Non-invasive, near-field terahertz imaging of hidden objects using a single pixel detector

Terahertz (THz) imaging has the ability to see through otherwise opaque materials. However, due to the long wavelengths of THz radiation ({\lambda}=300{\mu}m at 1THz), far-field THz imaging techniques are heavily outperformed by optical imaging in regards to the obtained resolution. In this work we demonstrate near-field THz imaging with a single-pixel detector. We project a time-varying optical mask onto a silicon wafer which is used to spatially modulate a pulse of THz radiation. The far-field transmission corresponding to each mask is recorded by a single element detector and this data is used to reconstruct the image of an object placed on the far side of the silicon wafer. We demonstrate a proof of principal application where we image a printed circuit board on the underside of a 115{\mu}m thick silicon wafer with ~100{\mu}m ({\lambda}/4) resolution. With subwavelength resolution and the inherent sensitivity to local conductivity provided by the THz probe frequencies, we show that it is possible to detect fissures in the circuitry wiring of a few microns in size. Imaging systems of this type could have other uses where non-invasive measurement or imaging of concealed structures with high resolution is necessary, such as in semiconductor manufacturing or in bio-imaging

Real time THz imaging - opportunities and challenges for skin cancer detection

It was first suggested that terahertz imaging has the potential to detect skin cancer twenty years ago. Since then, THz instrumentation has improved significantly: real time broadband THz imaging is now possible and robust protocols for measuring living subjects have been developed. Here, we discuss the progress that has been made as well as highlight the remaining challenges for applying THz imaging to skin cancer detection

The macrophage in HIV-1 infection: From activation to deactivation?

Macrophages play a crucial role in innate and adaptative immunity in response to microorganisms and are an important cellular target during HIV-1 infection. Recently, the heterogeneity of the macrophage population has been highlighted. Classically activated or type 1 macrophages (M1) induced in particular by IFN-γ display a pro-inflammatory profile. The alternatively activated or type 2 macrophages (M2) induced by Th-2 cytokines, such as IL-4 and IL-13 express anti-inflammatory and tissue repair properties. Finally IL-10 has been described as the prototypic cytokine involved in the deactivation of macrophages (dM). Since the capacity of macrophages to support productive HIV-1 infection is known to be modulated by cytokines, this review shows how modulation of macrophage activation by cytokines impacts the capacity to support productive HIV-1 infection. Based on the activation status of macrophages we propose a model starting with M1 classically activated macrophages with accelerated formation of viral reservoirs in a context of Th1 and proinflammatory cytokines. Then IL-4/IL-13 alternatively activated M2 macrophages will enter into the game that will stop the expansion of the HIV-1 reservoir. Finally IL-10 deactivation of macrophages will lead to immune failure observed at the very late stages of the HIV-1 disease

Macrophage signaling in HIV-1 infection

The human immunodeficiency virus-1 (HIV-1) is a member of the lentivirus genus. The virus does not rely exclusively on the host cell machinery, but also on viral proteins that act as molecular switches during the viral life cycle which play significant functions in viral pathogenesis, notably by modulating cell signaling. The role of HIV-1 proteins (Nef, Tat, Vpr, and gp120) in modulating macrophage signaling has been recently unveiled. Accessory, regulatory, and structural HIV-1 proteins interact with signaling pathways in infected macrophages. In addition, exogenous Nef, Tat, Vpr, and gp120 proteins have been detected in the serum of HIV-1 infected patients. Possibly, these proteins are released by infected/apoptotic cells. Exogenous accessory regulatory HIV-1 proteins are able to enter macrophages and modulate cellular machineries including those that affect viral transcription. Furthermore HIV-1 proteins, e.g., gp120, may exert their effects by interacting with cell surface membrane receptors, especially chemokine co-receptors. By activating the signaling pathways such as NF-kappaB, MAP kinase (MAPK) and JAK/STAT, HIV-1 proteins promote viral replication by stimulating transcription from the long terminal repeat (LTR) in infected macrophages; they are also involved in macrophage-mediated bystander T cell apoptosis. The role of HIV-1 proteins in the modulation of macrophage signaling will be discussed in regard to the formation of viral reservoirs and macrophage-mediated T cell apoptosis during HIV-1 infection

Simultaneous measurement of Orthogonal Terahertz fields enabled via a THz MODEM (modulator/demodulator) scheme

A scheme is proposed and demonstrated that realizes the rapid simultaneous measurement of orthogonal terahertz fields. A fibre-coupled multi-pixel THz emitter on InGaAs generated orthogonal polarization states, with a dynamic range and bandwidth comparable to a commercial antenna. We developed a dual-frequency modulation/demodulation scheme that used a conventional photoconductive detector to record the orthogonal polarization states. This work has significant potential to improve the speed of polarization-resolved THz spectroscopy and imaging. We demonstrate its efficiency by characterizing birefringent crystalline materials and anisotropic metamaterial

Weaning Date for Spring Calving Cows Grazing Sandhills Range

A two-year experiment was conducted with March calving cows to determine the effect of the weaning date on cow body condition score, cow body weight, and calf body weight. Treatments were of eight weaning dates imposed at consecutive two-week intervals, beginning in mid-August and ending in late November. Cow body condition score declined linearly as weaning date was later in the fall. Calf body weight gains from August through November increased with weaning dates from August 18 through October 13; however, weaning after October 13 provided no advantage of increased calf body weight gain

What goes around comes around: The effects of sanctions on Swedish firms in the wake of the Ukraine crisis

This study uses the sanctions imposed on and by Russia in 2014 as an exogenous shock on Swedish firms. The results suggest that the total short‐run cost of these sanctions on the Swedish economy amounted to around 1 billion SEK in 2013 prices, which implies a rather limited impact (around 0.025% of the Swedish GDP). The sanction effects were, however, highly asymmetric, and the direct effect on firms exporting banned products to Russia was a 70% drop in exports to Russia and an increased probability of exiting this market with 0.6 units. The indirect effects on nonbanned products were a 36% drop in sales and an increased probability of exiting of around 0.2 units. The disruption on the Russian market also created ripple effects outside this market, which was manifested in a 20% drop in the domestic production of banned products, a 12% drop in sales on markets outside Russia and a new export pattern. These negative ripple effects were also found to be pronounced in firms with their core products exposed to these sanctions, in firms with financial distress and in regions with a relatively low level of labour productivity