ANALISIS PERBEDAAN HEDGING KAKAO FUTURES DENGAN CROSS HEDGING KOPI ROBUSTA FUTURES YANG DIPERDAGANGAN DI BURSA BERJANGKA JAKARTA PERIODE: 2012-2016

Penelitian ini dilakukan untuk menganalisis perbedaan antara hedging kakao futures dengan cross hedging kopi robusta futures dalam meminimalkan risiko di pasar fisik komoditi kakao dengan membandingkan nilai varians return yang dihasilkan dari kedua kontrak futures. Data yang digunakan pada penelitian ini adalah data harian kakao spot, kakao futures, dan kopi robusta futures yang diperdagangkan di Bursa Berjangka Jakarta (BBJ) pada periode 2012-2016. Alat analisis yang digunakan adalah uji korelasi pearson yang bertujuan untuk menguji hubungan antara harga spot dengan futures pada saat melakukan hedging ataupun cross hedging; uji akar unit digunakan untuk melihat kestasioneritas data sebelum dilakukan uji beda; uji regresi sederhana digunakan untuk menghitung nilai ratio hedged dan ratio cross hedged; uji independent sample t-test digunakan untuk membandingkan nilai varians return yang dihasilkan dari kedua kontrak futures tersebut. Hasil analisis menunjukkan bahwa tidak terdapat perbedaan varian returns yang dihasilkan dari keduanya. Dalam hal ini, penanganan risiko pada komoditi kakao di pasar fisiknya pada saat melakukan hedging ataupun cross hedging memiliki tingkat risiko yang sama, sehingga hedging kakao futures dan cross hedging kopi robusta futures sama-sama dapat digunakan untuk meminimalkan risiko pada pasar fisik kakao

A Meta-Analysis of Parental Smoking and the Risk of Childhood Brain Tumors

<div><p>Objective</p><p>Previous studies regarding the association between parental smoking and the risk of childhood brain tumors (CBT) have reported inconsistent results. We performed a meta-analysis to summarize evidence on this association and to quantify the potential dose-response relationship.</p><p>Methods</p><p>A systematic literature search was conducted in the Medline and Embase databases. The summary relative risks (RRs) with 95% confidence intervals (CIs) were calculated. Dose–response meta-analysis was also performed for studies that reported categorical risk estimates for a series of smoking exposure levels.</p><p>Results</p><p>A total of 17 studies fulfilled the inclusion criteria. In the meta-analyses, the summary RRs (95% CIs) of CBT for maternal smoking during pregnancy, paternal smoking during pregnancy, maternal smoking before pregnancy, and paternal smoking before pregnancy were 0.96 (0.86–1.07), 1.09 (0.97–1.22), 0.93 (0.85–1.00), and 1.09 (1.00–1.20), respectively. Dose-response meta-analysis also showed no significant association between parental smoking and the risk of CBT.</p><p>Conclusions</p><p>Findings from our meta-analysis indicate that parental smoking may not be associated with a risk of CBT.</p></div

Flowchart of study assessment and selection.

<p>Flowchart of study assessment and selection.</p

Results of subgroup analyses of the association between maternal smoking before pregnancy and the risk of childhood brain tumors.

<p>* <i>P</i> for heterogeneity of the stratum-specific summary RRs.</p

Forest plot of maternal smoking during pregnancy and the risk of CBT.

<p>Forest plot of maternal smoking during pregnancy and the risk of CBT.</p

Dose-response analysis of maternal smoking during pregnancy and the risk of CBT.

<p>The solid line represents point estimates of association between maternal smoking during pregnancy and CBT risk; dashed lines are 95% CIs. Circles are the dose-specific RR estimates. The relative size of each circle is proportional to the inverse variance of the RR.</p

Quasi-Racemic X‑ray Structures of K27-Linked Ubiquitin Chains Prepared by Total Chemical Synthesis

Quasi-racemic crystallography has been used to determine the X-ray structures of K27-linked ubiquitin (Ub) chains prepared through total chemical synthesis. Crystal structures of K27-linked di- and tri-ubiquitins reveal that the isopeptide linkages are confined in a unique buried conformation, which provides the molecular basis for the distinctive function of K27 linkage compared to the other seven Ub chains. K27-linked di- and triUb were found to adopt different structural conformations in the crystals, one being symmetric whereas the other triangular. Furthermore, bioactivity experiments showed that the ovarian tumor family de-ubiquitinase 2 significantly favors K27-linked triUb than K27-linked diUb. K27-linked triUb represents the so-far largest chemically synthesized protein (228 amino acids) that has been crystallized to afford a high-resolution X-ray structure

Monomer/Oligomer Quasi-Racemic Protein Crystallography

Racemic or quasi-racemic crystallography recently emerges as a useful technology for solution of the crystal structures of biomacromolecules. It remains unclear to what extent the biomacromolecules of opposite handedness can differ from each other in racemic or quasi-racemic crystallography. Here we report a finding that monomeric d-ubiquitin (Ub) has propensity to cocrystallize with different dimers, trimers, and even a tetramer of l-Ub. In these cocrystals the unconnected monomeric d-Ubs can self-assemble to form pseudomirror images of different oligomers of l-Ub. This monomer/oligomer cocrystallization phenomenon expands the concept of racemic crystallography. Using the monomer/oligomer cocrystallization technology we obtained, for the first time the X-ray structures of linear M1-linked tri- and tetra-Ubs and a K11/K63-branched tri-Ub