On Approximability of Steiner Tree in ℓp\ell_p-metrics

In the Continuous Steiner Tree problem (CST), we are given as input a set of points (called terminals) in a metric space and ask for the minimum-cost tree connecting them. Additional points (called Steiner points) from the metric space can be introduced as nodes in the solution. In the Discrete Steiner Tree problem (DST), we are given in addition to the terminals, a set of facilities, and any solution tree connecting the terminals can only contain the Steiner points from this set of facilities. Trevisan [SICOMP'00] showed that CST and DST are APX-hard when the input lies in the $\ell_1$-metric (and Hamming metric). Chleb\'ik and Chleb\'ikov\'a [TCS'08] showed that DST is NP-hard to approximate to factor of $96/95\approx 1.01$ in the graph metric (and consequently $\ell_\infty$-metric). Prior to this work, it was unclear if CST and DST are APX-hard in essentially every other popular metric! In this work, we prove that DST is APX-hard in every $\ell_p$-metric. We also prove that CST is APX-hard in the $\ell_{\infty}$-metric. Finally, we relate CST and DST, showing a general reduction from CST to DST in $\ell_p$-metrics. As an immediate consequence, this yields a $1.39$-approximation polynomial time algorithm for CST in $\ell_p$-metrics.Comment: Abstract shortened due to arxiv's requirement

PERANCANGAN DAN REALISASI BPF RESONATOR DIELEKTRIK BERBASIS MIKROSTRIP PADA FREKUENSI 10360 MHz – 10430 MHz

ABSTRAKSI: Resonator adalah suatu rangkaian yang dapat meloloskan frekuensi tertentu dan meredam frekuensi yang tidak di inginkan. Resonator dielektrik adalah suatu bahan dengan konstanta dielektrik tinggi dan rugi-rugi rendah. Dalam pembuatan BPF frekuensi tinggi diperlukan suatu bahan resonator dielektrik untuk mempermudah pembuatannya. Kelebihan dari penggunaan metode ini adalah saat realisasi dapat dilakukan optimasi tanpa pencetakan mikrostrip lagi sedangkan kekurangannya pengaturan letak resonator dielektrik yang sulit untuk menghasilkan output yang diharapkan.Tugas akhir ini merancang dan merealisasi dielektrik resonator BPF berbasis mikrostrip pada frekuensi 10.360 MHz – 10.430 MHz untuk aplikasi radar pengawas pantai. Saluran transmisi pembuatan filter ini akan menggunakan saluran mikrostip, yaitu saluran transmisi yang terdiri dari konduktor strip dengan lebar, ketipisan strip konduktor, diletakkan pada sebuah substrat. Dielektrik substrat memiliki groundplate di bawahnya. Pada filter ini juga diletakkan resonator dielektrik dalam pembuatan filter. Keluaran yang diharapkan mendapatkan nilai insertion loss dan bandwidth lebih baik dari perancanganperancangan sebelumnya.Pengukuran filter dilakukan dengan menggunakan network analyzer untuk memperoleh informasi tentang kinerja dan karakteristik prototype yang telah dibuat. Parameter-parameter yang diukur antara lain: respon frekuensi, bandwidth, insertion loss,Return Loss, Standing Wave Ratio, dan Impedansi terminal. Adapun hasil pengukuran adalah : frekuensi tengah 10.540 GHz dengan bandwidth 570 MHz , insertion loss 1.840 dB, return loss 15.369 dB (input) dan 30.288 dB (output), SWR 1.410 (input) dan 1.047 (output), impedansi terminal 70.411+j2.143 Ω (input) dan 41.229+j116.875 Ω (output).Kata Kunci : Resonator Dielektrik ,BPF, MikrostripABSTRACT: Resonator is a circuit that can pass certain frequencies and muffle unwanted frequencies. Dielectric resonator is a material with a high dielectric constant and low losses. In the manufacture of high-frequency BPF is required a dielectric resonator materials for simplify of design. The advantages of using this method is when the realization of optimization can be done without printing microstrip again, the drawback is the setting of dielectric resonator layout that are difficult to produce the expected output.This thesisdesign and realize a dielectric resonator BPF based on microstrip on frequency 10360 MHz - 10430 MHz for coastal guard radar applications. This filter manufacture transmission line will use mikrostip channel, which consists of a transmission line conductor strip width, the thinness of the strip conductor, placed on a substrate. Dielectric substrate have agroundplate underneath. At these filtersalso be put in a dielectric resonator for filter manufacturing.Output that expected to get the value of insertion loss and better bandwidth than previous designs.Filter measurements is performed by using a network analyzer to obtain information on the performance and characteristics of the prototype that has been made. The parameters measured include: frequency response, bandwidth, insertion loss, return loss, Standing Wave Ratio, and terminal impedance. The measurement results are: center frequency 10.540 GHz with a bandwidth of 570 MHz, insertion loss 1.840 dB, return loss 15.369 dB (input) and 30.288 dB (output), SWR 1.410 (input) and 1.047 (output),terminal impedance 70.411+j2.143 Ω (input) dan 41.229+j116.875 Ω (output).Keyword: Dielectric Resonator, BPF, Microstri

RYBP is important for cardiac progenitor cell development and sarcomere formation

We have previously established that epigenetic regulator RING1 and YY1 binding protein (RYBP) is required for the contractility of embryonic stem (ES) cell derived cardiomyocytes (CMCs), suggesting its essential role in contractility. In order to investigate the underlying molecular events of this phenotype, we compared the transcriptomic profile of the wild type and Rybp null mutant ES cells and CMCs differentiated from these cell lines. We identified genes related to ion homeostasis, cell adhesion and sarcomeric organization affected in the Rybp null mutant CMCs, by using hierarchical gene clustering and Gene Ontology analysis. We have also demonstrated that the amount of RYBP is drastically reduced in the terminally differentiated wild type CMCs whilst it is broadly expressed in the early phase of differentiation when progenitors form. We also describe that RYBP is important for the proper expression of key cardiac transcription factors including Mesp1, Shh and Mef2c. These findings identify Rybp as a gene important for both early cardiac gene transcription and consequent sarcomere formation necessary for contractility. Since impairment of sarcomeric function and contractility plays a central role in reduced cardiac pump function leading to heart failures in human, current results might be relevant to the pathophysiology of cardiomyopathies

Pengaruh Kuat Arus terhadap Sifat Mekanis pada Aluminium Al-Si-Fe dengan Filler Er 4043 Metode Pengelasan GTAW

Aluminium paduan tempa memiliki berbagai macam aplikasi dalam bidang industry pertahanan dan dirgantara, termasuk untuk pembuatan tangki bahan bakar. Masalah utama dalam pengelasan fusi Alumium paduan adalah pembentukan porositas dalam logam las (Welding Metals), karena kelarutan hidrogen yang tinggi pada suhu tinggi dalam kondisi cair. Tujuan penelitian ini adalah mengetahui pengaruh kuat arus terhadap sifat mekanis (kekuatan tarik dan kekuatan lengkung) paduan Al-Si-Fe dengan menggunakan filler metal Er 4043 dan menggunakan metode pengelasan GTAW. Penelitian mengunakan jenis mesin las GTAW untuk mengelas aluminium paduan dengan variasi kuat arus (140, 160 dan 180 A). Test coupon plat aluminium berukuran 15x 15 mm dengan ketebalan 5 mm dibuat kampuh V. Pada penelitian ini digunakan logam pengisi ER4043 berdiameter 3.2 mm dengan polaritas DCEN. Hasil penelitian menunjukkan distribusi nilai kekerasan vickers pada daerah las lebih tinggi dibanding daerah logam dasar dan daerah terpengaruh panas (Haz). Mikrostruktur daerah las mengalami peningkatan ukuran denrite sedangkan mikrostruktur pada daerah Haz membentuk butiran kolumnar. Nilai kekuatan tarik tarik optimum diperoleh pada kuat arus 140 A. Pengamatan fraktografi menggunakan SEM pada permukaan patah uji tarik menunjukkan patah ulet

Blistering Failure of Elastic Coatings with Applications to Corrosion Resistance

A variety of polymeric surfaces, such as anti-corrosion coatings and polymer-modified asphalts, are prone to blistering when exposed to moisture and air. As water and oxygen diffuse through the material, dissolved species are produced, which generate osmotic pressure that deforms and debonds the coating.These mechanisms are experimentally well-supported; however, comprehensive macroscopic models capable of predicting the formation osmotic blisters, without extensive data-fitting, is scant. Here, we develop a general mathematical theory of blistering and apply it to the failure of anti-corrosion coatings on carbon steel. The model is able to predict the irreversible, nonlinear blister growth dynamics, which eventually reaches a stable state, ruptures, or undergoes runaway delamination, depending on the mechanical and adhesion properties of the coating. For runaway delamination, the theory predicts a critical delamination length, beyond which unstable corrosion-driven growth occurs. The model is able to fit multiple sets of blister growth data with no fitting parameters. Corrosion experiments are also performed to observe undercoat rusting on carbon steel, which yielded trends comparable with model predictions. The theory is used to define three dimensionless numbers which can be used for engineering design of elastic coatings capable of resisting visible deformation, rupture, and delamination.Comment: 29 pages, 11 figures, submitted to Electrochimica Acta (under review

Evolving Role of RING1 and YY1 Binding Protein in the Regulation of Germ-Cell-Specific Transcription

Separation of germline cells from somatic lineages is one of the earliest decisions of embryogenesis. Genes expressed in germline cells include apoptotic and meiotic factors, which are not transcribed in the soma normally, but a number of testis-specific genes are active in numerous cancer types. During germ cell development, germ-cell-specific genes can be regulated by specific transcription factors, retinoic acid signaling and multimeric protein complexes. Non-canonical polycomb repressive complexes, like ncPRC1.6, play a critical role in the regulation of the activity of germ-cell-specific genes. RING1 and YY1 binding protein (RYBP) is one of the core members of the ncPRC1.6. Surprisingly, the role of Rybp in germ cell differentiation has not been defined yet. This review is focusing on the possible role of Rybp in this process. By analyzing whole-genome transcriptome alterations of the Rybp-/- embryonic stem (ES) cells and correlating this data with experimentally identified binding sites of ncPRC1.6 subunits and retinoic acid receptors in ES cells, we propose a model how germ-cell-specific transcription can be governed by an RYBP centered regulatory network, underlining the possible role of RYBP in germ cell differentiation and tumorigenesis

Polycomb protein RYBP activates transcription factor Plagl1 during in vitro cardiac differentiation of mouse embryonic stem cells

RING1 and YY1 binding protein (RYBP) is primarily known to function as a repressor being a core component of the non-canonical polycomb repressive complexes 1 (ncPRC1s). However, several ncPRC1-independent functions of RYBP have also been described. We previously reported that RYBP is essential for mouse embryonic development and that Rybp null mutant embryonic stem cells cannot form contractile cardiomyocytes (CMCs) in vitro . We also showed that PLAGL1, a cardiac transcription factor, which is often mutated in congenital heart diseases (CHDs), is not expressed in Rybp -null mutant CMCs. However, the underlying mechanism of how RYBP regulates Plagl1 expression was not revealed. Here, we demonstrate that RYBP cooperated with NKX2-5 to transcriptionally activate the P1 and P3 promoters of the Plagl1 gene and that this activation is ncPRC1-independent. We also show that two non-coding RNAs residing in the Plagl1 locus can also regulate the Plagl1 promoters. Finally, PLAGL1 was able to activate Tnnt2 , a gene important for contractility of CMCs in transfected HEK293 cells. Our study shows that the activation of Plagl1 by RYBP is important for sarcomere development and contractility, and suggests that RYBP, via its regulatory functions, may contribute to the development of CHDs

REFLEKSI DIRI GURU BAHASA INDONESIA DALAM PEMBELAJARAN BERDIFERENSIASI DI SEKOLAH PENGGERAK

Tujuan penelitian ini adalah mendeskripsikan refleksi guru bahasa Indonesia dalam mengimplementasikan pembelajaran berdiferensiasi, (b) menggambarkan perbaikan-perbaikan yang dilakukan guru bahasa Indonesia dalam implementasi pembelajaran berdiferensiasi. Penelitian ini menggunakan teknik wawancara sebagai pengumpulan datanya, teknik dokumentasi berupa gambar yang berada lingkungan kelas dan sekolah. Sumber data penelitian ini salah satu guru komite pembelajar di sekolah penggerak. Data dianalisis menggunakan teknik analisis data miles amd Hubbermen, yakni teknik analisis mengalir. Hasil penelitian ini menunjukkan bahwa refleksi guru bahasa Indonesia dalam pembelajaran berdiferensiasi yang dilakukan di sekolah penggerak melingkupi asesmen diagnosis, diferensiasi konten, diferensiasi, proses, dan diferensiasi produk. Secara lebih detail pelaksanaannya tersebut cukup banyak mengalami kendala bahkan terdapat kegiatan yang diluar dari ketentuan kurikulum merdeka. Hal tersebut diantaranya, asesmen diagnosis yang belum memenuhi ketentuan/melaui tahapan sebuah Tindakan asesmen, guru masih kebingungan dalam mengintegrasikan kesiapan belajar, gaya belajar, dan kesiapan belajar. Selain itu, hasil refleksi juga mengungkapkan bahwa guru memiliki keunggulan dalam implementasi pembelajaran berdiferensiasi. Keunggulan tersbut, yakni bahwa guru sering memvariasi dalam pembelajaran, guru menjadi idola para peserta didik, dan guru secara resmi dipilih oleh masyarakat SMA N 1 Gapura. Hal ini menjadikan murid lebih santai saat pelajaran bahasa IndonesiaKata Kunci: Refleksi guru dan pembelajaran berdiferensias