Phase Conversions in Neutron Stars: Implications for Stellar Stability and Gravitational Wave Astrophysics

We review the properties of hybrid stars with a quark matter core and a hadronic mantle, focusing on the role of key micro-physical properties such as the quark/hadron surface and curvature tensions and the conversion speed at the interface between both phases. We summarize the results of works that have determined the surface and curvature tensions from microscopic calculations. If these quantities are large enough, mixed phases are energetically suppressed and the quark core would be separated from the hadronic mantle by a sharp interface. If the conversion speed at the interface is slow, a new class of dynamically stable hybrid objects is possible. Densities tens of times larger than the nuclear saturation density can be attained at the center of these objects. We discuss possible formation mechanisms for the new class of hybrid stars and smoking guns for their observational identification.

Azaporphyrins Embedded on Carbon-Based Nanomaterials for Potential Use in Electrochemical Sensing—A Review

Phthalocyanines and porphyrazines as macrocyclic aza-analogues of well-known porphyrins were deposited on diverse carbon-based nanomaterials and investigated as sensing devices. The extended π-conjugated electron system of these macrocycles influences their ability to create stable hybrid systems with graphene or carbon nanotubes commonly based on π–π stacking interactions. During a 15-year period, the electrodes modified by deposition of these systems have been applied for the determination of diverse analytes, such as food pollutants, heavy metals, catecholamines, thiols, glucose, peroxides, some active pharmaceutical ingredients, and poisonous gases. These procedures have also taken place, on occasion, in the presence of various polymers, ionic liquids, and other moieties. In the review, studies are presented that were performed for sensing purposes, involving azaporphyrins embedded on graphene, graphene oxide or carbon nanotubes (both single and multi-walled ones). Moreover, possible methods of electrode fabrication, limits of detection of each analyte, as well as examples of macrocyclic compounds applied as sensing materials, are critically discussed.

Evaluasi kegenjahan dan daya hasil jagung manis hibrida Indonesia menggunakan analisis GGE biplot pada lingkungan yang berbeda

AbstrakUji multilokasi merupakan fase yang penting dalam menyeleksi hibrida jagung yang stabil pada lingkungan yang luas dan menyeleksi hibrida superior untuk lokasi spesifik. Tujuan penelitian ini yaitu untuk mengetahui kegenjahan dan daya hasil hibrida Padjadjaran, serta menentukan interaksi genotip dengan lingkungan (G x E), stabilitas, dan adaptabilitas karakter kegenjahan hibrida Padjadjaran di tiga lokasi selama dua musim yang berbeda di Jawa Barat. Rancangan percobaan yang digunakan adalah Rancangan Acak Kelompok dengan delapan belas perlakuan yang terdiri dari enam belas hibrida Padjadjaran dan dua kultivar cek. Percobaan dilaksanakan selama dua tahun berturut- turut yaitu tahun ke-1 (Maret sampai Juli, 2014) dan tahun ke-2 (Maret sampai Juli, 2015) di tiga lokasi di Jawa Barat, yaitu: Jatinangor - Sumedang, Lembang - Kabupaten Bandung Barat, dan Wanayasa - Kabupaten Purwakarta. Uji lanjut yang digunakan untuk mengetahui perbedaan nilai rerata kegenjahan dan daya hasil digunakan analisis Duncan Multiple Range Test (DMRT), sedangkan untuk menentukan interaksi G x E, stabilitas, dan adaptabilitas menggunakan Genotype plus Genotype x Environment (GGE) biplot. Hasil memperlihatkan bahwa analisis GGE dapat menentukan interaksi G x E, stabilitas, dan adaptabilitas jagung manis hibrida Indonesia di Jawa Barat secara akurat. Model GGE disarankan untuk dapat digunakan sebagai aplikasi analisis untuk perilisan hibrida unggul di Indonesia oleh Kementerian Pertanian.Kata Kunci: Adaptabilitas, Interaksi G x E, kegenjahan, Stabilitas Abstract. Multi-environment testing is an important stage to select stable hybrid for broad environment and to select superior hybrid for a specific environment. To determined G x E (Genotype x Environment) interaction, stability and adaptability of Padjadjaran sweet corn in Indonesia, sixteen new Padjadjaran sweetcorn hybrids and two commercial hybrids were tested in three locations for two different seasons in West Java, Indonesia. Duncan multiple range was used to elaborate the difference between sweetcorn hybrids for short duration and yield, while Genotype plus Genotype x Environment (GGE) biplot analysis was used to determine G x E interaction, stability, and adaptability. Results showed that GGE analysis was accurately determined G x E interaction, stability, and adaptability of Indonesian sweet corn in West Java. The GGE model is suggested to implement as a tool for Ministry of Agriculture to release superior hybrid in Indonesia.Keywords: Adaptability, G x E interaction, Short duration, Stability

Gene surfing of underdominant alleles promotes formation of hybrid zones

The distribution of genetic diversity over geographic space has long been investigated in population genetics and serves as a useful tool to understand evolution and history of populations. Within some species or across regions of contact between two species, there are instances where there is no apparent ecological determinant of sharp changes in allele frequencies or divergence. To further understand these patterns of spatial genetic structure and potential species divergence, we model the establishment of clines that occur due to the surfing of underdominant alleles during range expansions. We provide analytical approximations for the fixation probability of underdominant alleles at expansion fronts and demonstrate that gene surfing can lead to clines in 1D range expansions. We extend these results to multiple loci via a mixture of analytical theory and individual-based simulations. We study the interaction between the strength of selection against heterozygotes, migration rates, and local recombination rates on the formation of stable hybrid zones. A key result of our study is that clines created by surfing at different loci can attract each other and align after expansion, if they are sufficiently close in space and in terms of recombination distance. Our findings suggest that range expansions can set the stage for parapatric speciation due to the alignment of multiple selective clines, even in the absence of ecologically divergent selection.