Hyperbolic slicings of spacetime: singularity avoidance and gauge shocks

I study the Bona-Masso family of hyperbolic slicing conditions, considering in particular its properties when approaching two different types of singularities: focusing singularities and gauge shocks. For focusing singularities, I extend the original analysis of Bona et. al and show that both marginal and strong singularity avoidance can be obtained for certain types of behavior of the slicing condition as the lapse approaches zero. For the case of gauge shocks, I re-derive a condition found previously that eliminates them. Unfortunately, such a condition limits considerably the type of slicings allowed. However, useful slicing conditions can still be found if one asks for this condition to be satisfied only approximately. Such less restrictive conditions include a particular member of the 1+log family, which in the past has been found empirically to be extremely robust for both Brill wave and black hole simulations.Comment: 11 pages, revtex4. Change in acknowledgment

Cortical–subcortical interactions in hypersomnia disorders: Mechanisms underlying cognitive and behavioral aspects of the sleep–wake cycle

Subcortical circuits mediating sleep–wake functions have been well characterized in animal models, and corroborated by more recent human studies. Disruptions in these circuits have been identified in hypersomnia disorders (HDs) such as narcolepsy and Kleine–Levin Syndrome, as well as in neurodegenerative disorders expressing excessive daytime sleepiness. However, the behavioral expression of sleep–wake functions is not a simple on-or-off state determined by subcortical circuits, but encompasses a complex range of behaviors determined by the interaction between cortical networks and subcortical circuits. While conceived as disorders of sleep, HDs are equally disorders of wake, representing a fundamental instability in neural state characterized by lapses of alertness during wake. These episodic lapses in alertness and wakefulness are also frequently seen in neurodegenerative disorders where electroencephalogram demonstrates abnormal function in cortical regions associated with cognitive fluctuations (CFs). Moreover, functional connectivity MRI shows instability of cortical networks in individuals with CFs. We propose that the inability to stabilize neural state due to disruptions in the sleep–wake control networks is common to the sleep and cognitive dysfunctions seen in hypersomnia and neurodegenerative disorders

Aplikasi Media Informasi Website Pengenalan Tempat Pariwisata Belitung

Pariwisata menjadi salah satu sektor yang berkembang sangat cepat, bahkan di beberapa negara pariwisata menjadi faktor pendukung utama dalam perekonomian suatu negara. Belitung merupakan bagian dari Provinsi Kepulauan Bangka Belitung yang memiliki potensi pariwisata yang cukup baik dengan segala sumber daya yang dimilikinya. Tapi karena belum banyak dikenal oleh masyarakat. Maka dibuatlah penelitian ini sehingga masyarakat mengetahui tempat – tempat pariwisata yang ada di Belitung, dengan membuat perancangan sistem, melakukan analisis, dan pengujian sistem serta implementasi pada sistem aplikasi perancangan aplikasi media informasi pengenalan tempat pariwisata di belitung berbasis web. Dalam pengembangan sistem perancangan aplikasi media informasi pengenalan tempat pariwisata di belitung berbasis web penulis menggunakan beberapa metode dalam penelitiannya yaitu metode analisis untuk merencanakan, menganalisis, mendesain, dan mengimplementasi rancangan sistem, metode perancangan untuk merancang spesifikasi file sistem serta input dan output layar, metode pengumpulan data yaitu studi kepustakaan dan kuisioner dari sistem yang dibuat. Hasil dari dibangunnya perancangan aplikasi media informasi pengenalan tempat pariwisata di Belitung berbasis web diharapkan dapat memberi manfaat dan informasi tentang tempat – tempat pariwisata yang ada di Belitung kepada masyarakat. Untuk menguji sistem yang telah dibuat maka penulis melakukan survei dalam bentuk kuisioner. Maka berdasarkan kuisioner yang telah dibagikan dan diisi oleh para pengguna, dapat simpulkan bahwa aplikasi media informasi pengenalan tempat pariwisata di Belitung ini bermanfaat bagi pengguna karena membantu pengguna untuk lebih mengenal tempat – tempat pariwisata yang ada di Belitung, baik yang mengetahui atau tidak mengetahui tentang tempat pariwisata di Belitung

Proteomic biomarkers of the apnea hypopnea index and obstructive sleep apnea: Insights into the pathophysiology of presence, severity, and treatment response

Obstructive sleep apnea (OSA), a disease associated with excessive sleepiness and increased cardiovascular risk, affects an estimated 1 billion people worldwide. The present study examined proteomic biomarkers indicative of presence, severity, and treatment response in OSA. Participants

Impact of densitized lapse slicings on evolutions of a wobbling black hole

We present long-term stable and second-order convergent evolutions of an excised wobbling black hole. Our results clearly demonstrate that the use of a densitized lapse function extends the lifetime of simulations dramatically. We also show the improvement in the stability of single static black holes when an algebraic densitized lapse condition is applied. In addition, we introduce a computationally inexpensive approach for tracking the location of the singularity suitable for mildly distorted black holes. The method is based on investigating the fall-off behavior and asymmetry of appropriate grid variables. This simple tracking method allows one to adjust the location of the excision region to follow the coordinate motion of the singularity.Comment: 10 pages, 8 figure