicking conditions, alternate respiratory diagnoses, and direct admissions or transfers. Primary outcomes were admission rates and standardized costs. Outcomes were compared by guideline availability and different admission thresholds. Mixed effects regression was adjusted for age, sex, race, payer, previous croup encounters, and year. Twenty hospitals (52.6%) had guidelines. Fourteen recommended 2 RE treatments and 3 recommended 3 RE treatment before admission. Among 121 284 croup encounters, overall mean admission rate was 5.7% (range 0.6% to 18.5%). Hospitals with guidelines demonstrated lower unadjusted admission rate (4.6% vs 6.6%; mean difference -2.0, 95% confidence interval -2.3 to -1.7) and higher costs ($704 vs $651; mean difference 53, 95% confidence interval 43 to 63) compared with hospitals without guidelines. Hospitals with guidelines recommending 3 RE treatments demonstrated similar unadjusted mean admission rate (5.1%) and lower costs ($658 vs $713) compared with hospitals with guidelines recommending 2 RE treatments. After adjustment, all above-mentioned differences were not statistically significant. Many children's hospitals lack guidelines for croup. Admission rates and costs were not significantly different between hospitals with or without guidelines after adjusting for confounders.

Admission control for a capacitated supply system with real-time replenishment information

Control towers can provide real-time information on logistic processes to support decision making. The question however, is how to make use of it and how much it may save. We consider this issue for a company supplying expensive spare parts and which has limited production capacity. Besides deciding on base stock levels, it can accept or reject customers. The real-time status information is captured by a k-Erlang distributed replenishment lead time. First we model the problem with patient customers as an infinite-horizon Markov decision process and minimize the total expected discounted cost. We prove that the optimal policy can be characterized using two thresholds: a base work storage level that determines when ordering takes place and an acceptance work storage level that determines when demand of customers should be accepted. In a numerical study, we show that using real-time status information on the replenishment item and adopting admission control can lead to significant cost savings. The cost savings are highest when the optimal admission threshold is a work storage level with a replenishment item halfway in process. This finding is different from the literature, where it is stated that the cost increase of ignoring real-time information is negligible under either the lost sales or the backordering case. Next we study the problem where customers are of limited patience. We find that the optimal admission policy is not always of threshold type. This is different from the literature which assumes an exponential production lead time.

Trade-Offs of Attending Better Schools: Achievement, Self-Perceptions and Educational Trajectories

Abstract This paper estimates the impacts of attending better middle schools on the test scores, on-time graduation, self-reported socio-emotional skills, aspirations and high school track choices of marginally admitted students. A regression discontinuity design comparing students just above and below the admission threshold to higher-achieving middle schools in Mexico shows some modest gains on externally graded tests, but adverse effects on grade point average and on-time graduation. By the end of middle school, marginally admitted students feel academically inferior to their peers, obtain worse scores on measures of conscientiousness, and are more likely to shift their aspirations and subsequent schooling choices from academic to vocational programmes. The results are consistent with the hypothesis that unfavourable peer comparisons, stemming from direct observation or subjective teacher assessments, can be sufficiently important to affect students’ educational trajectories.