Colonization of diatoms in and on porcine bone substrate and considerations of diatom ecology for forensic science

The presence of diatom algae in bone marrow has been used as forensic evidence of drowning for several decades; however, these studies are based on known or suspected recent drowning events. This study addresses the potential for diatoms to enter the bone marrow of skeletal remains, that is, de-fleshed long bones post-mortem. In laboratory and field experiments, bones were either inflicted with two access points by a cut and acid pitting or left intact. The bones were submerged in water for at least 1 week and up to 3 months. Samples of the bone surface and marrow were inspected for diatoms. The analysis considered the time required for diatoms to enter marrow and whether genus characteristics like size or mobility affect entry. The presence of an access point influenced diatom entry in that bones without an introduced access point had zero to one diatom present in the marrow, whereas a bone with an access point had >150 diatoms present in the marrow. The results of both laboratory and field phases suggest that diatoms will reliably colonize bone in as quickly as 1 week, establishing and maintaining communities for at least 3 months. However, the bone surface assemblages differ from the source community. Bone marrow displayed even more restrictive access to diatom colonization, resulting in communities dominated by small raphid diatoms. Based on these findings, we suggest some caveats on the use of diatoms as trace evidence in forensic science with recommendations for future avenues of research.     

“同舟共济”与适应性变革:经济增长、权力转移及中美关系

由于经济增长的差异,新兴市场日益崛起,亚太地区日益崛起,其中中国崛起尤为瞩目。纵观权力转移历史、理论与现实,中国积极寻求融入当前美国主导的国际制度安排,在战略上是正确的,中国成为这一制度的得利较多者,也是满意者和维护者。因此综合长期战略和当前金融危机冲击下的策略,除了积极推动美国对当前制度进行适应性变革外,对于美国目前的困境,中国应该量力积极帮助,共同促进全球经济早日复苏和全球善治,与美国"同舟共济"符合中国战略利益,中国需要战略规划;同时,需要面向未来,准备好美国经济复苏后的策略变化。美国凭其发达的金融业在全球财富再分配中占领制高点,金融业的发展意味着可以在财富的再分配中获得竞争优势,因此中国需要大力发展现代金融业。     

静态资源关系观及其批判

最近几十年里,关于人类资源关系的辩论越来越激烈。学者们大致形成了两个对立的流派。资源悲观主义认为,人类资源关系是零和的,一个人群消耗的资源增加了,其他群体可能得到的资源就会减少。因此,随着资源越来越匮乏,人类资源冲突会愈演愈烈。资源乐观主义认为,人类资源关系是非零和的,资源冲突能够避免。悲观主义和乐观主义尽管尖锐对立,但有共同缺陷——都是静态理论,对资源关系的解释力有限。对此,本文提出了动态的资源关系理论,能够更好地解释人类资源关系。     

Axonal injury in young pediatric head trauma: a comparison study of β-amyloid precursor protein (β-APP) immunohistochemical staining in traumatic and nontraumatic deaths

We tested the independent utility of β-amyloid precursor protein (β-APP) immunohistochemical staining as evidence of brain trauma in the deaths of young children. Blinded reviewers retrospectively reviewed immunostained brain tissues from homicidal deaths, age-matched control cases without evidence of trauma, as well as cases of sudden infant death syndrome (SIDS). The reviewers correctly identified five of the seven cases with documented inflicted head trauma. However, one of seven age-matched control cases and one of 10 SIDS/sudden unexplained death in infancy (SUDI) cases demonstrated staining patterns similar to those seen in cases of inflicted trauma. We discuss these cases and the circumstances surrounding them with the intent to explain the difficulties associated with immunohistological interpretation of axonal injury. Although the utility of β-APP is quite powerful if not confounded by global hypoxic-ischemic injury, ultimately, β-APP studies should be only one piece of information in the determination of cause and manner of death.     

Target screening and confirmation of 35 licit and illicit drugs and metabolites in hair by LC-MSMS

A liquid chromatography-tandem mass spectrometry (LC-MSMS) target screening in 50mg hair was developed and fully validated for 35 analytes (Δ9-tetrahidrocannabinol (THC), morphine, 6-acetylmorphine, codeine, methadone, fentanyl, amphetamine, methamphetamine, 3,4-methylenedioxyamphetamine, 3,4-methylenedioxymethamphetamine, benzoylecgonine, cocaine, lysergic acid diethylamide, ketamine, scopolamine, alprazolam, bromazepam, clonazepam, diazepam, flunitrazepam, 7-aminoflunitrazepam, lorazepam, lormetazepam, nordiazepam, oxazepam, tetrazepam, triazolam, zolpidem, zopiclone, amitriptyline, citalopram, clomipramine, fluoxetine, paroxetine and venlafaxine). Hair decontamination was performed with dichloromethane, and incubation in 2 mL of acetonitrile at 50°C overnight. Extraction procedure was performed in 2 steps, first liquid-liquid extraction, hexane:ethyl acetate (55:45, v:v) at pH 9, followed by solid-phase extraction (Strata-X cartridges). Chromatographic separation was performed in AtlantisT3 (2.1 mm × 100 mm, 3 μm) column, acetonitrile and ammonium formate pH 3 as mobile phase, and 32 min total run time. One transition per analyte was monitored in MRM mode. To confirm a positive result, a second injection monitoring 2 transitions was performed. The method was specific (no endogenous interferences, n=9); LOD was 0.2-50 pg/mg and LOQ 0.5-100 pg/mg; linearity ranged from 0.5-100 to 2000-20,000 pg/mg; imprecision <15%; analytical recovery 85-115%; extraction efficiency 4.1-85.6%; and process efficiency 2.5-207.7%; 27 analytes showed ion suppression (up to -86.2%), 4 ion enhancement (up to 647.1%), and 4 no matrix effect; compounds showed good stability 24-48 h in autosampler. The method was applied to 17 forensic cases. In conclusion, a sensitive and specific target screening of 35 analytes in 50mg hair, including drugs of abuse (THC, cocaine, opiates, amphetamines) and medicines (benzodiazepines, antidepressants) was developed and validated, achieving lower cut-offs than Society of Hair Testing recommendations.     

人力资源管理思想:三个里程碑及其在中国的升华

人力资源管理实践历程中三个标志性实验成果昭示了人力资源管理思想演变的客观规律,是人力资源管理思想嬗变过程中的三大里程碑。科学管理实验使人力资源管理从自发管理走向自觉管理、科学管理和制度管理;霍桑实验系统发现了提高生产效率的社会心理因素,使人力资源管理从技术管理走向社会管理、行为管理和心理管理;职业生涯实验显示员工职业发展也是现代企业管理目标,现代企业目标和员工职业发展目标共存共长。三次实验的思想脉络、理论构造、功能机制有机对接、联动传承并推向纵深,成为人力资源管理历史上三个具有划时代意义的丰碑。科学人才观提出的"以人为本"的思想和理念是人力资源管理思想在当代中国的发展和升华。