Bereavement in adulthood and risks of incident and recurrent cardiovascular diseases

Bereavement, the loss of a family member or a loved one, is a severely stressful life event that may occur at least once in most individuals’ life. Bereaved persons are likely to be influenced by the loss in multiple aspects of their life, such as daily routines, financial security, or sleep quality. Furthermore, accumulating evidence suggests that bereaved individuals have increased risks of psychological and somatic morbidity, as well as death. The death of a partner in middle- and old age has been found in several studies to be related to increased risks of incident CVD and cardiovascular mortality. However, knowledge about the association between the death of a child, i.e., one of the most stressful life events, and the risk of CVD, is limited. Additionally, the question of whether bereavement could lead to poor prognosis in CVD has received very little attention. Therefore, in this thesis, we aimed to investigate the association between the death of a child and parental risk of CVD (studies Ⅰ and Ⅱ) and between the death of a close family member or friend and prognosis in acute myocardial infarction (AMI) (studies Ⅲ and Ⅳ). In studies Ⅰ and Ⅱ, we investigated whether bereaved parents had increased risks of ischemic heart diseases (IHD), AMI, and heart failure (HF). Studies Ⅰ and Ⅱ were bi-national population-based cohort studies including 6.7 million parents who had at least one child born during 1973-2016 in Denmark or during 1973-2014 in Sweden. We obtained information on children’s death, parental sociodemographic and health-related characteristics, and parental heart diseases from several Danish and Swedish nationwide registries. We observed modest associations between the death of a child and the risks of IHD (incidence rate ratio (IRR) [95% confidence intervals (CIs)]: 1.20 [1.18-1.23]), AMI (IRR [95% CIs]: 1.21 [1.17-1.25]), and HF (IRR [95% CIs]: 1.35 [1.29-1.41]). The associations were found irrespective of the child’s causes of death (due to CVD, other natural causes, or unnatural causes). There were U-shaped associations with the risks of IHD, AMI, and HF when we categorized exposure according to the age of the deceased child at loss. Bereaved parents who lost an infant or an adult child had higher risks of the studied heart diseases than those who lost a child aged 2-17 years. The relative risk of AMI was highest in the week immediately after the loss and persisted throughout the follow-up. The relative risk of HF did not differ substantially according to the time since the loss. In study Ⅲ, we investigated whether the loss of a family member or a close friend one year before the first AMI was associated with prognosis in AMI. We conducted a population-based cohort study involving 1732 first-AMI patients from the Stockholm Heart Epidemiology Program during 1992-1994 whom we followed for a median of 14 years. We retrieved information on bereavement and several other characteristics of study participants from questionnaires completed by patients or their family members during or shortly after the hospitalization, while information on outcomes (i.e., non-fatal recurrent AMI, death due to IHD, all-cause mortality, HF and stroke) was from national health and mortality registers. We found no association between any loss one year before the first AMI and the combination of non-fatal recurrent AMI and death due to IHD. However, the patients who lost their partner one year before the first AMI had an increased risk of non-fatal recurrent AMI or death due to IHD (hazard ratio [95% CIs]: 1.55 [1.06-2.27]). In study Ⅳ, we investigated further, using a larger sample, whether AMI patients had a poor prognosis if they experienced bereavement. This study included 266,651 patients with a first AMI recorded in the SWEDEHEART (acronym for Swedish Web-system for Enhancement and Development of Evidence-based care in Heart disease Evaluated According to Recommended Therapies) from 1991 to 2018. We collected information on bereavement as well as study participants’ characteristics and outcomes from several Swedish nationwide registers. We defined exposure as the death of a partner, child, grandchild, sibling, or parent one year before the first AMI or during the 4.4 years median follow-up. We found that bereaved AMI patients had a slightly increased risk of the combination of non-fatal recurrent AMI and death due to IHD. The association was strongest for the loss of a partner, followed by the loss of a child, grandchild, sibling, and parent, but was similar with respect to natural and unnatural deaths. The prognosis of AMI was poor during most of the periods when the loss occurred except for the year immediately after the first AMI. Similar associations were observed for all-cause mortality, HF, and stroke in relation to bereavement. In conclusion, the death of a child was associated with increased risks of IHD, AMI, and HF. Loss of a partner, child, grandchild, and sibling was associated with an increased risk of poor prognosis in AMI. If our findings are confirmed by future studies, support from family and society as well as attention from health care professionals would be beneficial for bereaved individuals’ cardiovascular health

Lipid and Protein Transfer between Nanolipoprotein Particles and Supported Lipid Bilayers.

A nanolipoprotein particle (NLP) is a lipid bilayer disc stabilized by two amphipathic "scaffold" apolipoproteins. It has been most notably utilized as a tool for solubilizing a variety of membrane proteins while preserving structural and functional properties. Transfer of functional proteins from NLPs into model membrane systems such as supported lipid bilayers (SLBs) would enable new opportunities, for example, two-dimensional protein crystallization and studies on protein-protein interactions. This work used fluorescence microscopy and atomic force microscopy to investigate the interaction between NLPs and SLBs. When incubated with SLBs, NLPs were found to spontaneously deliver lipid and protein cargo. The impact of membrane composition on lipid exchange was explored, revealing a positive correlation between the magnitude of lipid transfer and concentration of defects in the target SLB. Incorporation of lipids capable of binding specifically to polyhistidine tags encoded into the apolipoproteins also boosted transfer of NLP cargo. Optimal conditions for lipid and protein delivery from NLPs to SLBs are proposed based on interaction mechanisms

An Efficient Constructive Heuristic to Balance Trade-Offs Between Makespan and Flowtime in Permutation Flow Shop Scheduling

Balancing trade-offs between production cost and holding cost is critical for production and operations management. Utilization of a production line affects production cost, which relates to makespan, and work-in-process (WIP) inventories in a production line affect holding cost, which relate to flowtime. There are trade-offs between two objectives, to minimize makespan and to minimize flowtime. Without addressing trade-off balancing issues in flow shop scheduling, WIP inventories are still high in manufacturing, generating unnecessary holding cost. However, utilization is coupled with WIP inventories. Low WIP inventory levels might lower utilization and generate high production cost. Most existing constructive heuristics focus only on single-objective optimization. In the current literature, the NEH heuristic proposed by Nawaz, Enscore, and Ham (1983) is the best constructive heuristic to minimize makespan, and the LR heuristic proposed by Liu and Reeves (2001) is the best to minimize flowtime. In this paper, we propose a current and future deviation (CFD) heuristic to balance trade-offs between makespan and flowtime minimizations. Based on 5400 randomly generated instances, 120 instances in Taillard’s benchmarks, and one-year historical records of operating room scheduling from University of Kentucky HealthCare (UKHC), our CFD heuristic outperforms the NEH and LR heuristics on trade-off balancing, and achieves the most stable performances from the perspective of statistical process control (SPC)

Method to determine test profile in accelerated reliability demonstration test under Type-I censoring

Conventional reliability demonstration test (RDT) based on statistical method is widely used in industry as it is simple and convenient to apply. But for products with high reliability and long life, this test method fails to satisfy the demand for short cycle and low cost, and is liable to cause the phenomenon of over-test and short-test. This paper gives a method to determine the accelerated stress profile for RDT under multiple stresses and mechanisms, making it faster to make decision of accept or reject. By raising the levels of sensitive stresses that the product would experience, the test time can be cut down remarkably. We can derive the overall acceleration factor based on the narrow reliability bounds theory. Then we choose the test plan referring to GJB 899A. Furthermore, combined with the reliability qualification test (RQT) profile, the accelerated test profile is acquired. An example is given to illustrate the superior performance of the proposed method over traditional methods

Dynamical Analysis of Jettison Piloting for Air Bomb with Bomblets

The main parachutes drawn down by a pilot parachute is the generally used method of thejettison of air bomb with bomblets and their interaction process is the basis and key for thebomb projection. A mechanical model loaded by the string of pilot parachute is theoreticallyestablished, and under different projection velocities, the design method of the length and strengthfor the string of the pilot parachute is suggested. The results show that for a certain 500 kg airbomb, if the projection velocity is 222 m/s and the strength of the string is 5000 N, the lengthof the string 3 m cannot meet the requirement

Luby Transform Coding Aided Iterative Detection for Downlink SDMA Systems

A Luby Transform (LT) coded downlink Spatial Division Multiple Access (SDMA) system using iterative detection is proposed, which invokes a low-complexity near-Maximum-Likelihood (ML) Sphere Decoder (SD). The Ethernet-based Internet section of the transmission chain inflicts random packet erasures, which is modelled by the Binary Erasure Channel (BEC), which the wireless downlink imposes both fading and noise. A novel log-Likelihood Ratio based packet reliability metric is used for identifying the channel-decoded packets, which are likely to be error-infested. Packets having residual errors must not be passed on to the KT decoder for the sake of avoiding LT-decoding –induced error propagation. The proposed scheme is capable of maintaining an infinitesimally low packet error ratio in the downlink of the wireless Internet for Eb/n0 values in excess of about 3dB