Singlet Fermionic Dark Matter with Dark ZZ

We present a fermionic dark matter model mediated by the hidden gauge boson. We assume the QED-like hidden sector which consists of a Dirac fermion and U(1)$_X$ gauge symmetry, and introduce an additional scalar electroweak doublet field with the U(1)$_X$ charge as a mediator. The hidden U(1)$_X$ symmetry is spontaneously broken by the electroweak symmetry breaking and there exists a massive extra neutral gauge boson in this model which is the mediator between the hidden and visible sectors. Due to the U(1)$_X$ charge, the additional scalar doublet does not couple to the Standard Model fermions, which leads to the Higgs sector of type I two Higgs doublet model. The new gauge boson couples to the Standard Model fermions with couplings proportional to those of the ordinary $Z$ boson but very suppressed, thus we call it the dark $Z$ boson. We study the phenomenology of the dark $Z$ boson and the Higgs sector, and show the hidden fermion can be the dark matter candidate.Comment: 10 pages, 3 figure

Identification of parental line specific effects of MLF2 on resistance to coccidiosis in chickens

<p>Abstract</p> <p>Background</p> <p><it>MLF2</it> was the candidate gene associated with coccidiosis resistance in chickens. Although single marker analysis supported the association between <it>MLF2</it> and coccidiosis resistance, causative mutation relevant to coccidiosis was not identified yet. Thus, this study suggested segregation analysis of <it>MLF2</it> haplotype and the association test of the other candidate genes using improved data transformation.</p> <p>Results</p> <p>A haplotype probably originated from one parental line was found out of 4 major haplotypes of <it>MLF2</it>. Frequency of this haplotype was 0.2 in parental chickens and its offspring in 12 families. Allele substitution effect of the <it>MLF2</it> haplotype originated from a specific line was associated with increased body weight and fecal egg count explaining coccidiosis resistance. Nevertheless Box-Cox transformation was able to improve normality; association test did not produce obvious different results compared with analysis with log transformed phenotype.</p> <p>Conclusion</p> <p>Allele substitution effect analysis and classification of <it>MLF2</it> haplotype identified the segregation of haplotype associated with coccidiosis resistance. The haplotype originated from a specific parental line was associated with improving disease resistance. Estimating effect of <it>MLF2</it> haplotype on coccidiosis resistance will provide useful information for selecting animals or lines for future study.</p

Phenomenology of a two-component dark matter model

We study a two-component dark matter model consisting of a Dirac fermion and a complex scalar charged under new U(1) gauge group in the hidden sector. The dark fermion plays the dominant component of dark matter which explains the measured DM relic density of the Universe. It has no direct coupling to ordinary standard model particles, thus evading strong constraints from the direct DM detection experiments. The dark fermion is self-interacting through the light dark gauge boson and it would be possible to address that this model can be a resolution to the small scale structure problem of the Universe. The light dark gauge boson, which interacts with the standard model sector, is also stable and composes the subdominant DM component. We investigate the model parameter space allowed by current experimental constraints and phenomenological bounds. We also discuss the sensitivity of future experiments such as SHiP, DUNE and ILC, for the obtained allowed parameter space.Comment: 13 pages, 1 figure, journal versio

Vacuum stability of conformally invariant scalar dark matter models

We discuss vacuum structure and vacuum stability in classically scale-invariant renormalizable models with a scalar dark matter multiplet of global O(N) symmetry together with an electroweak singlet scalar mediator. Our conformally invariant scalar potential generates the electroweak symmetry breaking via the Coleman-Weinberg mechanism, and the new scalar singlet mediator acquires its mass through radiative corrections of the scalar dark matters as well as of the standard model particles. Taking into account the present collider bounds, we find the region of parameter space where the scalar potential is stable and all the massless couplings are perturbative up to the Planck scale. With the obtained parameter sets satisfying the vacuum stability condition, we present the allowed region of new physics parameters satisfying the recent measurement of relic abundance, and predict the elastic scattering cross section of the new scalar multiplet into target nuclei for a direct detection of the dark matter. We also discuss the collider signatures and future discovery potentials of the new scalars.Comment: 11 pages, 6 figures (partly updated), journal version. arXiv admin note: text overlap with arXiv:1904.1020

Challenges of refugee teachers in Malaysian community-based learning centers

Because Malaysia is not a signatory to the 1951 RefugeeConvention, the children of refugees living in Malaysia are deprived of any formal education. Children are taught mostly by the refugees themselves, many of whom are volunteers. Most of the community-based learning centers, which encounter many academic and management problems, are also sustained by the refugees. This qualitative study aims to apply the framework of resources and demands theory to explore the work demands encountered by these refugees’ teachers and whether they have enough resources to meet the demands, as the learning centers are self-supported or supported by non-governmental organizations. This study collected data using the focus group method, recruiting participants through purposive sampling. Participants were organized into eight groups, each with seven volunteer participants, and open-ended questions were used for the participants to fully express their views and experiences. The data were analyzed using thematic analysis. The result showed that participants are burdened by academic and administrative tasks, lack of resources, poor infrastructure, and self-incompetence. The findings of the study proposed that more non-government organizations, local communities, and other stakeholders provide expertise and financial assistance to these community-based learning centers as education is the human right of each child. Karena Malaysia bukan merupakan penandatangan Konvensi Pengungsi 1951, hak anak-anak pengungsi untuk mendapat pendidikan resmi telah menjadi sebuah masalah yang tidak begitu diperhatikan. Kebanyakan anak-anak ini diajar oleh guru yang terdiri dari para pengungsi yang bekerja sebagai sukarelawan. Pusat pembelajaran berbasis komunitas dikelola dan dikendalikan oleh pengungsi sering menghadapi pelbagai isu dari segi akademik dan manajemen. Studi pendekatan kualitatif ini menggunakan teori sumber daya dan permintaan sebagai kerangka kajian untuk mengetahui apa saja tuntutan pekerjaan yang dihadapi guru pengungsi dan apakah mereka memiliki sumber daya yang cukup untuk menghadapi tuntutan tersebut, karena pusat pembelajaran bersifat swadaya atau didukung oleh Lembaga Swadaya Masyarakat (LSM). Sumber pembelajaran yang tersedia perlu dikaji supaya cukup menampung serta memenuhi permintaan kerja. Pengumpulan data menggunakan metode focus group dan partisipan direkrut melalui purposive sampling. Partisipan dikumpulkan ke delapan kelompok, masing-masing kelompok terdiri dari tujuh partisipan sukarelawan. Pertanyaan terbuka (open-ended questions) digunakan untuk mendapat pandangan serta pengalaman berkaitan isu yang dikaji. Data dianalisis menggunakan teknik analisis tematik. Hasil temuan menunjukkan bahwa para guru memikul beban yang berat dalam menjalankan tugas akademik serta administrasi. Mereka juga menghadapi isu kurangnya sumber daya, keadaan infrastruktur yang serba kekurangan serta keyakinan diri dalam kompetensi mengajar. Temuan studi ini mengusulkan agar lebih banyak LSM, masyarakat setempat, dan pemangku kepentingan lain menyumbangkan keahlian dan bantuan keuangan pada pusat-pusat pembelajaran tersebut karena pendidikan adalah hak asasi manusia bagi setiap anak-anak

Antibacterial Effect of Persicaria thunbergii on Staphylococcus aureus

With the discovery of various antibiotic resistant bacteria, evaluations of antimicrobial activities of natural compounds have been preceded on antibiotic susceptible and resistant microorganisms. Several types of natural compounds have been reported to have similar effects on target microorganisms as compared to the widely used antibiotics. Persicaria thunbergii (Polygonaceae) has been known to have anti-tumoral, anti-angiogenesis, anti-oxidation and anti-inflammation functions. In this study, aerial parts of P. thunbergii were extracted using methanol, chloroform, and ethyl acetate to identify possible anti-bacterial effects. Agar disk diffusion method and time-kill assay were done to evaluate the antibacterial effect of P. thunbergii extracts. Two extracts ethyl acetate (EAE), and chloroform (CFE) were tested against Staphylococcus aureus. As a result, the extract from CFE and EAE showed antibacterial effect against S. aureus. The extract EAE showed the strongest inhibition effect compared to CFE. These results demonstrate that the EAE extract which originated from P. thunbergii can probably play a role as an antibacterial agent